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:
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-- ---------------------------- -- 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
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<?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:
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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; } @Override public String toString(){ return this .userName+ " " + this .userAge+ " " + this .userAddress; } } |
IUserOperaton定义:
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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:
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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()); } } } |
以上所述是小编给大家介绍的Mybatis实现增删改查(CRUD)实例代码 ,希望对大家有所帮助,如果大家有任何疑问请给我留言,小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持!