mybatis基本操作（二）

　在这里《mybatis基本操作（一）》我介绍了mybatis使用配置文件对数据库进行增删改查。下面将介绍mybatis使用注解进行相应的操作。首先，使用注解同样要配置总配置文件，JavaBean，以及properties文件。只是将（一）中的student.xml文件替换为studentMapper.java。如下:

 1 package com.zhouxy.ibatis;
 2
 3 import java.util.List;
 4
 5 import org.apache.ibatis.annotations.Delete;
 6 import org.apache.ibatis.annotations.Insert;
 7 import org.apache.ibatis.annotations.Select;
 8 import org.apache.ibatis.annotations.Update;
 9
10
11 /**
12  * studentMapper.java是一个接口.在接口中将sql语句传入相应的注解中。
13  * @author zhouxy
14  *
15  */
16 public interface StudentMapper {
17
18     @Select("select * from student")
19     public List<Student> getAllStudents();
20
21     @Select("select * from student where id = #{id}")
22     public Student getStudentById(int id);
23
24     @Select("select * from student where name like \"%\"#{name}\"%\"")
25     public List<Student> getStudentByName(String name);
26
27     @Insert("insert into student(name,age) values(#{name},#{age})")
28     public void addStudent(Student student);
29
30     @Update("update student set name = #{name},age=#{age}")
31     public void updateStudent(Student student);
32
33     @Delete("delete from student where id = #{id}")
34     public void deleteStudentById(int id);
35 }

　上面编写了StudentMapper,它相当于使用配置文件中的student.xml文件。下面是对StudentMapper进行注册，返回获得了sqlsession对象的studentMapper对象:

 1 package com.zhouxy.ibatis;
 2
 3 import java.util.List;
 4
 5 import org.apache.ibatis.session.SqlSession;
 6 import org.apache.ibatis.session.SqlSessionFactory;
 7
 8 public class StudentDaoByAnnotation {
 9     //得到studentMapper对象,就像使用配置文件要获取SqlSession对象一样.
10     public static StudentMapper getStudentMapper(){
11         StudentMapper studentMapper = null;
12         SqlSessionFactory sqlSessionFactory = SessionFactoryUtils.getSqlSessionFactory();
13
14         sqlSessionFactory.getConfiguration().addMapper(StudentMapper.class);//必须注册StudentMapper
15
16         SqlSession sqlSession = sqlSessionFactory.openSession();
17         studentMapper = sqlSession.getMapper(StudentMapper.class);
18
19         return studentMapper;
20     }
21 }

　测试：

 1 package com.zhouxy.ibatis;
 2
 3 public class TestMapper {
 4     //获得指定学生
 5     public static void getStudentById(int id){
 6         StudentMapper studentMapper = StudentDaoByAnnotation.getStudentMapper();
 7         Student student = studentMapper.getStudentById(id);
 8
 9         System.out.println(student.toString());
10     }
11
12     public static void main(String[] args) {
13         getStudentById(8);
14     }
15 }

　测试结果：

　这两种方式在不同的情况下使用不同的方式会带来各自的好处，可以择优选取。