使用mybatis实现CRUD

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　　本文介绍的是mybatis3的使用，针对使用mybatis3作为持久层框架的入门学习。下面具体讲解：

• 
  mybatis需要程序员手动建表，用于测试的建表语句如下：
  --oracle10g
  CREATE TABLE user_tbl (
  id int PRIMARY KEY ,
  name varchar2(20),
  age int,
  sex varchar2(5),
  password varchar2(20)
  )
  create sequence user_seq;
  INSERT INTO user_tbl VALUES (1, 'zs',18, '张三', 'zs');
  
  
   
  
• 
  连接数据库的工具类：
  
  package util;
  import java.io.IOException;
  import java.io.InputStream;
  import org.apache.ibatis.io.Resources;
  import org.apache.ibatis.session.SqlSession;
  import org.apache.ibatis.session.SqlSessionFactory;
  import org.apache.ibatis.session.SqlSessionFactoryBuilder;
  /**
  * 连接数据库的工具类
  * @author Jzl
  *
  */
  public class MybatisUtil {
  private static SqlSessionFactory sessionFactory;
  private SqlSession session;
  static {
  String resource = "mybatis3-config.xml";
  InputStream inputStream = null;
  try {
  inputStream = Resources.getResourceAsStream(resource);
  } catch (IOException e) {
  e.printStackTrace();
  }
  sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
  }
  public static SqlSessionFactory getSqlsessionfactory() {
  return sessionFactory;
  }
  public static SqlSession getSession() {
  return sessionFactory.openSession(false);
  }
  public void closeSession(SqlSession session) {
  if (session != null) {
  session.close();
  session = null;
  }
  }
  }
  
  
  
   
  
• 
  UserDao，用于实现对User表的CRUD操作：
  
  package dao;
  import java.util.List;
  import entity.User;
  public interface UserDao {
  public List<User> getUserByName(String name);
  public List<User> getAllUser();
  public User getUser(String name);
  public void insertUser(User user);
  public void updateUser(User user);
  public void deleteUser(int id);
  }
  
  
  
   
  
• 
  不同于hibernate，mybatis映射文件（这里是UserDao.xml）映射的是Dao层的方法，用于将Dao层的方法与具体的sql语句绑定。
  
  <?xml version="1.0" encoding="UTF-8" ?>
  <!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
  <mapper namespace="dao.UserDao">
  <select id="getAllUser" resultType="entity.User">
  select * from user_tbl
  </select>
  <select id="getUserByName" parameterType="String" resultType="entity.User">
  select * from user_tbl
  where name like #{name}
  </select>
  <select id="getUser" parameterType="String" resultType="entity.User">
  select * from user_tbl where
  name=#{name}
  </select>
  <insert id="insertUser" parameterType="entity.User">
  <selectKey resultType="int" order="BEFORE" keyProperty="id">
  select user_seq.nextval from dual
  </selectKey>
  insert into user_tbl (id,name,age,sex,password)
  values
  (#{id},#{name},#{age},#{sex},#{password})
  </insert>
  <update id="updateUser" parameterType="entity.User">
  update user_tbl set name = #{name},age =
  #{age},
  sex = #{sex},password = #{password} where id = #{id}
  </update>
  <delete id="deleteUser" parameterType="int">
  delete from user_tbl where id = #{id}
  </delete>
  </mapper>
  
  
   
  
• 
  实体类User如下：
  
  package entity;
  public class User {
  private int id;
  private String name;
  private int age;
  private String sex;
  private String password;
  public User() {
  System.out.println("--调用无参数构造方法--");
  }
  public int getId() {
  return id;
  }
  public void setId(int id) {
  this.id = id;
  }
  public String getName() {
  return name;
  }
  public void setName(String name) {
  this.name = name;
  }
  public int getAge() {
  return age;
  }
  public void setAge(int age) {
  this.age = age;
  }
  public String getSex() {
  return sex;
  }
  public void setSex(String sex) {
  this.sex = sex;
  }
  public String getPassword() {
  return password;
  }
  public void setPassword(String password) {
  this.password = password;
  }
  }
  
  
  
   
  
• 
  最后就可以测试了，测试类TestUser如下：
  
  package test;
  import java.util.List;
  import org.apache.ibatis.session.SqlSession;
  import org.junit.Test;
  import util.MybatisUtil;
  import dao.UserDao;
  import entity.User;
  public class TestUser {
  public void testGetByName() {
  SqlSession session = MybatisUtil.getSession();
  List<User> users = session.selectList("getUserByName", "%s%");
  for (User user : users) {
  System.out.println(user.getId() + "==" + user.getName());
  }
  session.commit();
  session.close();
  }
  public void testGetAll() {
  SqlSession session = MybatisUtil.getSession();
  List<User> users = session.selectList("getAllUser");
  for (User user : users) {
  System.out.println(user.getId() + "==" + user.getName());
  }
  session.commit();
  session.close();
  }
  public void testGet() {
  SqlSession session = MybatisUtil.getSession();
  UserDao userDao = session.getMapper(UserDao.class);
  User user = userDao.getUser("zs");
  System.out.println(user.getId() + "==" + user.getName());
  session.commit();
  session.close();
  }
  @Test
  public void testAdd() {
  SqlSession session = MybatisUtil.getSession();
  UserDao userDao = session.getMapper(UserDao.class);
  User user = new User();
  // user.setId(10);
  user.setName("zs");
  user.setPassword("zs");
  user.setAge(20);
  user.setSex("女");
  try {
  userDao.insertUser(user);
  System.out.println("id:" + user.getId());
  // session.commit();
  } catch (Exception e) {
  e.printStackTrace();
  }
  // session.close();
  }
  public void testUpdate() {
  SqlSession session = MybatisUtil.getSession();
  UserDao userDao = session.getMapper(UserDao.class);
  User user = userDao.getUser("sb");
  user.setName("sa");
  user.setAge(19);
  userDao.updateUser(user);
  session.commit();
  session.close();
  }
  public void testDelete() {
  SqlSession session = MybatisUtil.getSession();
  UserDao userDao = session.getMapper(UserDao.class);
  userDao.deleteUser(1001);
  session.commit();
  session.close();
  }
  }
  
  
  
   
  
• 
  附上测试项目的源代码。