mybatis（3）--第一个mybatis的demo

首先就是搭建环境啦!!!

https://github.com/mybatis/mybatis-3/releases

从这个链接下载mybatis的开发包下载下来

其中mybatis-3.4.4.jar就是其核心包
lib下的包就是相关的日志包，还有代理cglib包，common包等

再加一个log.properties

#开发环境下设置成debug，生产环境设置成info或者errorlog4j.rootLogger=DEBUG,A1log4j.logger.org.mybatis = DEBUGlog4j.appender.A1=org.apache.log4j.ConsoleAppenderlog4j.appender.A1.layout=org.apache.log4j.PatternLayoutlog4j.appender.A1.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss,SSS} [%t] [%c]-[%p] %m%n

接下来就是配置文件啦！
SqlMapConfig.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>    <!-- 环境变量的配置，但是在和spring整合之后就没用啦 -->    <environments default="development">        <environment id="development">            <transactionManager type="JDBC">            </transactionManager>            <dataSource type="POOLED">                <property name="driver" value="com.mysql.jdbc.Driver" />                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" />                <property name="username" value="root" />                <property name="password" value="1234" />            </dataSource>        </environment>    </environments>    <!-- 加载映射文件 -->    <mappers>        <mapper resource="sqlmap/UserMapper.xml"/>    </mappers></configuration>

创建pojo：

package com.ddd.mybatis.pojo;import java.util.Date;/** * 用户类pojo * @author Dan * */public class User {    //和数据库表的user的字段对应    private int id;    private String username;    private String sex;    private Date birthday;    private String address;    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 getSex() {        return sex;    }    public void setSex(String sex) {        this.sex = sex;    }    public Date getBirthday() {        return birthday;    }    public void setBirthday(Date birthday) {        this.birthday = birthday;    }    public String getAddress() {        return address;    }    public void setAddress(String address) {        this.address = address;    }    @Override    public String toString() {        return "User [id=" + id + ", username=" + username + ", sex=" + sex + ", birthday=" + birthday + ", address="                + address + "]";    }}

然后写映射文件：

<?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" ><!-- namespace命名空间，作用是对sql进行分类化管理，理解sql隔离 使用mapper代理的方法开发namespace有很重要的作用  --><mapper namespace="test" >    <!-- 在映射文件中配置很多sql语句 -->    <!-- 通过select执行查询     id:用来表示文件中的sql，将sql语句封装到mappedstatement对象中，所以id其实是statement的id    parameterType:指定输入参数类型，id是int型    #{}表示一个占位符    #{id}表示id是接受的输入参数，名字是id，如果输入参数是简单类型，#{}中的参数名可以任意，可以是value或者其他名称    resultType：    -->    <!-- 通过id查询用户 -->    <select id="findUserById" parameterType="int" resultType="com.ddd.mybatis.pojo.User">        SELECT * FROM USER WHERE id=#{id}    </select></mapper>

写完记得将其加入到sqlMapConfig中去

写完之后来测试吧！

package com.ddd.mybatis.first;import java.io.IOException;import java.io.InputStream;import java.io.Reader;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 org.junit.Test;import com.ddd.mybatis.pojo.User;/** * 测试mybatisdemo * @author Dan * */public class MybatisFirst {    //根据id查询用户信息得到一条结果记录    @Test    public void findUserByIdTest() throws IOException{        //加载mybatis文件        String fileSource="SqlMapConfig.xml";        //获取文件流        InputStream inputStream=Resources.getResourceAsStream(fileSource);        //根据加载的配置文件信息创建SqlSessionFactory        SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(inputStream);        //得到sqlsession        SqlSession sqlSession=sqlSessionFactory.openSession();        //sqlSession操作数据库        //第一个参数：映射文件中的statement的id：也就是namespace+"."+statement的id        //第二个参数：指定和映射文件中所匹配的parameterType类型的参数        //接受参数就是resultType中指定的对象类型        User u=sqlSession.selectOne("test.findUserById", 1);        System.out.println(u);        sqlSession.close();    }}

运行结果:

2017-07-16 16:50:41,356 [main] [org.apache.ibatis.logging.LogFactory]-[DEBUG] Logging initialized using 'class org.apache.ibatis.logging.slf4j.Slf4jImpl' adapter.2017-07-16 16:50:41,621 [main] [org.apache.ibatis.datasource.pooled.PooledDataSource]-[DEBUG] PooledDataSource forcefully closed/removed all connections.2017-07-16 16:50:41,622 [main] [org.apache.ibatis.datasource.pooled.PooledDataSource]-[DEBUG] PooledDataSource forcefully closed/removed all connections.2017-07-16 16:50:41,622 [main] [org.apache.ibatis.datasource.pooled.PooledDataSource]-[DEBUG] PooledDataSource forcefully closed/removed all connections.2017-07-16 16:50:41,622 [main] [org.apache.ibatis.datasource.pooled.PooledDataSource]-[DEBUG] PooledDataSource forcefully closed/removed all connections.2017-07-16 16:50:41,763 [main] [org.apache.ibatis.transaction.jdbc.JdbcTransaction]-[DEBUG] Opening JDBC Connection2017-07-16 16:50:42,061 [main] [org.apache.ibatis.datasource.pooled.PooledDataSource]-[DEBUG] Created connection 998865748.2017-07-16 16:50:42,061 [main] [org.apache.ibatis.transaction.jdbc.JdbcTransaction]-[DEBUG] Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3b897b54]2017-07-16 16:50:42,065 [main] [test.findUserById]-[DEBUG] ==>  Preparing: SELECT * FROM USER WHERE id=? 2017-07-16 16:50:42,143 [main] [test.findUserById]-[DEBUG] ==> Parameters: 1(Integer)2017-07-16 16:50:42,195 [main] [test.findUserById]-[DEBUG] <==      Total: 1User [id=1, username=小明, sex=男, birthday=Fri Sep 09 00:00:00 CST 2011, address=北京市海淀区]2017-07-16 16:50:42,198 [main] [org.apache.ibatis.transaction.jdbc.JdbcTransaction]-[DEBUG] Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@3b897b54]2017-07-16 16:50:42,199 [main] [org.apache.ibatis.transaction.jdbc.JdbcTransaction]-[DEBUG] Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@3b897b54]2017-07-16 16:50:42,199 [main] [org.apache.ibatis.datasource.pooled.PooledDataSource]-[DEBUG] Returned connection 998865748 to pool.

第一个小程序完成，基本的mybatis运行原理差不多就是这样！开心！