springboot与mybatis整合操作数据库

    今天这篇博客主要介绍springboot与mybatis整合操作数据库，数据源采用阿里的Druid。mybatis可以基于注解也可以基于xml配置。至于怎么新建maven项目这里不再做介绍。

1、首先要新建一个maven项目，项目结构如下，注意启动类的springboot启动类要在所有类的父一级目录。



2、pom.xml配置如下：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion>

<groupId>com.example</groupId>
<artifactId>demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>demo</name>
<description>Demo project for Spring Boot</description>

<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.6.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>

<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>

<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>

<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<!-- druid数据库连接池 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.0.26</version>
</dependency>
<!-- springboot的mybatis -->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.1.1</version>
</dependency>
<!-- MySql数据库驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
</dependency>
<!-- Springboot 热部署 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
<optional>true</optional>
</dependency>
</dependencies>

<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>

</project>
2、配置application.properties文件
主要包括数据库连接池，mapper映射等

#数据库设置
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test_db
spring.datasource.username=root
spring.datasource.password=root
#--------------------------
# 下面为连接池的补充设置，应用到上面所有数据源中
# 初始化大小，最小，最大
spring.datasource.initialSize=5
spring.datasource.minIdle=5
spring.datasource.maxActive=20
# 配置获取连接等待超时的时间
spring.datasource.maxWait=60000
# 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
spring.datasource.timeBetweenEvictionRunsMillis=60000
# 配置一个连接在池中最小生存的时间，单位是毫秒
spring.datasource.minEvictableIdleTimeMillis=300000
spring.datasource.validationQuery=SELECT 1 FROM DUAL
spring.datasource.testWhileIdle=true
spring.datasource.testOnBorrow=false
spring.datasource.testOnReturn=false
# 打开PSCache，并且指定每个连接上PSCache的大小
spring.datasource.poolPreparedStatements=true
spring.datasource.maxPoolPreparedStatementPerConnectionSize=20
# 配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙
spring.datasource.filters=stat,wall,log4j
# 通过connectProperties属性来打开mergeSql功能；慢SQL记录
spring.datasource.connectionProperties=druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
# 合并多个DruidDataSource的监控数据
#spring.datasource.useGlobalDataSourceStat=true

#配置mapper映射
mybatis.mapperLocations=classpath*:com/example/mapper/*.xml
mybatis.typeAliasesPackage=com.example.domain3、创建mapper文件UserMapper.java
package com.example.mapper;

import org.apache.ibatis.annotations.Mapper;

import com.example.domain.User;

@Mapper
public interface UserMapper {

// @Select({"select * from t_user where id=#{id}"})
// User getUserById(@Param("id") Integer id);

User getUserById(Integer id);
}
备注：目前展示的是mybatis基于xml配置的方式操作数据库，如果想基于注解的方式可以直接使用注释部分代码，不用再去创建xml映射配置，同时application.properties中如下配置可以去掉。
#配置mapper映射
mybatis.mapperLocations=classpath*:com/example/mapper/*.xml
mybatis.typeAliasesPackage=com.example.domain

4、创建sql_userMapper.xml
<?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.example.mapper.UserMapper" >

<select id="getUserById" resultType="com.example.domain.User">
select * from t_user where id = #{id,jdbcType=NUMERIC}
</select>

</mapper>5、接下来就是创建DAO,Service类。这部分代码就不粘贴了。
6、创建controller类，UserController.java

package com.example.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import com.example.domain.User;
import com.example.service.UserService;

@RestController
@RequestMapping("/user")
public class UserController {

@Autowired
private UserService userService;

@RequestMapping("/getUserbyId")
public User getUser(@RequestParam String id){

User user= userService.getUserById(Integer.valueOf(id));

return user;
}

}

7、启动类DemoApplication.java

package com.example;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.transaction.annotation.EnableTransactionManagement;

@SpringBootApplication
//启注解事务管理
@EnableTransactionManagement
public class DemoApplication {

public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}
备注：点击@SpringBootApplication进入源码会发现这个注解已经包含了一系列的注解，所以引用了@SpringBootApplication这个注解就可以不用再去引用@EnableAutoConfiguration，@ComponentScan这些注解了。
8、运行DemoApplication.java，在浏览器中输入
http://localhost:8080/user/getUserbyId?id=1，可以看到返回的数据