Spring Boot详解各类请求和响应的处理方法

来源：jb51　　时间：2022/7/19 9:55:39　　对本文有异议

1. HttpServletRequest与HttpServletResponse

浏览器输入：http://localhost:8080/community/alpha/http?code=10

@RequestMapping("/http")
public void http(HttpServletRequest request, HttpServletResponse response) {
    // 获取请求数据
    System.out.println(request.getMethod());
    System.out.println(request.getServletPath());
    Enumeration<String> enumeration = request.getHeaderNames();
    while (enumeration.hasMoreElements()) {
        String name = enumeration.nextElement();
        String value = request.getHeader(name);
        System.out.println(name + ": " + value);
    }
    System.out.println(request.getParameter("code"));
    // 返回响应数据
    response.setContentType("text/html;charset=utf-8");
    try {
        PrintWriter writer = response.getWriter();
        writer.write("<h1>nowcoder</h1>");
    } catch (IOException e) {
        e.printStackTrace();
    }
}

前端页面显示：nowcoder

同时，IDEA控制台输出：

GET
/alpha/http
host: localhost:8080
connection: keep-alive
sec-ch-ua: " Not;A Brand";v="99", "Google Chrome";v="97", "Chromium";v="97"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Windows"
upgrade-insecure-requests: 1
user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/97.0.4692.99 Safari/537.36
accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
sec-fetch-site: none
sec-fetch-mode: navigate
sec-fetch-user: ?1
sec-fetch-dest: document
accept-encoding: gzip, deflate, br
accept-language: zh-CN,zh;q=0.9
cookie: Idea-10659edd=72fa12c3-9b68-4da6-8b68-38a81c822aa0
10

2. GET类型的请求

在AlphaController中增加方法，处理GET类型的请求。

2.1 /students?current=1&limit=20

浏览器输入：http://localhost:8080/community/alpha/students?current=1&limit=100

@GetMapping("/students")
@ResponseBody
public String getStudents(
        @RequestParam(name = "current" ,required = false, defaultValue = "1") int current,
        @RequestParam(name = "limit" ,required = false, defaultValue = "10") int limit) {
    System.out.println(current);
    System.out.println(limit);
    return "some students";
}

前端页面显示：some students

同时，IDEA控制台输出：

1
100

2.2 /student/123

浏览器输入：http://localhost:8080/community/alpha/student/123

@GetMapping("/student/{id}")
@ResponseBody
public String getStudent(@PathVariable("id") int id) {
    System.out.println(id);
    return "one student";
}

前端页面显示：one students

同时，IDEA控制台输出：

123

3. POST类型的请求

在AlphaController中增加方法，处理POST类型的请求。

浏览器输入：http://localhost:8080/community/html/student.html

@PostMapping("/student")
@ResponseBody
public String saveStudent(String name, int age) {
    System.out.println(name);
    System.out.println(age);
    return "success";
}

resources/static/html/student.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>增加学生</title>
</head>
<body>
  <form method="post" action="/community/alpha/student">
    <p>
      姓名：<input type="text" name="name">
    </p>
    <p>
      年龄：<input type="text" name="age">
    </p>
    <p>
      <input type="submit" value="保存">
    </p>
  </form>
</body>
</html>

前端页面显示一个表单，包含两行：姓名、年龄，还有一个 “保存” 按钮。

输入 “Lebron”、38 后，点击 “保存” 后，显示 “success”。

4. 响应HTML格式的数据

在AlphaController中增加方法，向浏览器响应HTML格式的数据。

4.1 使用ModelAndView

浏览器输入：http://localhost:8080/community/alpha/teacher

@GetMapping("/teacher")
public ModelAndView getTeacher() {
    ModelAndView mav = new ModelAndView();
    mav.addObject("name", "Lebron");
    mav.addObject("age", 38);
    mav.setViewName("/demo/view");
    return mav;
}

前端页面显示：

Lebron
38

4.2 使用Model

浏览器输入：http://localhost:8080/community/alpha/school

@GetMapping("/school")
public String getSchool(Model model) {
    model.addAttribute("name", "xx大学");
    model.addAttribute("age", 100);
    return "/demo/view";
}

resources/templates/demo/view.html

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Teacher</title>
</head>
<body>
    <p th:text="${name}"></p>
    <p th:text="${age}"></p>
</body>
</html>

前端页面显示：

xx大学
100

5. 响应JSON格式的数据

在AlphaController中增加方法，向浏览器响应JSON格式的数据。

5.1 单组数据

浏览器输入：http://localhost:8080/community/alpha/emp

@GetMapping("/emp")
@ResponseBody
public Map<String, Object> getEmp() {
    Map<String, Object> emp = new HashMap<>();
    emp.put("name", "Kitty");
    emp.put("age", 20);
    emp.put("salary", 12000.00);
    return emp;
}

前端页面显示：

{"name":"Kitty","salary":12000.0,"age":20}

5.2 多组数据

浏览器输入：http://localhost:8080/community/alpha/emps

@GetMapping("/emps")
@ResponseBody
public List<Map<String, Object>> getEmps() {
    List<Map<String, Object>> list = new ArrayList<>();
    Map<String, Object> emp = new HashMap<>();
    emp.put("name", "Tom");
    emp.put("age", 20);
    emp.put("salary", 12000.00);
    list.add(emp);
    emp = new HashMap<>();
    emp.put("name", "Jerry");
    emp.put("age", 18);
    emp.put("salary", 15000.00);
    list.add(emp);
    emp = new HashMap<>();
    emp.put("name", "Leo");
    emp.put("age", 25);
    emp.put("salary", 8000.00);
    list.add(emp);
    return list;
}