MyBatis学习
MyBatis程序
2.1、创建一个SQL表
create database mybatis;
use mybatis;
create table user(
id int(20) primary key,
name varchar(30) default null,
pwd varchar(30) default null
)engine=innodb default charset=utf8;
insert into user (id,name,pwd) values(1,"张三","123456"),
(2,"李四","1234567"),
(3,"王五","12345678");
2.2、创建项目
- 新建一个Maven项目
Maven依赖
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.49</version>
</dependency>
<!--mybatis驱动-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.3</version>
</dependency>
<!--junit-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
<scope>test</scope>
</dependency>
2.3、创建模块
- 编写mybatis核心配置文件
<!--核心配置文件-->
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/><!--事务管理-->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?userSSL=true&userUnicode=true&characterEncoding=utf-8"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
</environments>
<!--每一个Mapper.xml都要在mybatis核心配置文件中注册-->
<mappers>
<mapper resource="com/my/dao/UserMapper.xml"/>
</mappers>
</configuration>
- 编写mybatis工具类
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
//sqlSessionFactory 构建sqlSession
public class MybatisUtils {
private static SqlSessionFactory sqlSessionFactory;
static {
try{
//使用mybatis第一步 获取sqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
/* 既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例。
SqlSession 提供了在数据库执行 命令所需的所有方法。
可以通过 SqlSession 实例来直接执行已映射的 SQL 语句*/
public static SqlSession getSqlSession(){
return sqlSessionFactory.openSession();
}
}
-
编写代码
-
实体类
//实体类
public class User {
private int id;
private String name;
private String pwd;
public User() {
}
public User(int id, String name, String pwd) {
this.id = id;
this.name = name;
this.pwd = pwd;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPwd() {
return pwd;
}
public void setPwd(String pwd) {
this.pwd = pwd;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", name='" + name + '\'' +
", pwd='" + pwd + '\'' +
'}';
}
}
- Dao接口
import com.my.pojo.User;
import java.util.List;
public interface UserDao {
List<User> getUserList();
}
- 接口实现类由原来的dao转换为一个Mapper配置文件
<?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">
<!--namespace会绑定一个对应的UserDao/Mapper接口-->
<mapper namespace="com.my.dao.UserDao">
<!--查询语句 id对应方法 resultType 结果集格式-->
<select id="getUserList" resultType="com.my.pojo.User">
select * from mybatis.user
</select>
</mapper>
2.4、测试
package com.my.dao;
import com.my.pojo.User;
import com.my.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;
public class UserDaoTest {
@Test
public void test(){
//第一步，获取sqlSession对象
SqlSession sqlSession = MybatisUtils.getSqlSession();
//方式一 执行sql getMapper
UserDao userDao = sqlSession.getMapper(UserDao.class);
List<User> userList = userDao.getUserList();
for (User user : userList) {
System.out.println(user);
}
//关闭sqlSession
sqlSession.close();
}
}
运行：
总流程
各个部分代码：
配置文件
<?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>
<!--父工程-->
<groupId>org.example</groupId>
<artifactId>MyBatis-Study</artifactId>
<packaging>pom</packaging>
<version>1.0-SNAPSHOT</version>
<modules>
<module>mybatis-01</module>
</modules>
<!--导入依赖-->
<dependencies>
<!--mysql驱动-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.49</version>
</dependency>
<!--mybatis驱动-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.3</version>
</dependency>
<!--junit-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.13</version>
<scope>test</scope>
</dependency>
</dependencies>
<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.xml</include>
<include>**/*.properties</include>
</includes>
</resource>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.xml</include>
<include>**/*.properties</include>
</includes>
</resource>
</resources>
</build>
</project>
工具类
package com.my.utils;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.InputStream;
//sqlSessionFactory 构建sqlSession
public class MybatisUtils {
private static SqlSessionFactory sqlSessionFactory;
static {
try{
//使用mybatis第一步 获取sqlSessionFactory对象
String resource = "mybatis-config.xml";
InputStream inputStream = Resources.getResourceAsStream(resource);
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
/* 既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例。
SqlSession 提供了在数据库执行 命令所需的所有方法。
可以通过 SqlSession 实例来直接执行已映射的 SQL 语句*/
public static SqlSession getSqlSession(){
return sqlSessionFactory.openSession();
}
}
mybatis配置文件
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<!--核心配置文件-->
<configuration>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/><!--事务管理-->
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&userUnicode=true&characterEncoding=utf-8"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</dataSource>
</environment>
</environments>
<!--每一个Mapper.xml都要在mybatis核心配置文件中注册-->
<mappers>
<mapper resource="com/my/dao/UserMapper.xml"/>
</mappers>
</configuration>
实体类
package com.my.pojo;
//实体类
public class User {
private int id;
private String name;
private String pwd;
public User() {
}
public User(int id, String name, String pwd) {
this.id = id;
this.name = name;
this.pwd = pwd;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPwd() {
return pwd;
}
public void setPwd(String pwd) {
this.pwd = pwd;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", name='" + name + '\'' +
", pwd='" + pwd + '\'' +
'}';
}
}
接口和Mapper.xml
package com.my.dao;
import com.my.pojo.User;
import java.util.List;
public interface UserDao {
List<User> getUserList();
}
<?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">
<!--namespace会绑定一个对应的UserDao/Mapper接口-->
<mapper namespace="com.my.dao.UserDao">
<!--查询语句 id对应方法 resultType 结果集格式-->
<select id="getUserList" resultType="com.my.pojo.User">
select * from mybatis.user
</select>
</mapper>