技術標籤：MyBatis學習筆記mybatis

可變引數

• Configuration XML 的引數可以是變化的，本例將資料庫IP、使用者名稱、密碼設為可變項。

1.修改mybatis-config.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://${server}/af_example?useUnicode=true&amp;characterEncoding=UTF-8"/>
        <property name="username" value="${username}"/>
        <property name="password" value="${password}"/>
      </dataSource>
    </environment>
  </environments>
  <mappers>
    <mapper resource="mybatis-mapper.xml"/>
  </mappers>
</configuration>
 

2.修改mybatis-mapper.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="af.test">
  <select id="getStudent" resultType="my.Student">
    select * from student where id = #{id}
  </select>
  
</mapper>
 

3.測試Properties 用法有點像HashMap

package my;

import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;

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 Test
{
	public static void main(String[] args) throws Exception
	{
		// 設定引數
		Properties props = new Properties();
		props.put("server", "127.0.0.1");
		props.put("username", "root");
		props.put("password", "a1b2c3");
		
		// 建立 SqlSessionFactory
		String resource = "mybatis-config.xml";
		InputStream inputStream = Resources.getResourceAsStream(resource);
		SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream,props);//傳入可變引數

		// 使用簡化的try-with-resources語法，等效於try..finally語句
		try (SqlSession session = sqlSessionFactory.openSession()) {
			Map<String,Object> para=new HashMap<>();
			para.put("id", 20190001);
			Student row = session.selectOne("af.test.getStudent",para);
			if(row != null)
				System.out.println("找到一條記錄");
		}
		System.out.println("Exit");
	}

}
 

4.結果