Spring Boot中最简单的数据持久化方案JdbcTemplate,JdbcTemplate虽然简单,但是用的并不多,因为它没有MyBatis方便,在Spring+SpringMVC中整合MyBatis步骤还是有点复杂的,要配置多个Bean,Spring Boot中对此做了进一步的简化,使MyBatis基本上可以做到开箱即用,下面来看看在spring boot中整合mybatis
创建项目
创建spring boot项目,导入web依赖和mysql以及mybatis的依赖,如下图所示
在pom.xml文件中导入druid依赖以及mysql-connector的版本信息
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.1.0</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid-spring-boot-starter</artifactId>
<version>1.1.10</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
<version>5.1.27</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
工程就算是创建成功了。读者注意,MyBatis和Druid依赖的命名和其他库的命名不太一样,是属于xxx-spring-boot-stater模式的,这表示该starter是由第三方提供的。
基本配置
接下来我们需要在application.properties中配置数据源信息
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.url=jdbc:mysql:///tb_user?useUnicode=true&characterEncoding=utf-8
配置完成后,我们就可以创建mapper接口以及接口映射文件了,在此之前先创建对应数据库字段的实体类
User类
package com.zhouym.mybatis.Bean;
/**
* 〈〉
*
* @author zhouym
* @create 2019/8/11
* @since 1.0.0
*/
public class User {
private Integer id;
private String name;
private String address;
public User() {
}
public User(Integer id, String name, String address) {
this.id = id;
this.name = name;
this.address = address;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", name='" + name + '\'' +
", address='" + address + '\'' +
'}';
}
}
这里需要注意的是,如果实体类中的属性名与数据库中的字段名不一致时,可以采用两种方式解决,一种是采用别名的形式,在sql语句中采用别名,还有一种是通过reslutMap,当然这都是在接口映射文件中完成的,还可以使用java注解的形式
@Results({
@Result(property = "id", column = "id"),
@Result(property = "username", column = "u"),
@Result(property = "address", column = "a")
})
@Select("select username as u,address as a,id as id from user where id=#{id}")
User getUserById(Long id);
接下来我们创建接口类以及接口映射文件,需要添加@Mapper注解,但是不建议这样做,如果有多个mapper接口类,就需要写很多个,我们可以直接在启动类,添加mapper的路径
package com.zhouym.mybatis.mapper;
import com.zhouym.mybatis.Bean.User;
import java.util.List;
/**
* 〈〉
*
* @author zhouym
* @create 2019/8/11
* @since 1.0.0
*/
public interface UserMapper {
List<User> getUser();
int updateUser(User user);
int addUser(User user);
int deleteUser(Integer id);
}
接口映射文件
<?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.zhouym.mybatis.mapper.UserMapper">
<select id="getUser" resultType="com.zhouym.mybatis.Bean.User">
select * from t_user
</select>
<update id="updateUser" parameterType="com.zhouym.mybatis.Bean.User">
update t_user set name = #{name} where id = #{id}
</update>
<insert id="addUser" parameterType="com.zhouym.mybatis.Bean.User">
insert into t_user(address,name) values (#{address},#{name})
</insert>
<delete id="deleteUser" parameterType="com.zhouym.mybatis.Bean.User">
delete from t_user where id = #{id}
</delete>
</mapper>
注意需要注意的是,当我们的接口映射文件和接口类在同一个包下面,但是spring boot默认是去resources去查找的,没有找到就直接报错,这时需要我们将xml文件的位置告诉spring boot,此时的解决方法就是在pom.xml文件中添加以下信息
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
</includes>
</resource>
<resource>
<directory>src/main/resources</directory>
</resource>
</resources>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
让spring boot去查找src/main/java目录下所有包下的以xml文件结尾的,但是这样的话,resources目录下的文件就不会去查找了,此时还需要我们放开对resources目录下的文件查找,再配置resources目录下包的路径,让spring boot也去resources目录下查找文件,当然我们也可以直接将xml文件放在resources目录下,但不建议这样做,一般我们都是把接口文件和接口类放在同一个包下面
接下来需要在启动类中添加mapper的扫描路径
package com.zhouym.mybatis;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
@MapperScan(basePackages = "com.zhouym.mybatis.mapper")
public class MybatisApplication {
public static void main(String[] args) {
SpringApplication.run(MybatisApplication.class, args);
}
}
我们在测试类中进行测试
package com.zhouym.mybatis;
import com.zhouym.mybatis.Bean.User;
import com.zhouym.mybatis.mapper.UserMapper;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import javax.annotation.Resource;
import java.util.List;
@RunWith(SpringRunner.class)
@SpringBootTest
public class MybatisApplicationTests {
@Resource
UserMapper userMapper;
@Test
public void contextLoads() {
List<User> user = userMapper.getUser();
System.out.println(user);
}
@Test
public void test(){
User user = new User();
user.setName("赵磊");
user.setId(4);
try {
userMapper.updateUser(user);
System.out.println("更新成功");
} catch (Exception e) {
e.printStackTrace();
}
}
@Test
public void test2(){
User user = new User();
user.setName("隔壁老潘");
user.setAddress("北京老胡同");
try {
userMapper.addUser(user);
System.out.println("添加成功");
} catch (Exception e) {
e.printStackTrace();
}
}
@Test
public void test3(){
try {
userMapper.deleteUser(5);
System.out.println("删除成功");
} catch (Exception e) {
e.printStackTrace();
}
}
}