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