SpringBoot入门4

SpringBoot入门4

整合SpringBoot连接池

• java为数据库连接池提供了公共的接口：DataSource
• 常见的连接池：CP30,DBCP,DRUID,hikariCP
• 用户调用getConnection()方法获得一个连接。如果连接池里没有连接，就会调用Driver（驱动）对象的connec()方法从数据中获取，并在连接池中存放一份，然后将连接返回给调用方。

整合HikariCP连接池

• 1.添加依赖

• 2.配置连接池
  spring.datasource.url=jdbc:mysql://localhost:3306/数据库?serverTimezone=GMT%2B8
  spring.datasource.username=root
  spring.datasource.password=root

@SpringBootTest
public class TestDataSource {

    // dataSource对象在运行时指向的具体对象是什么？HikariDataSource
    // dataSource是谁创建的？spring框架（基于底层自动配置）

    @Autowired
    private DataSource dataSource;

    @Test
    void testSource() throws SQLException {
        System.out.println(dataSource.getClass().getName());// com.zaxxer.hikari.HikariDataSource
        // 获取连接的过程？getConnection()查询是否有连接池，没有就构建
        // 基于Driver对象创建连接，并将链接放入池中，最后从池中获取用户需要的链接
        Connection connection = dataSource.getConnection();
        System.out.println(connection);

    }

}

整合MyBatis框架

• 添加Mybatis依赖：mybatis.org/spring

• 配置文件：

mybatis.configuration.default-statement-timeout=30
mybatis.configuration.map-underscore-to-camel-case=true
// sql映射的映射文件方式
mybatis.mapper-locations=classpath:/mapper/*/*.xml

// 日志输出
logging.level.com.cy=DEBUG

代码测试（按id删除数据库内容）

• 初始化数据库

drop database if exists dbgoods;
create database dbgoods default character set utf8;
use dbgoods;
create table tb_goods(
     id bigint primary key auto_increment,
     name varchar(100) not null,
     remark text,
     createdTime datetime not null
)engine=InnoDB;
insert into tb_goods values (null,'java','very good',now());
insert into tb_goods values (null,'mysql','RDBMS',now());
insert into tb_goods values (null,'Oracle','RDBMS',now());
insert into tb_goods values (null,'java','very good',now());
insert into tb_goods values (null,'mysql','RDBMS',now());
insert into tb_goods values (null,'Oracle','RDBMS',now());
insert into tb_goods values (null,'java','very good',now());
insert into tb_goods values (null,'mysql','RDBMS',now());
insert into tb_goods values (null,'Oracle','RDBMS',now());
insert into tb_goods values (null,'java','very good',now());
insert into tb_goods values (null,'mysql','RDBMS',now());
insert into tb_goods values (null,'Oracle','RDBMS',now());

• 创建com.py.pj.goods.dao.GoodsDao.java

package com.py.pj.goods.dao;



import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface GoodsDao {

    int deleteObjects(Integer... ids);
    
    @Delete("delete from tb_goods where id=#{id}")
    int deleteById(Integer id);

}

• 创建测试类 com.py.pj.goods.dao.TestDataSource.java

package com.py.pj.goods.dao;

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

/**
* @author WL
* @version 创建时间：2020-8-29 9:39:21
* @Description 测试mapper注释的接口功能
*/
@SpringBootTest
public class TestGoodsDao {
    
    /**
     *     关联数据层接口，并由spring注入值
     * 1.GoodsDao指向的对象是谁？由谁创建？由谁管理？
     * $Proxy56是代理对象  /由mybatis创建/   Spring框架         
     * 2.GoodsDao指向的对象内部会做什么事情？
     *     基于mybatis API进行会话操作。此变量指向的对象，底层会通过mybatis中的sqlsession实现与数据库对话    
     */
    
    //GoodsDao接口的实现类$Proxy56由mybatis创建，mybatis底层基于反射使用到了Proxy类，
    @Autowired
    private GoodsDao goodsdao; //此变量指向的对象，底层会通过mybatis中的sqlsession实现与数据库对话    
    
    
    @Test
    public void testGoods() {
        int rows = goodsdao.deleteById(3);
        System.out.println(rows);
    }
    
    @Test
    void testDeleteObjects() {
        int rows = goodsdao.deleteObjects( );
        System.out.println(rows);
        
    }

}

• 创建映射文件

  

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.py.pj.goods.dao.GoodsDao">


    <!--  -->
    <delete id="deleteObjects">
        delete from tb_goods where id in
        <foreach collection="ids" open="(" close=")" separator=","
            item="id">
            #{id}
        </foreach>
    </delete>
</mapper>