测试项目(二):重做后端

好家伙，上一篇做出来问题多多，

问题太多了，包括但不限于
前端报错：1.超出调用栈 2.跨域错误

vue3确实有很多我不熟悉的地方

所以，我们用回vue2吧

这里全部用回之前的方法

Springboot连接数据库 - 养肥胖虎 - 博客园 (cnblogs.com)

1、去新建一个spring boot项目

目录结构如下：

然后我们去到

application.properties这个文件中：

spring.datasource.url=jdbc:mysql://127.0.0.1:3306/test?useUnicode=true&characterEncoding=utf8&useSSL=false

spring.datasource.username=root
spring.datasource.password=root
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.max-idle=10
spring.datasource.max-wait=10000
spring.datasource.min-idle=5
spring.datasource.initial-size=5

server.port=8011
server.session.timeout=10
server.tomcat.uri-encoding=UTF-8

（注意，绿色那块不是注释）

TestController类：

package com.example.demo2.controller;   //按文件的实际路径来写

import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/mydb")
public class TestController {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    @RequestMapping("/getUsers")
    public List<Map<String, Object>> getDbType(){
        String sql = "select * from booktable";
        List<Map<String, Object>> list =  jdbcTemplate.queryForList(sql);
        for (Map<String, Object> map : list) {
            Set<Entry<String, Object>> entries = map.entrySet( );
            if(entries != null) {
                Iterator<Entry<String, Object>> iterator = entries.iterator( );
                while(iterator.hasNext( )) {
                    Entry<String, Object> entry =(Entry<String, Object>) iterator.next( );
                    Object key = entry.getKey( );
                    Object value = entry.getValue();
                    System.out.println(key+":"+value);
                }
            }
        }
        return list;
    }

    @RequestMapping("/user/{id}")
    public Map<String,Object> getUser(@PathVariable String id){
        Map<String,Object> map = null;

        List<Map<String, Object>> list = getDbType();

        for (Map<String, Object> dbmap : list) {

            Set<String> set = dbmap.keySet();

            for (String key : set) {
                if(key.equals("id")){
                    if(dbmap.get(key).equals(id)){
                        map = dbmap;
                    }
                }
            }
        }

        if(map==null)
            map = list.get(0);
        return map;
    }

}