1、直接把表单的参数写在Controller相应的方法的形参中，适用于GET 和 POST请求方式

这种方式不会校验请求里是否带参数，即下面的username和password不带也会响应成功

@RestController
@RequestMapping("/tools")
public class InnerController {
    @RequestMapping("/addUser1")
    public String addUser1(String username,String password) {
        System.out.println("username is:"+username);
        System.out.println("password is:"+password);
        return "success";
    }
}

测试代码

POST请求方式  <script>
    var xhr = new XMLHttpRequest()
    xhr.open('POST', 'http://localhost:8080/tools/addUser1') // 设置请求行
    xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded')
    xhr.send('username=zhangsan&password=123') // 以 urlencoded 格式设置请求体
    xhr.onload=function(){
      if(xhr.readyState!==4) return 
      console.log(xhr.responseText)
    }
  </script>

GET请求方式：  <script>
    var xhr = new XMLHttpRequest()
    xhr.open('GET', 'http://localhost:8080/tools/addUser1?username=zhangsan&password=123') // 设置请求行
    xhr.send() 
    xhr.onload=function(){
      if(xhr.readyState!==4) return 
      console.log(xhr.responseText)
    }
  </script>

2、通过一个bean来接收，适用于GET和POST请求方式

（1）建立一个和表单中参数对应的bean

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class DemoUser {
    private String username;
    private String password;
}

（2）用这个bean来封装接收的参数

@RequestMapping("/tools")
public class InnerController {
    @RequestMapping("/addUser3")
    public String addUser3(DemoUser user) {
        System.out.println("username is:"+user.getUsername());
        System.out.println("password is:"+user.getPassword());
        return "success";
    }
}

3、通过HttpServletRequest接收，适用于GET和POST请求方式

@RequestMapping("/tools")
public class InnerController {
    @RequestMapping("/addUser2")
    public String addUser2(HttpServletRequest request) {
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        System.out.println("username is:"+username);
        System.out.println("password is:"+password);
        return "success";
    }
}

4、通过@PathVariable获取路径中的参数，适用于GET请求

@RequestMapping("/tools")
public class InnerController {
    @RequestMapping(value="/addUser4/{username}/{password}",method=RequestMethod.GET)
    public String addUser4(@PathVariable String username,@PathVariable String password) {
        System.out.println("username is:"+username);
        System.out.println("password is:"+password);
        return "success";    }
}

测试代码

    var xhr = new XMLHttpRequest()
    xhr.open('GET', 'http://localhost:8080/tools/addUser4/username=zhangsan/password=123') // 设置请求行
    xhr.send() 
    xhr.onload=function(){
      if(xhr.readyState!==4) return 
      console.log(xhr.responseText)
    }
  </script>

自动将URL中模板变量{username}和{password}绑定到通过@PathVariable注解的同名参数上，即入参后username=zhangsan、password=123

5、使用@ModelAttribute注解获取参数，适用于POST请求

@RequestMapping("/tools")
public class InnerController {
    @RequestMapping(value="/addUser5",method=RequestMethod.POST)
    public String addUser5(@ModelAttribute("user") DemoUser user) {
        System.out.println("username is:"+user.getUsername());
        System.out.println("password is:"+user.getPassword());
        return "success";
    }
}

测试代码

    var xhr = new XMLHttpRequest()
    xhr.open('POST', 'http://localhost:8080/tools/addUser5') // 设置请求行
    xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded')
    xhr.send('username=zhangsan&password=123') 
    xhr.onload=function(){
      if(xhr.readyState!==4) return 
      console.log(xhr.responseText)
    }
  </script>

6、用注解@RequestParam绑定请求参数到方法入参，适用于GET 和 POST请求方式

@RequestMapping("/tools")
public class InnerController {
    @RequestMapping(value="/addUser6",method=RequestMethod.GET)
    public String addUser6(@RequestParam("username") String username,@RequestParam("password") String password) {
        System.out.println("username is:"+username);
        System.out.println("password is:"+password);
        return "success";
    }
}

7、用注解@RequestBody绑定请求参数到方法入参 ， 用于POST请求

@RequestMapping("/tools")
public class InnerController {

    @RequestMapping(value="/addUser7",method=RequestMethod.POST)
    public String addUser7(@RequestBody DemoUser user) {
        System.out.println("username is:"+user.getUsername());
        System.out.println("password is:"+user.getPassword());
        return "success";
    }
}

测试代码：请求头要指定为json类型

    var xhr = new XMLHttpRequest()
    xhr.open('POST', 'http://localhost:8080/tools/addUser7') // 设置请求行
    xhr.setRequestHeader('Content-Type','application/json')
    xhr.send('{"username":"zhangsan","password":"123"}') 
    xhr.onload=function(){
      if(xhr.readyState!==4) return 
      console.log(xhr.responseText)
    }
  </script>