synchronized(this)、synchronized(class)与synchronized(Object)的区别
在多线程开发中，我们经常看到synchronized(this)、synchronized(*.class)与synchronized(任意对象)这几种类型同步方法。但是是否知道这几种写法有什么区别了？下面根据代码来分析：
synchronized代码块间的同步性
- package com.zwz.thread.demo1;
- public class ObjectService {
- public void serviceMethodA(){
- try {
- synchronized (this) {
- System.out.println("A begin time="+System.currentTimeMillis());
- Thread.sleep(2000);
- System.out.println("A end time="+System.currentTimeMillis());
- }
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- public void serviceMethodB(){
- synchronized (this) {
- System.out.println("B begin time="+System.currentTimeMillis());
- System.out.println("B end time="+System.currentTimeMillis());
- }
- }
- }
package com.zwz.thread.demo1;
public class ObjectService {
public void serviceMethodA(){
try {
synchronized (this) {
System.out.println("A begin time="+System.currentTimeMillis());
Thread.sleep(2000);
System.out.println("A end time="+System.currentTimeMillis());
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public void serviceMethodB(){
synchronized (this) {
System.out.println("B begin time="+System.currentTimeMillis());
System.out.println("B end time="+System.currentTimeMillis());
}
}
}
- package com.zwz.thread.demo1;
- public class ThreadA extends Thread {
- private ObjectService objectService;
- public ThreadA(ObjectService objectService){
- super();
- this.objectService=objectService;
- }
- @Override
- public void run() {
- super.run();
- objectService.serviceMethodA();
- }
- }
package com.zwz.thread.demo1;
public class ThreadA extends Thread {
private ObjectService objectService;
public ThreadA(ObjectService objectService){
super();
this.objectService=objectService;
}
@Override
public void run() {
super.run();
objectService.serviceMethodA();
}
}
- package com.zwz.thread.demo1;
- public class ThreadB extends Thread {
- private ObjectService objectService;
- public ThreadB(ObjectService objectService){
- super();
- this.objectService=objectService;
- }
- @Override
- public void run() {
- super.run();
- objectService.serviceMethodB();
- }
- }
package com.zwz.thread.demo1;
public class ThreadB extends Thread {
private ObjectService objectService;
public ThreadB(ObjectService objectService){
super();
this.objectService=objectService;
}
@Override
public void run() {
super.run();
objectService.serviceMethodB();
}
}
- package com.zwz.thread.demo1;
- public class MainTest {
- public static void main(String[] args) {
- ObjectService service=new ObjectService();
- ThreadA a=new ThreadA(service);
- a.setName("a");
- a.start();
- ThreadB b=new ThreadB(service);
- b.setName("b");
- b.start();
- }
- }
package com.zwz.thread.demo1;
public class MainTest {
public static void main(String[] args) {
ObjectService service=new ObjectService();
ThreadA a=new ThreadA(service);
a.setName("a");
a.start();
ThreadB b=new ThreadB(service);
b.setName("b");
b.start();
}
}
运行结果：
结论：
当一个线程访问ObjectService的一个synchronized (this)同步代码块时，其它线程对同一个ObjectService中其它的synchronized (this)同步代码块的访问将是堵塞，这说明synchronized (this)使用的对象监视器是一个。
验证synchronized (this)代码块是锁定当前对象
- package com.zwz.thread.demo2;
- public class ObjectService {
- public void objectMethodA(){
- System.out.println("run----objectMethodA");
- }
- public void objectMethodB(){
- synchronized (this) {
- try {
- for (int i = 1; i <= 10; i++) {
- System.out.println("synchronized thread name:"+Thread.currentThread().getName()+"-->i="+i);
- Thread.sleep(1000);
- }
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- }
- }
package com.zwz.thread.demo2;
public class ObjectService {
public void objectMethodA(){
System.out.println("run----objectMethodA");
}
public void objectMethodB(){
synchronized (this) {
try {
for (int i = 1; i <= 10; i++) {
System.out.println("synchronized thread name:"+Thread.currentThread().getName()+"-->i="+i);
Thread.sleep(1000);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
- package com.zwz.thread.demo2;
- public class ThreadA extends Thread {
- private ObjectService objectService;
- public ThreadA(ObjectService objectService) {
- super();
- this.objectService = objectService;
- }
- @Override
- public void run() {
- super.run();
- objectService.objectMethodA();
- }
- }
package com.zwz.thread.demo2;
public class ThreadA extends Thread {
private ObjectService objectService;
public ThreadA(ObjectService objectService) {
super();
this.objectService = objectService;
}
@Override
public void run() {
super.run();
objectService.objectMethodA();
}
}
- package com.zwz.thread.demo2;
- public class ThreadB extends Thread {
- private ObjectService objectService;
- public ThreadB(ObjectService objectService) {
- super();
- this.objectService = objectService;
- }
- @Override
- public void run() {
- super.run();
- objectService.objectMethodB();
- }
- }
package com.zwz.thread.demo2;
public class ThreadB extends Thread {
private ObjectService objectService;
public ThreadB(ObjectService objectService) {
super();
this.objectService = objectService;
}
@Override
public void run() {
super.run();
objectService.objectMethodB();
}
}
- package com.zwz.thread.demo2;
- public class MainTest {
- public static void main(String[] args) throws InterruptedException {
- ObjectService service=new ObjectService();
- ThreadB b=new ThreadB(service);
- b.start();
- Thread.sleep(2000);
- ThreadA a=new ThreadA(service);
- a.start();
- }
- }
package com.zwz.thread.demo2;
public class MainTest {
public static void main(String[] args) throws InterruptedException {
ObjectService service=new ObjectService();
ThreadB b=new ThreadB(service);
b.start();
Thread.sleep(2000);
ThreadA a=new ThreadA(service);
a.start();
}
}
运行结果：
可以看到objectMethodA方法异步执行了，下面我们将objectMethodA()加上同步。
- package com.zwz.thread.demo2;
- public class ObjectService {
- public synchronized void objectMethodA(){
- System.out.println("run----objectMethodA");
- }
- public void objectMethodB(){
- synchronized (this) {
- try {
- for (int i = 1; i <= 10; i++) {
- System.out.println("synchronized thread name:"+Thread.currentThread().getName()+"-->i="+i);
- Thread.sleep(1000);
- }
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- }
- }
package com.zwz.thread.demo2;
public class ObjectService {
public synchronized void objectMethodA(){
System.out.println("run----objectMethodA");
}
public void objectMethodB(){
synchronized (this) {
try {
for (int i = 1; i <= 10; i++) {
System.out.println("synchronized thread name:"+Thread.currentThread().getName()+"-->i="+i);
Thread.sleep(1000);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
运行结果：
结论：
上面三个小例子我们可以知道，多个线程调用同一个对象中的不同名称的synchronized同步方法或synchronized(this)同步代码块时，是同步的。
1、synchronized同步方法
①对其它的synchronized同步方法或synchronized(this)同步代码块调用是堵塞状态；
②同一时间只有一个线程执行synchronized同步方法中的代码。
2、synchronized(this)同步代码块
①对其它的synchronized同步方法或synchronized(this)同步代码块调用是堵塞状态；
②同一时间只有一个线程执行synchronized同步方法中的代码。
将任意对象作为对象监视器
- package com.zwz.thread.demo3;
- public class ObjectService {
- private String uname;
- private String pwd;
- String lock=new String();
- public void setUserNamePassWord(String userName,String passWord){
- try {
- synchronized (lock) {
- System.out.println("thread name="+Thread.currentThread().getName()
- +" 进入代码快:"+System.currentTimeMillis());
- uname=userName;
- Thread.sleep(3000);
- pwd=passWord;
- System.out.println("thread name="+Thread.currentThread().getName()
- +" 进入代码快:"+System.currentTimeMillis()+"入参uname:"+uname+"入参pwd:"+pwd);
- }
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- }
package com.zwz.thread.demo3;
public class ObjectService {
private String uname;
private String pwd;
String lock=new String();
public void setUserNamePassWord(String userName,String passWord){
try {
synchronized (lock) {
System.out.println("thread name="+Thread.currentThread().getName()
+" 进入代码快:"+System.currentTimeMillis());
uname=userName;
Thread.sleep(3000);
pwd=passWord;
System.out.println("thread name="+Thread.currentThread().getName()
+" 进入代码快:"+System.currentTimeMillis()+"入参uname:"+uname+"入参pwd:"+pwd);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
- package com.zwz.thread.demo3;
- public class ThreadA extends Thread {
- private ObjectService objectService;
- public ThreadA(ObjectService objectService) {
- super();
- this.objectService = objectService;
- }
- @Override
- public void run() {
- objectService.setUserNamePassWord("a", "aa");
- }
- }
package com.zwz.thread.demo3;
public class ThreadA extends Thread {
private ObjectService objectService;
public ThreadA(ObjectService objectService) {
super();
this.objectService = objectService;
}
@Override
public void run() {
objectService.setUserNamePassWord("a", "aa");
}
}
- package com.zwz.thread.demo3;
- public class ThreadB extends Thread {
- private ObjectService objectService;
- public ThreadB(ObjectService objectService) {
- super();
- this.objectService = objectService;
- }
- @Override
- public void run() {
- objectService.setUserNamePassWord("b", "bb");
- }
- }
package com.zwz.thread.demo3;
public class ThreadB extends Thread {
private ObjectService objectService;
public ThreadB(ObjectService objectService) {
super();
this.objectService = objectService;
}
@Override
public void run() {
objectService.setUserNamePassWord("b", "bb");
}
}
- package com.zwz.thread.demo3;
- public class MainTest {
- public static void main(String[] args) {
- ObjectService service=new ObjectService();
- ThreadA a=new ThreadA(service);
- a.setName("A");
- a.start();
- ThreadB b=new ThreadB(service);
- b.setName("B");
- b.start();
- }
- }
package com.zwz.thread.demo3;
public class MainTest {
public static void main(String[] args) {
ObjectService service=new ObjectService();
ThreadA a=new ThreadA(service);
a.setName("A");
a.start();
ThreadB b=new ThreadB(service);
b.setName("B");
b.start();
}
}
运行结果：
下面我把String lock=new String();放在方法中会有啥结果了：
- package com.zwz.thread.demo3;
- public class ObjectService {
- private String uname;
- private String pwd;
- public void setUserNamePassWord(String userName,String passWord){
- try {
- String lock=new String();
- synchronized (lock) {
- System.out.println("thread name="+Thread.currentThread().getName()
- +" 进入代码快:"+System.currentTimeMillis());
- uname=userName;
- Thread.sleep(3000);
- pwd=passWord;
- System.out.println("thread name="+Thread.currentThread().getName()
- +" 进入代码快:"+System.currentTimeMillis()+"入参uname:"+uname+"入参pwd:"+pwd);
- }
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- }
package com.zwz.thread.demo3;
public class ObjectService {
private String uname;
private String pwd;
public void setUserNamePassWord(String userName,String passWord){
try {
String lock=new String();
synchronized (lock) {
System.out.println("thread name="+Thread.currentThread().getName()
+" 进入代码快:"+System.currentTimeMillis());
uname=userName;
Thread.sleep(3000);
pwd=passWord;
System.out.println("thread name="+Thread.currentThread().getName()
+" 进入代码快:"+System.currentTimeMillis()+"入参uname:"+uname+"入参pwd:"+pwd);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
运行结果：
结论：
多个线程持有对象监视器作为同一个对象的前提下，同一时间只有一个线程可以执行synchronized(任意自定义对象)同步代码快。
synchronized(任意自定义对象)与synchronized同步方法共用
- package com.zwz.thread.demo4;
- public class ObjectService {
- private String lock=new String();
- public void methodA(){
- try {
- synchronized (lock) {
- System.out.println("a begin");
- Thread.sleep(3000);
- System.out.println("a end");
- }
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- public synchronized void methodB(){
- System.out.println("b begin");
- System.out.println("b end");
- }
- }
package com.zwz.thread.demo4;
public class ObjectService {
private String lock=new String();
public void methodA(){
try {
synchronized (lock) {
System.out.println("a begin");
Thread.sleep(3000);
System.out.println("a end");
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public synchronized void methodB(){
System.out.println("b begin");
System.out.println("b end");
}
}
- package com.zwz.thread.demo4;
- public class ThreadA extends Thread {
- private ObjectService objectService;
- public ThreadA(ObjectService objectService) {
- super();
- this.objectService = objectService;
- }
- @Override
- public void run() {
- objectService.methodA();
- }
- }
package com.zwz.thread.demo4;
public class ThreadA extends Thread {
private ObjectService objectService;
public ThreadA(ObjectService objectService) {
super();
this.objectService = objectService;
}
@Override
public void run() {
objectService.methodA();
}
}
- package com.zwz.thread.demo4;
- public class ThreadB extends Thread {
- private ObjectService objectService;
- public ThreadB(ObjectService objectService) {
- super();
- this.objectService = objectService;
- }
- @Override
- public void run() {
- objectService.methodB();
- }
- }
package com.zwz.thread.demo4;
public class ThreadB extends Thread {
private ObjectService objectService;
public ThreadB(ObjectService objectService) {
super();
this.objectService = objectService;
}
@Override
public void run() {
objectService.methodB();
}
}
- package com.zwz.thread.demo4;
- public class MainTest {
- public static void main(String[] args) {
- ObjectService service=new ObjectService();
- ThreadA a=new ThreadA(service);
- a.setName("A");
- a.start();
- ThreadB b=new ThreadB(service);
- b.setName("B");
- b.start();
- }
- }
package com.zwz.thread.demo4;
public class MainTest {
public static void main(String[] args) {
ObjectService service=new ObjectService();
ThreadA a=new ThreadA(service);
a.setName("A");
a.start();
ThreadB b=new ThreadB(service);
b.setName("B");
b.start();
}
}
运行结果:
结论：
使用synchronized(任意自定义对象)进行同步操作，对象监视器必须是同一个对象。不过不是同一个，运行就是异步执行了。
静态同步synchronized方法与synchronized(*.class)代码块
静态同步synchronized方法
- package com.zwz.thread.demo6;
- public class ObjectService {
- public synchronized static void methodA(){
- try {
- System.out.println("static methodA begin 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
- Thread.sleep(3000);
- System.out.println("static methodA end 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- public synchronized static void methodB(){
- System.out.println("static methodB begin 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
- System.out.println("static methodB end 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
- }
- }
package com.zwz.thread.demo6;
public class ObjectService {
public synchronized static void methodA(){
try {
System.out.println("static methodA begin 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
Thread.sleep(3000);
System.out.println("static methodA end 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public synchronized static void methodB(){
System.out.println("static methodB begin 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
System.out.println("static methodB end 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
}
}
- package com.zwz.thread.demo6;
- public class ThreadA extends Thread {
- @Override
- public void run() {
- ObjectService.methodA();
- }
- }
package com.zwz.thread.demo6;
public class ThreadA extends Thread {
@Override
public void run() {
ObjectService.methodA();
}
}
- package com.zwz.thread.demo6;
- public class ThreadB extends Thread {
- @Override
- public void run() {
- ObjectService.methodB();
- }
- }
package com.zwz.thread.demo6;
public class ThreadB extends Thread {
@Override
public void run() {
ObjectService.methodB();
}
}
- package com.zwz.thread.demo6;
- public class MainTest {
- public static void main(String[] args) {
- ThreadA a=new ThreadA();
- a.setName("A");
- a.start();
- ThreadB b=new ThreadB();
- b.setName("B");
- b.start();
- }
- }
package com.zwz.thread.demo6;
public class MainTest {
public static void main(String[] args) {
ThreadA a=new ThreadA();
a.setName("A");
a.start();
ThreadB b=new ThreadB();
b.setName("B");
b.start();
}
}
运行结果：
结论：
synchronized应用在static方法上，那是对当前对应的*.Class进行持锁。
synchronized(*.class)代码块
- package com.zwz.thread.demo7;
- public class ObjectService {
- public void methodA(){
- try {
- synchronized (ObjectService.class) {
- System.out.println("methodA begin 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
- Thread.sleep(3000);
- System.out.println("methodA end 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
- }
- } catch (InterruptedException e) {
- e.printStackTrace();
- }
- }
- public void methodB(){
- synchronized (ObjectService.class) {
- System.out.println("methodB begin 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
- System.out.println("methodB end 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
- }
- }
- }
package com.zwz.thread.demo7;
public class ObjectService {
public void methodA(){
try {
synchronized (ObjectService.class) {
System.out.println("methodA begin 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
Thread.sleep(3000);
System.out.println("methodA end 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public void methodB(){
synchronized (ObjectService.class) {
System.out.println("methodB begin 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
System.out.println("methodB end 线程名称:"+Thread.currentThread().getName()+" times:"+System.currentTimeMillis());
}
}
}
- package com.zwz.thread.demo7;
- public class ThreadA extends Thread {
- private ObjectService objectService;
- public ThreadA(ObjectService objectService) {
- super();
- this.objectService = objectService;
- }
- @Override
- public void run() {
- objectService.methodA();
- }
- }
package com.zwz.thread.demo7;
public class ThreadA extends Thread {
private ObjectService objectService;
public ThreadA(ObjectService objectService) {
super();
this.objectService = objectService;
}
@Override
public void run() {
objectService.methodA();
}
}
- package com.zwz.thread.demo7;
- public class ThreadB extends Thread {
- private ObjectService objectService;
- public ThreadB(ObjectService objectService) {
- super();
- this.objectService = objectService;
- }
- @Override
- public void run() {
- objectService.methodB();
- }
- }
package com.zwz.thread.demo7;
public class ThreadB extends Thread {
private ObjectService objectService;
public ThreadB(ObjectService objectService) {
super();
this.objectService = objectService;
}
@Override
public void run() {
objectService.methodB();
}
}
- package com.zwz.thread.demo7;
- public class MainTest {
- public static void main(String[] args) {
- ObjectService service=new ObjectService();
- ThreadA a=new ThreadA(service);
- a.setName("A");
- a.start();
- ThreadB b=new ThreadB(service);
- b.setName("B");
- b.start();
- }
- }
package com.zwz.thread.demo7;
public class MainTest {
public static void main(String[] args) {
ObjectService service=new ObjectService();
ThreadA a=new ThreadA(service);
a.setName("A");
a.start();
ThreadB b=new ThreadB(service);
b.setName("B");
b.start();
}
}
运行结果:
上面测试方法是共同对象，下面我们分别实例化一个对象：
- package com.zwz.thread.demo7;
- public class MainTest {
- public static void main(String[] args) {
- ObjectService service1=new ObjectService();
- ObjectService service2=new ObjectService();
- ThreadA a=new ThreadA(service1);
- a.setName("A");
- a.start();
- ThreadB b=new ThreadB(service2);
- b.setName("B");
- b.start();
- }
- }
package com.zwz.thread.demo7;
public class MainTest {
public static void main(String[] args) {
ObjectService service1=new ObjectService();
ObjectService service2=new ObjectService();
ThreadA a=new ThreadA(service1);
a.setName("A");
a.start();
ThreadB b=new ThreadB(service2);
b.setName("B");
b.start();
}
}
运行结果：
结论：
同步synchronized(*.class)代码块的作用其实和synchronized static方法作用一样。Class锁对类的所有对象实例起作用。
synchronized(this)、synchronized(class)与synchronized(Object)的区别的更多相关文章
- java 多线程 Synchronized方法和方法块 synchronized(this)和synchronized(object)的理解
synchronized 关键字,它包括两种用法:synchronized 方法和 synchronized 块. 1. synchronized 方法:通过在方法声明中加入 synchronized ...
- Lock、synchronized和ReadWriteLock，StampedLock戳锁的区别和联系以及Condition
https://www.cnblogs.com/RunForLove/p/5543545.html 先来看一段代码,实现如下打印效果: 1 2 A 3 4 B 5 6 C 7 8 D 9 10 E 1 ...
- java-测试synchronized使用xxx.class和this使用的区别
synchronized测试1 写两个线程调用同一个方法,在其中分别做一个class和this的调用,看结果 1.xx.class public class Test{ public static v ...
- 使用synchronized修饰静态方法和非静态方法有什么区别
前言 最近被问到了这个问题,第一次回答的也是很不好,在此参考网上答案进行整理记录.供大家学习参考. Synchronized修饰非静态方法 Synchronized修饰非静态方法,实际上是对调用该方法 ...
- Python中type与Object的区别
Python中type与Object的区别 在查看了Python的API后,总算明白了.现在总结如下: 先来看object的说明: Python中关于object的说明很少,甚至只有一句话: clas ...
- Java不定参数Object… obj 和 Object[] 的区别
Java不定参数Object… obj 和 Object[] 的区别 简述: java中方法重载可以实现参数不同自动匹配对应方法.但现实中也存在这种问题.普通传参对于形如下面的方法,却显得臃肿而失优雅 ...
- 新手向-同步关键字synchronized对this、class、object、方法的区别
synchronized的语义 实验 分析 在看源代码时遇到多线程需要同步的时候,总是会看见几种写法,修饰方法.修饰静态方法.synchronized(Xxx.class).synchronized( ...
- map泛型 map不指定泛型 与 Map<Object,Object>的区别
map泛型 map不指定泛型 与 Map<Object,Object>的区别 private void viewDetail(){ Map map1 = new HashMap(); Ma ...
- Java的synchronized的同步代码块和同步方法的区别
synchronized同步方法和同步代码块的区别 同步方法默认使用this或者当前类做为锁. 同步代码块可以选择以什么来加锁,比同步方法更精确,我们可以选择只有会在同步发生同步问题的代码加锁,而并不 ...
随机推荐
- BAM/SAM格式
本质上就是二进制压缩的SAM文件,大部分生物信息学流程都需要这个格式,为了节省存储空间以及方便索引. # BiocInstaller::biocLite('Rsamtools') library(Rs ...
- 能量项链 （区间DP）
能量项链 (区间DP) 问题引入 能量项链 洛谷 P1063 思路 诸如此类不能线性规划的问题要用到区间DP,区间DP一般就是三层循环,第一层表示区间长度(本题即\(n\)),第二层枚举起点并根据第一 ...
- nodejs fs读取静态json文件
let fs = require('fs'),stream = fs.createReadStream('./obd.json'),data = ""; stream.on('da ...
- adb自救指南
以下只能自救专用 adb.exe root adb remount adb.exe connect <Ip> adb.exe install [-r] [-d] <apkPath&g ...
- swiper、fullPage、hammer几种滑动插件对比
1.使用hammer,自己实现滑动垂直切换页面 <!DOCTYPE html> <html lang="en"> <head> <titl ...
- flume将数据发送到kafka、hdfs、hive、http、netcat等模式的使用总结
1.source为http模式,sink为logger模式,将数据在控制台打印出来. conf配置文件如下: # Name the components on this agent a1.source ...
- org.hibernate.QueryException: duplicate alias: r hibernate别名重复问题解决
今天做项目的过程中发现,多表查询的时候如果使用hibernate的DetachedCriteria离线查询方式的时候, 在多表关联的时候我们需要使用别名的方式去实现. 但是代码运行的过程中抛出了下面的 ...
- 1、java线程模型
要了解多线程,先需要把java线程模型搞清楚,否则有时候很难理清楚一个问题. 硬件多线程: 物理机硬件的并发问题跟jvm中的情况有不少相似之处,物理机的并发处理方案对于虚拟机也有相当大的参考意义.在买 ...
- 读书笔记-NIO的工作方式
读书笔记-NIO的工作方式 1.BIO是阻塞IO,一旦阻塞线程将失去对CPU的使用权,当前的网络IO有一些解决办法:1)一个客户端对应一个处理线程:2)采用线程池.但也会出问题. 2.NIO的关键类C ...
- URAL ——1249——————【想法题】
Ancient Necropolis Time Limit:5000MS Memory Limit:4096KB 64bit IO Format:%I64d & %I64u ...