共同学习SpringMVC源码--DispatcherServlet(二)

private static final Properties defaultStrategies;

这个静态final的Properties类是默认策略，所谓默认策略就是同一包下有个DispatcherServlet.properties文件，里面定义了一些属性，其实就是一些处理器的实现类的类名。

static {
// Load default strategy implementations from properties file.
// This is currently strictly internal and not meant to be customized
// by application developers.
try {
ClassPathResource resource = new ClassPathResource(DEFAULT_STRATEGIES_PATH, DispatcherServlet.class);
defaultStrategies = PropertiesLoaderUtils.loadProperties(resource);
}
catch (IOException ex) {
throw new IllegalStateException("Could not load 'DispatcherServlet.properties': " + ex.getMessage());
}
}

这个静态块就是加载上面说的那个配置文件。

/** Detect all HandlerMappings or just expect "handlerMapping" bean? */

private boolean detectAllHandlerMappings = true;

/** Detect all HandlerAdapters or just expect "handlerAdapter" bean? */

private boolean detectAllHandlerAdapters = true;

/** Detect all HandlerExceptionResolvers or just expect "handlerExceptionResolver" bean? */

private boolean detectAllHandlerExceptionResolvers = true;

/** Detect all ViewResolvers or just expect "viewResolver" bean? */

private boolean detectAllViewResolvers = true;

这些boolean变量代表是否检测所有变量名中detect之后的组件，true代表要检测所有，false的话只检测是不是有变量名中detect之后的那个bean。

/** Throw a NoHandlerFoundException if no Handler was found to process this request? **/

private boolean throwExceptionIfNoHandlerFound = false;

这个boolean变量代表如果没有找到handler，就抛异常，默认为false，也就是不抛异常。

/** Perform cleanup of request attributes after include request? */

private boolean cleanupAfterInclude = true;

这个boolean变量代表include方法调用后是否清楚request的属性。执行include方法的servlet执行完后，再返回到原来的servlet执行response的输出（如果有），就是PrintWriter在转发后仍然会继续输出，如果有要输出内容的话。