mybatis系列一：mybatis实现增删改查

1.效果图：

2.Mybatis的步骤：

本内容涉及到mysql数据库，先去下载一个数据库，新建一个User表和Article表

Create TABLE `user` ( `id` int(11) NOT NULL AUTO_INCREMENT, `userName` varchar(50) DEFAULT NULL, `userAge` int(11) DEFAULT NULL, `userAddress` varchar(200) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8; Insert INTO `user` VALUES ('1', 'summer', '100', 'shanghai,pudong');Drop TABLE IF EXISTS `article`; Create TABLE `article` ( `id` int(11) NOT NULL auto_increment, `userid` int(11) NOT NULL, `title` varchar(100) NOT NULL, `content` text NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8; -- 添加几条测试数据 -- ---------------------------- Insert INTO `article` VALUES ('1', '1', '11111', 'dsgfd'); Insert INTO `article` VALUES ('2', '1', '22222', 'dfsdgds'); Insert INTO `article` VALUES ('3', '1', 'dddd3','dfsfsdfd'); Insert INTO `article` VALUES ('4', '1', 'ddd4', '5555');

2.1先将mybatis-3.2.7.jar和mysql-connector-java-5.1.22-bin.jar两个需要用到的jar包拷到WEB-INF下面的lib文件夹

2.2 看上图中的架构，新建包和类，按顺序新建

Article类：

package com.mybatis.model;public class Article {private int id;private User user;private String title;private String content;public int getId() {return id;}public void setId(int id) {this.id = id;}public User getUser() {return user;}public void setUser(User user) {this.user = user;}public String getTitle() {return title;}public void setTitle(String title) {this.title = title;}public String getContent() {return content;}public void setContent(String content) {this.content = content;}}

User类：

package com.mybatis.model;public class User {private int id; private String userName; private String userAge; private String userAddress;public int getId() {return id;}public void setId(int id) {this.id = id;}public String getUserName() {return userName;}public void setUserName(String userName) {this.userName = userName;}public String getUserAge() {return userAge;}public void setUserAge(String userAge) {this.userAge = userAge;}public String getUserAddress() {return userAddress;}public void setUserAddress(String userAddress) {this.userAddress = userAddress;}}

IUserOperation接口：

package com.mybatis.interfaces;import com.mybatis.model.*;import java.util.List;public interface IUserOperation {//定义的接口名需与User.xml里的id值要对应public List<User> getUserList(String userName);public List<Article> getUserAticles(int id);public User selectUserByID(int id);public int insertUserInfo(User user);public int updateUserInfo(User user);public int deleteUserInfo(int id);}

新建User.xml:

<?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="com.mybatis.interfaces.IUserOperation">     <!--  通过用户id返回用户信息 --><select id="selectUserByID" parameterType="int" resultType="User">select * from `user` where id = #{id}</select><!-- 返回List而定义的resultMap，注意column是数据库中定义的列字段，而property是我们自定义的字段，能够解决属性和数据库字段不一致的问题 --><resultMap type="User" id="resultUserList"><id column="id" property="id"></id><result column="userName" property="userName"/><result column="userAge" property="userAge"/><result column="userAddress" property="userAddress"/></resultMap><!-- 通过用户名返回用户列表 --><!-- 记住：在获取List列表的时候，resultMap="resultUserList"千万别写成resultType="resultUserList"，否则报错 --><select id="getUserList" parameterType="string"  resultMap="resultUserList">select * from `user` where userName like #{userName}</select><!-- 记住type="Article"新加一个class，要去configuration.xml进行别名定义，否则找不到报错 --><!-- 通过association来关联user，达到多对一的效果，多篇文章对应一个用户 --><!-- column="aid"给数据库列id命了一个别名，区分关联的id,否则只能查询出一条数据 --><resultMap type="Article" id="resultUserArticleList"><id column="aid" property="id"></id><result column="title" property="title"/><result column="content" property="content"/>    <!-- <association property="user" javaType="User"><id column="id" property="id"></id><result column="userName" property="userName"/><result column="userAddress" property="userAddress"/></association> --><!-- 上面的association等同于下面的这个，前提条件是之前就已经定义过resultUserList --><association property="user" javaType="User"  resultMap="resultUserList"></association></resultMap><!-- 获取用户的多个文章 --><select id="getUserAticles" parameterType="int"  resultMap="resultUserArticleList">select user.id,user.userName,user.userAddress,       article.id aid,article.title,article.content        from user,article        where user.id=article.userid and user.id=#{id}</select> <!-- useGeneratedKeys设置为"true"表明要MyBatis获取由数据库自动生成的主键；keyProperty="id"指定把获取到的主键值注入到User的id属性 --><insert id="insertUserInfo"  parameterType="User" useGeneratedKeys="true" keyProperty="id">insert into `user`(userName,userAge,userAddress) values (#{userName},#{userAge},#{userAddress})</insert><update id="updateUserInfo" parameterType="User">update user set userName=#{userName},userAge=#{userAge},userAddress=#{userAddress} where id=#{id}</update><delete id="deleteUserInfo" parameterType="int">delete from `user` where id=#{id}</delete></mapper><!-- namespace命名空间中的值一定要对应包定义的接口"com.mybatis.interfaces.IUserOperation"，否则报错 -->

新建配置文件configuration.xml

<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration><!-- mybatis别名定义 --><typeAliases><typeAlias alias="User" type="com.mybatis.model.User" /><typeAlias alias="Article" type="com.mybatis.model.Article" /></typeAliases><environments default="development"><environment id="development"><transactionManager type="JDBC" /><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver" /><property name="url" value="jdbc:mysql://127.0.0.1:3306/mybatis" /><property name="username" value="root" /><property name="password" value="password" /></dataSource></environment></environments><mappers><mapper resource="com/mybatis/model/User.xml" /></mappers></configuration><!-- Ctrl+Shift+F 自动排版 -->

最后开始测试，新建一个测试类：

package com.mybatis.test;import com.mybatis.interfaces.IUserOperation;import com.mybatis.model.User;import com.mybatis.model.Article;import java.io.Reader;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 java.util.List;public class Test {private static SqlSessionFactory sqlFactory;private static Reader reader;private static User user;private static int Ret;/*static{}(即static块)，会在类被加载的时候执行且仅会被执行一次，一般用来初始化静态变量和调用静态方*/static {try {reader = Resources.getResourceAsReader("Configuration.xml");sqlFactory = new SqlSessionFactoryBuilder().build(reader);} catch (Exception e) {e.printStackTrace();}}public static SqlSessionFactory getSession() {return sqlFactory;}//获取用户列表public static void GetUserList(List<User> UserList){if(UserList.size()>0){for(User u:UserList){System.out.println("Id:"+u.getId()+";UserName:"+u.getUserName()+";UserAge:"+u.getUserAge()+";UserAddress:"+u.getUserAddress());}}else{System.out.println("用户不存在！");}}//获取用户文章列表public static void GetUserArticle(List<Article> articleList){if(articleList.size()>0){for(Article a:articleList){System.out.println("UserName:"+a.getUser().getUserName()+";UserAddress:"+a.getUser().getUserAddress()+";ArticleTitle:"+a.getTitle()+";ArticleContent:"+a.getContent());}}else{System.out.println("用户不存在！");}}public static void main(String[] args) {SqlSession session = sqlFactory.openSession();try {IUserOperation operation=session.getMapper(IUserOperation.class);//新增/*user=new User();user.setUserName("Amyli");user.setUserAge("20");user.setUserAddress("Ludun BaLin");Ret=operation.insertUserInfo(user);if(Ret>0){System.out.println("新增成功！");}else{System.out.println("新增失败！");}*///删除/*Ret=operation.deleteUserInfo(27);if(Ret>0){System.out.println("删除成功！");}else{System.out.println("删除失败！");}*///修改user = operation.selectUserByID(24);user.setUserAge("23");user.setUserAddress("Chendu SiChuan");Ret=operation.updateUserInfo(user);if(Ret>0){System.out.println("修改成功！");}else{System.out.println("修改失败！");}session.commit();  //记住，做增删改操作，一定要记得调用commit提交，否则无效。//查询user = operation.selectUserByID(24);System.out.println(user.getId());System.out.println(user.getUserName());System.out.println(user.getUserAge());System.out.println(user.getUserAddress());System.out.println("");Test.GetUserList(operation.getUserList("DaLei"));System.out.println("文章：");Test.GetUserArticle(operation.getUserAticles(24));} finally {session.close();}}}

里面有好几个细节要注意，具体看代码，里面有详细注释！

Mybatis代码下载 ：Mybatis代码