本文將介紹使用框架mybatis開發(fā)原始Dao層來對一個(gè)對數(shù)據(jù)庫進(jìn)行增刪改查的案例。
Mapper動(dòng)態(tài)代理開發(fā)Dao層請閱讀我的下一篇博客：MyBatis開發(fā)Dao層的兩種方式（Mapper動(dòng)態(tài)代理方式）
本次使用的mybatis版本為mybatis-3.2.7，開發(fā)工具為eclipse，數(shù)據(jù)庫為mysql，jdk版本jdk1.8.0_151。
SqlSession使用范圍
SqlSessionFactoryBuilder
SqlSessionFactory
SqlSession
1、首先，使用eclipse新建一個(gè)java工程，在lib目錄下加入mybatis核心包、依賴包、數(shù)據(jù)驅(qū)動(dòng)包，然后BuildPath一下。。
2、添加日志文件，在classpath下創(chuàng)建log4j.properties如下：
# 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
3、在classpath下創(chuàng)建config資源文件夾，并在config文件夾下創(chuàng)建SqlMapConfig.xml，如下：
<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configurationPUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration> <environments default="development"> <environment id="development"> <!-- 使用jdbc事務(wù)管理--> <transactionManager type="JDBC" /> <!-- 數(shù)據(jù)庫連接池--> <dataSource type="POOLED"> <property name="driver" value="com.mysql.jdbc.Driver" /> <property name="url" value="jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf-8" /> <property name="username" value="root" /> <property name="password" value="root" /> </dataSource> </environment> </environments></configuration>
SqlMapConfig.xml是mybatis核心配置文件，上邊文件的配置內(nèi)容為數(shù)據(jù)源、事務(wù)管理。
4、創(chuàng)建數(shù)據(jù)封裝使用的User類
package com.xyfer.po;import java.util.Date;/** * * @author xyfer * 數(shù)據(jù)封裝使用的User類 * */public class User { private int id; //id private String username; //姓名 private String sex; //性別 private Date birthday; // 生日 private String address; // 地址 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 String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public Date getBirthday() { return birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; }}5、在classpath下的資源文件夾sqlmapper目錄下創(chuàng)建sql映射文件User.xml：
<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapperPUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="test"> <!-- 根據(jù)id查詢用戶 --> <select id="findUserById" parameterType="int" resultType="com.xyfer.po.User"> select * from user where id = #{id} </select> <!-- 添加用戶 --> <insert id="insertUser" parameterType="com.xyfer.po.User"> <selectKey keyProperty="id" order="AFTER" resultType="java.lang.Integer"> select LAST_INSERT_ID() </selectKey> insert into user(username,birthday,sex,address) values(#{username},#{birthday},#{sex},#{address}) </insert> <!-- 修改用戶 --> <update id="updateUser" parameterType="com.xyfer.po.User"> update user set username=#{username},birthday=#{birthday},sex=#{sex},address=#{address} where id=#{id} </update> <!-- 刪除用戶 --> <delete id="deleteUserById" parameterType="int"> delete from user where id=#{id} </delete></mapper>6、mybatis框架需要加載映射文件，將Users.xml添加在SqlMapConfig.xml，如下：
<mappers> <mapper resource="User.xml"/></mappers>
7、dao層接口
package com.xyfer.dao;import com.xyfer.po.User;public interface UserDao { public User getUserById(int id); //根據(jù)id值查詢一個(gè)用戶 public void insertUser(User user); //新增一個(gè)用戶 public void updateUser(User user); //修改一個(gè)用戶 public void deleteUser(int id); //刪除一個(gè)用戶 }dao層接口實(shí)現(xiàn)類
package com.xyfer.dao.impl;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import com.xyfer.dao.UserDao;import com.xyfer.po.User;public class UserDaoImpl implements UserDao { //注入SqlSessionFactory public UserDaoImpl(SqlSessionFactory sqlSessionFactory){ this.setSqlSessionFactory(sqlSessionFactory); } private SqlSessionFactory sqlSessionFactory; public SqlSessionFactory getSqlSessionFactory() { return sqlSessionFactory; } public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) { this.sqlSessionFactory = sqlSessionFactory; } @Override public User getUserById(int id) { SqlSession session = sqlSessionFactory.openSession(); User user = null; try { //通過sqlsession調(diào)用selectOne方法獲取一條結(jié)果集 //參數(shù)1：指定定義的statement的id,參數(shù)2：指定向statement中傳遞的參數(shù) user = session.selectOne("test.findUserById", 1); System.out.println(user); } finally{ session.close(); } return user; } @Override public void insertUser(User user) { SqlSession sqlSession = sqlSessionFactory.openSession(); try { sqlSession.insert("test.insertUser", user); sqlSession.commit(); } finally{ sqlSession.close(); } } @Override public void updateUser(User user) { SqlSession sqlSession = sqlSessionFactory.openSession(); try { sqlSession.update("test.updateUser", user); sqlSession.commit(); } finally{ sqlSession.close(); } } @Override public void deleteUser(int id) { SqlSession sqlSession = sqlSessionFactory.openSession(); try { sqlSession.update("test.deleteUserById", id); sqlSession.commit(); } finally{ sqlSession.close(); } }}8、創(chuàng)建一個(gè)JUnit的測試類，對UserDao進(jìn)行測試。
package com.xyfer.dao.impl;import static org.junit.Assert.*;import java.io.InputStream;import java.util.Date;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.junit.Before;import org.junit.Test;import com.xyfer.dao.UserDao;import com.xyfer.po.User;public class UserDaoImplTest { private SqlSessionFactory sqlSessionFactory; @Before public void init() throws Exception { SqlSessionFactoryBuilder sessionFactoryBuilder = new SqlSessionFactoryBuilder(); InputStream inputStream = Resources.getResourceAsStream("SqlMapConfig.xml"); sqlSessionFactory = sessionFactoryBuilder.build(inputStream); } @Test public void testGetUserById() { UserDao userDao = new UserDaoImpl(sqlSessionFactory); User user = userDao.getUserById(22); System.out.println(user); } @Test public void testInsertUser() { User user = new User(); user.setUsername("小李"); user.setSex("男"); user.setBirthday(new Date()); user.setAddress("杭州市"); UserDao userDao = new UserDaoImpl(sqlSessionFactory); userDao.insertUser(user); } @Test public void testUpdateUser() { User user = new User(); user.setId(10); user.setUsername("小威"); user.setSex("男"); user.setBirthday(new Date()); user.setAddress("杭州市"); UserDao userDao = new UserDaoImpl(sqlSessionFactory); userDao.updateUser(user); } @Test public void testDeleteUser() { UserDao userDao = new UserDaoImpl(sqlSessionFactory); userDao.deleteUser(10); }}以上步驟，完成使用mybatis框架開發(fā)原始dao層，并對數(shù)據(jù)庫進(jìn)行增刪改查操作。
需要注意的是，上文提到的config文件夾和sqlmapper文件夾均為資源文件夾（source folder），默認(rèn)會(huì)加載該路徑下的文件。希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持VeVb武林網(wǎng)。
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