一、开发流程

1)引jar包

//mybatis_coremybatis3.4core\asm-5.2.jarmybatis3.4core\cglib-3.2.5.jarmybatis3.4core\commons-logging-1.2.jarmybatis3.4core\log4j-1.2.17.jarmybatis3.4core\mybatis-3.4.4.jar//db connectorDB-connector\mysql-connector-java-5.1.40-bin.jar

2)变写实体类Student

package com.huitong.entity;public class Student {        private Integer id;    private String sname;    private double salary;        public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getSname() {        return sname;    }    public void setSname(String sname) {        this.sname = sname;    }            public double getSalary() {        return salary;    }    public void setSalary(double salary) {        this.salary = salary;    }    @Override    public String toString() {        return sname + ":" + salary;    }}

3）写映射文件StudentMapper.xml，配置mybatis.xml

     
         
          
              
               
                       
               
                       
              
          
      
               INSERT INTO student(sname, salary) VALUES("allen",34.23);    
              
      
               INSERT INTO student(sname, salary) VALUES(#{sname},#{salary});    
              
              SELECT id,sname,salary FROM student WHERE id=#{id};            
              SELECT id,sname,salary FROM student;            
      
               UPDATE student SET sname=#{sname},salary=#{salary} WHERE id=#{id}    
              
      
               DELETE FROM student WHERE id=#{id}    
      
     

注意：如果查询结果返回的对象和数据表中字段，名称名不一致，需要使用resultMap，否则使用resultType。

 

配置mybatis.xml

 

4)写工具类MybatisUtil

package com.huitong.util.mybatis;import java.io.IOException;import java.io.Reader;import java.sql.Connection;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;public class MybatisUtil {        private static ThreadLocal
      
        threadLocal = new ThreadLocal
       
        ();    private static SqlSessionFactory sqlSessionFactorysion;        //禁止通过new创建对象    private MybatisUtil(){}        /**     * 加载mybatis配置文件     */    static{        try {            Reader reader = Resources.getResourceAsReader("mybatis.xml");            sqlSessionFactorysion = new SqlSessionFactoryBuilder().build(reader);                    } catch (IOException e) {            e.printStackTrace();            throw new RuntimeException(e);        }            }        /**     * 获取sqlsession     * @return     */    public static SqlSession getSqlSession(){        SqlSession sqlSession = threadLocal.get();        if(sqlSession == null){            sqlSession = sqlSessionFactorysion.openSession();            threadLocal.set(sqlSession);                    }        return sqlSession;    }        /**     * 关闭sqlsession     */    public static void closeSqlSession(){        SqlSession sqlSession = threadLocal.get();                if(sqlSession != null){            //关闭sqlsession            sqlSession.close();            //分离当前线程与sqlsession关系            threadLocal.remove();        }            }        public static void main(String[] args) {         Connection connection = MybatisUtil.getSqlSession().getConnection();         System.out.println(connection!=null?"连接成功":"没有连接成功");            }    }
       
      

5)StudentDao数据持久层Dao

package com.huitong.dao;import java.util.List;import org.apache.ibatis.session.SqlSession;import com.huitong.entity.Student;import com.huitong.util.mybatis.MybatisUtil;import com.huitong.util.mybatis.mybatisutil2;public class StudentDao {        /**     * 增加学生     * @throws Exception     */    public void add() throws Exception{        SqlSession sqlSession = null;                try{            sqlSession = MybatisUtil.getSqlSession();            int n = sqlSession.insert("com.huitong.entity.StudentMapper.add");                        System.out.println(n);            sqlSession.commit();                    } catch (Exception e){            e.printStackTrace();            sqlSession.rollback();                    } finally {            MybatisUtil.closeSqlSession();                    }            }        public void add2(Student stu) throws Exception{        SqlSession sqlSession = null;                try{            sqlSession = MybatisUtil.getSqlSession();            int n = sqlSession.insert("com.huitong.entity.StudentMapper.add2",stu);                        System.out.println(n);            sqlSession.commit();                    } catch (Exception e){            e.printStackTrace();            sqlSession.rollback();                    } finally {            MybatisUtil.closeSqlSession();                    }            }        public Student getStudentById(int id) throws Exception{                SqlSession sqlSession = MybatisUtil.getSqlSession();                try{            Student student = sqlSession.selectOne(Student.class.getName() + ".getStudentById", id);            return student;        } catch(Exception e){            e.printStackTrace();            throw new RuntimeException(e);                    } finally {            MybatisUtil.closeSqlSession();        }                    }        public List
      
        getAll() throws Exception{        SqlSession sqlSession = MybatisUtil.getSqlSession();                try{            return sqlSession.selectList(Student.class.getName() + ".getAll");                                } catch(Exception e){            e.printStackTrace();            throw new RuntimeException(e);                    } finally {            MybatisUtil.closeSqlSession();        }    }        public void update(Student stu) throws Exception{        SqlSession sqlSession = MybatisUtil.getSqlSession();                try{            int n = sqlSession.update(Student.class.getName() + ".update",stu);            System.out.println(n);                        sqlSession.commit();                    }catch(Exception e){            e.printStackTrace();            sqlSession.rollback();            throw new RuntimeException(e);        }finally{            MybatisUtil.closeSqlSession();                    }            }        public void delete(int id){        SqlSession sqlSession = MybatisUtil.getSqlSession();                try{            int n = sqlSession.delete(Student.class.getName() + ".delete", id);            System.out.println(n);                        sqlSession.commit();        } catch(Exception e){            e.printStackTrace();            sqlSession.rollback();                        throw new RuntimeException(e);        } finally{            MybatisUtil.closeSqlSession();                    }    }        public static void main(String[] args) {        StudentDao studentDao = new StudentDao();//        Student stu = new Student();//        stu.setId(2);//        stu.setSname("beed");//        stu.setSalary(20.12);//                try {            studentDao.delete(3);                    } catch (Exception e) {            e.printStackTrace();            throw new RuntimeException(e);        }    }}