MyBatis学习教程(二)—如何使用MyBatis对users表执行CRUD操作

<?xml version="." encoding="utf-" ?>
<!doctype mapper public "-//mybatis.org//dtd mapper .//en" "http://mybatis.org/dtd/mybatis--mapper.dtd">
<!-- 为这个mapper指定一个唯一的namespace，namespace的值习惯上设置成包名+sql映射文件名，这样就能够保证namespace的值是唯一的
例如namespace="me.gacl.mapping.usermapper"就是me.gacl.mapping(包名)+usermapper(usermapper.xml文件去除后缀)
-->
<mapper namespace="me.gacl.mapping.usermapper">
<!-- 在select标签中编写查询的sql语句， 设置select标签的id属性为getuser，id属性值必须是唯一的，不能够重复
使用parametertype属性指明查询时使用的参数类型，resulttype属性指明查询返回的结果集类型
resulttype="me.gacl.domain.user"就表示将查询结果封装成一个user类的对象返回
user类就是users表所对应的实体类
-->
<!-- 
根据id查询得到一个user对象
-->
<select id="getuser" parametertype="int" 
resulttype="me.gacl.domain.user">
select * from users where id=#{id}
</select>
<!-- 创建用户(create) -->
<insert id="adduser" parametertype="me.gacl.domain.user">
insert into users(name,age) values(#{name},#{age})
</insert>
<!-- 删除用户(remove) -->
<delete id="deleteuser" parametertype="int">
delete from users where id=#{id}
</delete>
<!-- 修改用户(update) -->
<update id="updateuser" parametertype="me.gacl.domain.user">
update users set name=#{name},age=#{age} where id=#{id}
</update>
<!-- 查询全部用户-->
<select id="getallusers" resulttype="me.gacl.domain.user">
select * from users
</select>
</mapper> 

package me.gacl.test;
import java.util.list;
import me.gacl.domain.user;
import me.gacl.util.mybatisutil;
import org.apache.ibatis.session.sqlsession;
import org.junit.test;
public class testcrudbyxmlmapper {
@test
public void testadd(){
//sqlsession sqlsession = mybatisutil.getsqlsession(false);
sqlsession sqlsession = mybatisutil.getsqlsession(true);
/**
* 映射sql的标识字符串，
* me.gacl.mapping.usermapper是usermapper.xml文件中mapper标签的namespace属性的值，
* adduser是insert标签的id属性值，通过insert标签的id属性值就可以找到要执行的sql
*/
string statement = "me.gacl.mapping.usermapper.adduser";//映射sql的标识字符串
user user = new user();
user.setname("用户孤傲苍狼");
user.setage();
//执行插入操作
int retresult = sqlsession.insert(statement,user);
//手动提交事务
//sqlsession.commit();
//使用sqlsession执行完sql之后需要关闭sqlsession
sqlsession.close();
system.out.println(retresult);
}
@test
public void testupdate(){
sqlsession sqlsession = mybatisutil.getsqlsession(true);
/**
* 映射sql的标识字符串，
* me.gacl.mapping.usermapper是usermapper.xml文件中mapper标签的namespace属性的值，
* updateuser是update标签的id属性值，通过update标签的id属性值就可以找到要执行的sql
*/
string statement = "me.gacl.mapping.usermapper.updateuser";//映射sql的标识字符串
user user = new user();
user.setid();
user.setname("孤傲苍狼");
user.setage();
//执行修改操作
int retresult = sqlsession.update(statement,user);
//使用sqlsession执行完sql之后需要关闭sqlsession
sqlsession.close();
system.out.println(retresult);
}
@test
public void testdelete(){
sqlsession sqlsession = mybatisutil.getsqlsession(true);
/**
* 映射sql的标识字符串，
* me.gacl.mapping.usermapper是usermapper.xml文件中mapper标签的namespace属性的值，
* deleteuser是delete标签的id属性值，通过delete标签的id属性值就可以找到要执行的sql
*/
string statement = "me.gacl.mapping.usermapper.deleteuser";//映射sql的标识字符串
//执行删除操作
int retresult = sqlsession.delete(statement,);
//使用sqlsession执行完sql之后需要关闭sqlsession
sqlsession.close();
system.out.println(retresult);
}
@test
public void testgetall(){
sqlsession sqlsession = mybatisutil.getsqlsession();
/**
* 映射sql的标识字符串，
* me.gacl.mapping.usermapper是usermapper.xml文件中mapper标签的namespace属性的值，
* getallusers是select标签的id属性值，通过select标签的id属性值就可以找到要执行的sql
*/
string statement = "me.gacl.mapping.usermapper.getallusers";//映射sql的标识字符串
//执行查询操作，将查询结果自动封装成list<user>返回
list<user> lstusers = sqlsession.selectlist(statement);
//使用sqlsession执行完sql之后需要关闭sqlsession
sqlsession.close();
system.out.println(lstusers);
}
} 

package me.gacl.mapping;
import java.util.list;
import me.gacl.domain.user;
import org.apache.ibatis.annotations.delete;
import org.apache.ibatis.annotations.insert;
import org.apache.ibatis.annotations.select;
import org.apache.ibatis.annotations.update;
/**
* @author gacl
* 定义sql映射的接口，使用注解指明方法要执行的sql
*/
public interface usermapperi {
//使用@insert注解指明add方法要执行的sql
@insert("insert into users(name, age) values(#{name}, #{age})")
public int add(user user);
//使用@delete注解指明deletebyid方法要执行的sql
@delete("delete from users where id=#{id}")
public int deletebyid(int id);
//使用@update注解指明update方法要执行的sql
@update("update users set name=#{name},age=#{age} where id=#{id}")
public int update(user user);
//使用@select注解指明getbyid方法要执行的sql
@select("select * from users where id=#{id}")
public user getbyid(int id);
//使用@select注解指明getall方法要执行的sql
@select("select * from users")
public list<user> getall();
}

<?xml version="." encoding="utf-"?>
<!doctype configuration public "-//mybatis.org//dtd config .//en" "http://mybatis.org/dtd/mybatis--config.dtd">
<configuration>
<environments default="development">
<environment id="development">
<transactionmanager type="jdbc" />
<!-- 配置数据库连接信息 -->
<datasource type="pooled">
<property name="driver" value="com.mysql.jdbc.driver" />
<property name="url" value="jdbc:mysql://localhost:/mybatis" />
<property name="username" value="root" />
<property name="password" value="xdp" />
</datasource>
</environment>
</environments>
<mappers>
<!-- 注册usermapper.xml文件， 
usermapper.xml位于me.gacl.mapping这个包下，所以resource写成me/gacl/mapping/usermapper.xml-->
<mapper resource="me/gacl/mapping/usermapper.xml"/>
<!-- 注册usermapper映射接口-->
<mapper class="me.gacl.mapping.usermapperi"/>
</mappers>
</configuration> 

package me.gacl.test;
import java.util.list;
import me.gacl.domain.user;
import me.gacl.mapping.usermapperi;
import me.gacl.util.mybatisutil;
import org.apache.ibatis.session.sqlsession;
import org.junit.test;
public class testcrudbyannotationmapper {
@test
public void testadd(){
sqlsession sqlsession = mybatisutil.getsqlsession(true);
//得到usermapperi接口的实现类对象，usermapperi接口的实现类对象由sqlsession.getmapper(usermapperi.class)动态构建出来
usermapperi mapper = sqlsession.getmapper(usermapperi.class);
user user = new user();
user.setname("用户xdp");
user.setage();
int add = mapper.add(user);
//使用sqlsession执行完sql之后需要关闭sqlsession
sqlsession.close();
system.out.println(add);
}
@test
public void testupdate(){
sqlsession sqlsession = mybatisutil.getsqlsession(true);
//得到usermapperi接口的实现类对象，usermapperi接口的实现类对象由sqlsession.getmapper(usermapperi.class)动态构建出来
usermapperi mapper = sqlsession.getmapper(usermapperi.class);
user user = new user();
user.setid();
user.setname("孤傲苍狼_xdp");
user.setage();
//执行修改操作
int retresult = mapper.update(user);
//使用sqlsession执行完sql之后需要关闭sqlsession
sqlsession.close();
system.out.println(retresult);
}
@test
public void testdelete(){
sqlsession sqlsession = mybatisutil.getsqlsession(true);
//得到usermapperi接口的实现类对象，usermapperi接口的实现类对象由sqlsession.getmapper(usermapperi.class)动态构建出来
usermapperi mapper = sqlsession.getmapper(usermapperi.class);
//执行删除操作
int retresult = mapper.deletebyid();
//使用sqlsession执行完sql之后需要关闭sqlsession
sqlsession.close();
system.out.println(retresult);
}
@test
public void testgetuser(){
sqlsession sqlsession = mybatisutil.getsqlsession();
//得到usermapperi接口的实现类对象，usermapperi接口的实现类对象由sqlsession.getmapper(usermapperi.class)动态构建出来
usermapperi mapper = sqlsession.getmapper(usermapperi.class);
//执行查询操作，将查询结果自动封装成user返回
user user = mapper.getbyid();
//使用sqlsession执行完sql之后需要关闭sqlsession
sqlsession.close();
system.out.println(user);
}
@test
public void testgetall(){
sqlsession sqlsession = mybatisutil.getsqlsession();
//得到usermapperi接口的实现类对象，usermapperi接口的实现类对象由sqlsession.getmapper(usermapperi.class)动态构建出来
usermapperi mapper = sqlsession.getmapper(usermapperi.class);
//执行查询操作，将查询结果自动封装成list<user>返回
list<user> lstusers = mapper.getall();
//使用sqlsession执行完sql之后需要关闭sqlsession
sqlsession.close();
system.out.println(lstusers);
}
} 

package me.gacl.util;
import java.io.inputstream;
import org.apache.ibatis.session.sqlsession;
import org.apache.ibatis.session.sqlsessionfactory;
import org.apache.ibatis.session.sqlsessionfactorybuilder;
public class mybatisutil {
/**
* 获取sqlsessionfactory
* @return sqlsessionfactory
*/
public static sqlsessionfactory getsqlsessionfactory() {
string resource = "conf.xml";
inputstream is = mybatisutil.class.getclassloader().getresourceasstream(resource);
sqlsessionfactory factory = new sqlsessionfactorybuilder().build(is);
return factory;
}
/**
* 获取sqlsession
* @return sqlsession
*/
public static sqlsession getsqlsession() {
return getsqlsessionfactory().opensession();
}
/**
* 获取sqlsession
* @param isautocommit 
* true 表示创建的sqlsession对象在执行完sql之后会自动提交事务
* false 表示创建的sqlsession对象在执行完sql之后不会自动提交事务，这时就需要我们手动调用sqlsession.commit()提交事务
* @return sqlsession
*/
public static sqlsession getsqlsession(boolean isautocommit) {
return getsqlsessionfactory().opensession(isautocommit);
}
}