[深圳|结业弟子]JAVA-韦杰|2017年08月08日的日报-技能树.IT修真院

发表于： 2017-08-08 21:26:31

2 907

一、今天完成的任务

1.使用mybatis连接数据库，并测试一个查询语句

（1）新建java项目，导入mybatis-3.3.0.jar和mysql-connector-jav-5.1.43-bin.jar

（2）新建数据库mybatis，新建表users，插入如下数据

（3）创建与表对应的实体类

package com.step17.mybatis;
public class users {
       private int id;
       private String name;
       private int age;
       public int getId() {
              return id;
       }
       public void setId(int id) {
              this.id = id;
       }
       public String getName() {
              return name;
       }
       public void setName(String name) {
              this.name = name;
       }
       public int getAge() {
              return age;
       }
       public void setAge(int age) {
              this.age = age;
       }
       @Override
       public String toString(){
              return "User[id="+id+", name="+name+", age="+age+"]";
       }
}

（4）定义操作Users表的sql映射文件usersMampper.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">

<mapper namespace="com.step17.mybatis.usersMapper">

<select id="getUser" parameterType="int"

resultType="com.step17.mybatis.Users">

select * from users where id=#{id}

</select>

</mapper>

（5）配置全局配置文件

在src文件下新建一个SqlMapConfig.xml文件，作为mybatis的全局配置文件，内容如下

<?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" />
                <property name="username" value="root" />
                <property name="password" value="123456" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/step17/mybatis/usersMapper.xml" />
    </mappers>
</configuration>

得到如下目录结构

（6）编写测试代码，执行定义的select语句

package com.step17.mybatis;
import java.io.IOException;
//import java.io.InputStream;方法一调用
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;
public class Test1 {
       public static void main(String[] args) throws IOException {
              String resource = "SqlMapConfig.xml";
              /*
               * 方法一  用类加载器加载mybatis的配置文件（它也加载关联的映射文件）
              InputStream is = Resources.getResourceAsStream(resource);
              SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);
              SqlSession session = sessionFactory.openSession();
               */
              //方法二 用mybatis提供的Resoucces类加载mybatis的配置文件（它也加载关联的映射文件）
              Reader reader = Resources.getResourceAsReader(resource);
              SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
              SqlSession session = sessionFactory.openSession();
              //通过Sqlsession操作数据库
              String statement = "com.step17.mybatis.usersMapper.getUser";
              Users user = session.selectOne(statement, 1);
              System.out.println(user);
              //释放资源，关闭sqlsession
              session.close();
       }
}