Struts1x项目开发中的统一异常处理

在项目开发中如果能使用统一异常处理的话，则不但可以简化开发过程，而且还更容易团队的开发与合作，事半功倍。以下通过使用struts1X 结合实现一个项目的统一异常处理解决方案的例子：

第一步：
  配置好Struts整合web。

第二步：
  编写统一异常类：SystemException.java
Java代码
package com.changtu.oa.managers;  
/** 
* 统一异常类 
* 用于存储异常信息，供抛出 
* @author Mike 
*/ 
public class SystemException extends RuntimeException {  
    //异常代码  
    private String key;  
    private Object[] values;  
    // 构造器重载  
    public SystemException() {  
        super();  
    }  
    public SystemException(String message, Throwable throwable) {  
        super(message, throwable);  
    }  
    public SystemException(String message) {  
        super(message);  
    }  
    public SystemException(Throwable throwable) {  
        super(throwable);  
    }  
    public SystemException(String message,String key){  
        super(message);  
        this.key = key;  
    }  
    public SystemException(String message,String key,Object value){  
        super(message);  
        this.key = key;  
        this.values = new Object[]{value};  
    }  
    public SystemException(String message,String key,Object[] values){  
        super(message);  
        this.key = key;  
        this.values = values;  
    }  
    public String getKey() {  
        return key;  
    }  
    public Object[] getValues() {  
        return values;  
    }  
} 

package com.changtu.oa.managers;
/**
* 统一异常类
* 用于存储异常信息，供抛出
* @author Mike
*/
public class SystemException extends RuntimeException {
//异常代码
private String key;
private Object[] values;
// 构造器重载
public SystemException() {
super();
}
public SystemException(String message, Throwable throwable) {
super(message, throwable);
}
public SystemException(String message) {
super(message);
}
public SystemException(Throwable throwable) {
super(throwable);
}
public SystemException(String message,String key){
super(message);
this.key = key;
}
public SystemException(String message,String key,Object value){
super(message);
this.key = key;
this.values = new Object[]{value};
}
public SystemException(String message,String key,Object[] values){
super(message);
this.key = key;
this.values = values;
}
public String getKey() {
return key;
}
public Object[] getValues() {
return values;
}
}



  编写统一异常处理类：SystemExceptionHandler.java
Java代码
package com.changtu.oa.web;  
…  
import com.changtu.oa.managers.SystemException;  
 
/** 
* 统一异常处理类 
* @author Mike 
*/ 
public class SystemExceptionHandler extends ExceptionHandler {  
    private static Log logger = LogFactory.getLog(SystemExceptionHandler.class);  
    /** 
     * 处理SystemException异常 
     */ 
    @Override 
    public ActionForward execute(  
            Exception ex,   
            ExceptionConfig ae,   
            ActionMapping mapping,   
            ActionForm formInstance,   
            HttpServletRequest request,   
            HttpServletResponse response) throws ServletException {  
          
        ActionForward forward = null;  
        if(ae.getPath() != null){  
            forward = new ActionForward(ae.getPath());  
        }else{  
            forward = mapping.getInputForward();  
        }  
          
        logger.debug("出现异常", ex);  
          
        // 在控制台显示的异常信息  
        ex.printStackTrace();  
          
        // 如果抛出的异常是自定义的统一异常  
        if(ex instanceof SystemException){  
            SystemException se = (SystemException)ex;  
              
            //取出key值  
            String key = se.getKey();  
              
            // 储存异常信息......  
            ActionMessage error = null;  
            if( key == null){  
                error = new ActionMessage(ae.getKey(),se.getMessage());  
            }else{  
                if(se.getValues() != null){  
                    error = new ActionMessage(key,se.getValues());  
                }else{  
                    error = new ActionMessage(key);  
                }  
            }  
              
            this.storeException(request, key, error, forward, ae.getScope());  
              
            return forward;  
        }  
          
        return super.execute(ex, ae, mapping, formInstance, request, response);  
    }  
 
} 

package com.changtu.oa.web;
…
import com.changtu.oa.managers.SystemException;

/**
* 统一异常处理类
* @author Mike
*/
public class SystemExceptionHandler extends ExceptionHandler {
private static Log logger = LogFactory.getLog(SystemExceptionHandler.class);
/**
* 处理SystemException异常
*/
@Override
public ActionForward execute(
Exception ex,
ExceptionConfig ae,
ActionMapping mapping,
ActionForm formInstance,
HttpServletRequest request,
HttpServletResponse response) throws ServletException {

ActionForward forward = null;
if(ae.getPath() != null){
forward = new ActionForward(ae.getPath());
}else{
forward = mapping.getInputForward();
}

logger.debug("出现异常", ex);

// 在控制台显示的异常信息
ex.printStackTrace();

// 如果抛出的异常是自定义的统一异常
if(ex instanceof SystemException){
SystemException se = (SystemException)ex;

//取出key值
String key = se.getKey();

// 储存异常信息......
ActionMessage error = null;
if( key == null){
error = new ActionMessage(ae.getKey(),se.getMessage());
}else{
if(se.getValues() != null){
error = new ActionMessage(key,se.getValues());
}else{
error = new ActionMessage(key);
}
}

this.storeException(request, key, error, forward, ae.getScope());

return forward;
}

return super.execute(ex, ae, mapping, formInstance, request, response);
}

}



第三步：
  编写struts配置文件：
    1、在src目录下新建文件名为：MessageResources.properties 资源文件，内容如下：
       errors.detail={0}
    2、struts-config.xml配置文件信息如下：
    Java代码
    <?xml version="1.0" encoding="UTF-8"?>  
<!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN" "http://struts.apache.org/dtds/struts-config_1_2.dtd">  
 
<struts-config>  
      
    <!-- 统一异常处理 -->  
    <global-exceptions >  
        <exception   
            key="errors.detail"   
            type="java.lang.Exception" 
            path="/common/exception.jsp" 
            scope="request" 
            handler="com.changtu.oa.web.SystemExceptionHandler" 
        ></exception>  
    </global-exceptions>  
      
    <action-mappings>  
          
          
    </action-mappings>  
    <!-- 加载国际化资源文件 -->  
    <message-resources parameter="MessageResources" />      
</struts-config>  
     

    <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN" "http://struts.apache.org/dtds/struts-config_1_2.dtd">

<struts-config>

<!-- 统一异常处理 -->
<global-exceptions >
<exception
key="errors.detail"
type="java.lang.Exception"
path="/common/exception.jsp"
scope="request"
handler="com.changtu.oa.web.SystemExceptionHandler"
></exception>
</global-exceptions>

<action-mappings>


</action-mappings>
<!-- 加载国际化资源文件 -->
<message-resources parameter="MessageResources" />
</struts-config>
   

第四步：编写业务逻辑：UserManager.java  UserManagerImple.java
  UserManagerImpl.java
  Java代码
   package com.changtu.oa.managers.impl;  
   //...  
 
public class UserManagerImpl implements UserManager {  
        
      // 登陆  
      public User login(String username, String password) {  
 
        /** 
         * 因为设置了User的auto-import="false"，所以，在这里使用 
         * HQL查询的时候，必须使用全路径的类名 
         */ 
        User user = (User)getSession().createQuery(  
                "select u from com.changtu.oa.model.User u where u.username = ?")  
            .setParameter(0, username)  
            .uniqueResult();  
          
        if(user == null){  
            throw new SystemException("没有这个用户");  
        }  
          
        if(!user.getPassword().equals(password)){  
            throw new SystemException("密码错误！");  
        }  
          
        return user;  
    }  
}  
   

   package com.changtu.oa.managers.impl;
   //...

public class UserManagerImpl implements UserManager {
     
      // 登陆
      public User login(String username, String password) {

/**
* 因为设置了User的auto-import="false"，所以，在这里使用
* HQL查询的时候，必须使用全路径的类名
*/
User user = (User)getSession().createQuery(
"select u from com.changtu.oa.model.User u where u.username = ?")
.setParameter(0, username)
.uniqueResult();

if(user == null){
throw new SystemException("没有这个用户");
}

if(!user.getPassword().equals(password)){
throw new SystemException("密码错误！");
}

return user;
}
}
 


第五步：异常页面 exception.jsp
Java代码
<%@ page language="java" contentType="text/html; charset=GB18030" 
    pageEncoding="GB18030"%>  
<%@include file="/common/common.jsp" %>  
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">  
<html>  
<head>  
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">  
<title>Insert title here</title>  
</head>  
<body>  
<html:errors/>  
</body>  
</html> 

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>
<%@include file="/common/common.jsp" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030">
<title>Insert title here</title>
</head>
<body>
<html:errors/>
</body>
</html>


第六步：编写自己的Action进行测试。在Action中出自定义的异常时，struts会自动根据你的配置跳转到异常界面，显示异常信息。(其中有不完整的，需自己补充)