Mybatis框架一：搭建测试

Mybatis框架不再介绍：

在JDBC中存在一些问题：

1.频繁连接和释放资源浪费内存

2.编码完成后不便于维护

于是产生了简化数据库操作的框架：Hibernate、Mybatis等等，这里介绍Mybatis

下载地址：https://github.com/mybatis/mybatis-3/releases

接下来做一个搭建Mybatis的示例：

导包：这些是必须包

准备一个POJO：

package pojo;

import java.io.Serializable;
import java.util.Date;

public class User implements Serializable {
    private static final long serialVersionUID = 1L;
    private Integer id;
    private String username;// 用户姓名
    private String sex;// 性别
    private Date birthday;// 生日
    private String address;// 地址


    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 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 + "]";
    }

}

数据库建表：

CREATE DATABASE mybatis;
USE mybatis;
CREATE TABLE `user` (
  `id` INT(11) NOT NULL AUTO_INCREMENT,
  `username` VARCHAR(32) NOT NULL COMMENT '用户名称',
  `birthday` DATE DEFAULT NULL COMMENT '生日',
  `sex` CHAR(1) DEFAULT NULL COMMENT '性别',
  `address` VARCHAR(256) DEFAULT NULL COMMENT '地址',
  PRIMARY KEY (`id`)
) ENGINE=INNODB AUTO_INCREMENT=27 DEFAULT CHARSET=utf8;
INSERT INTO `user` VALUES ('1', '王五', NULL, '2', NULL);
INSERT INTO `user` VALUES ('10', '张三', '2014-07-10', '1', '北京市');
INSERT INTO `user` VALUES ('16', '张小明', NULL, '1', '河南郑州');
INSERT INTO `user` VALUES ('22', '陈小明', NULL, '1', '河南郑州');
INSERT INTO `user` VALUES ('24', '张三丰', NULL, '1', '河南郑州');
INSERT INTO `user` VALUES ('25', '陈小明', NULL, '1', '河南郑州');
INSERT INTO `user` VALUES ('26', '王五', NULL, NULL, NULL);

接下来配置文件：

核心配置文件：

注意名字必须是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>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC" />
            <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="xuyiqing" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="sqlmap/User.xml"/> 
    </mappers>
</configuration>

其他配置文件：log4j.properties（非必须）

# Global logging configuration
log4j.rootLogger=DEBUG, stdout
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

 User.xml配置文件：在这里写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="test">
    <!-- 通过ID查询一个用户 -->
    <select id="findUserById" parameterType="Integer" resultType="pojo.User">
        select * from user where id = #{v}
    </select>
</mapper>

测试类：

package junit;

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;
import org.junit.Test;

import pojo.User;

public class MybatisTest {
    @Test
    public void testMybatis() throws Exception {
        //加载核心配置文件
        String resource = "sqlMapConfig.xml";
        InputStream in = Resources.getResourceAsStream(resource);
        //创建SqlSessionFactory
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
        //创建SqlSession
        SqlSession sqlSession = sqlSessionFactory.openSession();
        
        //执行Sql语句 
        User user = sqlSession.selectOne("test.findUserById", 10);
        
        System.out.println(user);
    }
}

完成！查询成功！

最后附上目录图：

注意：这里的一些配置文件信息在实际开发中并不会使用，只是用于搭建测试