ActionMessages与ActionErrors

在Struts里进行表单验证和业务逻辑验证真是一个很麻烦的事情，下面讲一下简单的经验（自己的与他人的结合），

经验就是：
1、ActionErrors 是ActionMessages的子类，同样ActionError 是ActionMessage的子类。

2、在ActionFrom中使用ActionErrors

错误信息添加用errors.add(“error_key“,new ActionError(“error.input.name“))
方法注解：void add(java.lang.String property, ActionError error)
           Add an error message to the set of errors for the specified property.

jsp中使用显示错误。<html:errors property="error_key"/>

3、在Actoin中使用ActionMessages
它有两个add方法：
void add(ActionMessages messages)
           Adds the messages from the given ActionMessages object to this set of messages.
void add(java.lang.String property, ActionMessage message)
           Add a message to the set of messages for the specified property.

错误信息添加使用errors.add(“error_key“,new ActioinMessage(“errors.loginerror“))
另外要调用this.saveMessages(request,errors)方法;
这是org.apache.struts.action.Action中的方法，要用到的大概有两个：
saveErrors（少用）
protected void saveErrors(javax.servlet.http.HttpServletRequest request,
                           ActionErrors errors)
Save the specified error messages keys into the appropriate request attribute for use by the <html:errors> tag, if

any messages are required. Otherwise, ensure that the request attribute is not created.

Parameters:
request - The servlet request we are processing
errors - Error messages object

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saveMessages（常用）
protected void saveMessages(javax.servlet.http.HttpServletRequest request,
                             ActionMessages messages)
Save the specified messages keys into the appropriate request attribute for use by the <html:messages> tag (if

messages="true" is set), if any messages are required. Otherwise, ensure that the request attribute is not

created.

Parameters:
request - The servlet request we are processing
messages - Messages object
Since:
Struts 1.1

<html:messages id="errors" message="true">
<font color="red"><bean:write name="errors"/></font>
</html:messages>
jsp中使用来显示错误。不要管id和name中是什么，只要两者一样，就会显示所有的ActionMessages出来