mybatis入门(四)

mybatis入门

需求:根据id查询用户的信息

mysql数据库:

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`(`id`,`username`,`birthday`,`sex`,`address`) values (1,'王五',NULL,'2',NULL),(10,'张三','2014-07-10','1','北京市'),(16,'张小明',NULL,'1','河南郑州'),(22,'陈小明',NULL,'1','河南郑州'),(24,'张三丰',NULL,'1','河南郑州'),(25,'陈小明',NULL,'1','河南郑州'),(26,'王五',NULL,NULL,NULL);

eclipse中的项目结构

 

要引入的jar包:

日志文件:

log4j.properties

# Global logging configuration
#在开发环境下日志级别要设置成DEBUG,生成环境设置成info或error
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

 

pojo类:

package ql.mybatis.pojo;

import java.util.Date;

public class User {

    //属性名和数据库的字段对应
    private Integer id;
    private String username;//用户名
    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 + "]";
    }
}

映射文件:

User.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">
<!-- namespace命名空间,作用就死对sql进行分类化管理,理解sql隔离 注意:使用mapper代理方法开发,namespace有特殊重要的作用(刚开始学还不能理解) -->
<mapper namespace="test">
    <!-- 在映射文件中配置很多sql语句-->
    <!-- 需求:通过id查询用户表的记录 -->
    <!-- 通过select 执行数据库的查询
    id:标识映射文件的sql
    将sql语句封装到mappedStatement对象中,所以将id称为statement的id
    parameterType:指定输入参数的类型,这里指定int型
    #{}表示一个占位符
    #{id}:其中的id表示接受输入的参数,参数名称就是id,如果输入的参数是简单类型,#{}中的参数可以任意
    resultType:指定sql输出的结果的所映射的java对象类型,select指定restultType表示将单条记录映射成java对象
    -->
    <select id="findUserById" parameterType="int" resultType="ql.mybatis.pojo.User">
        select * from User where id=#{id}
    </select>

</mapper>

配置文件:
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>
    <!-- 和spring整合后 environments配置将废除-->
    <environments default="development">
        <environment id="development">
        <!-- 使用jdbc事务管理,由mybatis管理-->
            <transactionManager type="JDBC" />
        <!-- 数据库连接池,由mybatis管理-->
            <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="123456" />
            </dataSource>
        </environment>
    </environments>
    
    <mappers>
        <mapper resource="sqlmap/User.xml"/>
    </mappers>
</configuration>  


测试类:

package ql.mybatis.first;

import java.io.IOException;
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 ql.mybatis.pojo.User;

public class MybatisTest {

    // 根据id查询用户的信息,得到一条记录结果
    @Test
    public void findUserByIdTest() {
        // 通过工厂得到SqlSession
        SqlSession sqlSession = null;
        try {
            // mybatis配置文件
            String resource = "SqlMapConfig.xml";
            // 得到配置文件流
            InputStream inputStream = Resources.getResourceAsStream(resource);
            // 创建会话工厂,传入mybatis的配置文件信息
            SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
            sqlSession = sqlSessionFactory.openSession();
            // 通过SqlSession操作数据库
            // 第一个参数:映射文件中statement的id,等于=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
            // sqlSession.selectOne结果 是与映射文件中所匹配的resultType类型的对象
            // selectOne查询出一条记录
            User user=sqlSession.selectOne("test.findUserById", 1);
            System.out.println(user);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }finally{
            if(sqlSession!=null){
                //释放资源
                sqlSession.close();
            }
            
        }
        
        
    }
}

结果:

DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - PooledDataSource forcefully closed/removed all connections.
DEBUG [main] - Opening JDBC Connection
DEBUG [main] - Created connection 411390898.
DEBUG [main] - Setting autocommit to false on JDBC Connection [com.mysql.jdbc.JDBC4Connection@188553b2]
DEBUG [main] - ==>  Preparing: select * from User where id=?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <==      Total: 1
User [id=1, username=王五, sex=2, birthday=null, address=null]
DEBUG [main] - Resetting autocommit to true on JDBC Connection [com.mysql.jdbc.JDBC4Connection@188553b2]
DEBUG [main] - Closing JDBC Connection [com.mysql.jdbc.JDBC4Connection@188553b2]
DEBUG [main] - Returned connection 411390898 to pool.

 

posted @ 2015-05-25 13:53  加肥猫咪  阅读(...)  评论(...编辑  收藏