MyBatis系列教程(一)--入门(QuickStart)

所需要用到的其他工具或技术:

项目管理工具 : Maven

测试运行工具 : Junit

数据库 : Derby

废话不多说,直接代码

Maven Dependencies:

<dependencies><dependency><groupId>org.mybatis</groupId><artifactId>mybatis</artifactId><version>3.2.7</version></dependency><dependency><groupId>junit</groupId><artifactId>junit</artifactId><version>4.9</version><scope>test</scope></dependency><dependency><groupId>org.apache.derby</groupId><artifactId>derby</artifactId><version>10.10.2.0</version></dependency><dependency><groupId>org.apache.derby</groupId><artifactId>derbyclient</artifactId><version>10.10.2.0</version></dependency></dependencies>

SQL 建表及数据插入:

CREATE TABLE USER_TEST_TB(ID INT PRIMARY KEY,USERNAME VARCHAR(20) NOT NULL,PASSWORD VARCHAR(20) NOT NULL,NICKNAME VARCHAR(20) NOT NULL);INSERT INTO USER_TEST_TB VALUES(1,'1st','111','Jack');INSERT INTO USER_TEST_TB VALUES(2,'2nd','222','Rose');INSERT INTO USER_TEST_TB VALUES(3,'3rd','333','Will');

Mybatis配置文件 src/main/resource源目录下

test-mybatis-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><properties><property name="driver" value="org.apache.derby.jdbc.ClientDriver" /><property name="url"value="jdbc:derby://localhost:1527/freud;create=true" /></properties><environments default="development"><environment id="development"><transactionManager type="JDBC" /><dataSource type="POOLED"><property name="driver" value="${driver}" /><property name="url" value="${url}" /></dataSource></environment></environments><mappers><!-- <mapper class="com.freud.practice.UserMapper" /> --><mapper resource="com/freud/practice/UserMapper.xml" /></mappers></configuration>

UserMapper.xml  Mapper文件（src/main/java/com.freud.practice目录下）

<?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.freud.practice.UserMapper"><select id="getUser" resultType="com.freud.practice.User">select *from USER_TEST_TB</select></mapper>

User.java对象类（src/main/java/com.freud.practice目录下）

package com.freud.practice;public class User{private Integer id;private String username;private String password;private String nickname;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 String getPassword(){return password;}public void setPassword(String password){this.password = password;}public String getNickname(){return nickname;}public void setNickname(String nickname){this.nickname = nickname;}}

UserMapper.java Mapper类（src/main/java/com.freud.practice目录下）

package com.freud.practice;import java.util.List;import org.apache.ibatis.annotations.Select;public interface UserMapper{//@Select("SELECT * FROM USER_TEST_TB")public List<User> getUser();}

测试类TestMyBatis.java（src/test/java/com.freud.practice目录下）

package com.freud.practice;import java.io.InputStream;import java.text.MessageFormat;import java.util.List;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.junit.Before;import org.junit.Test;public class TestMyBatis{private String source;private InputStream inputStream;private SqlSessionFactory sqlSessionFactory;@Beforepublic void setUp(){source = "test-mybatis-configuration.xml";}@Testpublic void testXMLConfingureSessionFactory(){try{inputStream = TestMyBatis.class.getClassLoader().getResourceAsStream(source);sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);SqlSession session = sqlSessionFactory.openSession();List<User> users = (List) session.selectList("com.freud.practice.UserMapper.getUser");System.out.println("Query by XML configuration...");this.printUsers(users);UserMapper userMapper = session.getMapper(UserMapper.class);System.out.println("\r\nQuery by annotation configuration...");this.printUsers(userMapper.getUser());}catch (Exception e){e.printStackTrace();}}private void printUsers(final List<User> users){int count = 0;for (User user : users){System.out.println(MessageFormat.format("==User[{0}]=================", ++count));System.out.println("User Id: " + user.getId());System.out.println("User UserName: " + user.getUsername());System.out.println("User Password: " + user.getPassword());System.out.println("User nickname: " + user.getNickname());}}}

以上是使用XML作为Mapper配置文件的一个入门，其实Mybatis还支持Annotation的方式，具体操作如下：

1. 打开UserMapper.java中的注释。

2. 打开test-mybatis-configuration.xml中的注释，并注释掉现有的Mapper

3. 删除UserMapper.xml文件

这种是Mybatis的Annotation方式的Mapper配置。个人比较偏向于XML方式，所以后续的教程会更倾向于XML配置的方式来写。

OK了，这就是今天要写得。