struts源码学习5

最新推荐文章于 2024-05-06 00:05:37 发布

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本文详细介绍了Struts2框架在启动过程中的核心组件初始化流程，包括全局转发配置、异常处理配置及动作配置等关键步骤。

ActionServlet.init()

1、initModuleForwards

配置全局forwards

    protected void initModuleForwards(ModuleConfig config)
        throws ServletException {
        if (log.isDebugEnabled()) {
            log.debug("Initializing module path '" + config.getPrefix()
                + "' forwards");
        }

        // Process forwards extensions.
        //获取到ForwardConfigs
        ForwardConfig[] forwards = config.findForwardConfigs();

        for (int i = 0; i < forwards.length; i++) {
            ForwardConfig forward = forwards[i];
            //处理继承，实际上需要配置extends才有效，但是已被dtd限制，和前面的formbean一样
            processForwardExtension(forward, config, null);
        }

        for (int i = 0; i < forwards.length; i++) {
            ForwardConfig forward = forwards[i];
            //必须配置path，否则抛异常
            // Verify that required fields are all present for the forward
            if (forward.getPath() == null) {
                handleValueRequiredException("path", forward.getName(),
                    "global forward");
            }
        }
    }

2、initModuleExceptionConfigs

配置全局异常处理

 protected void initModuleExceptionConfigs(ModuleConfig config)
        throws ServletException {
        if (log.isDebugEnabled()) {
            log.debug("Initializing module path '" + config.getPrefix()
                + "' forwards");
        }
        //异常处理配置
        // Process exception config extensions.
        ExceptionConfig[] exceptions = config.findExceptionConfigs();

        for (int i = 0; i < exceptions.length; i++) {
            ExceptionConfig exception = exceptions[i];

            processExceptionExtension(exception, config, null);
        }

        for (int i = 0; i < exceptions.length; i++) {
            ExceptionConfig exception = exceptions[i];
<span style="white-space:pre">		</span>//必须配置key
            // Verify that required fields are all present for the config
            if (exception.getKey() == null) {
                handleValueRequiredException("key", exception.getType(),
                    "global exception config");
            }
        }
    }

3、initModuleActions

    protected void initModuleActions(ModuleConfig config)
        throws ServletException {
        if (log.isDebugEnabled()) {
            log.debug("Initializing module path '" + config.getPrefix()
                + "' action configs");
        }

        // Process ActionConfig extensions.
        ActionConfig[] actionConfigs = config.findActionConfigs();
        
        for (int i = 0; i < actionConfigs.length; i++) {
            ActionConfig actionConfig = actionConfigs[i];

            processActionConfigExtension(actionConfig, config);
        }
        for (int i = 0; i < actionConfigs.length; i++) {
            ActionConfig actionConfig = actionConfigs[i];

            // Verify that required fields are all present for the forward
            // configs
            //forwards处理
            ForwardConfig[] forwards = actionConfig.findForwardConfigs();

            for (int j = 0; j < forwards.length; j++) {
                ForwardConfig forward = forwards[j];

                if (forward.getPath() == null) {
                    handleValueRequiredException("path", forward.getName(),
                        "action forward");
                }
            }
            //异常处理
            // ... and the exception configs
            ExceptionConfig[] exceptions = actionConfig.findExceptionConfigs();

            for (int j = 0; j < exceptions.length; j++) {
                ExceptionConfig exception = exceptions[j];

                if (exception.getKey() == null) {
                    handleValueRequiredException("key", exception.getType(),
                        "action exception config");
                }
            }
        }
    }

4、moduleConfig.freeze

该方法调用moduleConfig中所有config的freeze方法（比如actionConfig，controllerConfig等等）

调用该方法之后，所有的Config均不能调用setXX方法，一旦调用，将抛出异常

5、init其余代码

在拿到其它ServletConfig参数后，遍历

 Enumeration names = getServletConfig().getInitParameterNames();

            while (names.hasMoreElements()) {
                String name = (String) names.nextElement();
<span style="white-space:pre">		</span>//如果name已config开头，则认为是一个新的ActionServlet配置，这个ActionServlet配置是带prefix的。之前的配置中是没有prefix的
                if (!name.startsWith(configPrefix)) {
                    continue;
                }

                String prefix = name.substring(configPrefixLength);

                moduleConfig =
                    initModuleConfig(prefix,
                        getServletConfig().getInitParameter(name));
                initModuleMessageResources(moduleConfig);
                initModulePlugIns(moduleConfig);
                initModuleFormBeans(moduleConfig);
                initModuleForwards(moduleConfig);
                initModuleExceptionConfigs(moduleConfig);
                initModuleActions(moduleConfig);
                moduleConfig.freeze();
            }

            this.initModulePrefixes(this.getServletContext());

            this.destroyConfigDigester();