Java实战应用:MyBatis实现单表的增删改

文章出自：http://www.linuxidc.com/Linux/2014-06/103456.htm

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结果集的检索。MyBatis 使用简单的 XML或注解用于配置和原始映射，将接口和 Java 的POJOs（Plain Old Java Objects，普通的 Java对象）映射成数据库中的记录。

每个MyBatis应用程序主要都是使用SqlSessionFactory实例的，一个SqlSessionFactory实例可以通过SqlSessionFactoryBuilder获得。SqlSessionFactoryBuilder可以从一个xml配置文件或者一个预定义的配置类的实例获得。

用xml文件构建SqlSessionFactory实例是非常简单的事情。推荐在这个配置中使用类路径资源（classpath resource)，但你可以使用任何Reader实例，包括用文件路径或file://开头的url创建的实例。MyBatis有一个实用类----Resources，它有很多方法，可以方便地从类路径及其它位置加载资源。

MyBatis插入时候获取自增主键方法 http://www.linuxidc.com/Linux/2014-03/98965.htm

[Java][MyBatis]物理分页实现 http://www.linuxidc.com/Linux/2014-04/99889.htm

一、首先建立项目的整体效果图：

以下是MyBatis单表的增删改：



二、项目代码：

1）实体类：News中：

public class News {

private Integer id;

private String title;

private String content;

private Date pubDate;

private Integer typeId;

private String photo;

private String tname;

//get,set方式省去

2）dao层借口层的INewsDAO：

import java.util.List;

import java.util.Map;

import org.liky.vo.News;

public interface INewsDAO {

public void doCreate(News news) throws Exception;

public void doUpdate(News news) throws Exception;

public void doRemove(int id) throws Exception;

public List<News> findAll() throws Exception;

public News findById(int id) throws Exception;

public List<News> findAllSplit(Map<String, Object> map) throws Exception;

public int getAllCount(Map<String, Object> map) throws Exception;

}

3)dao层的实现，INewDAO.xml，正常不是myBatis,这里是写dao层的实现类的：myBatis的优势也是在这里，将sql语句抽调出来单独写入到一个xml中，便于管理数据库。它是更接近于jdbc的，所以处理的速度很快，它是外网项目中需要用到框架。

<mapper namespace="org.liky.dao.INewsDAO">

<resultMap type="News" id="NewsResult">

<id column="id" property="id" />

<result column="title" property="title" />

<result column="content" property="content" />

<result column="pub_date" property="pubDate" />

<result column="type_id" property="typeId" />

<result column="photo" property="photo" />

</resultMap>

<insert id="doCreate" parameterType="News">

INSERT INTO news

(id,title,content,pub_date,type_id,photo) VALUES

(news_seq.nextVal,#{title},#{content},#{pubDate},#{typeId},#{photo})

</insert>

<update id="doUpdate" parameterType="News">

UPDATE news

SET title =

#{title},content=#{content},pub_date = #{pubDate},type_id =

#{typeId},photo=#{photo}

WHERE id = #{id}

</update>

<delete id="doRemove" parameterType="java.lang.Integer">

DELETE FROM news WHERE id =

#{id}

</delete>

<select id="findAll" resultMap="NewsResult">

SELECT * FROM news

</select>

<select id="findById" resultType="News" parameterType="java.lang.Integer">

SELECT

id,title,content,pub_date AS pubDate,type_id AS typeId,photo,tname FROM news n,news_type nt

WHERE id = #{id} AND n.type_id = nt.tid

</select>

<select id="findAllSplit" resultType="News" parameterType="java.util.Map">

SELECT temp.* FROM (SELECT

id,title,content,pub_date

AS pubDate,type_id

AS typeId,photo,ROWNUM rn

FROM news WHERE ${column}

LIKE #{keyword} AND

ROWNUM <= #{endNumber}) temp WHERE temp.rn >

#{startNumber}

</select>

<select id="getAllCount" resultType="int" parameterType="java.util.Map">

SELECT

COUNT(*) FROM news WHERE ${column} LIKE #{keyword}

</select>

</mapper>

4)这一步可以写mybatis的总配置文件，初始加载连接数据库。

<configuration>

<typeAliases>

<package name="org.liky.vo" />

</typeAliases>

<environments default="development">

<environment id="development">

<transactionManager type="JDBC" />

<dataSource type="POOLED">

<property name="driver" value="Oracle.jdbc.driver.OracleDriver" />

<property name="url" value="jdbc:oracle:thin:@localhost:1521:ORCL" />

<property name="username" value="sunxun" />

<property name="password" value="123" />

</dataSource>

</environment>

</environments>

<mappers>

<mapper resource="org/liky/dao/INewsDAO.xml" />

</mappers>

</configuration>

5）建立MyBATISSqlSessionFactory类：

import java.io.InputStream;

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 MyBATISSqlSessionFactory {

// 配置文件的所在位置和名称

private static String CONFIG_FILE_LOCATION = "mybatis-config.xml";

// 用来实现连接池的，该类类似Map集合。

private static final ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();

// Hibernate用来读取配置文件的类

private static InputStream is;

// 用来建立连接的，该类就是连接池，使用单例设计模式

private static SqlSessionFactory sqlsessionFactory;

// 备用的配置文件位置

private static String configFile = CONFIG_FILE_LOCATION;

// 静态块，类加载时最先执行

static {

try {

// 加载配置文件到内存中

is = Resources.getResourceAsStream(configFile);

// 建立连接池以及里面的连接

sqlsessionFactory = new SqlSessionFactoryBuilder().build(is);

} catch (Exception e) {

System.err.println("%%%% Error Creating SessionFactory %%%%");

e.printStackTrace();

}

}

private MyBATISSqlSessionFactory() {

}

/**

* 取得数据库连接对象

*

* @return Session

* @throws HibernateException

*/

public static SqlSession getSession() {

// 先从ThreadLocal中取得连接。

SqlSession session = (SqlSession) threadLocal.get();

// 如果手头没有连接，则取得一个新的连接

if (session == null) {

session = sqlsessionFactory.openSession();

// 把取得出的连接记录到ThreadLocal中，以便下次使用。

threadLocal.set(session);

}

return session;

}

/**

* 连接关闭的方法

*

* @throws HibernateException

*/

public static void closeSession() {

SqlSession session = (SqlSession) threadLocal.get();

// 将ThreadLocal清空，表示当前线程已经没有连接。

threadLocal.set(null);

// 连接放回到连接池

if (session != null) {

session.close();

}

}

}

6）写service层实现的借口：

import java.util.List;

import java.util.Map;

import org.liky.vo.News;

public interface INewsService {

public void insert(News news) throws Exception;

public News findById(int id) throws Exception;

public List<News> findAll() throws Exception;

public Map<String, Object> list(int pageNo, int pageSize, String column,

String keyword) throws Exception;

}

7）解耦合，写service的工厂：

import org.liky.service.INewsService;

import org.liky.service.impl.NewsServiceImpl;

public class ServiceFactory {

public static INewsService getINewsServiceInstance() {

return new NewsServiceImpl();

}

}

8）service的实现类：

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import org.liky.dao.INewsDAO;

import org.liky.dbc.MyBATISSqlSessionFactory;

import org.liky.service.INewsService;

import org.liky.vo.News;

public class NewsServiceImpl implements INewsService {

public List<News> findAll() throws Exception {

List<News> all = null;

try {

all = MyBATISSqlSessionFactory.getSession().getMapper(

INewsDAO.class).findAll();

} catch (Exception e) {

e.printStackTrace();

throw e;

} finally {

MyBATISSqlSessionFactory.closeSession();

}

return all;

}

public News findById(int id) throws Exception {

News news = null;

try {

news = MyBATISSqlSessionFactory.getSession().getMapper(

INewsDAO.class).findById(id);

} catch (Exception e) {

e.printStackTrace();

throw e;

} finally {

MyBATISSqlSessionFactory.closeSession();

}

return news;

}

public void insert(News news) throws Exception {

try {

MyBATISSqlSessionFactory.getSession().getMapper(INewsDAO.class)

.doCreate(news);

MyBATISSqlSessionFactory.getSession().commit();

} catch (Exception e) {

e.printStackTrace();

MyBATISSqlSessionFactory.getSession().rollback();

throw e;

} finally {

MyBATISSqlSessionFactory.closeSession();

}

}

public Map<String, Object> list(int pageNo, int pageSize, String column,

String keyword) throws Exception {

Map<String, Object> map = new HashMap<String, Object>();

// 设置要向DAO中传递的参数

Map<String, Object> params = new HashMap<String, Object>();

params.put("column", column);

params.put("keyword", "%" + keyword + "%");

params.put("endNumber", pageNo * pageSize);

params.put("startNumber", (pageNo - 1) * pageSize);

try {

map.put("allNews", MyBATISSqlSessionFactory.getSession().getMapper(

INewsDAO.class).findAllSplit(params));

map.put("count", MyBATISSqlSessionFactory.getSession().getMapper(

INewsDAO.class).getAllCount(params));

} catch (Exception e) {

e.printStackTrace();

} finally {

MyBATISSqlSessionFactory.closeSession();

}

return map;

}

}

9）测试类NewsServiceImplTest：

import java.util.Date;

import java.util.UUID;

import org.junit.Test;

import org.liky.factory.ServiceFactory;

import org.liky.vo.News;

public class NewsServiceImplTest {

@Test

public void testFindAll() throws Exception {

System.out.println(ServiceFactory.getINewsServiceInstance().findAll());

}

@Test

public void testFindById() throws Exception {

System.out.println(ServiceFactory.getINewsServiceInstance()

.findById(61).getTname());

}

@Test

public void testInsert() throws Exception {

News news = new News();

news.setTitle("MyBATIS测试");

news.setContent("MyBATIS添加测试");

news.setTypeId(3);

news.setPubDate(new Date());

news.setPhoto(UUID.randomUUID().toString() + ".jpg");

ServiceFactory.getINewsServiceInstance().insert(news);

}

@Test

public void testListSplit() throws Exception {

System.out.println(ServiceFactory.getINewsServiceInstance().list(1, 5,

"title", ""));

}

}