struts2：JSP页面及Action中获取HTTP参数（parameter）的几种方式

本文演示了JSP中获取HTTP参数的几种方式，还有action中获取HTTP参数的几种方式。

1. 创建JSP页面（testParam.jsp）

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

<%@ page isELIgnored="false"%>

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

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

    <head>

    </head>

    <body>

        JSP页面中三种获取HTTP Parameter的方法：

        <br/>

        1.<s:property value="#parameters.username"/>

        <br/>

        2.<s:property value="#parameters['remark']"/>

        <br/>

        3.<%=request.getParameter("username")%>

        <br/>

        <s:form action="testParam" method="post">

            用户名：<s:textfield name="username"></s:textfield>

            <br/>

            备注：<s:textfield name="remark"></s:textfield>

            <br/>

            <s:submit value="提交"></s:submit>

            <br/>

        </s:form>

    </body>

</html>

2. 创建Action类（ParameterTestAction.java）

package com.clzhang.struts2.demo4;

import java.util.*;

import com.opensymphony.xwork2.ActionSupport;

import com.opensymphony.xwork2.ActionContext;

import org.apache.struts2.ServletActionContext;

import javax.servlet.http.HttpServletRequest;

public class ParameterTestAction extends ActionSupport {

    public static final long serialVersionUID = 1;

    private String username;

    private String remark;

    public String getUsername() {

        return username;

    }

    public void setUsername(String username) {

        this.username = username;

    }

    public String getRemark() {

        return remark;

    }

    public void setRemark(String remark) {

        this.remark = remark;

    }

    public String execute() throws Exception {

        // 方式一：将参数设置为Action的属性，OGNL会自动填充它

        System.out.println("1.把参数作为Action的属性...");

        System.out.println("username=" + this.username);

        System.out.println("remark=" + this.remark);

        // 方法二：在Action中使用ActionContext得到包含parameter的Map以获取参数

        ActionContext context = ActionContext.getContext();

        Map parameterMap = context.getParameters();

        String usernameArray[] = (String[]) parameterMap.get("username");

        String remarkArray[] = (String[]) parameterMap.get("remark");

        System.out.println("2.通过ActionContext.getContext().getParameters()取得...");

        System.out.println("username: " + usernameArray[0]);

        System.out.println("remark: " + remarkArray[0]);

        // 方法三：在Action中取得HttpServletRequest对象，常规方法取得

        HttpServletRequest request = (HttpServletRequest) context

                .get(ServletActionContext.HTTP_REQUEST);

        String username = request.getParameter("username");

        String remark = request.getParameter("remark");

        System.out.println("3.通过HttpServletRequest对象取得...");

        System.out.println("username: " + username);

        System.out.println("remark: " + remark);

        return SUCCESS;

    }

}

3. 修改struts.xml文件

        <action name="testParam" class="com.clzhang.struts2.demo4.ParameterTestAction">

            <result name="success">/struts2/demo4/testParam.jsp</result>

        </action>