1、通过的ServletAPI获取

只需要在控制器的方法的形参位置设置HTTPRequest  request 类型的形参就i可以在控制器方法种使用request对象获取请求参数

@RequestMapping("/servletAPI")
    public String getByServletAPI(HttpServletRequest request){
        HttpSession session = request.getSession();
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        System.out.println("username = " + username + "," + "password = " +  password);
        return "success";

2、通过控制器方法的形参获取请求参数

前端页面

<form th:action="@{/param}" method="post">
    用户名：<input type="text" name="username"><br>
    密码：<input type="password" name="password"><br>
    <input type="submit" value="登录">
</form>

@RequestMapping("/param")
public String getParam(String username,String password){ 
        System.out.println("username:"+username+",password:"+password);
       return "success";
}

 * 只需要在控制器方法的形参位置，设置一个形参，形参的名字和请求参数的名字一致即可

3、通过@RequestParam获取请求参数

@RequestParam是将请求参数和控制器方法的形参创建映射关系

http://localhost:8080/springmvc_rest/param?password=123

@RequestMapping("/param")
public String getParam(@RequestParam(value = "username",required = true,        defaultValue = "hello")String username, String password){
     System.out.println("username:" + username + ",password:" + password);
     return "success";
}

@RequestParam注解的属性：
value：设置和形参绑定的请求参数的名字
required:设置是否必须传输value所对应的请求参数

• 默认值为true，表示value所对应的请求参数必须传输否则页面报错 Required String parameter 'xxx' is not present
• 若设置为false，则表示value所对应的请求参数不是必须传输，如果此时获取该参数的值，则为nul

defaultValue：设置当没有传输value所对应的请求参数时，为形参设置的默认值，此时和required属性值无关

4、通过@RequestHeaher获取请求参数

@RequestParam是将请求头信息和控制器方法的形参创建映射关系

@RequestMapping("/param")
    public String getParam(String username, String password,
                           @RequestHeader("referer") String referer){
        System.out.println("username = " + username + "," + "password = " +  password);
        System.out.println("referer = " + referer);
   
        return "success";

}

5、通过@CookieValue获取请求参数

@CookieValue是将cookie数据和控制器方法的形参创建映射关系

@RequestMapping("/param")
    public String getParam(String username, String password,
                           @CookieValue("JSESSIONID") String jsessionId){
        System.out.println("username = " + username + "," + "password = " +  password);
      
        System.out.println("jsessionId = " + jsessionId);
        return "success";
    }

 返回结果

 6、通过pojo获取请求参数

先创建实体类

package com.pojo;
public class User {
    private  Integer id;
    private String username;
    private String password;
    public User() {    }
    public User(Integer id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }
    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 String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    @Override
    public String toString() {
        return "User{" +
                "id=" + id + 
               ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

前端页面

<form th:action="@{/param/pojo}" method="post">
    用户名：<input type="text" name="username"><br>
    密码：<input type="password" name="password"><br>
    <input type="submit" value="登录">
</form>

控制器

@RequestMapping("/param/pojo")
public String getParamByPojo(User user){
    System.out.println(user);
    return "success";
}