Mybatis - 使用XML配置完成CRUD操作
阿新 • • 發佈：2019-01-13
使用XML完成CRUD操作
查詢db_mybatis/tb_student中的學生資料，並完成新增/刪除/更新操作。
1. 配置mybatis-cfg.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> <!-- 將jdbc配置檔案引入專案之中 --> <properties resource="jdbc.properties"/> <!-- 為專案中的model宣告類型別名，如果沒有宣告則在使用時需要包名.類名 --> <typeAliases> <typeAlias alias="Student" type="com.java1234.model.Student"/> </typeAliases> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="${jdbc.driverClassName}" /> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.username}" /> <property name="password" value="${jdbc.password}" /> </dataSource> </environment> </environments> <!-- 類似hibernate 引入對映檔案或者在使用註解時引入pojo類 --> <mappers> <mapper resource="com/java1234/mappers/StudentMapper.xml"/> </mappers> </configuration>
2. 新增jdbc.properties檔案
jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/db_mybatis
jdbc.username=root
jdbc.password=1234563. Student.java
package com.java1234.model; public class Student { private int id; private String name; private int age; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "Student [id=" + id + ", name=" + name + ", age=" + age + "]"; } }
4. StudentMapper.java
package com.java1234.mappers; import java.util.List; import com.java1234.model.Student; public interface StudentMapper { public int addStudent(Student student); public int updateStudent(Student student); public int deleteStudent(int stuId); public Student findStduentById(int stuId); public List<Student> findAllStduent(); }
5. StudentMapper.xml
<?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">
<!-- 宣告對應的對映介面 -->
<mapper namespace="com.java1234.mappers.StudentMapper">
<!-- 宣告插入：
<insert id="對映介面中方法名" parameterType="傳入引數型別：需要mybatis-config.xml中起別名，沒有起別名需要用包名.類名">
#{name} -> Student物件中的屬性名
-->
<insert id="addStudent" parameterType="Student">
insert into tb_student values(null, #{name},#{age})
</insert>
<!-- 宣告更新：與insert非常類似，只需要注意sql語句的正確性 -->
<update id="updateStudent" parameterType="Student">
update tb_student set age=#{age} where name=#{name}
</update>
<!-- 宣告刪除：
delete from tb_student where id=#{stuId}，注意stuId與Mapper介面中deleteStudent的形參名對應
-->
<delete id="deleteStudent" parameterType="Integer">
delete from tb_student where id=#{stuId}
</delete>
<!-- 宣告只有一個返回值的查詢：
resultType="Student" 與public Student findStduentById(int stuId);對應
-->
<select id="findStduentById" parameterType="Integer" resultType="Student">
select * from tb_student where id=#{stuId}
</select>
<!-- 宣告多結果查詢：
需要宣告一個自定義的結果集物件來儲存查詢到的結果
-->
<select id="findAllStduent" resultMap="StudentMap">
select * from tb_student
</select>
<!-- 宣告自定義結果集：
type="Student"：集合中的子元素都是Student物件
<id property="id" column="id"/>：只有主鍵才能夠使用這個。property都是Student實體類中的屬性，column對應資料庫表中的行
<result property="name" column="name"/>：其他屬性使用，property都是Student實體類中的屬性，column對應資料庫表中的行
-->
<resultMap type="Student" id="StudentMap">
<id property="id" column="id"/>
<result property="name" column="name"/>
<result property="age" column="age"/>
</resultMap>
</mapper>6. 測試類 - ApplicationText.java
6.1獲取Mybatis的SqlSession物件
類似Hibernate通過sqlSession物件完成所有的資料庫操作。通過sqlSessionFactory獲取。
package com.java1234.utils;
import java.io.IOException;
import java.io.InputStream;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class MybatisUtils {
private static SqlSessionFactory sqlSessionFactory;
private static SqlSessionFactory getSqlSessionFactory(){
if(sqlSessionFactory == null){
try {
InputStream inputStream = Resources.getResourceAsStream("mybatis-cfg.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
} catch (IOException e) {
e.printStackTrace();
}
}
return sqlSessionFactory;
}
public static SqlSession getSqlSession(){
return getSqlSessionFactory().openSession();
}
}
package com.java1234.Mybatis.MybatisCRUD;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import com.java1234.mappers.StudentMapper;
import com.java1234.model.Student;
import com.java1234.utils.MybatisUtils;
import junit.framework.TestCase;
public class ApplicationTest extends TestCase {
SqlSession sqlSession = null;
@Override
protected void setUp() throws Exception {
sqlSession = MybatisUtils.getSqlSession();
}
@Override
protected void tearDown() throws Exception {
sqlSession.close();
}
@Test
public void testInsert(){
StudentMapper studentMapper = (StudentMapper) sqlSession.getMapper(StudentMapper.class);
Student student = new Student();
student.setName("Lily");
student.setAge(25);
int i = studentMapper.addStudent(student);
if(i != 0){
System.out.println("Insert success!");
}
sqlSession.commit();
}
@Test
public void testUpdate(){
StudentMapper studentMapper = (StudentMapper) sqlSession.getMapper(StudentMapper.class);
Student student = new Student();
student.setName("Lily");
student.setAge(57);
int i = studentMapper.updateStudent(student);
if(i != 0){
System.out.println("update success!");
}
sqlSession.commit();
}
@Test
public void testDelete(){
StudentMapper studentMapper = (StudentMapper) sqlSession.getMapper(StudentMapper.class);
int i = studentMapper.deleteStudent(7);
if(i != 0){
System.out.println("delete success!");
}
sqlSession.commit();
}
@Test
public void testFindById(){
StudentMapper studentMapper = (StudentMapper) sqlSession.getMapper(StudentMapper.class);
Student student = studentMapper.findStduentById(1);
if(student != null){
System.out.println("select success! "+student);
}
sqlSession.commit();
}
@Test
public void testFindAll(){
StudentMapper studentMapper = (StudentMapper) sqlSession.getMapper(StudentMapper.class);
List<Student> students = studentMapper.findAllStduent();
for(Student student : students){
System.out.println(student);
}
sqlSession.commit();
}
}
總結一下
使用Mybaitis，相較於Hibernate更加輕量級，語法也更加人性化。使用XML配置一個完整的Mybatis例項，只需要配置如下部分：
（1）mybatis-cfg.xml檔案 - 完成app級別的配置
主要包含1. 配置jdbc聯結器，2. 引入對映檔案/對映類（Annotation），當然對於需要起別名的app也需要在本檔案中宣告別名。
（2）pojo類 - 對應資料庫中的表
（3）**Mapper.java - 在介面中定義操作db的方法，類似與DAO類
（4）**Mapper.xml - 使用xml配置，對應Mapper介面中的每一個方法。