struts2：異常處理

時間 2019-11-06

原文原文鏈接

Struts2框架提供了本身的異常處理機制，只須要在struts.xml文件中配置異常處理便可，而不須要在Action方法中來捕捉異常。html

傳統方法

public String execute() throws Exception {
    try{
        //...
        
        return SUCCESS;
    }catch(SQLException ex) {  // SQL異常，返回ERROR
        ex.printStackTrace();
        return ERROR;
    }catch(InvalidInputException ex) { // Invalid異常，返回ERROR
        ex.printStackTrace();
        return ERROR;
    }catch(exception1 ex) {  // 自定義異常
        ex.printStackTrace();
        return "result1";
    }
}

Struts2方法

Strut2框架在struts.xml文件中配置異常一般有兩種方式：全局異常配置和局部異常配置。分別經過<global-exception-mappings../>標籤和<exception-mapping../>標籤來配置。java

下面模擬一個用戶登陸的場景，根據不一樣的輸入，拋出不一樣的異常，而後將由struts2處理。sql

1. 建立登陸頁面（login.jsp）

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!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=UTF-8">
<title>異常測試頁面</title>
</head>
<body>
<center>
<s:form action="user" theme="xhtml">
    <s:textfield label="Name(應該爲admin)" name="name"/>
    <s:textfield label="Age(應該爲18)" name="age" />
    <s:textfield label="Tel(應該爲13800138000)" name="tel"/>
    <s:submit></s:submit>
</s:form>
</center>
</body>
</html>

2. 建立三個異常顯示頁面

loginException.jspapp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!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=UTF-8">
<title>自定義異常SecurityException</title>
</head>
<body>
<h4>
    <font color="red"><s:property value="exception.message"/></font><br/>
    <s:property value="exceptionStack"/>
</h4>
</body>
</html>

Exception.jsp框架

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!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=UTF-8">
<title>全局定義異常Excepition</title>
</head>
<body>
<h4>
    <font color="red"><s:property value="exception.message"/></font><br/>
    <s:property value="exceptionStack"/>
</h4>
</body>
</html>

SQLException.jspjsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<!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=UTF-8">
<title>全局定義異常SQLException</title>
</head>
<body>
<h4>
    <font color="red"><s:property value="exception.message"/></font><br/>
    <s:property value="exceptionStack"/>
</h4>
</body>
</html>

3. 建立Action類

package com.clzhang.struts2.demo10;

import com.opensymphony.xwork2.ActionSupport;

public class UserAction extends ActionSupport {
    private static final long serialVersionUID = 1L;
    
    private String name;
    private String age;
    private String tel;

    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    public String getTel() {
        return tel;
    }
    public void setTel(String tel) {
        this.tel = tel;
    }

    @Override
    public String execute() throws Exception {
        if (!getName().equals("admin")) {
            throw new SecurityException("用戶名錯誤，應該爲admin！");

        } else if (!getAge().equals("18")) {
            throw new Exception("年齡錯誤，應該爲18歲！");
        } else if (!getTel().equals("13800138000")) {
            throw new java.sql.SQLException();
        } else {
            return SUCCESS;
        }
    }
}

4. 建立自定義異常類

package com.clzhang.struts2.demo10;

public class SecurityException extends Exception {
    private static final long serialVersionUID = 1L;
    
    public SecurityException() {
        super();
    }

    private String message;
    public SecurityException(String message) {
        this.message = message;
    }

    public String getMessage() {
        return message;
    }
}

5. 修改struts.xml

加入以下代碼：ide

        <global-results>
            <result name="Exception">/struts2/demo10/Exception.jsp</result>
            <result name="SQLException">/struts2/demo10/SQLException.jsp</result>
        </global-results>

        <global-exception-mappings>
            <exception-mapping exception="java.sql.SQLException" result="SQLException"/>
            <exception-mapping exception="java.lang.Exception" result="Exception"/>
        </global-exception-mappings>



        <action name="user" class="com.clzhang.struts2.demo10.UserAction">
            <exception-mapping exception="com.clzhang.struts2.demo10.SecurityException" result="login"/>
            <result name="login">/struts2/demo10/loginException.jsp </result>
            <result>/struts2/demo10/success.jsp</result>
        </action>