|
|
|
|
@ -0,0 +1,382 @@
|
|
|
|
|
基础支持层主要看一下mybatis实现ORM的基础代码实现。
|
|
|
|
|
## 反射工具包
|
|
|
|
|
### Reflector
|
|
|
|
|
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：
|
|
|
|
|
```java
|
|
|
|
|
public class Reflector {
|
|
|
|
|
|
|
|
|
|
/** JavaBean的Class类型，在调用Reflector的构造方法时初始化该值 */
|
|
|
|
|
private final Class<?> type;
|
|
|
|
|
|
|
|
|
|
/** 可读的属性列表 */
|
|
|
|
|
private final String[] readablePropertyNames;
|
|
|
|
|
private final String[] writablePropertyNames;
|
|
|
|
|
|
|
|
|
|
/** key属性名，value该属性名对应的setter方法调用器 */
|
|
|
|
|
private final Map<String, Invoker> setMethods = new HashMap<>();
|
|
|
|
|
private final Map<String, Invoker> getMethods = new HashMap<>();
|
|
|
|
|
|
|
|
|
|
/** key属性名称，value该属性setter方法的返回值类型 */
|
|
|
|
|
private final Map<String, Class<?>> setTypes = new HashMap<>();
|
|
|
|
|
private final Map<String, Class<?>> getTypes = new HashMap<>();
|
|
|
|
|
|
|
|
|
|
/** type的默认构造方法 */
|
|
|
|
|
private Constructor<?> defaultConstructor;
|
|
|
|
|
|
|
|
|
|
/** 所有属性名称的集合 */
|
|
|
|
|
private Map<String, String> caseInsensitivePropertyMap = new HashMap<>();
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* 里面的大部分方法都是通过简单的JDK反射操作实现的
|
|
|
|
|
* @param clazz
|
|
|
|
|
*/
|
|
|
|
|
public Reflector(Class<?> clazz) {
|
|
|
|
|
type = clazz;
|
|
|
|
|
addDefaultConstructor(clazz);
|
|
|
|
|
|
|
|
|
|
// 处理clazz中的所有getter方法，填充getMethods集合和getTypes集合
|
|
|
|
|
addGetMethods(clazz);
|
|
|
|
|
addSetMethods(clazz);
|
|
|
|
|
|
|
|
|
|
// 处理没有getter、setter方法的字段
|
|
|
|
|
addFields(clazz);
|
|
|
|
|
|
|
|
|
|
// 根据getMethods、setMethods集合初始化可读、可写的属性
|
|
|
|
|
readablePropertyNames = getMethods.keySet().toArray(new String[0]);
|
|
|
|
|
writablePropertyNames = setMethods.keySet().toArray(new String[0]);
|
|
|
|
|
|
|
|
|
|
// 初始化caseInsensitivePropertyMap集合，key属性名的大写，value属性名
|
|
|
|
|
for (String propName : readablePropertyNames) {
|
|
|
|
|
caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
|
|
|
|
|
}
|
|
|
|
|
for (String propName : writablePropertyNames) {
|
|
|
|
|
caseInsensitivePropertyMap.put(propName.toUpperCase(Locale.ENGLISH), propName);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
```
|
|
|
|
|
### ReflectorFactory
|
|
|
|
|
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。
|
|
|
|
|
```java
|
|
|
|
|
public interface ReflectorFactory {
|
|
|
|
|
|
|
|
|
|
boolean isClassCacheEnabled();
|
|
|
|
|
|
|
|
|
|
void setClassCacheEnabled(boolean classCacheEnabled);
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* 主要看一下这个方法，通过JavaBean的clazz获取该JavaBean对应的Reflector
|
|
|
|
|
*/
|
|
|
|
|
Reflector findForClass(Class<?> type);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
public class DefaultReflectorFactory implements ReflectorFactory {
|
|
|
|
|
private boolean classCacheEnabled = true;
|
|
|
|
|
|
|
|
|
|
/** 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 */
|
|
|
|
|
private final ConcurrentMap<Class<?>, Reflector> reflectorMap = new ConcurrentHashMap<>();
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* 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
|
|
|
|
|
*/
|
|
|
|
|
@Override
|
|
|
|
|
public Reflector findForClass(Class<?> type) {
|
|
|
|
|
if (classCacheEnabled) {
|
|
|
|
|
// synchronized (type) removed see issue #461
|
|
|
|
|
return reflectorMap.computeIfAbsent(type, Reflector::new);
|
|
|
|
|
} else {
|
|
|
|
|
return new Reflector(type);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
public DefaultReflectorFactory() {
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
@Override
|
|
|
|
|
public boolean isClassCacheEnabled() {
|
|
|
|
|
return classCacheEnabled;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
@Override
|
|
|
|
|
public void setClassCacheEnabled(boolean classCacheEnabled) {
|
|
|
|
|
this.classCacheEnabled = classCacheEnabled;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* 支持定制化ReflectorFactory
|
|
|
|
|
*/
|
|
|
|
|
public class CustomReflectorFactory extends DefaultReflectorFactory {
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
```
|
|
|
|
|
### ObjectFactory
|
|
|
|
|
改类也是接口+一个默认实现类，并且支持自定义扩展。
|
|
|
|
|
```java
|
|
|
|
|
/**
|
|
|
|
|
* MyBatis uses an ObjectFactory to create all needed new Objects.
|
|
|
|
|
*/
|
|
|
|
|
public interface ObjectFactory {
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Sets configuration properties.
|
|
|
|
|
*/
|
|
|
|
|
default void setProperties(Properties properties) {
|
|
|
|
|
// NOP
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Creates a new object with default constructor.
|
|
|
|
|
*/
|
|
|
|
|
<T> T create(Class<T> type);
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Creates a new object with the specified constructor and params.
|
|
|
|
|
*/
|
|
|
|
|
<T> T create(Class<T> type, List<Class<?>> constructorArgTypes, List<Object> constructorArgs);
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* Returns true if this object can have a set of other objects.
|
|
|
|
|
* It's main purpose is to support non-java.util.Collection objects like Scala collections.
|
|
|
|
|
*/
|
|
|
|
|
<T> boolean isCollection(Class<T> type);
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* 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
|
|
|
|
|
* 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
|
|
|
|
|
*/
|
|
|
|
|
public class DefaultObjectFactory implements ObjectFactory, Serializable {
|
|
|
|
|
|
|
|
|
|
private static final long serialVersionUID = -8855120656740914948L;
|
|
|
|
|
|
|
|
|
|
@Override
|
|
|
|
|
public <T> T create(Class<T> type) {
|
|
|
|
|
return create(type, null, null);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
@SuppressWarnings("unchecked")
|
|
|
|
|
@Override
|
|
|
|
|
public <T> T create(Class<T> type, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
|
|
|
|
|
Class<?> classToCreate = resolveInterface(type);
|
|
|
|
|
// we know types are assignable
|
|
|
|
|
return (T) instantiateClass(classToCreate, constructorArgTypes, constructorArgs);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* 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()
|
|
|
|
|
* 如果有参，则根据参数类型和参数值进行调用
|
|
|
|
|
*/
|
|
|
|
|
private <T> T instantiateClass(Class<T> type, List<Class<?>> constructorArgTypes, List<Object> constructorArgs) {
|
|
|
|
|
try {
|
|
|
|
|
Constructor<T> constructor;
|
|
|
|
|
if (constructorArgTypes == null || constructorArgs == null) {
|
|
|
|
|
constructor = type.getDeclaredConstructor();
|
|
|
|
|
try {
|
|
|
|
|
return constructor.newInstance();
|
|
|
|
|
} catch (IllegalAccessException e) {
|
|
|
|
|
if (Reflector.canControlMemberAccessible()) {
|
|
|
|
|
constructor.setAccessible(true);
|
|
|
|
|
return constructor.newInstance();
|
|
|
|
|
} else {
|
|
|
|
|
throw e;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
constructor = type.getDeclaredConstructor(constructorArgTypes.toArray(new Class[constructorArgTypes.size()]));
|
|
|
|
|
try {
|
|
|
|
|
return constructor.newInstance(constructorArgs.toArray(new Object[constructorArgs.size()]));
|
|
|
|
|
} catch (IllegalAccessException e) {
|
|
|
|
|
if (Reflector.canControlMemberAccessible()) {
|
|
|
|
|
constructor.setAccessible(true);
|
|
|
|
|
return constructor.newInstance(constructorArgs.toArray(new Object[constructorArgs.size()]));
|
|
|
|
|
} else {
|
|
|
|
|
throw 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);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
```
|
|
|
|
|
## 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
|
|
|
|
|
```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<>();
|
|
|
|
|
|
|
|
|
|
static {
|
|
|
|
|
for (JdbcType type : JdbcType.values()) {
|
|
|
|
|
codeLookup.put(type.TYPE_CODE, type);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
JdbcType(int code) {
|
|
|
|
|
this.TYPE_CODE = code;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
public static JdbcType forCode(int code) {
|
|
|
|
|
return codeLookup.get(code);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
```
|
|
|
|
|
### 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。
|
|
|
|
|
```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;
|
|
|
|
|
|
|
|
|
|
T getResult(ResultSet rs, int columnIndex) throws SQLException;
|
|
|
|
|
|
|
|
|
|
T getResult(CallableStatement cs, int columnIndex) throws SQLException;
|
|
|
|
|
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* 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);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
@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 class IntegerTypeHandler extends BaseTypeHandler<Integer> {
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* NonNull就是NoneNull，非空的意思
|
|
|
|
|
*/
|
|
|
|
|
@Override
|
|
|
|
|
public void setNonNullParameter(PreparedStatement ps, int i, Integer parameter, JdbcType jdbcType)
|
|
|
|
|
throws SQLException {
|
|
|
|
|
// IntegerTypeHandler就调用PreparedStatement的setInt方法
|
|
|
|
|
// BooleanTypeHandler就调用PreparedStatement的setBoolean方法
|
|
|
|
|
// 其它的基本数据类型，以此类推
|
|
|
|
|
ps.setInt(i, parameter);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
@Override
|
|
|
|
|
public Integer getNullableResult(ResultSet rs, String columnName)
|
|
|
|
|
throws SQLException {
|
|
|
|
|
int result = rs.getInt(columnName);
|
|
|
|
|
return result == 0 && rs.wasNull() ? null : result;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
@Override
|
|
|
|
|
public Integer getNullableResult(ResultSet rs, int columnIndex)
|
|
|
|
|
throws SQLException {
|
|
|
|
|
int result = rs.getInt(columnIndex);
|
|
|
|
|
return result == 0 && rs.wasNull() ? null : result;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
@Override
|
|
|
|
|
public Integer getNullableResult(CallableStatement cs, int columnIndex)
|
|
|
|
|
throws SQLException {
|
|
|
|
|
int result = cs.getInt(columnIndex);
|
|
|
|
|
return result == 0 && cs.wasNull() ? null : result;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
```
|
|
|
|
|
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>
|
|
|
|
|
|
|
|
|
|
|
AmyliaY
5 years ago