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使用Mybatis开发Dao，通常有两个方法：原始Dao开发方式和Mapper接口开发方式。

开发规范

Mapper接口开发方式比原始的DAO的方式要简便许多，但是这种简便是建立在规范之上的，所以在采用该方式时务必严格遵守开发规范.

在Mapper接口开发方式中有两个核心的东西：mapper.xml和mapper.java

mapper接口开发需要遵循以下规范：

• 1、mapper.xml文件中的namespace与mapper.java接口的类的全路径相同。
• 2、mapper.java接口中的方法名和mapper.xml中定义的每个sql的id相同
• 3、mapper.java接口中的方法的输入参数类型和mapper.xml中定义的每个sql的parameterType的类型保持一致
• 4、mapper.java接口中方法的输出参数类型和mapper.xml中定义的每个sql的resultType的类型保持一致

好了，我们现在就按照此规范来改造之前的例子

StudentMapper.java

/** * 本文作者：谷哥的小弟 * 博客地址：http://blog.csdn.net/lfdfhl */package cn.com;import java.util.List;public interface StudentMapper {
       public Student findStudentById(int id);    public List
   
     findStudentByName(String name);    public void insertStudent(Student student);    public void deleteStudent(int id);    public void updateStudent(Student student);}
   

StudentMapper.xml

   
       
            SELECT * FROM student WHERE id=#{value}        
            SELECT * FROM student WHERE name LIKE '%${value}%'        
            
     
                  SELECT LAST_INSERT_ID()        
             INSERT INTO student (name,gender,birthday) value (#{name},#{gender},#{birthday})    
        
    
             DELETE FROM student where id=#{id}    
        
    
             UPDATE student set name=#{name},gender=#{gender},birthday=#{birthday} where id=#{id}    
    
   

嗯哼，对照着这两个文件看就会发现：我们在书写的过程中严格遵守了开发规范。

TestCRUD.java

/** * 本文作者：谷哥的小弟 * 博客地址：http://blog.csdn.net/lfdfhl */package cn.com;import java.io.IOException;import java.io.InputStream;import java.util.Date;import java.util.List;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.Before;import org.junit.Test;public class TestCRUD {    private SqlSessionFactory sqlSessionFactory;    @Before    public void intiSqlSessionFactory() throws Exception {        String resource = "SqlMapConfig.xml";        InputStream inputStream = Resources.getResourceAsStream(resource);        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);    }    @Test    public void findStudentById() throws IOException{        SqlSession sqlSession=sqlSessionFactory.openSession();        StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);        Student student = studentMapper.findStudentById(5);        System.out.println(student);    }    @Test    public void findStudentByName() throws IOException {        SqlSession sqlSession = sqlSessionFactory.openSession();        StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);        List
   
     list = studentMapper.findStudentByName("木");        for (Student student : list) {            System.out.println(student);        }    }    @Test    public void insertStudent() throws IOException {        SqlSession sqlSession = sqlSessionFactory.openSession();        StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);        Student student=new Student();        student.setName("小小木希");        student.setGender("female");        student.setBirthday(new Date());        studentMapper.insertStudent(student);        sqlSession.commit();        sqlSession.close();        System.out.println(student.getId());    }    @Test    public void deleteStudent() throws IOException {        SqlSession sqlSession = sqlSessionFactory.openSession();        StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);        studentMapper.deleteStudent(5);        sqlSession.commit();        sqlSession.close();    }    @Test    public void updateStudent() throws IOException {        SqlSession sqlSession = sqlSessionFactory.openSession();        StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);        Student student=new Student();        student.setId(5);        student.setName("空空姐姐");        student.setGender("female");        student.setBirthday(new Date());        studentMapper.updateStudent(student);        sqlSession.commit();        sqlSession.close();    }}
   

这些测试用例中，最重要的就是：

StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);

得到Mapper，再调用它定义的增删改查方法

最后，按照惯例还是附上项目的结构图：

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