回顾
-------------
1、JVM
runtime data area.
a.method area
方法区，永久区，metaspace ， 共享
b.heap
堆区,共享
heap = young代 + old代理
young = 伊甸区 + 幸存区
幸存区 = 幸存一区(from) + 幸存二区(to)，内存碎片整理
所有对象诞生于伊甸区。
heap //堆
non-heap //非堆 , metaspace
off-heap //离堆 , os - jvm
//ByteBuffer.allocateDirect(1024) ; cleaner
-Xms //堆初始值
-Xmx //堆最大值
-Xmn //年轻代大小
-XX:NewSize
-XX:MaxNewSize
-XX:NewRatio //年老代是年轻代的倍数
-XX:SurvivorRatio //伊甸区是单个幸存区的倍数
-Xloggc:<file> //
c.java stack
线程，StackFrame(method frame) , push | pop
死递归 ，
-Xss1m
d.native method stack
e.program couter register
System.gc()
没有任何指针能够直接或间接到达他。
jvisualvm
jconsole
jmap
2、ClassLoader
类加载器，将类型映射到路径，加载对应字节码文件到内存的方法区。
三级类加载机制，Bootstrap(核心类) -> ExtClassLoader(jre\ext\xxx.jar) -> AppClassLoader
extends ClassLoader{
findClass(){
defineClass(byte[] .. ) ;
}
}
2、mybatis
sql映射，oop方式访问jdbc。
实现mybatis的一对多关联关系
---------------------------
1、修改Customer.class,增加集合属性
class Customer{
...
private List<Order> orders = new ArrayList<Order>();
//get/set
}
2、修改CustomerMapper.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">
<mapper namespace="customers">
<insert id="insert">
insert into customers(name, age) values(#{name} , #{age})
</insert>
<update id="update">
update customers set name = #{name} , age = #{age} where id = #{id}
</update>
<delete id="deleteOne">
delete from customers where id = #{id}
</delete>
<delete id="deleteAll">
delete from customers
</delete>
<select id="selectOne" resultMap="rmCustomer">
SELECT
c.id cid ,
c.name cname ,
c.age cage ,
o.id oid ,
o.orderno oorderno,
o.price oprice,
o.cid ocid
FROM
customes c left outer join orders o
ON
c.id = o.cid
WHERE
c.id = #{id}
</select>
<select id="selectAll" resultType="_Customer">
select * from customers
</select>
<resultMap id="rmCustomer" type="_Customer">
<id column="cid" property="id" />
<result column="cname" property="name" />
<result column="cage" property="age" />
<collection property="orders" ofType="_Order" column="ocid">
<id column="oid" property="id" />
<result column="oorderno" property="orderNo" />
<result column="oprice" property="price"/>
</collection>
</resultMap>
</mapper>
3、测试
@Test
public void testSelectOne() throws Exception {
InputStream in = Resources.getResourceAsStream("mybatis-conf.xml") ;
SqlSessionFactory f = new SqlSessionFactoryBuilder().build(in) ;
SqlSession s = f.openSession() ;
Customer c = s.selectOne("customers.selectOne" , 6) ;
s.commit();
s.close();
}
4、
自关联
-----------------
树形图 :
全国
|---河北省
|---保定
|---张家口
|---河南省
|--驻马店
|---开封
1.设计表
create table areas(id int primary key auto_increment , areaname varchar(20) , pid int) ;
2.创建Area类
public class Area {
private Integer id ;
private String areaName ;
private Area parentArea ;
//get/set
}
3.映射文件
<?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="areas">
<insert id="insert" useGeneratedKeys="true" keyProperty="id">
insert into areas(areaname , pid) values(#{areaName} , #{parentArea.id})
</insert>
</mapper>
4.配置文件
<?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>
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/big10"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</properties>
<!-- 定义类型别名 -->
<typeAliases>
<typeAlias type="com.oldboy.mybatis.domain.Customer" alias="_Customer" />
<typeAlias type="com.oldboy.mybatis.domain.Order" alias="_Order" />
<typeAlias type="com.oldboy.mybatis.domain.Area" alias="_Area" />
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="CustomerMapper.xml"/>
<mapper resource="OrderMapper.xml"/>
<mapper resource="AreaMapper.xml"/>
</mappers>
</configuration>
5.插入
@Test
public void testInsert() throws Exception {
InputStream in = Resources.getResourceAsStream("mybatis-conf.xml") ;
SqlSessionFactory f = new SqlSessionFactoryBuilder().build(in) ;
SqlSession s = f.openSession() ;
Area a1 = new Area("quanguo") ;
Area a2 = new Area("hebeisheng" , a1) ;
Area a3 = new Area("henansheng", a1) ;
Area a4 = new Area("baoding",a2) ;
Area a5 = new Area("zhangjiakou", a2) ;
Area a6 = new Area("zhumadian", a3) ;
Area a7 = new Area("kaifeng", a3) ;
s.insert("areas.insert" , a1);
s.insert("areas.insert" , a2);
s.insert("areas.insert" , a3);
s.insert("areas.insert" , a4);
s.insert("areas.insert" , a5);
s.insert("areas.insert" , a6);
s.insert("areas.insert" , a7);
s.commit();
s.close();
}
实现自关联查询
------------------
1.查询自己和上级的信息
select
s.id sid,
s.areaname sname ,
p.id pid ,
p.areaname pname
from
areas s left outer join areas p on s.pid = p.id ;
2.编写AreaMapper.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">
<mapper namespace="areas">
<insert id="insert" useGeneratedKeys="true" keyProperty="id">
insert into areas(areaname , pid) values(#{areaName} , #{parentArea.id})
</insert>
<select id="selectOne" resultMap="rmArea">
select
s.id sid,
s.areaname sname ,
p.id pid ,
p.areaname pname
from
areas s left outer join areas p on s.pid = p.id
WHERE
s.id = #{id}
</select>
<resultMap id="rmArea" type="_Area">
<id column="sid" property="id" />
<result column="sname" property="areaName" />
<association property="parentArea" column="pid" javaType="_Area">
<id column="pid" property="id" />
<result column="pname" property="areaName"/>
</association>
</resultMap>
</mapper>
3.实现查询
@Test
public void testSelectOne() throws Exception {
InputStream in = Resources.getResourceAsStream("mybatis-conf.xml") ;
SqlSessionFactory f = new SqlSessionFactoryBuilder().build(in) ;
SqlSession s = f.openSession() ;
Area a1 = s.selectOne("areas.selectOne" , 2) ;
s.commit();
s.close();
}
实现自关联的下级查询
----------------------
1.增加Area的集合属性
public class Area {
...
//所辖区域集合
private List<Area> children ;
//get/set
}
2.映射文件
<?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="areas">
<insert id="insert" useGeneratedKeys="true" keyProperty="id">
insert into areas(areaname , pid) values(#{areaName} , #{parentArea.id})
</insert>
<select id="selectOne" resultMap="rmArea">
select
p.id pid,
p.areaname pname ,
s.id sid ,
s.areaname sname ,
c.id cid ,
c.areaname cname
from
areas s
left outer join areas p on s.pid = p.id
left outer join areas c on c.pid = s.id
where
s.id = #{id}
</select>
<select id="selectAll" resultMap="rmArea">
select
p.id pid,
p.areaname pname ,
s.id sid ,
s.areaname sname ,
c.id cid ,
c.areaname cname
from
areas s
left outer join areas p on s.pid = p.id
left outer join areas c on c.pid = s.id
</select>
<resultMap id="rmArea" type="_Area">
<id column="sid" property="id" />
<result column="sname" property="areaName" />
<association property="parentArea" column="pid" javaType="_Area">
<id column="pid" property="id" />
<result column="pname" property="areaName"/>
</association>
<collection property="children" column="sid" ofType="_Area">
<id column="cid" property="id"/>
<result column="cname" property="areaName"/>
</collection>
</resultMap>
</mapper>
3.
public void testSelectOne() throws Exception {
InputStream in = Resources.getResourceAsStream("mybatis-conf.xml") ;
SqlSessionFactory f = new SqlSessionFactoryBuilder().build(in) ;
SqlSession s = f.openSession() ;
Area a1 = s.selectOne("areas.selectOne" , 2) ;
s.commit();
s.close();
}
@Test
public void testSelectAll() throws Exception {
InputStream in = Resources.getResourceAsStream("mybatis-conf.xml") ;
SqlSessionFactory f = new SqlSessionFactoryBuilder().build(in) ;
SqlSession s = f.openSession() ;
List<Area> list = s.selectList("areas.selectAll" ) ;
s.commit();
s.close();
}
一对一关系
---------------
1.创建husband,wife表。
[主键关联]
原理是一张表的主键和另外外一张表相一致。
create table husbands(id int primary key auto_increment , hname varchar(20)) ;
create table wifes(id int , wname varchar(20)) ;
[外键关联]
原理等同于多对一关联关系。
2.创建类
//丈夫类
public class Husband {
private Integer id ;
private String hname ;
//一对一关联关系
private Wife wife ;
}
//妻子类
public class Wife {
private Integer id ;
private String wname ;
//双向一对一关联
private Husband husband ;
...
}
3.映射文件
[丈夫]
<?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="husbands">
<insert id="insert" useGeneratedKeys="true" keyProperty="id">
insert into husbands(hname) values(#{hname})
</insert>
<select id="selectOne" resultMap="rmHusband">
select
h.id hid ,
h.hname hname ,
w.wname wname
FROM
husbands h left outer join wifes w on h.id = w.id
where
h.id = #{id}
</select>
<resultMap id="rmHusband" type="_Husband">
<id column="hid" property="id" />
<result column="hname" property="hname" />
<association property="wife" column="hid" javaType="_Wife">
<result column="wname" property="wname" />
<association property="husband" column="hid" javaType="_Husband">
<id column="hid" property="id"/>
<result column="hname" property="hname"/>
</association>
</association>
</resultMap>
</mapper>
[妻子]
<?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="wifes">
<insert id="insert">
insert into wifes(id , wname) values(#{husband.id} , #{wname})
</insert>
</mapper>
4.配置文件
<?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>
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/big10"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</properties>
<!-- 定义类型别名 -->
<typeAliases>
<typeAlias type="com.oldboy.mybatis.domain.Customer" alias="_Customer" />
<typeAlias type="com.oldboy.mybatis.domain.Order" alias="_Order" />
<typeAlias type="com.oldboy.mybatis.domain.Area" alias="_Area" />
<typeAlias type="com.oldboy.mybatis.domain.Husband" alias="_Husband" />
<typeAlias type="com.oldboy.mybatis.domain.Wife" alias="_Wife" />
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="CustomerMapper.xml"/>
<mapper resource="OrderMapper.xml"/>
<mapper resource="AreaMapper.xml"/>
<mapper resource="HusbandMapper.xml"/>
<mapper resource="WifeMapper.xml"/>
</mappers>
</configuration>
5.测试
@Test
public void testInsert() throws Exception {
InputStream in = Resources.getResourceAsStream("mybatis-conf.xml") ;
SqlSessionFactory f = new SqlSessionFactoryBuilder().build(in) ;
SqlSession s = f.openSession() ;
Husband h = new Husband();
h.setHname("huangxiaoming");
Wife w = new Wife();
w.setHusband(h);
w.setWname("ab");
s.insert("husbands.insert" , h) ;
s.insert("wifes.insert" , w) ;
s.commit();
s.close();
}
@Test
public void testSelectOne() throws Exception {
InputStream in = Resources.getResourceAsStream("mybatis-conf.xml") ;
SqlSessionFactory f = new SqlSessionFactoryBuilder().build(in) ;
SqlSession s = f.openSession() ;
Husband h = s.selectOne("husbands.selectOne",1);
s.commit();
s.close();
}
多对多关系
-----------------
1.创建表
create table teas(id int primary key auto_increment , tno varchar(20)) ;
create table stus(id int primary key auto_increment , sno varchar(20)) ;
create table links(tid int , sid int) ;
2.创建类
[Tea]
/**
* 教师类
*/
public class Tea {
private Integer id ;
private String tno ;
private List<Stu> stus = new ArrayList<Stu>();
}
[Stu]
/**
* 学生类
*/
public class Stu {
private Integer id ;
private String sno ;
private List<Tea> teas = new ArrayList<Tea>();
}
3.映射文件
[TeaMapper.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">
<mapper namespace="teas">
<insert id="insert" useGeneratedKeys="true" keyProperty="id">
insert into teas(tno) values(#{tno})
</insert>
<insert id="insertLinks">
<foreach collection="stus" item="s">
insert into links(tid,sid) values(#{id} , #{s.id});
</foreach>
</insert>
<select id="selectOne" resultMap="rmTea">
select
t.id tid ,
t.tno tno ,
s.id sid ,
s.sno sno
from
teas t
left outer join links l on l.tid = t.id
left outer join stus s on s.id = l.sid
where
t.id = #{id}
</select>
<resultMap id="rmTea" type="_Tea">
<id column="tid" property="id"/>
<result column="tno" property="tno" />
<collection property="stus" ofType="_Stu" column="tid">
<id column="sid" property="id" />
<result column="sno" property="sno" />
</collection>
</resultMap>
</mapper>
[StuMapper.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">
<mapper namespace="stus">
<insert id="insert" useGeneratedKeys="true" keyProperty="id">
insert into stus(sno) values(#{sno})
</insert>
</mapper>
4.修改配置文件，添加执行多条语句支持
<?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>
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/big10?allowMultiQueries=true"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</properties>
<!-- 定义类型别名 -->
<typeAliases>
<typeAlias type="com.oldboy.mybatis.domain.Customer" alias="_Customer" />
<typeAlias type="com.oldboy.mybatis.domain.Order" alias="_Order" />
<typeAlias type="com.oldboy.mybatis.domain.Area" alias="_Area" />
<typeAlias type="com.oldboy.mybatis.domain.Husband" alias="_Husband" />
<typeAlias type="com.oldboy.mybatis.domain.Wife" alias="_Wife" />
<typeAlias type="com.oldboy.mybatis.domain.Tea" alias="_Tea" />
<typeAlias type="com.oldboy.mybatis.domain.Stu" alias="_Stu" />
</typeAliases>
<environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="CustomerMapper.xml"/>
<mapper resource="OrderMapper.xml"/>
<mapper resource="AreaMapper.xml"/>
<mapper resource="HusbandMapper.xml"/>
<mapper resource="WifeMapper.xml"/>
<mapper resource="TeaMapper.xml"/>
<mapper resource="StuMapper.xml"/>
</mappers>
</configuration>
5.测试类
package com.oldboy.mybatis.test;
import com.oldboy.mybatis.domain.Husband;
import com.oldboy.mybatis.domain.Stu;
import com.oldboy.mybatis.domain.Tea;
import com.oldboy.mybatis.domain.Wife;
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 org.junit.Test;
import java.io.InputStream;
/**
* 测试多对多
*/
public class TestMany2Many {
@Test
public void testInsert() throws Exception {
InputStream in = Resources.getResourceAsStream("mybatis-conf.xml") ;
SqlSessionFactory f = new SqlSessionFactoryBuilder().build(in) ;
SqlSession s = f.openSession() ;
Stu s1 = new Stu("s1") ;
Stu s2 = new Stu("s2") ;
Stu s3 = new Stu("s3") ;
Stu s4 = new Stu("s4") ;
Tea t1 = new Tea("t1");
Tea t2 = new Tea("t2");
t1.addStus(s1 ,s2 , s3);
t2.addStus(s2 , s3 , s4);
s.insert("stus.insert" , s1);
s.insert("stus.insert" , s2);
s.insert("stus.insert" , s3);
s.insert("stus.insert" , s4);
s.insert("teas.insert" , t1);
s.insert("teas.insert" , t2);
s.insert("teas.insertLinks" , t1);
s.insert("teas.insertLinks" , t2);
s.commit();
s.close();
}
@Test
public void testSelectOne() throws Exception {
InputStream in = Resources.getResourceAsStream("mybatis-conf.xml") ;
SqlSessionFactory f = new SqlSessionFactoryBuilder().build(in) ;
SqlSession s = f.openSession() ;
Tea t = s.selectOne("teas.selectOne" , 3) ;
s.commit();
s.close();
}
}
