MyBatis 简单入门案例

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项目目录结构

 

项目依赖

<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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>xyz.cglzwz</groupId>
  <artifactId>mybatis-demo1</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>mybatis-demo1 Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
       <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
	<dependency>
   	 <groupId>javax.servlet</groupId>
   	 <artifactId>javax.servlet-api</artifactId>
   	 <version>4.0.1</version>
    	<scope>provided</scope>
	</dependency>
	
	<!-- https://mvnrepository.com/artifact/log4j/log4j -->
	<dependency>
    	<groupId>log4j</groupId>
    	<artifactId>log4j</artifactId>
    	<version>1.2.17</version>
	</dependency>
	
    
    <!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
	<dependency>
  	  <groupId>org.mybatis</groupId>
    	<artifactId>mybatis</artifactId>
    	<version>3.4.6</version>
	</dependency>
    <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
	<dependency>
    	<groupId>mysql</groupId>
    	<artifactId>mysql-connector-java</artifactId>
    	<version>8.0.12</version>
	</dependency>
  </dependencies>
  <build>
    <finalName>mybatis-demo1</finalName>
  </build>
</project>

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>
	<!-- 导入properties文件 -->
	<properties resource="jdbc.properties"/>
	
	<!-- alias别名 -->
	<typeAliases>
		<typeAlias alias="role" type="xyz.cglzwz.mybatis.demo1.pojo.Role"/>
	</typeAliases>
	
	<!-- 数据库环境 -->
	<environments default="development">
		<environment id="development">
			<!-- 使用jdbc事务管理 -->
			<transactionManager type="JDBC"/>
			<!-- 数据库连接池 -->
			<dataSource type="POOLED">
				<property name="driver" value="${database.driver}"/>
				<property name="url" value="${database.url}"/>
				<property name="username" value="${database.username}"/>
				<property name="password" value="${database.password}"/>
			</dataSource>
		</environment>
	</environments>
	
	<!-- 映射文件 -->
	<mappers>
		<mapper resource="xyz/cglzwz/mybatis/demo1/mapper/RoleMapper.xml"/>
	</mappers>

</configuration>

jdbc.properties和log4j.properties配置文件

database.driver=com.mysql.cj.jdbc.Driver
database.url=jdbc:mysql:///mybatis_demo1?serverTimezone=UTC&characterEncoding=UTF-8&useSSL=false
database.username=root
database.password=mima

log4j.rootLogger=DEBUG , stdout
log4j.logger.org.mybatis=DEBUG
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p %d %c: %m%n

pojo类Role.java

package xyz.cglzwz.mybatis.demo1.pojo;

/**
 * @author chgl16
 * @Date 2018.9.26
 */
public class Role {
	
	private Long id;
	private String roleName;
	private String note;
	
	public Long getId() {
		return id;
	}
	public void setId(Long id) {
		this.id = id;
	}
	public String getRoleName() {
		return roleName;
	}
	public void setRoleName(String roleName) {
		this.roleName = roleName;
	}
	public String getNote() {
		return note;
	}
	public void setNote(String note) {
		this.note = note;
	}
	
	public Role() {
		
	}
	public Role(Long id, String roleName, String note) {
		super();
		this.id = id;
		this.roleName = roleName;
		this.note = note;
	}
	
}

对应数据库数据表

DROP DATABASE IF EXISTS mybatis_demo1;
CREATE DATABASE mybatis_demo1 DEFAULT CHARACTER SET utf8;

USE mybatis_demo1;
CREATE TABLE t_role(
  id BIGINT(18) NOT NULL AUTO_INCREMENT,
  role_name VARCHAR(255) NOT NULL,
  note VARCHAR(255),
  PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO t_role VALUES(1, '小明', '明日之前');
INSERT INTO t_role VALUES(2, '小米', '小米科技');
INSERT INTO t_role VALUES(3, '小红', '红色的火');

SqlSession对象获取的工具类，也是读取mybatis-config配置类

package xyz.cglzwz.mybatis.demo1.util;

import java.io.InputStream;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

/**
 * @使用mybatis-conf.xml
 * @通过SqlSessionFactoryBuilder来构建SqlSessionFactory
 * @SqlSessionFactory应是单例模式，此处省略了单例锁代码
 * 
 * @author chgl16
 * @Date 2018.9.26
 */
public class SqlSessionFactoryUtil {
	
	/** 声明为static */
	public static SqlSession openSqlSession() throws Exception {
		String sqlConfigXML = "mybatis-config.xml";
		// 将资源文件输入到流
		InputStream inputStream = Resources.getResourceAsStream(sqlConfigXML);
		// SqlSessionFactoryBuilder对象调用build方法读取输入流
		SqlSessionFactory build = new SqlSessionFactoryBuilder().build(inputStream);
		return build.openSession();
	}
}

映射器（此处采用：由一个xml文件和java接口组成）

<?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表示对应的接口类 -->
<mapper namespace="xyz.cglzwz.mybatis.demo1.mapper.RoleMapper">

	<!-- role是使用了mybatis-config.xml里面的全局别名 -->
	<insert id="insertRole" parameterType="role">
		insert into t_role(role_name, note) values(#{roleName}, #{note})
	</insert>
	
	<delete id="deleteRole" parameterType="Long">
		delete from t_role where id = #{id}
	</delete>
	
	<update id="updateRole" parameterType="role">
		update t_role set role_name = #{roleName}, note = #{note} where id = #{id}
	</update>
	
	<!-- 此处包含sql到pojo的映射，所有字段和属性名要一致，故此处使用别名，也可以用resultMap结果集映射 -->
	<select id="getRole" parameterType="Long" resultType="role">
		select id, role_name as roleName, note from t_role where id = #{id}
	</select>
	
	<!-- 使用了sql匹配语法 -->
	<select id="findRoles" parameterType="String" resultType="role">
		select id, role_name as roleName, note from t_role
		where role_name like concat('%', #{roleName}, '%')
	</select>
		
</mapper>

package xyz.cglzwz.mybatis.demo1.mapper;

import java.util.List;
import xyz.cglzwz.mybatis.demo1.pojo.Role;;

/**
 * @映射器的接口类
 * 
 * @author chgl16
 * @Date 2018.9.26
 */

public interface RoleMapper {
	public int insertRole(Role role);
	public int deleteRole(Long id);
	public int updateRole(Role role);
	public Role getRole(Long id);
	public List<Role> findRoles(String roleName);
}

测试的主类

package xyz.cglzwz.mybatis.demo1.main;

import org.apache.ibatis.session.SqlSession;
import org.apache.log4j.Logger;

import xyz.cglzwz.mybatis.demo1.pojo.Role;
import xyz.cglzwz.mybatis.demo1.mapper.RoleMapper;
import xyz.cglzwz.mybatis.demo1.util.SqlSessionFactoryUtil;

/**
 * @主函数
 * 
 * @author chgl16
 * @Date 2018.9.26
 */

public class Main {

	public static void main(String[] args) {
		// 使用log4j打印日志
		Logger log = Logger.getLogger(Main.class);
		// 获取SqlSession对象
		SqlSession sqlSession = null;
		try {
			sqlSession = SqlSessionFactoryUtil.openSqlSession();
			// 通过映射器(接口和mapper.xml文件组合)方式发送SQL
			RoleMapper roleMapper = sqlSession.getMapper(RoleMapper.class);
			// 操作打印
			Role role1 = roleMapper.getRole(2L);
			log.info(role1.getRoleName());
			
			Role role2 = new Role();
			role2.setRoleName("小绿");
			role2.setNote("绿色出行");
			int flag = roleMapper.insertRole(role2);
			log.info(flag);
			// 增删改需要提交处理
			sqlSession.commit();
		} catch (Exception ex) {
			ex.printStackTrace();
		} finally {
			// 在finally里面关闭资源，终结SqlSession对象的生命周期
			if (sqlSession != null) {
				sqlSession.close();
			}
		}
	}
}

运行结果

DEBUG 2018-09-27 19:48:37,418 org.apache.ibatis.logging.LogFactory: Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
DEBUG 2018-09-27 19:48:37,566 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2018-09-27 19:48:37,566 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2018-09-27 19:48:37,566 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2018-09-27 19:48:37,566 org.apache.ibatis.datasource.pooled.PooledDataSource: PooledDataSource forcefully closed/removed all connections.
DEBUG 2018-09-27 19:48:37,754 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Opening JDBC Connection
DEBUG 2018-09-27 19:48:38,008 org.apache.ibatis.datasource.pooled.PooledDataSource: Created connection 1418385211.
DEBUG 2018-09-27 19:48:38,008 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Setting autocommit to false on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@548ad73b]
DEBUG 2018-09-27 19:48:38,008 xyz.cglzwz.mybatis.demo1.mapper.RoleMapper.getRole: ==>  Preparing: select id, role_name as roleName, note from t_role where id = ? 
DEBUG 2018-09-27 19:48:38,055 xyz.cglzwz.mybatis.demo1.mapper.RoleMapper.getRole: ==> Parameters: 2(Long)
DEBUG 2018-09-27 19:48:38,102 xyz.cglzwz.mybatis.demo1.mapper.RoleMapper.getRole: <==      Total: 1
 INFO 2018-09-27 19:48:38,102 xyz.cglzwz.mybatis.demo1.main.Main: 小米
DEBUG 2018-09-27 19:48:38,102 xyz.cglzwz.mybatis.demo1.mapper.RoleMapper.insertRole: ==>  Preparing: insert into t_role(role_name, note) values(?, ?) 
DEBUG 2018-09-27 19:48:38,102 xyz.cglzwz.mybatis.demo1.mapper.RoleMapper.insertRole: ==> Parameters: 小绿(String), 绿色出行(String)
DEBUG 2018-09-27 19:48:38,102 xyz.cglzwz.mybatis.demo1.mapper.RoleMapper.insertRole: <==    Updates: 1
 INFO 2018-09-27 19:48:38,102 xyz.cglzwz.mybatis.demo1.main.Main: 1
DEBUG 2018-09-27 19:48:38,102 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Committing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@548ad73b]
DEBUG 2018-09-27 19:48:38,196 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Resetting autocommit to true on JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@548ad73b]
DEBUG 2018-09-27 19:48:38,210 org.apache.ibatis.transaction.jdbc.JdbcTransaction: Closing JDBC Connection [com.mysql.cj.jdbc.ConnectionImpl@548ad73b]
DEBUG 2018-09-27 19:48:38,210 org.apache.ibatis.datasource.pooled.PooledDataSource: Returned connection 1418385211 to pool.

项目代码位置：https://github.com/chgl16/MyBatis-demo

Java编程代码规范：http://www.cglzwz.xyz/file/Java_manual.pdf