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.DruidDataSourcespring.datasource.driverClassName=com.mysql.jdbc.Driverspring.datasource.url=jdbc:mysql://localhost:3306/test_dbspring.datasource.username=rootspring.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=5spring.datasource.minIdle=5spring.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=300000spring.datasource.validationQuery=SELECT 1 FROM DUALspring.datasource.testWhileIdle=truespring.datasource.testOnBorrow=falsespring.datasource.testOnReturn=false# 打开PSCache，并且指定每个连接上PSCache的大小   spring.datasource.poolPreparedStatements=truespring.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/*.xmlmybatis.typeAliasesPackage=com.example.domain

3、创建mapper文件UserMapper.java

package com.example.mapper;import org.apache.ibatis.annotations.Mapper;import com.example.domain.User;@Mapperpublic 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/*.xmlmybatis.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 {@Autowiredprivate 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  @EnableTransactionManagementpublic 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