MyBatis 本是apache的一个开源项目iBatis, 2010年这个项目由apache software foundation 迁移到了google code，并且改名为MyBatis 。2013年11月迁移到Github。
MyBatis作为一款优秀的orm框架，经常与Hibernate拿来比较，身为目前较流行的MyBatis 避免了几乎所有的 JDBC 代码和手动设置参数以及获取结果集。接下来我们来看看如何搭建一个MyBaits项目。
因为idea并不支持mybatis的自动搭建，所以我们需要手动的导入一些jar包
需要准备的Jar包
mybatis-3.4.6.jar mybatis的主体mysql-connector-java-5.1.46.jar 链接数据的log4j-1.2.17 用于打印日志的
关于Mybatis的构建分为两种，我们先看XML方式
XML方式
1. Mybatis-configuration.xml
mybatis-configuration.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>
<!-- 引入配置文件 -->
<properties resource="db.properties"/>
<!-- 设置打印使用log4j -->
<settings>
<setting name="logImpl" value="STDOUT_LOGGING"/>
<setting name="logImpl" value="LOG4J"/>
</settings>
<!-- 设置运行时环境 -->
<!-- mybatis 允许存在多个运行时环境 -->
<environments default="development">
<environment id="development">
<!-- transactionManager 事务管理者 -->
<!-- 设置本次事务管理方式为JDBC -->
<transactionManager type="JDBC"/>
<!-- 数据源 连接池 -->
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${user}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<!-- 引入映射文件 -->
<mappers>
<mapper resource="model/UserMapper.xml"/>
</mappers>
</configuration>
2.User.java以及UserMapper.xml
User.java
package model;
/**
* Created by Administrator on 2018/10/31.
*/
public class User {
private int id;
private String username;
private String nickname;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getNickname() {
return nickname;
}
public void setNickname(String nickname) {
this.nickname = nickname;
}
@Override
public String toString() {
return "User{" +
"id=" + id +
", username='" + username + '\'' +
", nickname='" + nickname + '\'' +
'}';
}
}
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">
<!-- 命名空间 对自己取一个名字作为调用的唯一标识符-->
<mapper namespace="model.UserMapper">
<!-- id sql语句的id 调用时使用命名空间+sqlid方式进行调用 -->
<!-- parameterType 参数类型 -->
<!-- resultType 返回值类型 -->
<select id="selectUserById" parameterType="int" resultType="model.User">
<!-- 参数注入时使用#或$ -->
<!-- #是占位符,在预编译时使用?占位,可以预防sql注入的问题 -->
<!-- $是连接符,解析sql时直接使用变量替换,可能会引起sql注入的问题 -->
<!-- #和$ 相当于 preparedStatement和statement的区别 -->
<!-- 总的来说,能用#就别用$ -->
select id,username,nickname from user where id = #{id}
</select>
</mapper>
3.db.properties以及log4j.properties
db.properties
driver=com.mysql.jdbc.Driver
url=jdbc:mysql:///test
user=root
password=root
log4j.properties
log4j.rootLogger=DEBUG, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=[service] %d - %c -%-4r [%t] %-5p %c %x - %m%n
#log4j.appender.R=org.apache.log4j.DailyRollingFileAppender
#log4j.appender.R.File=../logs/service.log
#log4j.appender.R.layout=org.apache.log4j.PatternLayout
#log4j.appender.R.layout.ConversionPattern=[service] %d - %c -%-4r [%t] %-5p %c %x - %m%n
#log4j.logger.com.ibatis = debug
#log4j.logger.com.ibatis.common.jdbc.SimpleDataSource = debug
#log4j.logger.com.ibatis.common.jdbc.ScriptRunner = debug
#log4j.logger.com.ibatis.sqlmap.engine.impl.SqlMapClientDelegate = debug
#log4j.logger.java.sql.Connection = debug
log4j.logger.java.sql.Statement = debug
log4j.logger.java.sql.PreparedStatement = debug
log4j.logger.java.sql.ResultSet =debug
4. 测试一下
Main.java
import model.User;
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.Reader;
public class Main {
public static void main(String[] args) throws IOException {
//xml方式
//定义mybatis的配置文件的路径
String resource = "mybatis_config.xml";
//将配置文件转换为reader
Reader reader = Resources.getResourceAsReader(resource);
//使用sqlsessionfactorybuilder对配置文件进行加载
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
//获取sqlsession
SqlSession sqlSession = sqlSessionFactory.openSession();
User user = sqlSession.selectOne("model.UserMapper.selectUserById",1);
System.out.println(user);
}
}
最后看一下控制台的输出内容
[service] 2018-10-31 16:59:55,875 - org.apache.ibatis.logging.LogFactory -0 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
[service] 2018-10-31 16:59:56,047 - org.apache.ibatis.logging.LogFactory -172 [main] DEBUG org.apache.ibatis.logging.LogFactory - Logging initialized using 'class org.apache.ibatis.logging.log4j.Log4jImpl' adapter.
[service] 2018-10-31 16:59:56,075 - org.apache.ibatis.datasource.pooled.PooledDataSource -200 [main] DEBUG org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
[service] 2018-10-31 16:59:56,075 - org.apache.ibatis.datasource.pooled.PooledDataSource -200 [main] DEBUG org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
[service] 2018-10-31 16:59:56,075 - org.apache.ibatis.datasource.pooled.PooledDataSource -200 [main] DEBUG org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
[service] 2018-10-31 16:59:56,075 - org.apache.ibatis.datasource.pooled.PooledDataSource -200 [main] DEBUG org.apache.ibatis.datasource.pooled.PooledDataSource - PooledDataSource forcefully closed/removed all connections.
[service] 2018-10-31 16:59:56,207 - org.apache.ibatis.transaction.jdbc.JdbcTransaction -332 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Opening JDBC Connection
[service] 2018-10-31 16:59:56,541 - org.apache.ibatis.datasource.pooled.PooledDataSource -666 [main] DEBUG org.apache.ibatis.datasource.pooled.PooledDataSource - Created connection 836514715.
[service] 2018-10-31 16:59:56,541 - org.apache.ibatis.transaction.jdbc.JdbcTransaction -666 [main] DEBUG org.apache.ibatis.transaction.jdbc.JdbcTransaction - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@31dc339b]
[service] 2018-10-31 16:59:56,543 - model.UserMapper.selectUserById -668 [main] DEBUG model.UserMapper.selectUserById - ==> Preparing: select id,username,nickname from user where id = ?
[service] 2018-10-31 16:59:56,607 - model.UserMapper.selectUserById -732 [main] DEBUG model.UserMapper.selectUserById - ==> Parameters: 1(Integer)
[service] 2018-10-31 16:59:56,640 - model.UserMapper.selectUserById -765 [main] DEBUG model.UserMapper.selectUserById - <== Total: 1
User{id=1, username='赵大鹏', nickname='死亡列车'}
可以看到sql语句以及查询的结果都出来了，mybatis使用xml方式搭建完毕。
