Mybatis系列之简单示例
经过前两篇文章《Mybatis系列之入门》和《Mybatis系列之配置》的介绍，我们对Mybatis有了一定的了解，下面就接合一个实例学习案例，来巩固一下我们前面学习的知识。
环境搭建
IDE: STS(Spring Tools Suite)
Java Version: 1.6
Spring Version:3.1.1
Mybatis Version: 3.3.0
Database: Mysql 5.1.36
JUnit Version: 4.7
数据库
在Mysql中创建数据库mybatis，并在其中创建两张数据表，DDL语句如下：
CREATE TABLE `sys_user` ( `user_id` int(10) unsigned NOT NULL AUTO_INCREMENT, `user_name` varchar(64) NOT NULL, `user_password` varchar(32) NOT NULL, `nick_name` varchar(64) NOT NULL, `email` varchar(128) DEFAULT NULL, `user_type_id` smallint(4) NOT NULL, `is_valid` tinyint(1) NOT NULL DEFAULT '1', `created_time` datetime NOT NULL, `update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, `last_login_time` datetime DEFAULT NULL, `online` tinyint(4) NOT NULL DEFAULT '0', `language` varchar(6) NOT NULL DEFAULT 'zh-cn', `psd_changed_date` datetime DEFAULT NULL, `mphone` varchar(12) DEFAULT NULL, PRIMARY KEY (`user_id`), UNIQUE KEY `user_name` (`user_name`) USING BTREE ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8
CREATE TABLE `communicator` ( `communicator_id` int(10) NOT NULL AUTO_INCREMENT, `communicator_name` varchar(64) NOT NULL, `phone` varchar(32) DEFAULT NULL, `fax` varchar(32) DEFAULT NULL, `email` varchar(100) DEFAULT NULL, `user_id` int(10) DEFAULT NULL, `report_to` int(10) DEFAULT '0', `is_valid` tinyint(4) NOT NULL DEFAULT '1', `created_time` datetime DEFAULT NULL, `update_time` timestamp NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP, PRIMARY KEY (`communicator_id`), UNIQUE KEY `communicator_name` (`communicator_name`) USING BTREE ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8
Mybatis 配置
数据表映射文件
为了体验Mybatis配置的灵活性和多样性，这里个案例中使用了不同的数据映射方式。
数据表User，使用外部XML文件进行映射，而另一张数据表Communicator则使用了注解映射。
这里仅用于测试，因为在实际使用中，注解还是写在Java代码上的，所有当有变化时，还是需要重新编译程序的，这一点与Mybatis的初衷是背道而驰的。
INSERT INTO sys_user(user_name, user_password, nick_name, user_type_id, is_valid, created_time) VALUES(#{userName}, #{userPassword}, #{nickName}, #{userTypeId}, #{isValid}, #{createdTime}) UPDATE sys_user SET user_name = #{userName}, user_password = #{userPassword}, nick_name = #{nickName}, user_type_id = #{userTypeId}, is_valid, = #{isValid} WHERE user_id = #{id} DELETE FROM sys_user WHERE user_id = #{id} DELETE FROM sys_user WHERE user_id in #{item}
package com.emerson.learning.dao;
import java.util.List;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import com.emerson.learning.pojo.Communicator;
public interface ICommunicatorDao {
@Select("SELECT * FROM communicator WHERE communicator_id=#{id}")
public Communicator getById(@Param(value = "id") int id);
@Select("SELECT * FROM vw_communicator ORDER BY communicator_name")
public List getAll();
}
Java POJO类
创建用于封装数据表记录的值对象，有的朋友喜欢叫entity，有的叫domain，有的叫pojo，叫什么无所谓了，根据自己的喜好来吧 ：）
package com.emerson.learning.pojo;
import java.sql.Timestamp;
public class User {
/**
*
*/
private int userId;
/**
*
*/
private String userPassword;
/**
*
*/
private String userName;
/**
*
*/
private String nickName;
/**
*
*/
private int userTypeId;
/**
*
*/
private String email;
/**
*
*/
private int isValid;
/**
*
*/
private Timestamp createdTime;
/**
*
*/
private Timestamp updatedTime;
public int getIsValid() {
return isValid;
}
public void setIsValid(int isValid) {
this.isValid = isValid;
}
public Timestamp getCreatedTime() {
return createdTime;
}
public void setCreatedTime(Timestamp createdTime) {
this.createdTime = createdTime;
}
public Timestamp getUpdatedTime() {
return updatedTime;
}
public void setUpdatedTime(Timestamp updatedTime) {
this.updatedTime = updatedTime;
}
public int getUserId() {
return userId;
}
public void setUserId(int userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getNickName() {
return nickName;
}
public void setNickName(String nickName) {
this.nickName = nickName;
}
public String getEmail() {
return email;
}
public void setEmail(String eamil) {
this.email = eamil;
}
public String getUserPassword() {
return userPassword;
}
public void setUserPassword(String userPassword) {
this.userPassword = userPassword;
}
public User() {
this.createdTime = new Timestamp(System.currentTimeMillis());
}
public int getUserTypeId() {
return userTypeId;
}
public void setUserTypeId(int userTypeId) {
this.userTypeId = userTypeId;
}
@Override
public String toString() {
return "User [userId=" + userId + ", userName=" + userName + ", nickName=" + nickName + ", eamil=" + email
+ ", isValid=" + isValid + ", createdTime=" + createdTime + ", updatedTime=" + updatedTime + "]";
}
}
package com.emerson.learning.pojo;
import java.sql.Timestamp;
public class Communicator {
/**
*
*/
private long communicatorId;
/**
*
*/
private String communicatorName;
/**
*
*/
private String phone;
/**
*
*/
private String fax;
/**
*
*/
private String email;
/**
*
*/
private int reportTo;
/**
*
*/
private String reportToName;
/**
*
*/
private int isValid;
/**
*
*/
private Timestamp createdTime;
/**
*
*/
private Timestamp updatedTime;
public long getCommunicatorId() {
return communicatorId;
}
public void setCommunicatorId(long communicatorId) {
this.communicatorId = communicatorId;
}
public String getCommunicatorName() {
return communicatorName;
}
public void setCommunicatorName(String communicatorName) {
this.communicatorName = communicatorName;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getFax() {
return fax;
}
public void setFax(String fax) {
this.fax = fax;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public int getReportTo() {
return reportTo;
}
public void setReportTo(int reportTo) {
this.reportTo = reportTo;
}
public String getReportToName() {
return reportToName;
}
public void setReportToName(String reportToName) {
this.reportToName = reportToName;
}
public int getIsValid() {
return isValid;
}
public void setIsValid(int isValid) {
this.isValid = isValid;
}
public Timestamp getCreatedTime() {
return createdTime;
}
public void setCreatedTime(Timestamp createdTime) {
this.createdTime = createdTime;
}
public Timestamp getUpdatedTime() {
return updatedTime;
}
public void setUpdatedTime(Timestamp updatedTime) {
this.updatedTime = updatedTime;
}
@Override
public String toString() {
return "Communicator [communicatorId=" + communicatorId + ", communicatorName=" + communicatorName + ", phone="
+ phone + ", fax=" + fax + ", email=" + email + ", reportTo=" + reportTo + ", reportToName="
+ reportToName + ", isValid=" + isValid + ", createdTime=" + createdTime + ", updatedTime="
+ updatedTime + "]";
}
}
测试
一切基础工作做好后，就可以着手编写测试代码了。这里使用了JUnit测试框架，如果有朋友不了解，请自行补充学习。
我们先对使用外部XML文件进行映射的User表进行测试，测试代码如下。
package com.emerson.learning.mapping;
import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
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;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import com.emerson.learning.pojo.User;
public class UserMappingTest {
private Reader reader;
private SqlSessionFactory sqlSessionFactory;
@Before
public void setUp() throws Exception {
try {
reader = Resources.getResourceAsReader("mybatis.xml");
} catch (IOException e) {
e.printStackTrace();
}
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
}
@After
public void tearDown() throws Exception {
}
/**
* 下面使用的是直接从映射配置文件中读取相应的SQL语句并执行 返回的是Object对象，需要对其进行强类型转换后才可使用
*
* 该实现方便需要为每个实体类编写一个映射文件
*
*
*
*
* 并注册到Mybatis配置文件中的mappers节中
*
*
*
*/
@Test
public void testGetById() {
SqlSession session = sqlSessionFactory.openSession();
try {
User user;
Object obj = session.selectOne("com.emerson.learning.mapping.user.getByID", 1);
if (null == obj) {
System.out.println("the result is null.");
} else {
user = (User) obj;
System.out.println(user.getUserName());
System.out.println(user.getNickName());
System.out.println(user);
}
} finally {
session.close();
}
}
/**
* 测试模糊查询
*/
@Test
public void testQueryByName() {
SqlSession session = sqlSessionFactory.openSession();
try {
User user = new User();
user.setUserName("mao");
List list = session.selectList("com.emerson.learning.mapping.user.queryByName", user);
System.out.println(list.size());
for(User u: list) {
System.out.println(u);
}
} finally {
session.close();
}
}
/**
* 测试写入数据
*/
@Test
public void testInsertUser() {
SqlSession session = sqlSessionFactory.openSession();
try {
User user = new User();
user.setEmail("chris.mao.zb@###.com");
user.setNickName("Mybatis Tester");
user.setUserName("cmzb");
user.setIsValid(1);
user.setUserPassword("5f4dcc3b5aa765d61d8327deb882cf99");
session.insert("com.emerson.learning.mapping.user.insertUser", user);
System.out.println("New Id is " + user.getUserId()); //打印出新增记录的Id值
session.commit(); //这里一定要使用commit，否则事务不会被提交，数据操作不会反映到数据表中
} finally {
session.close();
}
}
/**
* 测试更新数据
*/
@Test
public void testUpdateUser() {
SqlSession session = sqlSessionFactory.openSession();
try {
User user = session.selectOne("com.emerson.learning.mapping.user.getByID", 2);
user.setEmail("chris.mao.zb@＃＃＃.com");
user.setNickName("ChrisMao");
user.setIsValid(0);
session.update("com.emerson.learning.mapping.user.updatetUser", user);
session.commit();//这里一个要commit，否则更新是不会写入到数据表中的
} finally {
session.close();
}
}
/**
* 测试单条删除
*/
@Test
public void testDeleteById() {
SqlSession session = sqlSessionFactory.openSession();
try {
session.delete("com.emerson.learning.mapping.user.deleteById", 3);
session.commit();
} finally {
session.close();
}
}
/**
* 测试批量删除
*/
@Test
public void testDeleteBatch() {
SqlSession session = sqlSessionFactory.openSession();
try {
List idList = new ArrayList();
idList.add(1);
idList.add(2);
session.delete("com.emerson.learning.mapping.user.deleteBatch", idList);
session.commit();
} finally {
session.close();
}
}
}
下在是对使用注解映射的数据表Communicator表进行测试。这里使用到了Mybatis接口式编程的特性，在后续的《Mybatis系列之接口式编程》会进一步阐述，这里就不多说了。
package com.emerson.learning.dao;
import java.io.IOException;
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;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import com.emerson.learning.pojo.Communicator;
public class CommunicatorDaoTest {
private Reader reader;
private SqlSessionFactory sqlSessionFactory;
@Before
public void setUp() throws Exception {
try {
reader = Resources.getResourceAsReader("mybatis.xml");
} catch (IOException e) {
e.printStackTrace();
}
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
}
@After
public void tearDown() throws Exception {
}
/**
* 下面使用了接口和注解的方式来执行同样的代码 定义一个操作数据实体表的接口，并使用注解方式把SQL查询语句与接口方法进行绑定 public
* interface ICommunicatorDao { @Select(
* "SELECT * FROM communicator WHERE communicator_id=#{id}") public
* Communicator getById(@Param(value = "id") int id); }
*
* 然后将接口注册到Mybatis的配置文件中即可
*
*
* 当数据表很多的时候，需要写很多的映射关系，这样也比较麻烦，Mybatis3.2.1提供了 一种更加简洁的方法，可以一次指定多个映射接口
*
*
*/
@Test
public void testGetById() {
SqlSession session = sqlSessionFactory.openSession();
try {
ICommunicatorDao cp = session.getMapper(ICommunicatorDao.class);
Communicator c = cp.getById(1);
if (null == c) {
System.out.println("the result is null.");
} else {
System.out.println(c);
}
} finally {
session.close();
}
}
@Test
public void testGetAll() {
SqlSession session = sqlSessionFactory.openSession();
try {
ICommunicatorDao cp = session.getMapper(ICommunicatorDao.class);
List list = cp.getAll();
for (Communicator c : list) {
System.out.println(c);
}
} finally {
session.close();
}
}
}
总结
至此，对Mybatis的单表测试代码部分已全部完成。对于上述案例进行如下总结：
- Mybatis大大减少了码农的编码工作，提高了工和效率
- 让程序猿可以把更多精力放在业务逻辑处理上，与数据库打交道的工作交由Mybatis完成
- 对于业务表的映射关系尽量使用外部文件进行配置
- 对于变动极小的基础数据表的映射可以考虑使用注解方式完成
最后，附上项目目录结构图。
