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@ -1,382 +1,346 @@
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基础支持层主要看一下mybatis实现ORM的基础代码实现。
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## 反射工具包
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### Reflector
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Reflector类主要实现了对JavaBean的元数据属性的封装，比如：可读属性列表，可写属性列表；及反射操作的封装，如：属性对应的setter方法，getter方法的反射调用。源码实现如下：
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在数据持久层，数据源和事务是两个非常重要的组件，对数据持久层的影响很大，在实际开发中，一般会使用mybatis集成第三方数据源组件，如：c3p0、Druid，另外，mybatis也提供了自己的数据源实现。而事务方面，一般使用spring进行事务的管理。下面我们看一下mybatis是如何对这两部分进行封装的。
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## 1 DataSource
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常见的数据源都会实现javax.sql.DataSource接口，mybatis中提供了两个该接口的实现类，分别是：PooledDataSource和UnpooledDataSource，并使用不同的工厂类分别管理这两个类的对象。
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### 1.1 DataSourceFactory
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DataSourceFactory系列类的设计比较简单，DataSourceFactory作为顶级接口，UnpooledDataSourceFactory实现了该接口，PooledDataSourceFactory又继承了UnpooledDataSourceFactory。
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```java
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public class Reflector {
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public interface DataSourceFactory {
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/** JavaBean的Class类型，在调用Reflector的构造方法时初始化该值 */
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private final Class<?> type;
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// 设置DataSource的属性，一般紧跟在DataSource初始化之后
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void setProperties(Properties props);
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/** 可读的属性列表 */
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private final String[] readablePropertyNames;
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private final String[] writablePropertyNames;
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/** key属性名，value该属性名对应的setter方法调用器 */
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private final Map<String, Invoker> setMethods = new HashMap<>();
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private final Map<String, Invoker> getMethods = new HashMap<>();
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/** key属性名称，value该属性setter方法的返回值类型 */
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private final Map<String, Class<?>> setTypes = new HashMap<>();
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private final Map<String, Class<?>> getTypes = new HashMap<>();
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/** type的默认构造方法 */
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private Constructor<?> defaultConstructor;
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/** 所有属性名称的集合 */
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private Map<String, String> caseInsensitivePropertyMap = new HashMap<>();
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/**
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* 里面的大部分方法都是通过简单的JDK反射操作实现的
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* @param clazz
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*/
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public Reflector(Class<?> clazz) {
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type = clazz;
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addDefaultConstructor(clazz);
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// 处理clazz中的所有getter方法，填充getMethods集合和getTypes集合
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addGetMethods(clazz);
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addSetMethods(clazz);
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// 处理没有getter、setter方法的字段
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addFields(clazz);
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// 根据getMethods、setMethods集合初始化可读、可写的属性
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readablePropertyNames = getMethods.keySet().toArray(new String[0]);
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writablePropertyNames = setMethods.keySet().toArray(new String[0]);
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// 初始化caseInsensitivePropertyMap集合，key属性名的大写，value属性名
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for (String propName : readablePropertyNames) {
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caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
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}
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for (String propName : writablePropertyNames) {
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caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
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}
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}
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// 获取DataSource对象
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DataSource getDataSource();
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}
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```
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### ReflectorFactory
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顾名思义，Reflector的工厂模式，跟大部分工厂类一样，里面肯定有通过标识获取对象的方法。类的设计也遵照了 接口，实现类的模式，虽然本接口只有一个默认实现。
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```java
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public interface ReflectorFactory {
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boolean isClassCacheEnabled();
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void setClassCacheEnabled(boolean classCacheEnabled);
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/**
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* 主要看一下这个方法，通过JavaBean的clazz获取该JavaBean对应的Reflector
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*/
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Reflector findForClass(Class<?> type);
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}
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public class UnpooledDataSourceFactory implements DataSourceFactory {
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public class DefaultReflectorFactory implements ReflectorFactory {
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private boolean classCacheEnabled = true;
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private static final String DRIVER_PROPERTY_PREFIX = "driver.";
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private static final int DRIVER_PROPERTY_PREFIX_LENGTH = DRIVER_PROPERTY_PREFIX.length();
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/** 大部分容器及工厂设计模式的管用伎俩，key：JavaBean的clazz，value：JavaBean对应的Reflector实例 */
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private final ConcurrentMap<Class<?>, Reflector> reflectorMap = new ConcurrentHashMap<>();
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protected DataSource dataSource;
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/**
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* 实例化一个ConcurrentMap全局变量，然后暴露一个方法从map中获取目标对象，这种设计是很多框架都会用的
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*/
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@Override
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public Reflector findForClass(Class<?> type) {
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if (classCacheEnabled) {
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// synchronized (type) removed see issue #461
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return reflectorMap.computeIfAbsent(type, Reflector::new);
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} else {
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return new Reflector(type);
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}
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}
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public DefaultReflectorFactory() {
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// 在实例化该工厂时，就完成了DataSource的实例化
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public UnpooledDataSourceFactory() {
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this.dataSource = new UnpooledDataSource();
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}
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@Override
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public boolean isClassCacheEnabled() {
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return classCacheEnabled;
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public void setProperties(Properties properties) {
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Properties driverProperties = new Properties();
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// 创建dataSource对应的MetaObject
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MetaObject metaDataSource = SystemMetaObject.forObject(dataSource);
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// 处理properties中配置的数据源信息
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for (Object key : properties.keySet()) {
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String propertyName = (String) key;
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if (propertyName.startsWith(DRIVER_PROPERTY_PREFIX)) {
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// 以"driver."开头的配置项是对DataSource的配置，将其记录到driverProperties中
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String value = properties.getProperty(propertyName);
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driverProperties.setProperty(propertyName.substring(DRIVER_PROPERTY_PREFIX_LENGTH), value);
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} else if (metaDataSource.hasSetter(propertyName)) {
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String value = (String) properties.get(propertyName);
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Object convertedValue = convertValue(metaDataSource, propertyName, value);
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metaDataSource.setValue(propertyName, convertedValue);
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} else {
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throw new DataSourceException("Unknown DataSource property: " + propertyName);
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}
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}
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if (driverProperties.size() > 0) {
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// 设置数据源UnpooledDataSource的driverProperties属性，
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// PooledDataSource中持有UnpooledDataSource对象
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metaDataSource.setValue("driverProperties", driverProperties);
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}
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}
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@Override
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public void setClassCacheEnabled(boolean classCacheEnabled) {
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this.classCacheEnabled = classCacheEnabled;
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public DataSource getDataSource() {
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return dataSource;
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}
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}
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/**
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* 支持定制化ReflectorFactory
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*/
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public class CustomReflectorFactory extends DefaultReflectorFactory {
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public class PooledDataSourceFactory extends UnpooledDataSourceFactory {
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// 与UnpooledDataSourceFactory的不同之处是，其初始化的DataSource为PooledDataSource
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public PooledDataSourceFactory() {
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this.dataSource = new PooledDataSource();
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}
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}
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```
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### ObjectFactory
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改类也是接口+一个默认实现类，并且支持自定义扩展。
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### 1.2 UnpooledDataSource
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本实现类实现了DataSource接口中的getConnection()及其重载方法，用于获取数据库连接。其中的主要属性及方法如下：
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```java
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/**
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* MyBatis uses an ObjectFactory to create all needed new Objects.
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*/
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public interface ObjectFactory {
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public class UnpooledDataSource implements DataSource {
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/**
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* Sets configuration properties.
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*/
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default void setProperties(Properties properties) {
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// NOP
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}
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// 加载Driver驱动类的 类加载器
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private ClassLoader driverClassLoader;
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/**
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* Creates a new object with default constructor.
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*/
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<T> T create(Class<T> type);
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// 数据库连接驱动的相关配置，通过UnpooledDataSourceFactory的setProperties()方法设置进来的
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private Properties driverProperties;
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/**
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* Creates a new object with the specified constructor and params.
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*/
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<T> T create(Class<T> type, List<Class<?>> constructorArgTypes, List<Object> constructorArgs);
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// 缓存所有已注册的数据库连接驱动Driver
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private static Map<String, Driver> registeredDrivers = new ConcurrentHashMap<>();
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/**
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* Returns true if this object can have a set of other objects.
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* It's main purpose is to support non-java.util.Collection objects like Scala collections.
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*/
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<T> boolean isCollection(Class<T> type);
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}
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// 数据库连接驱动名称
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private String driver;
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// 数据库url
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private String url;
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// 用户名
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private String username;
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// 密码
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private String password;
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/**
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* ObjectFactory接口的唯一直接实现，反射工厂，根据传入的参数列表，选择
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* 合适的构造函数实例化对象，不传参数，则直接调用其午餐构造方法
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*/
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public class DefaultObjectFactory implements ObjectFactory, Serializable {
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// 是否自动提交事务
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private Boolean autoCommit;
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// 默认的事务隔离级别
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private Integer defaultTransactionIsolationLevel;
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// 默认的网络连接超时时间
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private Integer defaultNetworkTimeout;
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private static final long serialVersionUID = -8855120656740914948L;
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@Override
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public <T> T create(Class<T> type) {
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return create(type, null, null);
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/**
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* UnpooledDataSource被加载时，会通过该静态代码块将已经在DriverManager
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* 中注册JDBC Driver复制一份到registeredDrivers
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*/
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static {
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Enumeration<Driver> drivers = DriverManager.getDrivers();
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while (drivers.hasMoreElements()) {
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Driver driver = drivers.nextElement();
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registeredDrivers.put(driver.getClass().getName(), driver);
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}
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}
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@SuppressWarnings("unchecked")
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@Override
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public <T> T create(Class<T> type, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
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Class<?> classToCreate = resolveInterface(type);
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// we know types are assignable
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return (T) instantiateClass(classToCreate, constructorArgTypes, constructorArgs);
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// getConnection()及其重载方法、doGetConnection(String username, String password)方法
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// 最终都会调用本方法
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private Connection doGetConnection(Properties properties) throws SQLException {
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// 初始化数据库驱动，该方法会创建配置中指定的Driver对象，
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// 并将其注册到DriverManager和registeredDrivers中
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initializeDriver();
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Connection connection = DriverManager.getConnection(url, properties);
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// 配置数据库连接属性，如：连接超时时间、是否自动提交事务、事务隔离级别
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configureConnection(connection);
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return connection;
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}
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/**
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* 通过反射来实例化给定的类，如果调用无参构造方法，则直接constructor.newInstance()
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* 如果有参，则根据参数类型和参数值进行调用
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*/
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private <T> T instantiateClass(Class<T> type, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
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try {
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Constructor<T> constructor;
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if (constructorArgTypes == null || constructorArgs == null) {
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constructor = type.getDeclaredConstructor();
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try {
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return constructor.newInstance();
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} catch (IllegalAccessException e) {
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if (Reflector.canControlMemberAccessible()) {
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constructor.setAccessible(true);
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return constructor.newInstance();
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} else {
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throw e;
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}
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}
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}
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constructor = type.getDeclaredConstructor(constructorArgTypes.toArray(new Class[constructorArgTypes.size()]));
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private synchronized void initializeDriver() throws SQLException {
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// 判断驱动是否已注册
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if (!registeredDrivers.containsKey(driver)) {
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Class<?> driverType;
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try {
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return constructor.newInstance(constructorArgs.toArray(new Object[constructorArgs.size()]));
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} catch (IllegalAccessException e) {
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if (Reflector.canControlMemberAccessible()) {
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constructor.setAccessible(true);
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return constructor.newInstance(constructorArgs.toArray(new Object[constructorArgs.size()]));
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if (driverClassLoader != null) {
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// 注册驱动
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driverType = Class.forName(driver, true, driverClassLoader);
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|
} else {
|
|
|
|
|
throw e;
|
|
|
|
|
driverType = Resources.classForName(driver);
|
|
|
|
|
}
|
|
|
|
|
// 通过反射 获取Driver实例对象
|
|
|
|
|
Driver driverInstance = (Driver)driverType.newInstance();
|
|
|
|
|
// 注册驱动到DriverManager，DriverProxy是UnpooledDataSource的内部类
|
|
|
|
|
// 也是Driver的静态代理类
|
|
|
|
|
DriverManager.registerDriver(new DriverProxy(driverInstance));
|
|
|
|
|
// 将driver缓存到registeredDrivers
|
|
|
|
|
registeredDrivers.put(driver, driverInstance);
|
|
|
|
|
} catch (Exception e) {
|
|
|
|
|
throw new SQLException("Error setting driver on UnpooledDataSource. Cause: " + e);
|
|
|
|
|
}
|
|
|
|
|
} catch (Exception e) {
|
|
|
|
|
String argTypes = Optional.ofNullable(constructorArgTypes).orElseGet(Collections::emptyList)
|
|
|
|
|
.stream().map(Class::getSimpleName).collect(Collectors.joining(","));
|
|
|
|
|
String argValues = Optional.ofNullable(constructorArgs).orElseGet(Collections::emptyList)
|
|
|
|
|
.stream().map(String::valueOf).collect(Collectors.joining(","));
|
|
|
|
|
throw new ReflectionException("Error instantiating " + type + " with invalid types (" + argTypes + ") or values (" + argValues + "). Cause: " + e, e);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
private void configureConnection(Connection conn) throws SQLException {
|
|
|
|
|
// 连接超时时间
|
|
|
|
|
if (defaultNetworkTimeout != null) {
|
|
|
|
|
conn.setNetworkTimeout(Executors.newSingleThreadExecutor(), defaultNetworkTimeout);
|
|
|
|
|
}
|
|
|
|
|
// 是否自动提交事务
|
|
|
|
|
if (autoCommit != null && autoCommit != conn.getAutoCommit()) {
|
|
|
|
|
conn.setAutoCommit(autoCommit);
|
|
|
|
|
}
|
|
|
|
|
// 事务隔离级别
|
|
|
|
|
if (defaultTransactionIsolationLevel != null) {
|
|
|
|
|
conn.setTransactionIsolation(defaultTransactionIsolationLevel);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
```
|
|
|
|
|
## 类型转换
|
|
|
|
|
类型转换是实现ORM的重要一环，由于 数据库中的数据类型与Java语言的数据类型并不对等，所以在PrepareStatement为sql语句绑定参数时，需要从Java类型转换成JDBC类型，而从结果集获取数据时，又要将JDBC类型转换成Java类型，mybatis使用TypeHandler完成了上述的双向转换。
|
|
|
|
|
### JdbcType
|
|
|
|
|
mybatis通过JdbcType这个枚举类型代表了JDBC中的数据类型
|
|
|
|
|
### 1.3 PooledDataSource
|
|
|
|
|
数据库建立连接是非常耗时的，且并发的连接数也非常有限。而数据库连接池可以实现数据库的重用、提高响应速度、防止数据库因连接过多而假死等。
|
|
|
|
|
数据库连接池的设计思路一般为：
|
|
|
|
|
1. 连接池初始化时创建一定数量的连接，并添加到连接池中备用；
|
|
|
|
|
2. 当程序需要使用数据库连接时，从连接池中请求，用完后会将其返还给连接池，而不是直接关闭；
|
|
|
|
|
3. 连接池会控制总连接上限及空闲连接上线，如果连接池中的连接总数已达上限，且都被占用，后续的连接请求会进入阻塞队列等待，直到有连接可用；
|
|
|
|
|
4. 如果连接池中空闲连接较多，已达到空闲连接上限，则返回的连接会被关闭掉，以降低系统开销。
|
|
|
|
|
|
|
|
|
|
PooledDataSource实现了简易的数据库连接池功能，其创建数据库连接的功能依赖了上面的UnpooledDataSource。
|
|
|
|
|
#### 1.3.1 PooledConnection
|
|
|
|
|
PooledDataSource通过管理PooledConnection来实现对java.sql.Connection的管理。PooledConnection封装了java.sql.Connection数据库连接对象及其代理对象（JDK动态代理生成的）。PooledConnection继承了JDK动态代理的InvocationHandler接口。
|
|
|
|
|
```java
|
|
|
|
|
/**
|
|
|
|
|
* 该枚举类描述了JDBC中的数据类型
|
|
|
|
|
*/
|
|
|
|
|
public enum JdbcType {
|
|
|
|
|
/*
|
|
|
|
|
* This is added to enable basic support for the
|
|
|
|
|
* ARRAY data type - but a custom type handler is still required
|
|
|
|
|
*/
|
|
|
|
|
ARRAY(Types.ARRAY),
|
|
|
|
|
BIT(Types.BIT),
|
|
|
|
|
TINYINT(Types.TINYINT),
|
|
|
|
|
SMALLINT(Types.SMALLINT),
|
|
|
|
|
INTEGER(Types.INTEGER),
|
|
|
|
|
BIGINT(Types.BIGINT),
|
|
|
|
|
FLOAT(Types.FLOAT),
|
|
|
|
|
REAL(Types.REAL),
|
|
|
|
|
DOUBLE(Types.DOUBLE),
|
|
|
|
|
NUMERIC(Types.NUMERIC),
|
|
|
|
|
DECIMAL(Types.DECIMAL),
|
|
|
|
|
CHAR(Types.CHAR),
|
|
|
|
|
VARCHAR(Types.VARCHAR),
|
|
|
|
|
LONGVARCHAR(Types.LONGVARCHAR),
|
|
|
|
|
DATE(Types.DATE),
|
|
|
|
|
TIME(Types.TIME),
|
|
|
|
|
TIMESTAMP(Types.TIMESTAMP),
|
|
|
|
|
BINARY(Types.BINARY),
|
|
|
|
|
VARBINARY(Types.VARBINARY),
|
|
|
|
|
LONGVARBINARY(Types.LONGVARBINARY),
|
|
|
|
|
NULL(Types.NULL),
|
|
|
|
|
OTHER(Types.OTHER),
|
|
|
|
|
BLOB(Types.BLOB),
|
|
|
|
|
CLOB(Types.CLOB),
|
|
|
|
|
BOOLEAN(Types.BOOLEAN),
|
|
|
|
|
CURSOR(-10), // Oracle
|
|
|
|
|
UNDEFINED(Integer.MIN_VALUE + 1000),
|
|
|
|
|
NVARCHAR(Types.NVARCHAR), // JDK6
|
|
|
|
|
NCHAR(Types.NCHAR), // JDK6
|
|
|
|
|
NCLOB(Types.NCLOB), // JDK6
|
|
|
|
|
STRUCT(Types.STRUCT),
|
|
|
|
|
JAVA_OBJECT(Types.JAVA_OBJECT),
|
|
|
|
|
DISTINCT(Types.DISTINCT),
|
|
|
|
|
REF(Types.REF),
|
|
|
|
|
DATALINK(Types.DATALINK),
|
|
|
|
|
ROWID(Types.ROWID), // JDK6
|
|
|
|
|
LONGNVARCHAR(Types.LONGNVARCHAR), // JDK6
|
|
|
|
|
SQLXML(Types.SQLXML), // JDK6
|
|
|
|
|
DATETIMEOFFSET(-155), // SQL Server 2008
|
|
|
|
|
TIME_WITH_TIMEZONE(Types.TIME_WITH_TIMEZONE), // JDBC 4.2 JDK8
|
|
|
|
|
TIMESTAMP_WITH_TIMEZONE(Types.TIMESTAMP_WITH_TIMEZONE); // JDBC 4.2 JDK8
|
|
|
|
|
|
|
|
|
|
public final int TYPE_CODE;
|
|
|
|
|
|
|
|
|
|
/** 该静态集合维护了 常量编码 与 JdbcType之间的关系 */
|
|
|
|
|
private static Map<Integer,JdbcType> codeLookup = new HashMap<>();
|
|
|
|
|
class PooledConnection implements InvocationHandler {
|
|
|
|
|
|
|
|
|
|
// 记录当前PooledConnection对象所属的PooledDataSource对象
|
|
|
|
|
// 当调用close()方法时会将PooledConnection放回该PooledDataSource
|
|
|
|
|
private final PooledDataSource dataSource;
|
|
|
|
|
// 真正的数据库连接对象
|
|
|
|
|
private final Connection realConnection;
|
|
|
|
|
// 代理连接对象
|
|
|
|
|
private final Connection proxyConnection;
|
|
|
|
|
// 从连接池中取出该连接时的时间戳
|
|
|
|
|
private long checkoutTimestamp;
|
|
|
|
|
// 创建该连接时的时间戳
|
|
|
|
|
private long createdTimestamp;
|
|
|
|
|
// 最后一次使用的 时间戳
|
|
|
|
|
private long lastUsedTimestamp;
|
|
|
|
|
// 由 数据库URL、用户名、密码 计算出来的hash值，可用于标识该连接所在的连接池
|
|
|
|
|
private int connectionTypeCode;
|
|
|
|
|
// 检测当前PooledConnection连接池连接对象是否有效，主要用于 防止程序通过close()方法将
|
|
|
|
|
// 连接还给连接池之后，依然通过该连接操作数据库
|
|
|
|
|
private boolean valid;
|
|
|
|
|
|
|
|
|
|
static {
|
|
|
|
|
for (JdbcType type : JdbcType.values()) {
|
|
|
|
|
codeLookup.put(type.TYPE_CODE, type);
|
|
|
|
|
/**
|
|
|
|
|
* invoke()方法是本类的重点实现，也是proxyConnection代理连接对象的代理逻辑实现
|
|
|
|
|
* 它会对close()方法的调用进行处理，并在调用realConnection的方法之前进行校验
|
|
|
|
|
*/
|
|
|
|
|
@Override
|
|
|
|
|
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
|
|
|
|
|
String methodName = method.getName();
|
|
|
|
|
// 如果调用的是close()方法，则将其放进连接池，而不是真的关闭连接
|
|
|
|
|
if (CLOSE.hashCode() == methodName.hashCode() && CLOSE.equals(methodName)) {
|
|
|
|
|
dataSource.pushConnection(this);
|
|
|
|
|
return null;
|
|
|
|
|
}
|
|
|
|
|
try {
|
|
|
|
|
if (!Object.class.equals(method.getDeclaringClass())) {
|
|
|
|
|
// 通过上面的valid字段 校验连接是否有效
|
|
|
|
|
checkConnection();
|
|
|
|
|
}
|
|
|
|
|
// 调用realConnection的对应方法
|
|
|
|
|
return method.invoke(realConnection, args);
|
|
|
|
|
} catch (Throwable t) {
|
|
|
|
|
throw ExceptionUtil.unwrapThrowable(t);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
JdbcType(int code) {
|
|
|
|
|
this.TYPE_CODE = code;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
public static JdbcType forCode(int code) {
|
|
|
|
|
return codeLookup.get(code);
|
|
|
|
|
private void checkConnection() throws SQLException {
|
|
|
|
|
if (!valid) {
|
|
|
|
|
throw new SQLException("Error accessing PooledConnection. Connection is invalid.");
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
```
|
|
|
|
|
### TypeHandler
|
|
|
|
|
TypeHandler是mybatis中所有类型转换器的顶层接口，主要用于 数据从Java类型到JdbcType类型的相互转换。
|
|
|
|
|
#### 1.3.2 PoolState
|
|
|
|
|
PoolState主要用于管理PooledConnection对象状态，其通过持有两个List<PooledConnection>集合分别管理空闲状态的连接 和 活跃状态的连接。另外，PoolState还定义了一系列用于统计的字段。
|
|
|
|
|
```java
|
|
|
|
|
public interface TypeHandler<T> {
|
|
|
|
|
|
|
|
|
|
/** 通过PreparedStatement为SQL语句绑定参数时，将数据从Java类型转换为JDBC类型 */
|
|
|
|
|
void setParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException;
|
|
|
|
|
|
|
|
|
|
/** 从结果集获取数据时，将数据由JDBC类型转换成Java类型 */
|
|
|
|
|
T getResult(ResultSet rs, String columnName) throws SQLException;
|
|
|
|
|
public class PoolState {
|
|
|
|
|
|
|
|
|
|
// 所属的连接池对象
|
|
|
|
|
protected PooledDataSource dataSource;
|
|
|
|
|
|
|
|
|
|
// 空闲的连接
|
|
|
|
|
protected final List<PooledConnection> idleConnections = new ArrayList<>();
|
|
|
|
|
// 活跃的连接
|
|
|
|
|
protected final List<PooledConnection> activeConnections = new ArrayList<>();
|
|
|
|
|
|
|
|
|
|
// 请求数据库连接的次数
|
|
|
|
|
protected long requestCount = 0;
|
|
|
|
|
// 获取连接的累计时间（accumulate累计）
|
|
|
|
|
protected long accumulatedRequestTime = 0;
|
|
|
|
|
// CheckoutTime = 记录 应用从连接池取出连接到归还连接的时长
|
|
|
|
|
// accumulatedCheckoutTime = 所有连接累计的CheckoutTime
|
|
|
|
|
protected long accumulatedCheckoutTime = 0;
|
|
|
|
|
// 超时连接的个数（当连接长时间未归还给连接池时，会被认为连接超时）
|
|
|
|
|
protected long claimedOverdueConnectionCount = 0;
|
|
|
|
|
// 累计超时时间
|
|
|
|
|
protected long accumulatedCheckoutTimeOfOverdueConnections = 0;
|
|
|
|
|
// 累计等待时间
|
|
|
|
|
protected long accumulatedWaitTime = 0;
|
|
|
|
|
// 等待次数
|
|
|
|
|
protected long hadToWaitCount = 0;
|
|
|
|
|
// 无效的连接数
|
|
|
|
|
protected long badConnectionCount = 0;
|
|
|
|
|
|
|
|
|
|
public PoolState(PooledDataSource dataSource) {
|
|
|
|
|
this.dataSource = dataSource;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
T getResult(ResultSet rs, int columnIndex) throws SQLException;
|
|
|
|
|
public synchronized long getRequestCount() {
|
|
|
|
|
return requestCount;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
T getResult(CallableStatement cs, int columnIndex) throws SQLException;
|
|
|
|
|
public synchronized long getAverageRequestTime() {
|
|
|
|
|
return requestCount == 0 ? 0 : accumulatedRequestTime / requestCount;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
public synchronized long getAverageWaitTime() {
|
|
|
|
|
return hadToWaitCount == 0 ? 0 : accumulatedWaitTime / hadToWaitCount;
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* 可用于实现自定义的TypeHandler
|
|
|
|
|
*/
|
|
|
|
|
public abstract class BaseTypeHandler<T> extends TypeReference<T> implements TypeHandler<T> {
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* 只是处理了一些数据为空的特殊情况，非空数据的处理都交给子类去处理
|
|
|
|
|
*/
|
|
|
|
|
@Override
|
|
|
|
|
public void setParameter(PreparedStatement ps, int i, T parameter, JdbcType jdbcType) throws SQLException {
|
|
|
|
|
if (parameter == null) {
|
|
|
|
|
if (jdbcType == null) {
|
|
|
|
|
throw new TypeException("JDBC requires that the JdbcType must be specified for all nullable parameters.");
|
|
|
|
|
}
|
|
|
|
|
try {
|
|
|
|
|
ps.setNull(i, jdbcType.TYPE_CODE);
|
|
|
|
|
} catch (SQLException e) {
|
|
|
|
|
throw new TypeException("Error setting null for parameter #" + i + " with JdbcType " + jdbcType + " . "
|
|
|
|
|
+ "Try setting a different JdbcType for this parameter or a different jdbcTypeForNull configuration property. "
|
|
|
|
|
+ "Cause: " + e, e);
|
|
|
|
|
}
|
|
|
|
|
} else {
|
|
|
|
|
try {
|
|
|
|
|
setNonNullParameter(ps, i, parameter, jdbcType);
|
|
|
|
|
} catch (Exception e) {
|
|
|
|
|
throw new TypeException("Error setting non null for parameter #" + i + " with JdbcType " + jdbcType + " . "
|
|
|
|
|
+ "Try setting a different JdbcType for this parameter or a different configuration property. "
|
|
|
|
|
+ "Cause: " + e, e);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
public synchronized long getHadToWaitCount() {
|
|
|
|
|
return hadToWaitCount;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
@Override
|
|
|
|
|
public T getResult(ResultSet rs, String columnName) throws SQLException {
|
|
|
|
|
try {
|
|
|
|
|
return getNullableResult(rs, columnName);
|
|
|
|
|
} catch (Exception e) {
|
|
|
|
|
throw new ResultMapException("Error attempting to get column '" + columnName + "' from result set. Cause: " + e, e);
|
|
|
|
|
}
|
|
|
|
|
public synchronized long getBadConnectionCount() {
|
|
|
|
|
return badConnectionCount;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
public synchronized long getClaimedOverdueConnectionCount() {
|
|
|
|
|
return claimedOverdueConnectionCount;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
public class IntegerTypeHandler extends BaseTypeHandler<Integer> {
|
|
|
|
|
public synchronized long getAverageOverdueCheckoutTime() {
|
|
|
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return claimedOverdueConnectionCount == 0 ? 0 : accumulatedCheckoutTimeOfOverdueConnections / claimedOverdueConnectionCount;
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}
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/**
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* NonNull就是NoneNull，非空的意思
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*/
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@Override
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public void setNonNullParameter(PreparedStatement ps, int i, Integer parameter, JdbcType jdbcType)
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throws SQLException {
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// IntegerTypeHandler就调用PreparedStatement的setInt方法
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// BooleanTypeHandler就调用PreparedStatement的setBoolean方法
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// 其它的基本数据类型，以此类推
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ps.setInt(i, parameter);
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public synchronized long getAverageCheckoutTime() {
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return requestCount == 0 ? 0 : accumulatedCheckoutTime / requestCount;
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}
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@Override
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public Integer getNullableResult(ResultSet rs, String columnName)
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throws SQLException {
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int result = rs.getInt(columnName);
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return result == 0 && rs.wasNull() ? null : result;
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public synchronized int getIdleConnectionCount() {
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return idleConnections.size();
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}
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@Override
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public Integer getNullableResult(ResultSet rs, int columnIndex)
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throws SQLException {
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int result = rs.getInt(columnIndex);
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return result == 0 && rs.wasNull() ? null : result;
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public synchronized int getActiveConnectionCount() {
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return activeConnections.size();
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}
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@Override
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public Integer getNullableResult(CallableStatement cs, int columnIndex)
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throws SQLException {
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int result = cs.getInt(columnIndex);
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return result == 0 && cs.wasNull() ? null : result;
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public synchronized String toString() {
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StringBuilder builder = new StringBuilder();
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builder.append("\n===CONFINGURATION==============================================");
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builder.append("\n jdbcDriver ").append(dataSource.getDriver());
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builder.append("\n jdbcUrl ").append(dataSource.getUrl());
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builder.append("\n jdbcUsername ").append(dataSource.getUsername());
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builder.append("\n jdbcPassword ").append(dataSource.getPassword() == null ? "NULL" : "************");
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builder.append("\n poolMaxActiveConnections ").append(dataSource.poolMaximumActiveConnections);
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builder.append("\n poolMaxIdleConnections ").append(dataSource.poolMaximumIdleConnections);
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builder.append("\n poolMaxCheckoutTime ").append(dataSource.poolMaximumCheckoutTime);
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builder.append("\n poolTimeToWait ").append(dataSource.poolTimeToWait);
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builder.append("\n poolPingEnabled ").append(dataSource.poolPingEnabled);
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builder.append("\n poolPingQuery ").append(dataSource.poolPingQuery);
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builder.append("\n poolPingConnectionsNotUsedFor ").append(dataSource.poolPingConnectionsNotUsedFor);
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|
builder.append("\n ---STATUS-----------------------------------------------------");
|
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|
|
|
builder.append("\n activeConnections ").append(getActiveConnectionCount());
|
|
|
|
|
builder.append("\n idleConnections ").append(getIdleConnectionCount());
|
|
|
|
|
builder.append("\n requestCount ").append(getRequestCount());
|
|
|
|
|
builder.append("\n averageRequestTime ").append(getAverageRequestTime());
|
|
|
|
|
builder.append("\n averageCheckoutTime ").append(getAverageCheckoutTime());
|
|
|
|
|
builder.append("\n claimedOverdue ").append(getClaimedOverdueConnectionCount());
|
|
|
|
|
builder.append("\n averageOverdueCheckoutTime ").append(getAverageOverdueCheckoutTime());
|
|
|
|
|
builder.append("\n hadToWait ").append(getHadToWaitCount());
|
|
|
|
|
builder.append("\n averageWaitTime ").append(getAverageWaitTime());
|
|
|
|
|
builder.append("\n badConnectionCount ").append(getBadConnectionCount());
|
|
|
|
|
builder.append("\n===============================================================");
|
|
|
|
|
return builder.toString();
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
```
|
|
|
|
|
TypeHandler主要用于单个参数的类型转换，如果多列值转换成一个Java对象，可以在映射文件中定义合适的映射规则<resultMap>
|
|
|
|
|
#### 1.3.3 PooledDataSource
|
|
|
|
|
PooledDataSource管理的数据库连接对象 是由其持有的UnpooledDataSource对象创建的，并由PoolState管理所有连接的状态。
|
|
|
|
|
PooledDataSource的getConnection()方法会首先调用popConnection()方法获取PooledConnection对象，然后通过PooledConnection的getProxyConnection()方法获取数据库连接的代理对象。popConnection()方法是PooledDataSource的核心逻辑之一，其整体的逻辑关系如下图：
|
|
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|
|
|
## 2 Transaction
|
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AmyliaY
5 years ago