Day 76

注意：MyBatis数据库增删改操作返回都是为int 类型的整数，但是select操作返回的却是所查询的数据库表的泛型

在UserMapper.xml文件中添加查询操作的SQL语句

• package com.atguigudb.mybatis.test;
  
  import com.atguigudb.mybatis.mapper.UserMapper;
  import com.atguigudb.mybatis.pojo.User;
  import org.apache.ibatis.annotations.Mapper;
  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 java.io.IOException;
  import java.io.InputStream;
  import java.util.List;
  
  public class Mybatis_Test {
      
  
  
      
  
      
  
      // MyBatis框架sql查询操作
      @Test
      public void testMyBatis() {
          // 获取InputStream 对象
          InputStream is = null;
          try {
              is = Resources.getResourceAsStream("mybatis-config.xml");
  
              // 获取SqlSessionFactoryBuilder
              SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
  
              // 获取SqlSessionFactory 对象
              SqlSessionFactory sf = sqlSessionFactoryBuilder.build(is);
  
              // 获取sqlSession 对象
              SqlSession sqlSession = sf.openSession(true);
  
              // 执行sql语句
              List users = sqlSession.selectList("com.atguigudb.mybatis.mapper.UserMapper.selectUser");
  
              // 输出结果
              System.out.println(users);
  
  
          } catch (IOException e) {
              e.printStackTrace();
          }finally {
              try {
                  is.close();
              } catch (IOException e) {
                  e.printStackTrace();
              }
          }
  
      }
  }
  ========================================
  [User{id=1, name='小明', age=19, address='北京'}, User{id=2, name='夏红', age=21, address='上海'}, User{id=3, name='小军', age=18, address='武汉'}, User{id=4, name='小王', age=17, address='北京'}, User{id=5, name='张三', age=17, address='北京'}]
  
  Process finished with exit code 0