MyBatis Demo
MyBatis Demo
项目目录总览：
1.向pom.xml中导入依赖
<dependencies>
<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.49</version>
</dependency>
<!-- https://mvnrepository.com/artifact/junit/junit -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
</dependencies>
2.在resources文件夹中创建mybatis-config.xml、db.properties
mybatis-config.xml内容：
<?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 resource="db.properties"/>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="${jdbc.driver}" />
<property name="url" value="${jdbc.url}" />
<property name="username" value="${jdbc.username}" />
<property name="password" value="${jdbc.password}" />
</dataSource>
</environment>
</environments>
<mappers>
<package name="com.ssm.mybatis.dao"/>
</mappers>
</configuration>
!!需要改package中的name，改为自己所建的dao包，例如：×××.××.××.dao
db.properties内容:
jdbc.driver = com.mysql.jdbc.Driver
jdbc.url = jdbc:mysql://localhost:3306/chapter03?useUnicode=true&characterEncoding=utf-8
jdbc.username = root
jdbc.password = ****
需要该为自己的数据库名字，把chapter03换为自己的数据库，和改username、password
3.分别建立三个包dao、pojo、utils
首先utils包中的MyBatisUtils类可以不用变直接粘贴下列代码
package com.ssm.mybatis.utils;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import java.io.IOException;
import java.io.Reader;
public class MyBatisUtils {
private static SqlSessionFactory sqlSessionFactory = null;
static {
try {
Reader reader = Resources.getResourceAsReader("mybatis-config.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
} catch (IOException e) {
e.printStackTrace();
}
}
public static SqlSession getSession()
{
return sqlSessionFactory.openSession();
}
}
pojo中的类要根据所给的信息，来和数据库中的表来相互关联，一张表对应一个类，要注意在一对多关系中，在一那个类中创建多那个类的集合。
Student类代码如下：
package com.ssm.mybatis.pojo;
public class Student {
private int sid;
private String sname;
private String age;
private String course;
public int getSid() {
return sid;
}
public void setSid(int sid) {
this.sid = sid;
}
public String getSname() {
return sname;
}
public void setSname(String sname) {
this.sname = sname;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public String getCourse() {
return course;
}
public void setCourse(String course) {
this.course = course;
}
@Override
public String toString() {
return "Student{" +
"sid=" + sid +
", sname='" + sname + '\'' +
", age='" + age + '\'' +
", course='" + course + '\'' +
'}';
}
}
StuClass类代码如下：
package com.ssm.mybatis.pojo;
import java.util.List;
public class StuClass {
private int cid;
private String cname;
private int sum;
private List<Student> stuList;
public int getCid() {
return cid;
}
public void setCid(int cid) {
this.cid = cid;
}
public String getCname() {
return cname;
}
public void setCname(String cname) {
this.cname = cname;
}
public int getSum() {
return sum;
}
public void setSum(int sum) {
this.sum = sum;
}
public List<Student> getStuList() {
return stuList;
}
public void setStuList(List<Student> stuList) {
this.stuList = stuList;
}
@Override
public String toString() {
return "StuClass{" +
"cid=" + cid +
", cname='" + cname + '\'' +
", sum=" + sum +
", stuList=" + stuList +
'}';
}
}
最后在dao包中创建mapper
IStudentMapper接口代码如下：
package com.ssm.mybatis.dao;
import com.ssm.mybatis.pojo.Student;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;
import java.util.List;
public interface IStudentMapper {
@Select("select * from stu_info where sid= #{sid}")
@Results({@Result(id = true, column = "sid", property = "sid"),
@Result(column = "sname", property = "sname"),
@Result(column = "age", property = "age"),
@Result(column = "course", property = "course")})
public Student selectStudentById(int id);
@Update("update stu_info set sname = #{sname}, age = #{age} where sid = #{sid}")
public int updateStudent(Student student);
@Select("select * from stu_info where classid = #{cid}")
public List<Student> selectStudentByCid(int cid);
}
IStuClassMapper接口代码如下：
package com.ssm.mybatis.dao;
import com.ssm.mybatis.pojo.StuClass;
import org.apache.ibatis.annotations.Many;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
public interface IStuClassMapper {
@Select("select * from stu_class where cid= #{cid}")
@Results({ @Result(id = true, column = "cid", property = "cid"),
@Result(column = "cname", property = "cname"),
@Result(column = "sum", property = "sum"),
@Result(column = "cid", property = "stuList",
many = @Many(
select = "com.ssm.mybatis.dao.IStudentMapper.selectStudentByCid"
)
)
})
public StuClass selectStudentByClassId(int id);
}
4.最后在与main同级的test次级目录绿色的java中创建个test包中创建MyBatisTest类来进行测试
需要注意的是要在方法名上方加上给@Test注解,这些方法如findStudentById都是随意起的名字
MyBatisTest类代码如下：
package test;
import com.ssm.mybatis.dao.IStuClassMapper;
import com.ssm.mybatis.dao.IStudentMapper;
import com.ssm.mybatis.pojo.StuClass;
import com.ssm.mybatis.pojo.Student;
import com.ssm.mybatis.utils.MyBatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;
public class MyBatisTest {
@Test
public void findStudentById(){
SqlSession session = MyBatisUtils.getSession();
IStudentMapper iStudentMapper = session.getMapper(IStudentMapper.class);
Student student = iStudentMapper.selectStudentById(1);
System.out.println(student.toString());
session.close();
}
@Test
public void findStudentByCid(){
SqlSession session = MyBatisUtils.getSession();
IStuClassMapper iStuClassMapper = session.getMapper(IStuClassMapper.class);
StuClass stuClass = iStuClassMapper.selectStudentByClassId(1);
List<Student> students = stuClass.getStuList();
for(Student student : students){
System.out.println(student.toString());
}
session.close();
}
@Test
public void updateStudentById(){
SqlSession session = MyBatisUtils.getSession();
IStudentMapper iStudentMapper = session.getMapper(IStudentMapper.class);
Student student = new Student();
student.setSid(1);
student.setSname("lihao");
student.setAge("20");
System.out.println(student);
int cnt = iStudentMapper.updateStudent(student);
if(cnt > 0){
System.out.println("update successful!");
}
session.commit();
session.close();
}
}
5.结束，应该能拿不少分数了😎
