基于Struts2和freemarker的错误提示信息的统一处理

基于Struts2和freemarker的异常提示信息的统一处理

public?abstract?class?BaseException?extends?RuntimeException?{
????private?static?final?long?serialVersionUID?=?-6765360320533958383L;

????private?String?messageCode;

????public?String?getMessageCode()?{
????????return?messageCode;
????}

????public?void?setMessageCode(String?messageCode)?{
????????this.messageCode?=?messageCode;
????}

????public?BaseException()?{
????????super();
????}

????public?BaseException(String?message)?{
????????super(message);
????}

????public?BaseException(String?message,?Throwable?cause)?{
????????super(message,?cause);
????}

????public?BaseException(Throwable?cause)?{
????????super(cause);
????}

????public?BaseException(String?messageCode,?String?message)?{
????????super(message);
????????setMessageCode(messageCode);

????}

????public?BaseException(String?messageCode,?String?message,?Throwable?cause)?{
????????super(message,?cause);
????????setMessageCode(messageCode);
????}

public?class?BusinessException?extends?BaseException?{

????private?static?final?long?serialVersionUID?=?-1657938434382769721L;
???????????????????
????public?BusinessException()?{
????????super();
????}
????
????public?BusinessException(String?message,?Throwable?cause)?{
????????super(message,?cause);
????}
????
????public?BusinessException(Throwable?cause)?{
????????super(cause);
????}
????
????public?BusinessException(String?messageCode,?String?message)?{
????????super(messageCode,?message);
????????setMessageCode(messageCode);
????}
????
????public?BusinessException(String?messageCode,?String?message,?Throwable?cause)?{
????????super(messageCode,?message,?cause);
????????setMessageCode(messageCode);
????}
}


拦截器类：ErrorHandlingInterceptor.java 用于拦截异常，并在此统一处理
public?class?ErrorHandlingInterceptor?extends?AbstractInterceptor?{

????private?static?final?long?serialVersionUID?=?1L;

????@Override
????public?String?intercept(ActionInvocation?invocation)?throws?Exception?{
????????try?{
????????????return?invocation.invoke();
????????}?catch?(Exception?e)?{
????????????e.printStackTrace();
????????????handleException(e);
????????}
????????return?Action.INPUT;
????}
????
????/**?*//**
?????*?处理异常
?????*?@param?e
?????*/
????private?void?handleException(Exception?e)?{
????????boolean?handled?=?false;
????????Throwable?throwEx?=?e;
????????while?(throwEx?!=?null)?{
????????????if(throwEx?instanceof?BusinessException)?{
????????????????BusinessException?be?=?(BusinessException)throwEx;
????????????????String?errorCode?=?be.getMessageCode();
????????????????
????????????????//?从缓存中通过ErrorCode取得对应message
????????????????//?实现略
????????????????String?errorMsg?=?getMessage(errorCode);
????????????????
????????????????//?页面显示错误提示信息
????????????????fillError4Display(errorMsg);
????????????????handled?=?true;
????????????}?
????????????throwEx?=?throwEx.getCause();
????????}
????????
????????if(!handled)?{
????????????fillDefaultError();
????????}
????}
????
????private?HttpServletRequest?getRequest()?{
????????return?(HttpServletRequest)ActionContext.getContext().get(StrutsStatics.HTTP_REQUEST);
????}
????
????private?void?fillDefaultError()?{
????????fillError4Display("系统忙，请稍候再试。");
????}
????
????private?void?fillError4Display(String?msg)?{
????????getRequest().setAttribute("_error_msg_",?msg);
????}
}

拦截所有的异常，并对其进行处理。
当为 自定义的BusinessException时，根据抛出异常时的msgCode，取得对应的显示信息。
msgCode与显示信息的对应关系 可先配置好，系统启动时将其缓存起来。

如果非BusinessException，则统一显示为 “系统忙，请稍候再试。”

将要显示的信息设置到Request中，下面来看看Freemarker模板的写法：

msg.ftl

<div?id='_err_msg_div'>
????<#if?Request['_error_msg_']?exists>
????????${Request['_error_msg_']}
????</#if>
</div>

<script?type="text/javascript">
if?(!this.Message)?{
????this.Message?=?{};
????(function()?{
????????/**//**
?????????*?show?client?message
?????????*/
????????Message.showMsg?=?function(msg)?{
????????????document.getElementById("_err_msg_div").innerHTML?=?msg;
????????};
????})();
};
</script>
在使用时，只要在页面上想要展现异常信息的地方插入如下代码即可：
<#include?"/msg.ftl">

这样 系统中的异常 将会被统一的显示。

当使用js做前台的表单验证的时候，提示用户的输入有问题，则可以使用 Message.showMsg('...')，提示信息也会显示在同一个位置。

这样就实现了异常提示信息的统一展示了。

这是一个比较简易的实现，只提供一个思路。

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