springboot（一）

目录准备工作

1、配置好JDK

2、IntelliJ编辑器

1、用IDEA新建spring boot项目

1、Developer Tools（必选）

         -Spring Boot DevTools

         -Lombok

2、Web （必选）

        -Spring Web

        -Spring Web Services 

3、Template Engines（可选，后期可在prom.xml文件中添加此依赖）

        -Thymeleaf

2、若编写Rest Api，则写入如下代码后，运行，直接访问http://localhost:8080/abc 即可

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController

public class DemoApplication {

    @RequestMapping("abc")
    public static String abc(){
        return "abc";
    }

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

}

3、若访问html，则需要以下配置

1、在resources/templates里面放置 html文件

2、在resources/static里面放置 css image js 等静态资源

3、在控制中写入如下代码

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

@Controller

public class DemoApplication {

    @GetMapping("def")
    public String he(){
        return "def";
    }

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

}

注：可以在application.properties配置项目

spring.thymeleaf.cache=false
spring.thymeleaf.prefix=classpath:/templates/
spring.thymeleaf.suffix=.html

4、连接数据库

4.1、引入依赖

<dependency>
  <groupId>mysql</groupId>
  <artifactId>mysql-connector-java</artifactId>
  <scope>runtime</scope>
</dependency>
<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-jdbc</artifactId>
   <version>2.2.6.RELEASE</version>
</dependency>

4.2、配置数据库（application.properties/application.yml）

此处有两种方法，任选其一即可

4.2.1、application.properties

此处注意，新版本的spring.datasource.driverClassName = com.mysql.cj.jdbc.Driver（老版本com.mysql.jdbc.Driver已弃用）

spring.datasource.url = jdbc:mysql://127.0.0.1:3306/jianshu?useUnicode=true&characterEncoding=utf-8&serverTimezone=GMT%2B8
spring.datasource.username = root123
spring.datasource.password = root123
spring.datasource.driverClassName = com.mysql.cj.jdbc.Driver

4.2.2、application.yml

此处注意，新版本的com.mysql.cj.jdbc.Driver（老版本 com.mysql.jdbc.Driver已弃用）

spring:
  datasource:
    username: root123
    password: root123
    url: jdbc:mysql://localhost:3306/jianshu
    driver-class-name: com.mysql.jdbc.Driver

4.3、打印数据

此处直接打印，快速测试用

import org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.List;
import java.util.Map;

@SpringBootApplication

public class DemoApplication {

    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(DemoApplication.class, args);

        JdbcTemplate jdbcTemplate = context.getBean(JdbcTemplate.class);

        List<Map<String, Object>> result = jdbcTemplate.queryForList("select * from students");

        System.out.println(result);
    }

}

4.4、增删改查CRUD

此处使用4个接口进行操作

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

import java.util.List;
import java.util.Map;

@RestController

public class JDBCController {

    @Autowired
    JdbcTemplate jdbcTemplate;

    @GetMapping("/userList")
    public List<Map<String, Object>> userList(){
        String sql = "select * from students";
        List<Map<String, Object>> maps = jdbcTemplate.queryForList(sql);
        return maps;
    }

    @GetMapping("/addUser")
    public String addUser(){
        String sql = "insert into students (name) values ('aa')";
        jdbcTemplate.update(sql);
        return 'add successfully, the sql is ' + sql;
    }

    @GetMapping("/updateUser/{id}")
    public String updateUser(@PathVariable("id") int id){
        String sql = "update students set name = ?,tel = ?  where id = " + id;
        Object[] objects = new Object[2];
        objects[0] = "wang";
        objects[1] = "13588888888";
        jdbcTemplate.update(sql, objects);
        return 'update successfully, the sql is ' + sql;
    }

    @GetMapping("/deleteUser/{id}")
    public int deleteUser(@PathVariable("id") int id){
        String sql = "delete from students where id =  ?";
        jdbcTemplate.update(sql, id);
        return 'delete successfully, the sql is ' + sql;
    }

}