基于Maven构建Mybatis项目
目录
- 项目根目录添加porm文件
- 在src/main/resources下创建数据库对应的实体类：Admin，其符合JavaBean的标准
- 在src/main/java下创建AdminMapper接口，用于操作Admin类
- 在src/main/resources下添加数据库配置文件：db.properties
- 在src/main/resources下添加mybatis配置文件：mybatis-config.xml
- 在AdminMapper接口的同一目录下创建AdminMapper.xml文件
- 创建工具类：SqlSessionFactoryUtil类，用于启动Mybatis，获得Mybatis的相关入口
- 执行main函数，测试代码，若能成功运行则构建正确
使用的数据库配置参考笔记-example数据库内容
项目根目录添加porm文件
<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.hao.example</groupId>
<artifactId>MavenMybatis</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<!-- 数据库驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.32</version>
</dependency>
<!-- 引入mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.3.0</version>
</dependency>
</dependencies>
<build>
<plugins>
<!-- 定义Java版本 -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>
</plugins>
<resources>
<resource>
<!-- 由于想将Mapper.xml文件和Mapper接口放在一起，
故将src/main/java添加到资源搜索目录 -->
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
<!-- 原有的src/main/resources也要添加到资源搜索目录 -->
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
</build>
</project>
在src/main/resources下创建数据库对应的实体类：Admin，其符合JavaBean的标准
package com.hao.example.po;
public class Admin {
private Integer id;
private String username;
private String password;
public Admin() {
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
@Override
public String toString() {
return "Admin [id=" + id + ", username=" + username + ", password="
+ password + "]";
}
}
在src/main/java下创建AdminMapper接口，用于操作Admin类
AdminMapper和Hibernate中的AdminDao是一个东西，只不过在Mybatis更习惯称为Mapper
package com.hao.example.mapper;
import com.hao.example.po.Admin;
public interface AdminMapper {
public Admin getAdmin(Integer id);
public int deleteAdmin(Integer id);
public int insertAdmin(Admin admin);
}
在src/main/resources下添加数据库配置文件：db.properties
jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/example?characterEncoding=utf-8
jdbc.username=root
jdbc.password=h66666
在src/main/resources下添加mybatis配置文件：mybatis-config.xml
<?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">
<configuration>
<!-- 引入数据源配置文件 -->
<properties resource="db.properties" />
<!-- 为了避免一直编写包全名，定义别名以方便引用Admin类，Admin类可查看代码 -->
<typeAliases>
<typeAlias type="com.hao.example.po.Admin" alias="admin"/>
</typeAliases>
<!-- 定义数据库环境，且默认使用development环境 -->
<environments default="development">
<!-- 定义id为development的数据库环境 -->
<environment id="development">
<!-- 采用jdbc事务管理 -->
<transactionManager type="JDBC"/>
<!-- 配置数据库连接信息 -->
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</dataSource>
</environment>
</environments>
<!-- 定义映射器 -->
<mappers>
<!-- 引入AdminMapper映射器配置文件 -->
<mapper resource="com/hao/example/mapper/AdminMapper.xml"/>
</mappers>
</configuration>
在AdminMapper接口的同一目录下创建AdminMapper.xml文件
AdminMapper.xml相当于AdminMapper接口的实现类，Mybatis框架会利用动态代理技术，将AdminMapper.xml文件转化为AdminMapper接口的实现类，因此要注意，AdminMapper接口中的函数，在AdminMapper.xml文件中都要有对应的标签，以执行相应的SQL语句
<?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.hao.example.mapper.AdminMapper">
<select id="getAdmin" resultType="admin" parameterType="int">
select * from admin where id = #{id}
</select>
<insert id="insertAdmin" parameterType="admin">
insert into admin(username, password) values(#{username}, #{password})
</insert>
<delete id="deleteAdmin" parameterType="int">
delete from admin where id = #{id}
</delete>
</mapper>
创建工具类：SqlSessionFactoryUtil类，用于启动Mybatis，获得Mybatis的相关入口
package com.hao.example.utils;
import java.io.InputStream;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
/**
* 创建SqlSessionFactory的工具类，实现为单例模式
*
*/
public class SqlSessionFactoryUtil {
// SqlSessionFactory对象
private static SqlSessionFactory sqlSessionFactory = null;
// 类线程锁
private static final Class<SqlSessionFactoryUtil> CLASS_LOCK = SqlSessionFactoryUtil.class;
/**
* 私有化默认构造函数
*/
private SqlSessionFactoryUtil() {
}
/**
* 构建SqlSessionFactory
* @return
*/
public static SqlSessionFactory initSqlSessionFactory(){
String resource = "mybatis-config.xml";
InputStream inputStream = null;
try {
inputStream = Resources.getResourceAsStream(resource);
} catch (Exception e) {
Logger.getLogger(SqlSessionFactoryUtil.class.getName()).log(Level.SEVERE, null, e);
}
// 为了避免并发状态下的SqlSessionFactory不唯一，需要添加锁
synchronized(CLASS_LOCK){
if(sqlSessionFactory == null){
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
}
}
return sqlSessionFactory;
}
/**
* 获得一个新的Session
* @return
*/
public static SqlSession openSession(){
if(sqlSessionFactory == null){
initSqlSessionFactory();
}
return sqlSessionFactory.openSession();
}
}
执行main函数，测试代码，若能成功运行则构建正确
package com.hao.example.main;
import org.apache.ibatis.session.SqlSession;
import com.hao.example.mapper.AdminMapper;
import com.hao.example.po.Admin;
import com.hao.example.utils.SqlSessionFactoryUtil;
public class Main {
public static void main(String[] args) throws Exception {
SqlSession sqlSession = null;
try {
sqlSession = SqlSessionFactoryUtil.openSession();
AdminMapper adminMapper = sqlSession.getMapper(AdminMapper.class);
Admin admin = adminMapper.getAdmin(2);
System.out.println(admin);
sqlSession.commit();
} catch (Exception e) {
System.out.println(e);
sqlSession.rollback();
}finally{
if(sqlSession != null){
sqlSession.close();
}
}
}
}
