4、struts2异常处理及全局异常与结果剖析、struts2模型驱动及分层体系架构

来源：互联网发布：双11外贸大数据编辑：程序博客网时间：2024/05/16 08:58

1、我们可以自定义异常，并且指定当异常出现时，转向哪一个处理页面，首先针对LoginAction这个Action来说，在execute（）方法中手工抛出两个异常：

UsernameException和PasswordException，异常定义：

package com.cdtax.exception;public class UsernameException extends Exception{private String message;public UsernameException(String message){super(message);this.message = message;}public String getMessage(){return message;}public void setMessage(String message){this.message = message;}}

package com.cdtax.exception;public class PasswordException extends Exception{private String message;public PasswordException(String message){super(message);this.message = message;}public String getMessage(){return message;}public void setMessage(String message){this.message = message;}}

然后配置struts.xml文件：

<action name="aas" class="com.cdtax.struts2.LoginAction"><exception-mapping result="usernameinvalid" exception="com.cdtax.exception.UsernameException"></exception-mapping><exception-mapping result="passwordinvalid" exception="com.cdtax.exception.PasswordException"></exception-mapping><result name="success">/result.jsp</result><result name="usernameinvalid">/usernameexception.jsp</result><result name="passwordinvalid">/passwordexception.jsp</result></action>

增加了两个exception-mapping和两个result

然后创建两个异常的处理页面usernameexception.jsp和passwordexception.jsp，这样当用户名抛出异常时，页面转向usernameexception.jsp，密码出现异常时，转向passwordexception.jsp。

2、全局的异常处理和全局的结果

全局的异常处理：struts.xml：

<global-results><result name="usernameinvalid">/usernameexception.jsp</result><result name="passwordinvalid">/passwordexception.jsp</result></global-results><action name="aas" class="com.cdtax.struts2.LoginAction"><exception-mapping result="usernameinvalid" exception="com.cdtax.exception.UsernameException"></exception-mapping><exception-mapping result="passwordinvalid" exception="com.cdtax.exception.PasswordException"></exception-mapping><result name="success">/result.jsp</result></action>

这时全局的异常处理：局部的优于全局的，就是说，如果在Action标签中也有<result name="usernameinvalid">/passwordexception.jsp</result>，那么页面将优先转向局部的result指向的页面，这里就是passwordexception.jsp。

全局的异常struts.xml：

<global-results><result name="usernameinvalid">/usernameexception.jsp</result><result name="passwordinvalid">/passwordexception.jsp</result></global-results><global-exception-mappings><exception-mapping result="usernameinvalid" exception="com.cdtax.exception.UsernameException"></exception-mapping><exception-mapping result="passwordinvalid" exception="com.cdtax.exception.PasswordException"></exception-mapping></global-exception-mappings><action name="aas" class="com.cdtax.struts2.LoginAction"><result name="success">/result.jsp</result></action>

也是局部优于全局的。

我们可以在action中定义异常与结果，也可以定义全局的异常和结果，局部总是优于全局的，如果定义成全局，俺么可以为所有action所共享，而局部的异常与结果只能被当前的action所独享，不能为其他action所共享。

3、struts2应用的分层体系结构：

登录的整个流程程序：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'login.jsp' starting page</title>    <meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">-->  </head>    <body>    <form action="aas.action">    username:<input type="text" name="username"><br>    password:<input type="password" name="password"><br>    age:<input type="text" name="aaa">    date:<input type="text" name="date">    <input type="submit" value="submit">    </form>  </body></html>

LoginAction：

package com.cdtax.struts2;import java.util.Date;import com.cdtax.exception.PasswordException;import com.cdtax.exception.UsernameException;import com.cdtax.service.LoginService;import com.cdtax.service.impl.LoginServiceImpl;import com.opensymphony.xwork2.ActionSupport;public class LoginAction extends ActionSupport{private String username;private String password;private int age;private Date date;private LoginService loginService = new LoginServiceImpl();public Date getDate(){return date;}public void setDate(Date date){this.date = date;}public int getAge(){return age;}public void setAge(int age){this.age = age;}public String getUsername(){return username;}public void setUsername(String username){this.username = username;}public String getPassword(){return password;}public void setPassword(String password){this.password = password;}public String execute() throws Exception{//if(!"hello".equals(username))//{//throw new UsernameException("username invalid");//}//if(!"world".equals(password))//{//throw new PasswordException("password invalid!");//}if(this.loginService.isLogin(username, password)){return SUCCESS;}return INPUT;}public String myExecute(){System.out.println("myExecute invoke!");return SUCCESS;}}

在这里，action增加了一个成员变量，作为对service的引用，execute方法进行业务逻辑判断，调用此service。

service接口定义对上层的服务：

package com.cdtax.service;public interface LoginService{public boolean isLogin(String username,String password);}

具体的service实现：

package com.cdtax.service.impl;import com.cdtax.service.LoginService;public class LoginServiceImpl implements LoginService{@Overridepublic boolean isLogin(String username, String password){if("hello".equals(username) && "world".equals(password)){return true;}return false;}}

struts.xml：

<action name="aas" class="com.cdtax.struts2.LoginAction"><result name="success">/result.jsp</result><result name="input">/login.jsp</result></action>

定义成功后的转向页面result.jsp。

4、struts2的模型驱动（Model Driven）

相对于上面的action模式，叫做属性驱动（Property Driven）

要想实现模型驱动，我们写的action还需要实现ModelDriven接口。

编写一个bean：Person，作为页面提交参数的对象

package com.cdtax.bean;import java.util.Date;public class Person{private String username;private String password;private int age;private Date date;public String getUsername(){return username;}public void setUsername(String username){this.username = username;}public String getPassword(){return password;}public void setPassword(String password){this.password = password;}public int getAge(){return age;}public void setAge(int age){this.age = age;}public Date getDate(){return date;}public void setDate(Date date){this.date = date;}}

编写模型驱动的Action：LoginAction2：

package com.cdtax.struts2;import com.cdtax.bean.Person;import com.opensymphony.xwork2.ActionSupport;import com.opensymphony.xwork2.ModelDriven;public class LoginAction2 extends ActionSupport implements ModelDriven<Person>{private Person person = new Person();@Overridepublic Person getModel(){return person;}@Overridepublic String execute() throws Exception{System.out.println(person.getUsername());return SUCCESS;}}

在struts.xml中添加action：

<action name="login2" class="com.cdtax.struts2.LoginAction2"><result name="success">/result.jsp</result></action>

编写登录jsp页面：login.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'login.jsp' starting page</title>    <meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">-->  </head>    <body>    <form action="login2a.action">    username:<input type="text" name="username"><br>    password:<input type="password" name="password"><br>    age:<input type="text" name="aaa">    date:<input type="text" name="date">    <input type="submit" value="submit">    </form>  </body></html>

编写结果页面result.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'result.jsp' starting page</title>    <meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">-->  </head>    <body>    username:${requestScope.username } <br>    password:${requestScope.password }<br>    age:${requestScope.age }    date:${requestScope.date }    aaa:${requestScope.aaa }  </body></html>

属性驱动与模型驱动的比较：

1）属性驱动灵活，准确；模型驱动不灵活，因为很多时候，页面提交过来的参数并不属于模型中的属性，也就是说页面所提交过来的参数与模型中的属性并不一致，这是很常见的情况。
2）模型驱动更加符合面向对象的编程风格，使得我们获得是对象而不是一个一个的离散的值。

小结：推荐使用属性驱动编写Action。