Spring MVC系列（三）之获取参数
介绍
Spring MVC的数据绑定功能做的很是强大，提供开发者以多种形式去获取页面传递过来的参数，今天我们一起看下spring支持以哪些方式获取值
①当我们业务场景是根据user的id去删除user的时候，url可能是如下几种
localhost:8080/spring-mvc/user/delete/1
localhost:8080/spring-mvc/user/delete/2
localhost:8080/spring-mvc/user/delete/3
根据我们上一节讲解的URL映射，我们可以写一个rest风格的映射，利用注解@RequestMapping，代码如下
package org.study.lyncc.web.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
@Controller
@RequestMapping(value="/user")
public class UserController {
@RequestMapping(value="/delete/{id}")
public ModelAndView delete(@PathVariable("id") Integer params){
System.out.println(params);
ModelAndView mav = new ModelAndView("test");
mav.addObject("deleteId", params);
return mav;
}
}
跳转的test.jsp页面我们也修改一下
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!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>hello</title>
</head>
<body>
${deleteId}
</body>
</html>
这样我们就可以获取到了映射到了，但是我们想获取URL中的用户id例如1,2,3这样的值（就是/delete/{id}中的id值），我们可以利用Spring提供的@PathVariable注解，需要注意的是{id}中大括号中的id必须和@RequestMapping中的名称保持一致，如上代码显示，那么spring会自动把页面传递的值绑定到params这个变量上，当你的url是http://localhost:8080/spring-mvc/user/delete/123123的时候，运行结果：
我们也可以简便一下写法，我们平时开发过程中通常是这样的
我们一般不指定@PathVariable的value，只需要把变量名与path中的名一样一样可以映射到
②我们以前开发的时候删除一个用户的URL通常是这样的
localhost:8080/spring-mvc/delete/user?id=1
localhost:8080/spring-mvc/delete/user?id=2
localhost:8080/spring-mvc/delete/user?id=345
我们想得到问号后面的值，我们可以使用@RequestParam这样的属性
package org.study.lyncc.web.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;
@Controller
public class UserController {
@RequestMapping(value="/delete/user")
public ModelAndView delete(@RequestParam(value="id") Integer params){
System.out.println(params);
ModelAndView mav = new ModelAndView("test");
mav.addObject("deleteId", params);
return mav;
}
}
这样我们可以依旧获取到值：
我们再举一个更加复杂的例子,当我们的url是http://localhost:8080/spring-mvc/delete/user?id=1&username=lyncc&age=26的时候
package org.study.lyncc.web.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;
@Controller
public class UserController {
@RequestMapping(value="/delete/user")
public ModelAndView delete(@RequestParam Integer id,@RequestParam String username,@RequestParam Integer age){
ModelAndView mav = new ModelAndView("test");
mav.addObject("deleteId", "id:"+id+"==username:"+username+"===age:"+age);
return mav;
}
}
注意我们也去掉了@RequestParam的value值，我们只需要一一对应值就可以了
③我们平时开发的时候，经常Ajax请求，例如我们写个ajax请求
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!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>hello</title>
<script type="text/javascript" src="js/jquery-1.7.2.js"></script>
</head>
<body>
</body>
<script type="text/javascript">
$(function(){
var param = {
"id":1,
"username":"fly100%",
"age":25
};
$.post("${pageContext.request.contextPath}/delete/user",param,function(data){
console.info(data);
});
});
</script>
</html>后台代码
package org.study.lyncc.web.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
@Controller
public class UserController {
@RequestMapping(value="/test")
public ModelAndView index(){
ModelAndView mav = new ModelAndView("test");
return mav;
}
@RequestMapping(value="/delete/user")
public ModelAndView delete(Integer id,String username,Integer age){
ModelAndView mav = new ModelAndView("test");
System.out.println("id:"+id+"==username:"+username+"===age:"+age);
mav.addObject("deleteId", "id:"+id+"==username:"+username+"===age:"+age);
return mav;
}
}
我们没有使用任何注解，运行结果：
发现依旧可以获取值
我们也可以这样，新建一个User对象
package org.study.lyncc.web.entity;
public class User {
private Integer id;
private String username;
private Integer age;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
}
修改一下Controller，把参数就替换成User对象
package org.study.lyncc.web.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;
import org.study.lyncc.web.entity.User;
@Controller
public class UserController {
@RequestMapping(value="/test")
public ModelAndView index(){
ModelAndView mav = new ModelAndView("test");
return mav;
}
@RequestMapping(value="/delete/user")
public ModelAndView delete(User u){
ModelAndView mav = new ModelAndView("test");
System.out.println("id:"+u.getId()+"==username:"+u.getUsername()+"===age:"+u.getAge());
mav.addObject("deleteId", "id:"+u.getId()+"==username:"+u.getUsername()+"===age:"+u.getAge());
return mav;
}
}
依旧可以获取值
Spring MVC的数据绑定功能是非常强大的，一般常用的就是这些了~