[Struts2学习笔记] -- 简单的类型转换

时间：2023-03-09 08:27:38
[Struts2学习笔记] -- 简单的类型转换

　　接下来学习一下Struts2简单的类型转换，Struts2基于ognl.jar实现了简单类型的数据转换。比如jsp页面中的form值与字段值的转换，下面写一个例子。

　　1、创建一个jsp页面，编写一个form表单模拟登录，有一个用户名username和密码password，在加入一个登录按钮。如图：

[Struts2学习笔记] -- 简单的类型转换

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<%@ taglib prefix="s" uri="/struts-tags" %>

<%

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 'index.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>

    <s:form name="login" method="post" action="login" namespace="/">

        <s:textfield label="username" name="username"></s:textfield>

        <s:textfield label="password" name="password"></s:textfield>

        <s:submit value="sgin in"></s:submit>

    </s:form>

  </body>

</html>

login.jsp代码

　　jsp代码中使用了struts2的标签库，标签库的.tld文件在struts2-core-2.3.24.1.jar/META-INF路径下。

　　2、创建LoginAction，为了可以将jsp中表单的自动转换提取到变量中，需要在action文件里建立两个字段，并提供get/set方法用于接收：

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;

}

private String username;

private String password;

　　其超类ActionSupport提供了验证功能，需要重写超类的validate()方法，对表单中的数据进行校验，并调用addFieldError()方法记录错误信息，当验证失败，会返回INPUT作为Result，所以需要在struts2.xml中配置返回值为input的result节点，LoginAction类具体代码如下：

package cn.net.bysoft.lesson2;

import com.opensymphony.xwork2.ActionSupport;

public class LoginAction extends ActionSupport {

    /**

     *

     */

    private static final long serialVersionUID = -549393995867033046L;

    @Override

    public String execute() throws Exception {

        // TODO Auto-generated method stub

        if ("admin".equals(getUsername()) && "password".equals(getPassword())) {

            return SUCCESS;

        } else {

            addFieldError("username",

                    "Sorry,wrong username or password,please login again");

            return INPUT;

        }

    }

    @Override

    public void validate() {

        // TODO Auto-generated method stub

        if (getUsername().length() == 0) {

            addFieldError("username", "username is required");

        }

        if (getPassword().length() == 0) {

            addFieldError("password", "password is required");

        }

    }

    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;

    }

    private String username;

    private String password;

}

LoginAction类

　　3、配置struts2.xml的内容：

<!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN" "http://struts.apache.org/dtds/struts-2.3.dtd">

<struts>

    <package name="struts2_3_24_1" extends="struts-default">

        <action name="helloWorld" class="cn.net.bysoft.lesson1.HelloWorldAction">

            <result>lesson1/hello.jsp</result>

        </action>

        <action name="login" class="cn.net.bysoft.lesson2.LoginAction">

            <result name="success">lesson2/success.jsp</result>

            <result name="input">lesson2/login.jsp</result>

        </action>

    </package>

</struts>

struts2.xml的内容

　　4、最后当登录成功时，跳转到success.jsp页面。若login.jsp表单中输入的数据格式有误，则进行提示，如图所示，当用户名或密码为空时，提示：

[Struts2学习笔记] -- 简单的类型转换

　　当用户名密码错误时提示（这里默认用户名为admin，密码为password为正确的信息）：

[Struts2学习笔记] -- 简单的类型转换

　　当用户名和密码正确时，跳转到success.jsp：

[Struts2学习笔记] -- 简单的类型转换

　　success.jsp的代码如下：

<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>

<%@ taglib prefix="s" uri="/struts-tags" %>

<%

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 'success.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: <s:property value="username"/><br>

    password: <s:property value="password"/><br>

  </body>

</html>

success.jsp的代码

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