mybatis实现business的全表查询（三种方法）

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实现business的全表查询 select * from business

方法一：

1.定义父接口

package com.neusoft.Idao;import com.neusoft.pojo.Business;import java.util.List;public interface OpBusinessDao {public List<Business> findBusi();
}

2.定义子的实现

<?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.neusoft.Idao.OpBusinessDao"><select id="findBusi" resultType="com.neusoft.pojo.Business">select * from business</select></mapper>

3.配置映射文件

4.代码实现

import com.neusoft.Idao.OpBusinessDao;
import com.neusoft.pojo.Business;
import com.neusoft.service.OpBusiService;
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 java.io.IOException;
import java.io.InputStream;
import java.util.List;public class TestBusi {public static void main(String[] args) {//        1.加载配置文件InputStream inputStream = null;try {inputStream =Resources.getResourceAsStream("mybatis.xml");
//            2.获取mybatis   数据库工厂类SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(inputStream);//                3.获取数据库连接SqlSession sqlSession = ssf.openSession();//        面向接口的mapper调用OpBusinessDao op= sqlSession.getMapper(OpBusinessDao.class);//根据父接口类型加载子类对象List<Business> list = op.findBusi();for (Business bb: list) {System.out.println(bb.toString());}} catch (IOException e) {e.printStackTrace();}}
}

方法二（使用Select注解）：

1.定义接口

package com.neusoft.Idao;import com.neusoft.pojo.Business;
import org.apache.ibatis.annotations.Select;import java.util.List;public interface OpBusinessDao {@Select("select * from  business")public List<Business> findBusi();
}

2.配置映射文件

3.测试实现

import com.neusoft.Idao.OpBusinessDao;
import com.neusoft.pojo.Business;
import com.neusoft.service.OpBusiService;
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 java.io.IOException;
import java.io.InputStream;
import java.util.List;public class TestBusi {public static void main(String[] args) {//        1.加载配置文件InputStream inputStream = null;try {inputStream =Resources.getResourceAsStream("mybatis.xml");
//            2.获取mybatis   数据库工厂类SqlSessionFactory ssf = new SqlSessionFactoryBuilder().build(inputStream);//                3.获取数据库连接SqlSession sqlSession = ssf.openSession();//        面向接口的mapper调用OpBusinessDao op= sqlSession.getMapper(OpBusinessDao.class);//根据父接口类型加载子类对象List<Business> list = op.findBusi();for (Business bb: list) {System.out.println(bb.toString());}} catch (IOException e) {e.printStackTrace();}}
}

方法三：

1.定义父接口

package com.neusoft.Idao;import com.neusoft.pojo.Business;import java.util.List;public interface OpBusinessDao {public List<Business> findBusi();
}

2.定义子的实现

<?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.neusoft.Idao.OpBusinessDao"><select id="findBusi" resultType="com.neusoft.pojo.Business">select * from business</select></mapper>

3.配置映射文件

4 .定义service层进行整理调用

package com.neusoft.service;import com.neusoft.Idao.OpBusinessDao;
import com.neusoft.pojo.Business;
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 java.io.IOException;
import java.io.InputStream;
import java.util.List;public class OpBusiService {static SqlSessionFactory ssf = null;static {InputStream inputStream = null;try {
//            1.加载配置文件inputStream = Resources.getResourceAsStream("mybatis.xml");
//            2.获取mybatis   数据库工厂类ssf = new SqlSessionFactoryBuilder().build(inputStream);} catch (IOException e) {e.printStackTrace();}}public List<Business> findBusiBiz(){SqlSession sqlSession = ssf.openSession();//        面向接口的mapper调用OpBusinessDao opBusinessDao = sqlSession.getMapper(OpBusinessDao.class);//根据父接口类型加载子类对象List<Business> list = opBusinessDao.findBusi();for (Business bb: list) {System.out.println(bb.toString());}return list;}
}

5.代码实现

import com.neusoft.pojo.Business;
import com.neusoft.service.OpBusiService;
import java.util.List;public class TestBusi {public static void main(String[] args) {OpBusiService opBusiService = new OpBusiService();List<Business> list = opBusiService.findBusiBiz();for (Business bb: list) {System.out.println(bb.toString());}}
}

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