MyBatis 安装和配置
2024-09-03 02:59:04
在这里我们使用 MyBatis 开发一个简单的 Java 项目（默认你已安装JDK和MySQL及会使用Maven的基本操作），可以与上一篇通过底层操作数据进行比较
1、新建表 students，插入数据
SQL Code
CREATE TABLE students(
stud_id INT(11) NOT NULL AUTO_INCREMENT,
stud_name VARCHAR(50) NOT NULL,
stud_email VARCHAR(50) NOT NULL,
stud_dob DATE DEFAULT NULL,
PRIMARY KEY (stud_id)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=latin1; INSERT INTO students(stud_id,stud_name,stud_email,stud_dob)
VALUES (1,'Student1','student1@qq.com','1992-01-01');
INSERT INTO students(stud_id,stud_name,stud_email,stud_dob)
VALUES (2,'Student2','student2@qq.com','1993-12-31');
2、新建一个Maven项目，在pom.xml中引入Mybatis.jar
2.1 创建Maven项目，名为HzMyBatis
2.2 在pom.xml中引入相应的jar包
pom.xml code
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.2</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.39</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.1</version>
</dependency>
<!-- 日志框架 -->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.25</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.7.25</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
</dependencies>说明：mysql-connector-java-5.1.39 mysql数据库的驱动包、mybatis-3.4.1 Mybatis包、lombok-1.18.2 减少重复代码量（getter/setter/toString等需要注解标注）
3、新建 mybatis-config.xml 和映射器 StudentMapper.xml 配置文件
mybatis-config.xml:包括数据库连接信息，类型别名等信息
StudentMapper.xml:映射的SQL语句
这两个xml文件需要放到classpath路径下
mybatis-config.xml Code
<?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>
<!-- 设置Bean别名 -->
<typeAliases>
<typeAlias alias="Student" type="com.hz.mybatis.bean.Student" />
</typeAliases> <!-- 设置当前环境 -->
<environments default="development">
<environment id="development">
<!-- 开启事务 JDBC使用数据库自己的事务（局部事务） -->
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://127.0.0.1:3306/hadoop" />
<property name="username" value="root" />
<property name="password" value="root" />
</dataSource>
</environment>
</environments> <!-- 映射文件路径 -->
<mappers>
<mapper resource="com/hz/mybatis/mapper/StudentMapper.xml" />
</mappers>
</configuration>StudentMapper.xml Code
<?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.hz.mybatis.mapper.StudentMapper">
<resultMap type="Student" id="StudentResult">
<id property="studId" column="stud_id" />
<result property="name" column="stud_name" />
<result property="email" column="stud_email" />
<result property="dob" column="stud_dob" />
</resultMap> <select id="findAllStudents" resultMap="StudentResult">
SELECT * FROM STUDENTS
</select> <select id="findStudentById" parameterType="java.lang.Integer" resultType="Student">
SELECT STUD_ID AS STUDID, STUD_NAME AS NAME, STUD_EMAIL AS EMAIL, STUD_DOB AS DOB FROM STUDENTS WHERE STUD_ID = #{Id}
</select> <insert id="insertStudent" parameterType="Student">
INSERT INTO STUDENTS(STUD_ID, STUD_NAME,STUD_EMAIL,STUD_DOB)
VALUES(#{studId}, #{name}, #{email}, #{dob})
</insert>
</mapper>
3、新建 MyBatisSqlSessionFactory 单例模式类
MyBatisSqlSessionFactory.java Code
import java.io.InputStream; import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder; /**
* 创建单例SqlSessionFactory
* @author DONG
*
*/
public class MyBatisSqlSessionFactory { private static SqlSessionFactory sqlSessionFactory; public static SqlSessionFactory getSqlSessionFactory(){
if (sqlSessionFactory == null) {
InputStream inputStream;
try {
inputStream = Resources.getResourceAsStream("mybatis-config.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (Exception e) {
e.printStackTrace();
}
}
return sqlSessionFactory;
}
}
4、新建映射器 StudentMapper 接口和 StudentService 类
创建一个 StudentMapper 接口，其定义的方法名和在 Mapper XML 配置文件定义的 SQL 映射语 句名称相同
创建一个 StudentService.java 类，包含了一些业务操作的实现
1、首先, 创建 JavaBean Student.java
Student.java Code
import java.util.Date; import lombok.Data; @Data
public class Student { private Integer studId;
private String name;
private String email;
private Date dob; }2、创建映射器 Mapper 接口 StudentMapper.java 其方法签名和 StudentMapper.xml 中定义的 SQL 映射定义名
相同StudentMapper.java Code
import java.util.List; import com.hz.mybatis.bean.Student; public interface StudentMapper {
List<Student> findAllStudents();
Student findStudentById(Integer id);
void insertStudent(Student student);
}3、现在创建 MyBatisStudentService.java 实现对表 students 的数据库操作
import java.util.List; import org.apache.ibatis.session.SqlSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory; import com.hz.mybatis.bean.Student;
import com.hz.mybatis.mapper.StudentMapper;
import com.hz.mybatis.util.MyBatisSqlSessionFactory; /**
* 学生业务操作
* @author DONG
*
*/
public class MyBatisStudentService { private static Logger logger = LoggerFactory.getLogger(MyBatisStudentService.class); /**
* 查询所有学生信息
* @return
*/
public List<Student> findAllStudents(){
SqlSession sqlSession = MyBatisSqlSessionFactory.openSession();
logger.debug("获取sqlSession信息: ", sqlSession);
try {
StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
return studentMapper.findAllStudents();
} finally {
sqlSession.close();
}
} /**
* 通过学生ID查询学生信息
* @param studId
* @return
*/
public Student findStudentById(Integer studId){
logger.debug("通过学生ID查询学生信息: ", studId); SqlSession sqlSession = MyBatisSqlSessionFactory.openSession(); try {
StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
return studentMapper.findStudentById(studId);
} finally {
sqlSession.close();
}
} /**
* 插入学生信息
*/
public void insertStudent(Student student){
SqlSession sqlSession = MyBatisSqlSessionFactory.openSession(); try {
StudentMapper studentMapper = sqlSession.getMapper(StudentMapper.class);
studentMapper.insertStudent(student);
} finally {
sqlSession.close();
} }
}
5、新建一个 JUnit 测试类来测试 MyBatisStudentService
import java.util.List; import org.junit.AfterClass;
import org.junit.BeforeClass;
import org.junit.Test; import com.hz.mybatis.bean.Student;
import com.hz.mybatis.service.MyBatisStudentService; /**
* 测试
* @author DONG
*
*/
public class TestStudentMapper { private static MyBatisStudentService studentService; @BeforeClass
public static void setup(){
studentService = new MyBatisStudentService();
} @AfterClass
public static void teardown(){
studentService = null;
} @Test
public void testFindAllStudents(){
List<Student> students = studentService.findAllStudents(); for (Student student : students) {
System.out.println(student);
}
}
}
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