mybatis学习笔记第一讲

第一步：先配置mybatis配置

<?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>
    <typeAliases>
        <typeAlias alias="Users" type="orm.Users"/>
    </typeAliases> 

    <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://127.0.0.1:3306/mybatis?characterEncoding=utf-8" />
            <property name="username" value="root"/>
            <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>

    <mappers>
        <mapper resource="orm/Users.xml"/>
    </mappers>
</configuration>

　第二步：创建一个实体对象

package orm;

public class Users {
	private Integer id;
	private String username;
	private String password;
	private Integer age;
	private Integer sex;

	public Users(Integer id, String username, String password, Integer age,
			Integer sex) {
		super();
		this.id = id;
		this.username = username;
		this.password = password;
		this.age = age;
		this.sex = sex;
	}
	//此处必须添加一个无参构造
	public Users() {

	}

	//set和get省略
	@Override
	public String toString() {
		// TODO Auto-generated method stub
		return super.toString();
	}

}

　第三步：配置一个简单的查询参数

<?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="orm.Users">
    <select id="selectUserByID"  parameterType="int" resultType="orm.Users">
        select * from Users where id = #{id}
    </select>
</mapper>

　第四步：测试（简洁版）

		 String resString="Configuration.xml";
		 Reader reader = Resources.getResourceAsReader(resString);
		 SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
		 SqlSession session =  sessionFactory.openSession();
		 String statement ="orm.Users.selectUserByID";
		 Users users = (orm.Users) session.selectOne(statement,2);
		 System.out.println(users.getUsername());

第四步：测试（完成版）

public class Test {
    private static SqlSessionFactory sqlSessionFactory;
    private static Reader reader; 

    static{
        try{
            reader    = Resources.getResourceAsReader("Configuration.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    public static SqlSessionFactory getSession(){
        return sqlSessionFactory;
    }

    public static void main(String[] args) {
        SqlSession session = sqlSessionFactory.openSession();
        try {
        Users users = (Users) session.selectOne("orm.Users.selectUserByID", 2);
        System.out.println(users);
        } finally {
        session.close();
        }
    }
}