java后端获取前端请求参数
纯servlet获取前端请求参数测试页面<body><h2>输入帐号密码</h2><form action="test" method="post">帐号: <input type="text" name="username"/><br/>密码: <input type="text" name="password"/&g
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纯servlet获取前端请求参数
测试页面
<body>
<h2>输入帐号密码</h2>
<form action="test" method="post">
帐号: <input type="text" name="username"/><br/>
密码: <input type="text" name="password"/><br/>
<input type="submit" value="登录"/>
</form>
</body>
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
{
//方式一 Parameter的参数是我们提交表单的时候name的数值
String username=request.getParameter("username");
String password=request.getParameter("password");
System.out.println(username+" "+password);
System.out.println("==============");
//获取所有参数
Enumeration<String> parmNames1=request.getParameterNames();
while (parmNames1.hasMoreElements())
{
String name = (String) parmNames1.nextElement();
String value=request.getParameter(name);
System.out.println(name+"=="+value);
}
System.out.println("==============");
// 获取所有参数的map形式
Map<String, String[]> map1=request.getParameterMap();
//把map转换到EntrySet
Set<Entry<String,String[]>> set1= map1.entrySet();
//获取set的迭代器
Iterator<Entry<String,String[]>> iterator1=set1.iterator();
//遍历set
for (Entry<String, String[]> entry : set1)
{
String name=entry.getKey();
//value是一个数组,只取第一个,因为我们只有一个数值
String value=entry.getValue()[0];
System.out.println(name+"=="+value);
}
}
Controller：
package com.ysl.PassingParameters.controller;
import java.util.List;
import java.util.Map;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import com.ysl.PassingParameters.bean.User;
import com.ysl.PassingParameters.dto.RetMsg;
@Controller
public class TestController {
/**
* List<String>传参
* @param listString
* @return
*/
@RequestMapping("/listString")
@ResponseBody
public RetMsg listString(@RequestParam("listString[]") List<String> listString){
System.out.println("listString:"+listString.toString());
return RetMsg.success();
}
/**
* List<User>传参
* @param listUser
* @return
*/
@RequestMapping("/listUsers")
@ResponseBody
public RetMsg listUsers(@RequestBody List<User> listUser){
System.out.println("username:"+listUser.get(0).getUsername());
return RetMsg.success();
}
/**
* User[]传参
* @param arrayUsers
* @return
*/
@RequestMapping("/arrayUsers")
@ResponseBody
public RetMsg arrayUsers(@RequestBody User[] arrayUsers){
System.out.println("username:"+arrayUsers[0].getUsername());
return RetMsg.success();
}
/**
* List<Map<String,Object>>传参
* @param listMap
* @return
*/
@RequestMapping("/listMap")
@ResponseBody
public RetMsg listMap(@RequestBody List<Map<String, String>> listMap){
System.out.println("username:"+listMap.get(0).get("username"));
return RetMsg.success();
}
/**
* User对象传参
* @param arrayUsers
* @return
*/
@RequestMapping("/users")
@ResponseBody
public RetMsg users(@RequestBody User users){
System.out.println("username:"+users.getUsername());
System.out.println("username:"+users.getList().get(0).getUsername());
return RetMsg.success();
}
}
页面：
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
<html>
<%application.setAttribute("path", request.getContextPath());%>
<head>
<script type="text/javascript" src="${path}/js/jquery.min.js"></script>
</head>
<body>
<h2>Hello World!</h2>
<button id="listString">List<String>传参</button>
<button id="listUser">List<User>传参</button>
<button id="arrayUsers">User[]传参</button>
<button id="listMap">List<Map<String,Object>>传参</button>
<button id="Users">User对象（属性包含List<User>）传参</button>
<script type="text/javascript">
// List<String>传参
$("#listString").click(function(){
var idList = new Array();
idList.push("1");
idList.push("1");
idList.push("1");
$.ajax({
type:"post",
url:"${path}/listString",
data:{"listString":idList},
dataType:"json",
success:function(retMsg){
if(retMsg.code==200){
alert("success");
}else{
alert("false");
}
}
})
})
// List<User>传参
$("#listUser").click(function(){
var userList = new Array();
userList.push({username: "zhangsan",password: "332"});
userList.push({username: "zhangsan",password: "332"});
$.ajax({
type:"post",
url:"${path}/listUsers",
data:JSON.stringify(userList),
dataType:"json",
contentType : 'application/json;charset=utf-8', //设置请求头信息
success:function(retMsg){
if(retMsg.code==200){
alert("success");
}else{
alert("false");
}
}
})
})
//传User对象数组
$("#arrayUsers").click(function(){
var userList = [{username: "李四",password: "123"},{username: "张三",password: "332"}];
$.ajax({
type: "POST",
url: "${path}/arrayUsers",
data: JSON.stringify(userList),//将对象序列化成JSON字符串
dataType:"json",
contentType : 'application/json;charset=utf-8', //设置请求头信息
success:function(retMsg){
if(retMsg.code==200){
alert("success");
}else{
alert("false");
}
}
});
})
// List<Map<String,Object>>传参
$("#listMap").click(function(){
var userList = new Array();
userList.push({username: "zhangsan",password: "332"});
userList.push({username: "zhangsan",password: "332"});
$.ajax({
type:"post",
url:"${path}/listMap",
data:JSON.stringify(userList),
dataType:"json",
contentType : 'application/json;charset=utf-8', //设置请求头信息
success:function(retMsg){
if(retMsg.code==200){
alert("success");
}else{
alert("false");
}
}
})
})
//User对象传参
$("#Users").click(function(){
var list = new Array();
list.push({username: "zhangsan",password: "332"});
list.push({username: "zhangsan",password: "332"});
var user = {};
user.username = "张三";
user.password = "密码";
user.list = list;
$.ajax({
type:"post",
url:"users",
data:JSON.stringify(user),
datatype:"json",
contentType:"application/json;charset=utf-8",
success:function(retMsg){
if(retMsg.code==200){
alert("success");
}else{
alert("false");
}
}
})
})
</script>
</body>
</html>
后端传值给前端
1，从Action中传值到JSP页面的方法
①在Action中定义一个成员变量，然后对这个成员变量提供get/set方法，在JSP页面就可以取到这个变量的值了。
1）在Action中定义成员变量
//定义一个成员变量
private String message;
//提供get/set方法
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
2）在JSP页面中取值
${message}
或者
<s:property value="message"/>
②使用一些Servlet API进行值的存取操作：HttpServletRequest、HttpSession和ServletContext。Struts2对这个三个对象用Map进行了封装，我们就可以使用Map对象来存取数据了。
1)在Action中存值
ActionContext actionContext = ActionContext.getContext();
//get HttpServletRequest
Map<String,Object> request = (Map) actionContext.get("request");
request.put("a", "a is in request");
//get HttpSession
//Map<String,Object> session = (Map) actionContext.get("session");
Map<String,Object> session = actionContext.getSession();
session.put("b", "b is in session");
//get ServletContext
//Map<String,Object> application = (Map) actionContext.get("application");
Map<String,Object> application = actionContext.getApplication();
application.put("c", "c is in application");
//get ServletActionContext.request
HttpServletRequest request=ServletActionContext.getRequest()
request.setAttribute("c2", "test5");
request.put("c3","test6")
//或者直接放入上下文中
ActionContext.getContext().put("d","d is in application");
2）在JSP页面上取值（使用EL表达式）
${a}
${b}
${c}
${d}
${c2}
${c3}
or
${requestScope.a}
${sessionScope.b}
${applicationScope.c}
${actionContext.d}
${requestScope.c2}
${requestScope.c3}
or<%=request.getAttribute("d")%> //使用ActionContext.getContext().put("d","d is an application")的情况
附加：ServletContext,ActionContext,ServletActionContext的区别
在ActionContext.getContext().put(“a”, " test3")后页面上用${a}或<s:property value=“#a”/>获得test3的值
#相当于ActionContext. getContext() ，#session.b表达式相当于ActionContext.getContext().getSession(). getAttribute(”b”)
③对于传递list的值，可以使用 actionContext的valueStack来传递值栈
1) 在后台使用Hibernate查询 ，EntityManager 通过createQuery()来getResultList()获得List，将list放入valueStack中
ActionContext.getContext().getValueStack().push(model);
2)在页面上通过<s:iterator>标签遍历list的每条值显示在table上。
<table class="tablelist" >
<thead>
<tr>
<th width="100px;">编号</th>
<th>影片类型</th>
<th>影片名称</th>
<th>发布人</th>
<th>发布时间</th>
<th>审核状态</th>
<th>操作</th>
</tr>
</thead>
<tbody>
<s:iterator value="recordList" var="o" status="i">
<tr>
<td>${o.id}</td>
<td>${o.name }</td>
<td>${o.type}</td>
<td>${o.updateMember.memberName }</td>
</tr>
</s:iterator>
</tbody>
</table>
从前台向后台传递参数
①通过表单传递参数
1)在前端jsp页面设置form表单，确定需要传递的参数name让用户在input中输入，通过点击按钮后submit()提交到后台
<s:form method="post" action="ActivityAction_toUI.action">
<table class="serTable">
<tbody>
<tr>
<td>
<label>活动名称</label>
</td>
<td>
<input type="text" class="serput" name="activityName" placeholder="输入文本"/>
</td>
<td>
<s:submit cssClass="btn1" value="搜索" onclick="submit();" />
</td>
</tr>
</tbody>
</table>
</s:form>
2)点击搜索后activityName会放到HttpServletRequest 中
HttpServletRequest httpReq = ServletActionContext.getRequest()；
String s = httpReq.getParameter("activityName");
另外，在后台也可以通过extends ActionSupport 并构建get/set方法在后台获得其值
private String activityName;
public String getActivityName() {
return activityName;
}
public void setActivityName(String activityName) {
this.activityName = activityName;
}
public String list(){
System.out.println(activityName);
}
②通过超链接传递参数
1)前台通过超链接跳转时将参数加到方法的后面
<s:a cssClass="acolor" target="mainBody" theme="simple" action="ActivityAction_info.action?Id=%{Id}&pageNum=%{pageNum}&infot=\"mylittlepony\"" ><img
src="${pageContext.request.contextPath}/images/info.png"
title="查看" /></s:a>
2)后台通过HttpServletRequest 获得超链接后面参数所对应的值
HttpServletRequest httpReq = ServletActionContext.getRequest()；
<pre name="code" class="java">Long id= Long.parseLong(httpReq.getParameter("Id"));
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