基于Mybatis实现CRUD操作过程解析(xml方式)

1、环境搭建

1.1 表结构

create table user ( id int primary key auto_increment, username varchar(20) not null, birthday date, sex char(1) default ’男’, address varchar(50));insert into user values (null, ’孙悟空’,’1980-10-24’,’男’,’花果山水帘洞’);insert into user values (null, ’白骨精’,’1992-11-12’,’女’,’白虎岭白骨洞’);insert into user values (null, ’猪八戒’,’1983-05-20’,’男’,’福临山云栈洞’);insert into user values (null, ’蜘蛛精’,’1995-03-22’,’女’,’?丝洞’);

1.2 创建项目

导入如下jar

1.3 准备配置文件

在src下准备配置文件：sqlMapConfig.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> <!--配置数据库连接参数--> <environments default='mybatis'> <environment id='mybatis'> <!--事务管理器--> <transactionManager type='JDBC'></transactionManager> <!--配置数据源--> <dataSource type='pooled'><property name='driver' value='com.mysql.jdbc.Driver'/><property name='url' value='jdbc:mysql:///test'/><property name='username' value='root'/><property name='password' value='root'/> </dataSource> </environment> </environments></configuration>

在 src 下准备配置文件：log4j.properties

# Global logging configurationlog4j.rootLogger=DEBUG, stdout

# Console output...log4j.appender.stdout=org.apache.log4j.ConsoleAppenderlog4j.appender.stdout.layout=org.apache.log4j.PatternLayoutlog4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

2-增删改查源码

1.1 执行结果

1.2 User类代码

import java.sql.Date;/** 用户实体类对象 */public class User { private Integer id; private String username; private Date birthday; private String sex; private String address; public User() { } public User(Integer id, String username, Date birthday, String sex, String address) { this.id = id; this.username = username; this.birthday = birthday; this.sex = sex; this.address = address; } public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } @Override public String toString() { return 'User{' +'id=' + id +', username=’' + username + ’’’ +', birthday=' + birthday +', sex=’' + sex + ’’’ +', address=’' + address + ’’’ +’}’; }}

1.3 UserMapper接口代码

package com.vg.dao;import com.vg.entity.User;import org.apache.ibatis.annotations.Param;import java.util.List;/** * 数据访问层接口：对用户进行增删改查操作 */public interface UserMapper {/** * 添加用户 */int addUser(User user);/** * 根据id删除用户 */void deleteUser(Integer id);/** * 通过id修改用户信息 *//** * 修改用户信息 */void updateUser(User user);/** * 查询所有用户 */List<User> findAllUsers();/** * 根据id查询用户 */User findUserById(int id);/** * 根据用户名模糊查询用户 */List<User> findUsersByName(String username);/** * 根据姓名和性别查询用户数据(姓名使用模糊查询) *//** * 根据用户名称模糊查询用户 */}}

1.4 UserMapper.xml接口映射文件

<?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'><!-- 映射的作用：一个映射文件就对应一个接口，一个接口可以有多个映射文件，一般是一对一关系。 mapper标签的namespace属性的作用：关联接口，需要配置对应接口的类全名字符串--><mapper namespace='com.vg.dao.UserMapper'> <!-- 完成接口映射配置文件UserMapper.xml的编写：这个映射文件就相当于UserMapper接口实现类配置 --> <!--select标签的作用：用来配置查询要执行的SQL语句 id属性：关联接口中的方法名 resultType属性：设置方法返回的数据类型，如果是集合则配置集合元素的类型 --> <select resultType='User'> select * from user </select> <select parameterType='int' resultType='User'> select * from user where id = #{id}; </select> <select parameterType='string' resultType='User'> select *from user where username like #{username} </select> <insert parameterType='user' > insert into user values(null,#{username},#{birthday},#{sex},#{address}); </insert> <update parameterType='user'> update user set username = #{username}, birthday = #{birthday},sex = #{sex}, address = #{address} where id = #{id} </update> <delete parameterType='integer'> delete from user where id = #{id} </delete></mapper>

1.5 在主配置文件中加载接口映射文件

<mappers> <!--mapper标签:一个该标签就配置一个接口映射文件 resource属性:配置映射文件的路径,路径分隔符使用 / : com/vg/dao/UserMapper.xml url:用于配置互联网上的映射文件的路径,比如:http://www.baidu.com/xxx.xml --> <!--<mapper resource='com/vg/dao/UserMapper.xml'></mapper>--> <package name='com.vg.dao'/></mappers>

1.6 测试类代码

package com.vg.test;import com.vg.dao.UserMapper;import com.vg.entity.User;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 org.junit.After;import org.junit.Before;import org.junit.BeforeClass;import org.junit.Test;import java.io.IOException;import java.io.InputStream;import java.sql.Date;import java.util.List;/** * 测试类 */public class TestUserMapper {private static SqlSessionFactory sqlSessionFactory =null;private SqlSession sqlSession =null;private UserMapper userMapper =null;// 该方法在所有测试方法执行之前执行1次@BeforeClasspublic static void init() throws Exception {// 1. 通过Resources类，加载sqlMapConfig.xml，得到文件输入流对InputStream in = Resources.getResourceAsStream('sqlMapConfig.xml');// 2. 实例化会话工厂创建类SqlSessionFactoryBuilder对象SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();// 3. 根据字节输入流获取SqlSessionFactory对象sqlSessionFactory = builder.build(in);}// 该方法会在每个测试方法执行之前执行1次@Beforepublic void before(){// 4. 获取SqlSession对象，等价连接对象// true:事务自动提交，false:不自动提交,默认值sqlSession = sqlSessionFactory.openSession();// 5. 创建接口 实现类对象userMapper = sqlSession.getMapper(UserMapper.class);}/** * 测试方法：通过用户名模糊查询用户 */@Testpublic void testAddUser() throws Exception{// 1. 获得接口代理对象UserMapper userMapper = sqlSession.getMapper(UserMapper.class);// 2. 创建User对象User u = new User();u.setUsername('如来佛祖111');u.setBirthday(Date.valueOf('1980-01-20'));u.setAddress('西天灵山');u.setSex('男');// 3. 保存用户信息int row = userMapper.addUser(u);System.out.println('row = ' + row);// 4. 手动提交事务sqlSession.commit();}/** * 测试方法：通过用户名模糊查询用户 */@Testpublic void testFindUserByName() throws Exception{List<User> userList = userMapper.findUsersByName('%精%');for (User user : userList) {System.out.println(user);}}/** * 测试方法：查询所有用户 */@Testpublic void testFindAllUsers() throws Exception{List<User> userList = userMapper.findAllUsers();for (User user : userList) {System.out.println(user);}}/** * 根据id查询用户 * @throws Exception */@Testpublic void testFindUserById()throws Exception{// 6. 调用接口的方法根据id查询用户User user = userMapper.findUserById(1);System.out.println('user = ' + user);}@Testpublic void testUpdateUser()throws Exception{// 创建用户对象User user = new User(6,'牛魔王',Date.valueOf('1998-02-20'),'妖','牛魔洞');// 更新用户userMapper.updateUser(user);// 提交事务sqlSession.commit();}@Testpublic void testDeleteUser()throws Exception{// 1. 获得接口代理对象UserMapper userMapper = sqlSession.getMapper(UserMapper.class);// 2. 根据id删除用户userMapper.deleteUser(6);// 3. 提交事务sqlSession.commit();}@Afterpublic void after() {// 7. 关闭会话，释放资源。sqlSession.close();}}

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