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210 lines
7.0 KiB
210 lines
7.0 KiB
# Spring MessageSource
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- Author: [HuiFer](https://github.com/huifer)
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- 源码阅读仓库: [huifer-spring](https://github.com/huifer/spring-framework-read)
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## 初始化入口
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- `org.springframework.context.support.AbstractApplicationContext.refresh`方法有`initMessageSource()`方法进行了`MessageSource`初始化
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```java
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protected void initMessageSource() {
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ConfigurableListableBeanFactory beanFactory = getBeanFactory();
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// 判断是否含有 messageSource
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if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {
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// 读取xml配置文件中 id="messageSource"的数据
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this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
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// Make MessageSource aware of parent MessageSource.
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if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) {
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HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource;
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if (hms.getParentMessageSource() == null) {
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// Only set parent context as parent MessageSource if no parent MessageSource
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// registered already.
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hms.setParentMessageSource(getInternalParentMessageSource());
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}
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}
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if (logger.isTraceEnabled()) {
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logger.trace("Using MessageSource [" + this.messageSource + "]");
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}
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}
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else {
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// Use empty MessageSource to be able to accept getMessage calls.
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// 没有使用默认的 DelegatingMessageSource
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DelegatingMessageSource dms = new DelegatingMessageSource();
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dms.setParentMessageSource(getInternalParentMessageSource());
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this.messageSource = dms;
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// 注册单例对象
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beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);
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if (logger.isTraceEnabled()) {
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logger.trace("No '" + MESSAGE_SOURCE_BEAN_NAME + "' bean, using [" + this.messageSource + "]");
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}
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}
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}
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```
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读取xml配置文件
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## getMessage
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- `org.springframework.context.support.AbstractApplicationContext#getMessage(java.lang.String, java.lang.Object[], java.util.Locale)`
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```java
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@Override
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public String getMessage(String code, @Nullable Object[] args, Locale locale) throws NoSuchMessageException {
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return getMessageSource().getMessage(code, args, locale);
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}
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```
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- `org.springframework.context.support.AbstractMessageSource#getMessage(java.lang.String, java.lang.Object[], java.util.Locale)`
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```java
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@Override
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public final String getMessage(String code, @Nullable Object[] args, Locale locale) throws NoSuchMessageException {
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// 获取对应的信息
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String msg = getMessageInternal(code, args, locale);
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if (msg != null) {
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return msg;
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}
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// 默认信息 null
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String fallback = getDefaultMessage(code);
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if (fallback != null) {
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return fallback;
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}
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throw new NoSuchMessageException(code, locale);
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}
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```
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- 两个方法
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1. `org.springframework.context.support.AbstractMessageSource#getDefaultMessage(java.lang.String)`
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```java
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@Nullable
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protected String getDefaultMessage(String code) {
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// 判断是否使用默认值
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if (isUseCodeAsDefaultMessage()) {
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return code;
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}
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return null;
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}
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```
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- 返回code本身或者`null`
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2. `org.springframework.context.support.AbstractMessageSource#getMessageInternal`
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```JAVA
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@Nullable
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protected String getMessageInternal(@Nullable String code, @Nullable Object[] args, @Nullable Locale locale) {
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if (code == null) {
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return null;
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}
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if (locale == null) {
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// 获取语言默认值
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locale = Locale.getDefault();
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}
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Object[] argsToUse = args;
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if (!isAlwaysUseMessageFormat() && ObjectUtils.isEmpty(args)) {
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// Optimized resolution: no arguments to apply,
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// therefore no MessageFormat needs to be involved.
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// Note that the default implementation still uses MessageFormat;
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// this can be overridden in specific subclasses.
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String message = resolveCodeWithoutArguments(code, locale);
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if (message != null) {
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return message;
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}
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}
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else {
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// Resolve arguments eagerly, for the case where the message
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// is defined in a parent MessageSource but resolvable arguments
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// are defined in the child MessageSource.
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argsToUse = resolveArguments(args, locale);
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MessageFormat messageFormat = resolveCode(code, locale);
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if (messageFormat != null) {
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synchronized (messageFormat) {
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return messageFormat.format(argsToUse);
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}
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}
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}
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// Check locale-independent common messages for the given message code.
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Properties commonMessages = getCommonMessages();
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if (commonMessages != null) {
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String commonMessage = commonMessages.getProperty(code);
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if (commonMessage != null) {
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return formatMessage(commonMessage, args, locale);
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}
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}
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// Not found -> check parent, if any.
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return getMessageFromParent(code, argsToUse, locale);
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}
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```
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- `org.springframework.context.support.ResourceBundleMessageSource#resolveCodeWithoutArguments`
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```JAVA
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@Override
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protected String resolveCodeWithoutArguments(String code, Locale locale) {
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Set<String> basenames = getBasenameSet();
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for (String basename : basenames) {
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// 加载 basename
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ResourceBundle bundle = getResourceBundle(basename, locale);
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if (bundle != null) {
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// 从basename对应的文件中获取对应的值
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String result = getStringOrNull(bundle, code);
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if (result != null) {
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return result;
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}
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}
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}
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return null;
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}
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```
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- 加载后截图
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获取方法`String result = getStringOrNull(bundle, code);`就是map获取
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- 没有配置文件的情况
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