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SpringMVC2

article 2025/9/13 2:22:48

一、springmvc 接收请求

类上、方法上

@RequestMapping

@GetMapping

@PostMapping

package com.hl.springmvc02.web;

import jdk.nashorn.internal.objects.annotations.Getter;
import org.springframework.web.bind.annotation.*;

@RestController
@RequestMapping("/user")
public class UserController {//get 请求默认访问方法@GetMappingpublic String welcome(){System.out.println("welcome");return "welcome!";}//post请求执行的默认方法@PostMappingpublic String welcome2(){System.out.println("welcome2");return "welcome2!";}/*url: http://localhost:8080/user/save@RequestMapping：默认情况下，接收任意类型请求限制只能接收特定请求  method = RequestMethod.GET 只接收get请求method = RequestMethod.GET|POST|PUT|DELETE*/@RequestMapping(value = {"/save1","/save2","/save"},method = RequestMethod.GET)public void save(){System.out.println("save");}
}

二、springmvc 接收数据

1、接收参数

package com.hl.springmvc02.web;

import com.hl.springmvc02.pojo.Product;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import javax.servlet.http.HttpServletRequest;

@RestController
@RequestMapping("/product")
public class ProductController {/*接收数据方式一、原生 HttpServletRequest 接收数据*/@RequestMapping("/save")public String save(HttpServletRequest request){//接收参数  返回值只能是字符串类型String name = request.getParameter("name");String id = request.getParameter("id");//类型转换时，需要手动转换if(id !=null && id!=""){System.out.println(Integer.parseInt(id));}return "save!"+id+"---"+name;}/*方式二：通过参数名称接收  要求  url后传递的参数名和方法的形参名保持一致http://localhost:8080/product/save2?id=11&name=admin尽可能使用包装类，而不是基本数据数据类型*/@RequestMapping("/save2")public String save2(Integer id,String name){return "save!"+id+"--"+name;}@RequestMapping("/save3")public String save3(int id,String name){return "save!"+id+"--"+name;}/*方式三、参数名称不一致时  @RequestParam(name = "username")  参数映射1、限制是否允许为空  @RequestParam 默认不允许为空@RequestParam(required = false)required = false  是否允许为空2、是否给默认值 @RequestParam(defaultValue = "12345")*/@RequestMapping("/save4")public String save4(@RequestParam(defaultValue = "12345",required = false) Integer id,@RequestParam(name = "username") String name){return id+"---"+name;}/*方式四、通过对象接收数据 (当前端传递的参数名和对象的属性名保持一致时)http://locahost:8080/product/save5?id=12&name=admin*/@RequestMapping("save5")public Product save5(Product product,String name1){System.out.println(name1);return  product;}/*方法五、restful风格接收（@PathVariable 地址栏传参）http://localhost:8080/product/save6/1/admin微服务中推荐的模式*/@RequestMapping("/save6/{id1}/{name}")public Product save6(@PathVariable(name = "id1") Integer id,@PathVariable(required = false) String name){System.out.println(id+"---"+name);return new Product(id,name);}

2、cookie数据

/*cookie传递数据@CookieValue 从cookie中获取数据，根据key找到value*/
@RequestMapping("/cookie")
public String getCookie(@CookieValue(name = "username",required = false)String username){return username;
}

3、请求头中数据

@RestController
@RequestMapping("/order")
public class OrderController {
/*@RequestHeader(name = "user-agent") String userAgent获取浏览器请求头中特定key对应的value*/@RequestMapping("/header")public String header(@RequestHeader(name = "User-Agent") String userAgent,@RequestHeader(name = "token") String token){return userAgent+"---"+token;}
}

4、接收其他controller转发的数据

业务操作：调用service

package com.hl.springmvc02.web;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestAttribute;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.servlet.http.HttpServletRequest;

@Controller
@RequestMapping("/s1")
public class DispatcherController {
@RequestMapping("/getMsg")public String getMsg(HttpServletRequest request){System.out.println("getMsg......");//获取浏览器传递的参数String msg = request.getParameter("msg");//一次转发过程中携带数据（传递数据）request.setAttribute("msg1","hello world!");//转发到其他的controller方法return "/s1/getData";}
@RequestMapping("/getData")public String getData(HttpServletRequest request,@RequestAttribute(required = false) String msg1){System.out.println("getData......");//获取request转发携带的数据System.out.println(request.getAttribute("msg1"));System.out.println("--注解获取--"+msg1);//转发到页面return "/index.html";}
}

三、前后端分离：返回数据给前端（前后端一体，转发，重定向页面跳转）

@ResponseBody

@RestController

统一返回数据格式

声明一个结果集R类

package com.hl.springmvc02.pojo;

import lombok.Data;

/*
R ---> 结果集对象（响应对象）
统一封装  服务端返回给前端的数据*/
@Data
public class R {private Integer code;//状态码private String msg;//描述信息private Object data;//传递的数据
//成功的方法public static R ok() {return new R(200,"操作成功",null);}//成功的方法public static R ok(Object data) {return new R(200,"操作成功",data);}//成功的方法public static R ok(String msg ,Object data) {return new R(200,msg,data);}//失败的方法public static R fail(String msg) {return new R(201,msg,null);}
public R(Integer code, String msg, Object data) {this.code = code;this.msg = msg;this.data = data;}
public R() {}
}

package com.hl.springmvc02.web;

import com.hl.springmvc02.pojo.R;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/response")
public class ResponseController {@RequestMapping("/data")public R data(){//业务逻辑return R.ok();}@RequestMapping("/data2")public R data2(){return R.ok("新增成功",null);}@RequestMapping("/data3")public R data3(){return R.fail("用户名已存在！");}
}

四、各种常见错误及解决方案

常见错误类型：
404：路径未找到 http://localhost:8080/product/save4
405: 方法不匹配前端get ----> 服务端@PostMapping @RequestMapping(method="")
400: 参数赋值错误
前端id=abc 服务端：Integer id
前端没有传递id null 服务端 int id null--->int 报错
前端id没有传值服务端 @RequestParam(required=true) Integer id
500: 服务端错误
1、接收到请求了
2、接收到数据
3、方法体报错