SpringBoot与Mysql

1.复习JDBC

//第一步，注册驱动程序
    Class.forName("数据库驱动的完整类名");
    //第二步，获取一个数据库的连接
    Commection conn = DriverManager.getConnection("数据库地址","用户名","密码");
    //第三步，创建一个会话
    Statement stmt = conn.createStatement();
    //第四步，执行SOL语句
    stmt.executeUpdate("SQL语句");
    //或者查询记录
    ResultSet rs = stmt.executeQuery("查询记录的SQL语句");
    //第五步，对查询的结果进行处理
    while(rs.next()){
        //操作
    }
    //第六步，关闭连接
    rs.close();
    stmt.close();
    conn.close();

2.引入JDBC依赖

在pom.xml文件中添加jdbc的场景启动器spring-boot-starter-jdbc和mysql-connector-java

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.23</version>
            <scope>runtime</scope>
        </dependency>

3.填写配置文件application.properties

#jdbc
spring.datasource.name==newbee-mall-datasource
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test_db?useUnicode=true&serverTimezone=Asia/Shanghai&characterEncoding=utf8&autoReconnect=true&useSSL=false&allowMultiQueries=true&useAffectedRows=true
spring.datasource.username=root
spring.datasource.password=123456

4.编写测试类测试数据库是否连接成功

在test文件下编写测试并运行，在其他地方编写测试类需要在配置文件中去掉

spring-boot-starter-test的scope

package ltd.newbee.mall;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

@SpringBootTest
class NewbeeMallApplicationTests {

    //注入数据源对象
    @Autowired
    private DataSource defaultDataSource;

    @Test
    public void datasourceTest() throws SQLException{
        //获取数据库连接对象
        Connection connection = defaultDataSource.getConnection();
        System.out.print("获取连接:");
        //判断连接对象是否为空
        System.out.println(connection !=null);
        connection.close();
    }

    @Test
    void contextLoads() {
    }
}

5. JDBCTemplate

5.1创建测试表

DROP TABLE IF EXISTS jdbc_test;

CREATE TABLE jdbc_test (
    ds_id int(11) NOT NULL AUTO_INCREMENT COMMENT '主键id',
    ds_type varchar(100) DEFAULT NULL COMMENT '数据源类型',
    ds_name varchar(100) DEFAULT NULL COMMENT '数据源名称',
    PRIMARY KEY (ds_id) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8;

/* Data for the table 'jdbc test' */
insert into jdbc_test (ds_id,ds_type,ds_name)
value (1,'com.java','java'),
(2,'com.jdbc','jdbc');

5.2对测试表的数据进行增删改查

public class JdbcController {

    //已经自动配置，因此可以直接通过@Autowired 注入进来
    @Autowired
    JdbcTemplate jdbcTemplate;

    //新增一条记录
    @GetMapping("/insert")
    public String insert(String type,String name){
        if (StringUtils.isEmpty(type)||StringUtils.isEmpty(name)){
            return "参数异常";
        }
        jdbcTemplate.execute("insert into jdbc_test('da_type','ds_name') value (\""+type+"\",\""+name+"\")");
        return "SQL执行完毕";
    }

    //删除一条记录
    @GetMapping("/delete")
    public String delete(int id){
        if (id < 0){
            return "参数异常";
        }
        List<Map<String,Object>> result = jdbcTemplate.queryForList("select * from jdbc_test where ds_id = \"" + id +"\"");
        if (CollectionUtils.isEmpty(result)){
            return"不存在该记录，删除失败";
        }
        jdbcTemplate.execute("delete from jdbc_test where ds_id=\"" + id + "\"");

        return "SQL执行完毕";
    }

    //修改一条记录
    @GetMapping("/update")
    public String update(int id ,String type,String name){
        if (id<0||StringUtils.isEmpty(type)||StringUtils.isEmpty(name)){
            return "参数异常";
        }
        List<Map<String,Object>>result = jdbcTemplate.queryForList("select * from jdbc_test where ds_id = \"" + id + "\"");
        if (CollectionUtils.isEmpty(result)){
            return "不存在该记录，无法修改";
        }
        jdbcTemplate.execute("update jdbc_test set ds_type=\""+ type + "\",ds_name = \"" + "\" where ds_id=\"" + id + "\"");
        return "SQL执行完毕";
    }

    //查询所有记录
    @GetMapping("/queryALL")
    public List<Map<String,Object>> queryALL(){
        List<Map<String,Object>> list = jdbcTemplate.queryForList("select * from jdbc_test");
        return list;
    }
}