Mybatis实现增删改查（CRUD）实例代码

MyBatis简介

MyBatis 是支持普通 SQL 查询，存储过程和高级映射的优秀持久层框架。 MyBatis 消除了几乎所有的 JDBC 代码和参数的手工设置以及对结果集的检索。MyBatis 可以使用简单的XML 或注解用于配置和原始映射，将接口和 Java 的 POJO（Plain Old Java Objects，普通的Java对象）映射成数据库中的记录。

MyBatis下载：https://github.com/mybatis/mybatis-3/releases

Mybatis实例

对一个User表的CRUD操作：

User表：

-- ------------------------------ Table structure for `user`-- ----------------------------DROP TABLE IF EXISTS `user`;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=6 DEFAULT CHARSET=utf8;-- ------------------------------ Records of user-- ----------------------------INSERT INTO `user` VALUES ('1', 'summer', '30', 'shanghai');INSERT INTO `user` VALUES ('2', 'test2', '22', 'suzhou');INSERT INTO `user` VALUES ('3', 'test1', '29', 'some place');INSERT INTO `user` VALUES ('4', 'lu', '28', 'some place');INSERT INTO `user` VALUES ('5', 'xiaoxun', '27', 'nanjing'); 在Src目录下建一个mybatis的xml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.test.User"/> </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="admin"/></dataSource></environment></environments><!-- mybatis的mapper文件，每个xml配置文件对应一个接口 --><mappers><mapper resource="com/mybatis/test/User.xml"/></mappers></configuration> 

定义User mappers的User.xml配置文件

<?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.test.IUserOperation"><!-- select语句 --><select id="selectUserByID" parameterType="int" resultType="User">select * from `user` where user.id = #{id}</select><!-- 定义的resultMap，可以解决类的属性名和数据库列名不一致的问题--><!-- <resultMap type="User" id="userResultMap"><id property="id" column="user_id" /><result property="userName" column="user_userName" /><result property="userAge" column="user_userAge" /><result property="userAddress" column="user_userAddress" /></resultMap> --><!-- 返回list的select语句，注意 resultMap的值是指向前面定义好的 --><!-- <select id="selectUsersByName" parameterType="string" resultMap="userResultMap">select * from user where user.userName = #{userName}</select> --><select id="selectUsersByName" parameterType="string" resultType="User">select * from user where user.userName = #{userName}</select><!--执行增加操作的SQL语句。id和parameterType分别与IUserOperation接口中的addUser方法的名字和参数类型一致。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="addUser" parameterType="User" useGeneratedKeys="true" keyProperty="id"> insert into user(userName,userAge,userAddress) values(#{userName},#{userAge},#{userAddress}) </insert><update id="updateUser" parameterType="User" >update user set userName=#{userName},userAge=#{userAge},userAddress=#{userAddress} where id=#{id}</update><delete id="deleteUser" parameterType="int">delete from user where id=#{id}</delete></mapper> 

配置文件实现了接口和SQL语句的映射关系。selectUsersByName采用了2种方式实现，注释掉的也是一种实现，采用resultMap可以把属性和数据库列名映射关系定义好，property为类的属性，column是表的列名，也可以是表列名的别名！

User类的定义：

package com.mybatis.test;public class User {private int id;private String userName;private int 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 int getUserAge() {return userAge;}public void setUserAge(int userAge) {this.userAge = userAge;}public String getUserAddress() {return userAddress;}public void setUserAddress(String userAddress) {this.userAddress = userAddress;}@Overridepublic String toString(){return this.userName+" "+this.userAge+" "+this.userAddress;}}

IUserOperaton定义：

package com.mybatis.test;import java.util.List;public interface IUserOperation {public User selectUserByID(int id);public List<User> selectUsersByName(String userName);public void addUser(User user);public void updateUser(User user);public void deleteUser(int id);} 

IUserOperation为操作接口，函数名和mybatis的xml配置文件中的操作id名对应。

测试类Test：

package com.mybatis.test;import java.io.Reader;import java.util.List;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 Test {private static SqlSessionFactory sqlSessionFactory;private static Reader reader;static {try {reader = Resources.getResourceAsReader("Configuration.xml");sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);} catch (Exception e) {e.printStackTrace();}}public static SqlSessionFactory getSession() {return sqlSessionFactory;}public void getUserByID(int userID) {SqlSession session = sqlSessionFactory.openSession();try {IUserOperation userOperation = session.getMapper(IUserOperation.class);User user = userOperation.selectUserByID(userID);if (user != null) {System.out.println(user.getId() + ":" + user.getUserName()+ ":" + user.getUserAddress());}} finally {session.close();}}public void getUserList(String userName) {SqlSession session = sqlSessionFactory.openSession();try {IUserOperation userOperation = session.getMapper(IUserOperation.class);List<User> users = userOperation.selectUsersByName(userName);for (User user : users) {System.out.println(user.getId() + ":" + user.getUserName()+ ":" + user.getUserAddress());}} finally {session.close();}}/*** 增加后要commit*/public void addUser() {User user = new User();user.setUserAddress("place");user.setUserName("test_add");user.setUserAge(30);SqlSession session = sqlSessionFactory.openSession();try {IUserOperation userOperation = session.getMapper(IUserOperation.class);userOperation.addUser(user);session.commit();System.out.println("新增用户ID：" + user.getId());} finally {session.close();}}/*** 修改后要commit*/public void updateUser() {SqlSession session = sqlSessionFactory.openSession();try {IUserOperation userOperation = session.getMapper(IUserOperation.class);User user = userOperation.selectUserByID(1);if (user != null) {user.setUserAddress("A new place");userOperation.updateUser(user);session.commit();}} finally {session.close();}}/*** 删除后要commit.* * @param id*/public void deleteUser(int id) {SqlSession session = sqlSessionFactory.openSession();try {IUserOperation userOperation = session.getMapper(IUserOperation.class);userOperation.deleteUser(id);session.commit();} finally {session.close();}}public static void main(String[] args) {try {Test test = new Test();// test.getUserByID(1);// test.getUserList("test1");// test.addUser();// test.updateUser();// test.deleteUser(6);} catch (Exception e) {System.out.println(e.getMessage());}}}

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