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;

@Before
public void setUp()
{
source = "test-mybatis-configuration.xml";
}

@Test
public 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。