Struts2的三种传值方式

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1.普通的传值方式

UserActionForCommonParam类

Action类接收三个参数,分别是id,username,content.

package com.struts.action;public class UserActionForCommonParam {    private int id;    private String username;    private String content;    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getUsername() {        return username;    }    public void setUsername(String username) {        this.username = username;    }    public String getContent() {        return content;    }    public void setContent(String content) {        this.content = content;    }        // 从前台页面接收到参数后会在这个方法里打印    public String addUser() {        System.out.println("ID: " + this.getId());        System.out.println("Username: " + this.getUsername());        System.out.println("Content: " + this.getContent());        return "success";    }}

对应的struts.xml

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE struts PUBLIC        "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"        "http://struts.apache.org/dtds/struts-2.3.dtd"><struts>    <constant name="struts.enable.DynamicMethodInvocation" value="true"/>    <constant name="struts.devMode" value="true"/>    <package name="default" namespace="/" extends="struts-default">        <action name="UserActionForCommonParam" class="com.struts.action.UserActionForCommonParam" method="addUser">            <result name="success">/UserPage.jsp</result>        </action>    </package></struts>

前台页面UserPage.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %><%@ taglib prefix="s" uri="/struts-tags" %><html><head>    <title>UserPage</title></head><body>    <%--下面的Table用于提交参数(id,username,content)--%>    <form action="UserActionForCommonParam" method="POST">        <table border="1">            <tr>                <td>ID:</td>                <td><input type="text" name="id"/></td>            </tr>            <tr>                <td>Username:</td>                <td><input type="text" name="username"/></td>            </tr>            <tr>                <td>Content:</td>                <td><input type="text" name="content"/></td>            </tr>            <tr>                <td colspan="2" align="center">                    <input type="submit" value="提交"/>                </td>            </tr>        </table>    </form>    <br/>    <%--下面的Table用于显示传递回来id,username,content--%>    <table border="1">        <tr>            <td>ID: </td>            <td><input type="text" value="${id}"/></td>        </tr>        <tr>            <td>Username: </td>            <td><input type="text" value="${username}"/></td>        </tr>        <tr>            <td>Content: </td>            <td><input type="text" value="${content}"/></td>        </tr>    </table>    <%--用于查看ValueStack中的传递的值--%>    <s:debug/></body></html>

在实践后会发现,如果遇到参数非常多的情况,那么就需要在Action类中写非常多的属性以及对应的get/set方法.所以这种方式不太可取.解决问题的方法必然是封装一个JavaBean.这就用到了Strut2的第二种传值方式--DomainModel

2.DomainModel传值

首先要创建一个存储的JavaBean

User类

把id,username,content封装的到一个User类当中.

package com.struts.model;public class User {    private int id;    private String username;    private String content;    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getUsername() {        return username;    }    public void setUsername(String username) {        this.username = username;    }    public String getContent() {        return content;    }    public void setContent(String content) {        this.content = content;    }}

UserActionForDomainModel类

package com.struts.action;import com.opensymphony.xwork2.ActionSupport;import com.struts.model.User;public class UserActionForDomainModel extends ActionSupport{    private User user;    public User getUser() {        return user;    }    public void setUser(User user) {        this.user = user;    }    public String addUser() {        System.out.println("ID: " + user.getId());        System.out.println("Username: " + user.getUsername());        System.out.println("Content: " + user.getContent());        return "success";    }}

对应的struts.xml

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE struts PUBLIC        "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"        "http://struts.apache.org/dtds/struts-2.3.dtd"><struts>    <constant name="struts.enable.DynamicMethodInvocation" value="true"/>    <constant name="struts.devMode" value="true"/>    <package name="default" namespace="/" extends="struts-default">        <action name="userForDomainModel" class="com.struts.action.UserActionForDomainModel" method="addUser">            <result name="success">/UserPage.jsp</result>        </action>    </package></struts>

前台页面UserPage.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %><%@ taglib prefix="s" uri="/struts-tags" %><html><head>    <title>UserPage</title></head><body>    <%--要特别注意的是DomainModel的传值方式必须要使用对象.参数方式进行赋值以及取值--%>    <form action="userForDomainModel" method="POST">        <table border="1">            <tr>                <td>ID:</td>                <td><input type="text" name="user.id"/></td>            </tr>            <tr>                <td>Username:</td>                <td><input type="text" name="user.username"/></td>            </tr>            <tr>                <td>Content:</td>                <td><input type="text" name="user.content"/></td>            </tr>            <tr>                <td colspan="2" align="center">                    <input type="submit" value="提交"/>                </td>            </tr>        </table>    </form>    <br/>    <%--下面的Table用于显示传递回来id,username,content--%>    <table border="1">        <tr>            <td>ID: </td>            <td><input type="text" value="${user.id}"/></td>        </tr>        <tr>            <td>Username: </td>            <td><input type="text" value="${user.username}"/></td>        </tr>        <tr>            <td>Content: </td>            <td><input type="text" value="${user.content}"/></td>        </tr>    </table>    <%--用于查看ValueStack中的传递的值--%>    <s:debug/></body></html>

实际上User类不需要显式的实例化,struts会自动帮你实例化,但前提条件是,传值时需要使用对象.参数名的方式进行传递.

除了这种传值方式外,struts2还提供另外一种传值方式.

3.ModelDriven传值

依然要创建User的JavaBean

User类

package com.struts.model;public class User {    private int id;    private String username;    private String content;    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public String getUsername() {        return username;    }    public void setUsername(String username) {        this.username = username;    }    public String getContent() {        return content;    }    public void setContent(String content) {        this.content = content;    }}

UserActionForModelDriven类

package com.struts.action;import com.opensymphony.xwork2.ModelDriven;import com.struts.model.User;public class UserActionForModelDriven implements ModelDriven<User>{    private User user;    public String addUser() {        System.out.println("ID: " + user.getId());        System.out.println("Username: " + user.getUsername());        System.out.println("Content: " + user.getContent());        return "success";    }    @Override    public User getModel() {        if (user == null) {            user = new User();        }        return user;    }}

这种方式可以不用在Action类中编写对应的get/set方法,但是需要实例化User类.

前台UserPage.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %><%@ taglib prefix="s" uri="/struts-tags" %><html><head>    <title>UserPage</title></head><body>    <form action="userForModelDriven" method="POST">        <table border="1">            <tr>                <td>ID:</td>                <td><input type="text" name="id"/></td>            </tr>            <tr>                <td>Username:</td>                <td><input type="text" name="username"/></td>            </tr>            <tr>                <td>Content:</td>                <td><input type="text" name="content"/></td>            </tr>            <tr>                <td colspan="2" align="center">                    <input type="submit" value="提交"/>                </td>            </tr>        </table>    </form>    <br/>    <%--下面的Table用于显示传递回来id,username,content--%>    <table border="1">        <tr><span id="transmark"></span>            <td>ID: </td>            <td><input type="text" value="${id}"/></td>        </tr>        <tr>            <td>Username: </td>            <td><input type="text" value="${username}"/></td>        </tr>        <tr>            <td>Content: </td>            <td><input type="text" value="${content}"/></td>        </tr>    </table>    <%--用于查看ValueStack中的传递的值--%>    <s:debug/></body></html>

页面还是和普通传值一样.

可以去ValueStack当中观察参数的存储,更透彻的理解Struts2的参数传递.

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