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0.写在前面

本文仅介绍 mybatis 的入门级使用，即对单个表的增删改查操作。

1. 准备环境

• IDEA 14.1.7
• Mysql 5.5
• maven

2. 数据库

学生表：stu

3. 配置文件

• jdbc.properties

jdbc.driver=com.mysql.jdbc.Driverjdbc.url=jdbc:mysql://localhost:3306/mybatis01?useUnicode=true&characterEncoding=utf8jdbc.username=rootjdbc.password=335588

4. 项目结构

• SqlMapConfig.xml

• stu 映射文件（stu.xml）

   
       
    
           INSERT stu(name)VALUES (#{name})    
        
    
             DELETE FROM stu WHERE `name` LIKE '${name}%'    
        
    
             UPDATE stu SET `name`=#{name} WHERE id=#{id}    
        
          SELECT id,`name` FROM stu WHERE id=#{id}        
            SELECT id,`name` FROM stu WHERE `name`=#{name}    
   

• pom.xml

   
       
    
     4.0.0
        
    
     com.czd.mybatis_test
        
    
     MybatisTest
        
    
     1.0-SNAPSHOT
        
            
             
                 
      
       log4j
                  
      
       log4j
                  
      
       1.2.17
              
             
             
                 
      
       mysql
                  
      
       mysql-connector-java
                  
      
       5.1.37
                  
      
       runtime
              
             
                 
      
       c3p0
                  
      
       c3p0
                  
      
       0.9.1.2
              
             
             
                 
      
       org.mybatis
                  
      
       mybatis
                  
      
       3.3.0
              
             
                 
      
       org.mybatis
                  
      
       mybatis-spring
                  
      
       1.2.3
              
             
             
                 
      
       junit
                  
      
       junit
                  
      
       4.12
                  
      
       test
              
         
    
   

5. java 代码

• StudenDao 接口：

public interface StudentDao {    Student findById(int id);    Student findByName(String name);    void insertStudent(Student student);    void deleteStudent(String name);    void updateStudent(Student student);}

• mybatis 工作流程：

  1. 通过 Reader 对象读取src目录下的 SqlMapConfig.xml 配置文件(该文本的位置和名字可任意)
  2. 通过 SqlSessionFactoryBuilder 对象创建 SqlSessionFactory 对象
  3. 从当前线程中获取 SqlSession 对象
  4. 通过 SqlSession 对象读取 stu.xml 映射文件中的 id，从而读取 sql 语句
  5. 事务提交，必写
  6. 关闭 SqlSession 对象，让 GC 尽早回收

• 测试类：

package dao;import com.czd.mybatis01.bean.Student;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.Reader;import java.util.HashMap;import java.util.Map;/** * Created by czd on 2017/5/4. */public class StudentDao {
       private static SqlSessionFactory sqlSessionFactory;    private static Reader reader;    private static String nameSpace = "com.czd.mybatis01.dao.StudentDao";    static {        try {            reader = Resources.getResourceAsReader("SqlMapConfig.xml");            sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);        } catch (Exception e) {            e.printStackTrace();        }    }    public static SqlSessionFactory getSession() {        return sqlSessionFactory;    }    @Test    public void main() throws Exception {        StudentDao studentDao = new StudentDao();        // 增加//        Student student = new Student();//        student.setName("a");//        studentDao.testInsertStudent(student);        // 删除//        studentDao.testDeleteStudent("a");        // 更改//        Student student2 = new Student();//        student2.setId(2);//        student2.setName("czd2");//        studentDao.testUpdateStudent(student2);        // 根据id查询        System.out.println(studentDao.testFindById(1));        // 根据name查询        System.out.println(studentDao.testFindByName("czd2"));    }    public void testInsertStudent(Student student) throws Exception {        SqlSession sqlSession = getSession().openSession();        sqlSession.insert(nameSpace + ".insertStudent", student);        sqlSession.commit();        sqlSession.close();    }    public void testDeleteStudent(String name) throws Exception {        SqlSession sqlSession = getSession().openSession();        Map
   
     map = new HashMap();        map.put("name", name);        sqlSession.delete(nameSpace + ".deleteStudent", map);        sqlSession.commit();        sqlSession.close();    }    public void testUpdateStudent(Student student) throws Exception {        SqlSession sqlSession = getSession().openSession();        sqlSession.insert(nameSpace + ".updateStudent", student);        sqlSession.commit();        sqlSession.close();    }    public Student testFindById(int id) throws Exception {        SqlSession sqlSession = getSession().openSession();        Student student = sqlSession.selectOne(nameSpace + ".findById", id);        sqlSession.commit();        sqlSession.close();        return student;    }    public Student testFindByName(String name) throws Exception {        SqlSession sqlSession = getSession().openSession();        Student student = sqlSession.selectOne(nameSpace + ".findByName", name);        sqlSession.commit();        sqlSession.close();        return student;    }}