4.Spring MVC入门

文章目录

• [1. HTTP协议](#1. HTTP协议)
• [2. Spring MVC](#2. Spring MVC)
• • [2.1. 三层架构](#2.1. 三层架构)
  • [2.2. MVC（解决表现层的问题）](#2.2. MVC（解决表现层的问题）)
  • [2.3. 核心组件](#2.3. 核心组件)
• [3. Thymeleaf](#3. Thymeleaf)
• • [3.1. 模板引擎](#3.1. 模板引擎)
  • [3.2. Thymeleaf](#3.2. Thymeleaf)
  • [3.3. 常用语法](#3.3. 常用语法)
• 代码

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1. HTTP协议

网址：https://www.ietf.org/ （官网网址）
https://developer.mozilla.org/zh-CN/ （易于理解）

HyperText Transfer Potocal

用于传输HTML等内容的应用层协议

规定了浏览器和服务器之间如何通信，以及通信时的数据格式

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2. Spring MVC

2.1. 三层架构

表现层、业务层、数据访问层

2.2. MVC（解决表现层的问题）

Model： 模型层

View： 视图层

Controller：控制层

2.3. 核心组件

前端控制器：DispatcherServlet

3. Thymeleaf

网址：http://thymeleaf.org/

3.1. 模板引擎

生成动态的HTML

3.2. Thymeleaf

倡导自然模板，即以HTML文件为模板

3.3. 常用语法

标准表达式、判断与循环、模板的布局

代码

package com.test.community.controller;

import com.test.community.service.AlphaService;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.servlet.ModelAndView;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;

/**
 * @ClassName AlphaController
 * @Description TODO
 * @Author lcx
 * @Date 2024/2/21 15:22
 * @Version 1.0
 */
@Controller
@RequestMapping("/alpha")
public class AlphaController {

    @Autowired
    private AlphaService alphaService;

    @RequestMapping("/hello")
    @ResponseBody
    public String sayHello() {
        return "Hello Spring Boot!";
    }

    @RequestMapping("/data")
    @ResponseBody
    public String getData() {
        return alphaService.find();
    }

    // SpringMVC获得请求对象和响应对象
    @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);
        }

        // 请求体
        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>牛客网</h1>");
        } catch (IOException e) {
            e.printStackTrace();
        }

    }


    // GET请求
    // 查询所有学生  /students?current=1&limit=20
    @RequestMapping(path = "/students", method = RequestMethod.GET)
    @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";
    }

    // /student/123
    @RequestMapping(path = "/student/{id}", method = RequestMethod.GET)
    @ResponseBody
    public String getStudent(@PathVariable("id") int id) {
        System.out.println(id);
        return "a student";
    }

    // 浏览器向服务器提交数据
    // POST请求
    @RequestMapping(path = "/student", method = RequestMethod.POST)
    @ResponseBody
    public String saveStudent(String name, int age) {
        System.out.println(name);
        System.out.println(age);
        return "success";
    }

    // 响应HTML数据
    @RequestMapping(path = "/teacher", method = RequestMethod.GET)
    @ResponseBody
    public ModelAndView getTeacher() {
        ModelAndView mav = new ModelAndView();
        mav.addObject("name", "张三");
        mav.addObject("age", 12);
        mav.setViewName("/demo/view");
        return mav;
    }

    @RequestMapping(path = "/school", method = RequestMethod.GET)
    public String getSchool(Model model) {
        model.addAttribute("name", "北京大学");
        model.addAttribute("age", 123);
        return "/demo/view";
    }

    // 异步请求中响应JSON数据
    // java对象 -> JSON字符串 -> JS对象
    @RequestMapping(path = "/emp", method = RequestMethod.GET)
    @ResponseBody
    public Map<String, Object> getEmp() {
        Map<String, Object> emp = new HashMap<>();
        emp.put("name", "张三");
        emp.put("age", 12);
        emp.put("salary", 8000.00);
        return emp;
    }

    @RequestMapping(path = "/emps", method = RequestMethod.GET)
    @ResponseBody
    public List<Map<String, Object>> getEmps() {
        List<Map<String, Object>> list = new ArrayList<>();
        Map<String, Object> emp = new HashMap<>();
        emp.put("name", "张三");
        emp.put("age", 12);
        emp.put("salary", 8000.00);
        list.add(emp);
        emp = new HashMap<>();
        emp.put("name", "李四");
        emp.put("age", 22);
        emp.put("salary", 9000.00);
        list.add(emp);
        emp = new HashMap<>();
        emp.put("name", "王五");
        emp.put("age", 32);
        emp.put("salary", 10000.00);
        list.add(emp);
        return list;
    }



}

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