首页 > 代码库 > MyBatis系列：（3）基于MyBatisUtils工具类完成CRUD操作
MyBatis系列：（3）基于MyBatisUtils工具类完成CRUD操作
Emp.java
package com.rk.entity;
public class Emp {
private Integer id;
private String name;
private Double sal;
public Emp(){}
public Emp(Integer id, String name, Double sal) {
this.id = id;
this.name = name;
this.sal = sal;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Double getSal() {
return sal;
}
public void setSal(Double sal) {
this.sal = sal;
}
}EmpMapper.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">
<!-- namespace属性是名称空间，必须唯一 -->
<mapper namespace="mynamespace">
<insert id="add" parameterType="com.rk.entity.Emp">
insert into emp(id,name,sal) values(#{id},#{name},#{sal})
</insert>
<update id="update" parameterType="com.rk.entity.Emp">
update emp set name=#{name},sal=#{sal} where id=#{id}
</update>
<select id="findById" resultType="com.rk.entity.Emp">
select id,name,sal from emp where id=#{anything123}
</select>
<select id="findAll" resultType="com.rk.entity.Emp">
select id,name,sal from emp
</select>
<delete id="delete" parameterType="com.rk.entity.Emp">
delete from emp where id=#{id}
</delete>
</mapper>findById也可以这样写
<!-- 根据ID查询
如果参数不是一个实体的话，只是一个普通变量，例如:int,double,String
这里的#{中间的变量名可以随便写}，不过提倡就用方法的形参
-->
<select id="findById" parameterType="int" resultType="com.rk.entity.Emp">
select id,name,sal from students where id = #{id}
</select>mybatis.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> <environments default="development"> <environment id="development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="http://www.mamicode.com/com.mysql.jdbc.Driver"/> <property name="url" value="http://www.mamicode.com/jdbc:mysql://127.0.0.1:3306/testdb"/> <property name="username" value="http://www.mamicode.com/root"/> <property name="password" value="http://www.mamicode.com/root"/> </dataSource> </environment> </environments> <mappers> <mapper resource="com/rk/entity/EmpMapper.xml"/> </mappers> </configuration>
MyBatisUtils.java
package com.rk.utils;
import java.io.IOException;
import java.io.Reader;
import java.sql.Connection;
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 ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();
private static SqlSessionFactory sqlSessionFactory;
static{
try {
Reader reader = Resources.getResourceAsReader("mybatis.xml");
sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
} catch (IOException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
private MyBatisUtils() {}
public static SqlSession getSqlSession(){
SqlSession sqlSession = threadLocal.get();
if(sqlSession == null){
sqlSession = sqlSessionFactory.openSession();
threadLocal.set(sqlSession);
}
return sqlSession;
}
public static void closeSqlSession(){
SqlSession sqlSession = threadLocal.get();
if(sqlSession != null){
sqlSession.close();
threadLocal.remove();
}
}
public static void main(String[] args) {
Connection conn = MyBatisUtils.getSqlSession().getConnection();
System.out.println(conn!=null ? "连接成功" : "连接失败");
}
}EmpDao.java
package com.rk.dao;
import java.util.List;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import com.rk.entity.Emp;
import com.rk.utils.MyBatisUtils;
public class EmpDao {
@Test
public void add(){
Emp emp = new Emp(3, "小刚", 300D);
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlSession();
int i = sqlSession.insert("mynamespace.add", emp);
System.out.println("本次操作影响"+i+"行数据");
sqlSession.commit();
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
}
@Test
public void update(){
Emp emp = new Emp(3, "Tomcat", 400D);
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlSession();
int i = sqlSession.update("mynamespace.update", emp);
System.out.println("本次操作影响"+i+"行数据");
sqlSession.commit();
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
}
@Test
public void findById(){
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlSession();
Emp emp = sqlSession.selectOne("mynamespace.findById", 3);
System.out.println( emp.getName() + ":"+emp.getSal());
sqlSession.commit();
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
}
@Test
public void findAll(){
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlSession();
List<Emp> list = sqlSession.selectList("mynamespace.findAll");
if(list != null && list.size()>0){
for(Emp emp : list){
System.out.println( emp.getName() + ":"+emp.getSal());
}
}
sqlSession.commit();
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
}
@Test
public void delete(){
SqlSession sqlSession = null;
try {
sqlSession = MyBatisUtils.getSqlSession();
Emp emp = new Emp(3, "", 0D);
sqlSession.delete("mynamespace.delete", emp);
sqlSession.commit();
} catch (Exception e) {
e.printStackTrace();
sqlSession.rollback();
}
finally{
MyBatisUtils.closeSqlSession();
}
}
}MyBatis系列：（3）基于MyBatisUtils工具类完成CRUD操作
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