简单的来解释一下 10个人 要从A点到B点 要花1秒钟
有10条路(10线程) 每条路在A到B点之间同时只能有1个人,如果只有1条路开启(1线程)则需要10秒钟才能全部到达。
如果 有10条路(线程)全部开启,那么每个人都单独走1条路(1线程),这个时候只需要1秒钟就全部到达。
通过以上的例子 可以明白
线程开通得越多,下载的速度越
java多线程下载还是和单线程一样
本人不才,下面这个是从网络上转来的不知可有帮助
这是codeproject的关于ftp的实现,你可以去down源代码
Introduction
StuffFTP is a free for life FTP client This FTP client will allow you to connect to FTP servers and upload and download files
Motivation
Why did I create and continue to support StuffFTP First it is a learning experience, and since I just got laid off from my company, I decided to use some of the tools they have provided, its legal as I technically bought them and they do not have other programmers following in my footstep nor do they plan on hiring any, to create something for the community I also used another FTP program that was freeware for a while and then became pay to use software with little to no notice That irked me and a friend suggested I create my own FTP client So I am
Progress
This is currently a work in progress and I would be the first to say there is a lot of work to do Since I am laid off, I have lots of time on my hands And this is an excellent chance for me to learn some of the concepts of C++ that I wanted to, but never had the chance while I was working I was hoping to get a job in San Jose, CA, but decided to hold off and live on saving for a while
Guarantee
I will support this program as best as I can I have already setup a website and forum for it, here I use the forum because I have trouble responding to email especially when I get a whole bunch of SPAM everyday There is no adware or spyware in the program, and I guarantee that it will be free for the life of the program
Some people have already asked why I don't open source the project The main reason is I do not know if I can StuffFTP uses some proprietary third party libraries I do not know if I can post the source code or header files to those libraries So everyone will have to wait until I can get rid of those libraries or hear back from the companies concerning my question about releasing header and associated help files
Tools
MS Windows XP Professional
MS Visual Studio NET C++/MFC
Clickteam Install Maker
Clickteam Patch Maker
Betaonenet forum members
CXListCtrl by Hans Dietrich
3rd Party Libraries
The application uses Catalyst Socket Tools Library Edition and Professional UI GUI library So far the support has been fair with Prof-UI and outstanding with Catalyst The Catalyst tool is for the actual FTP connection and, as the name suggests, Prof-UI is being used for the GUI
Updates
You can find the latest updates here and you can also find my latest ramblings, blogs, and support here This is where you can find out all the latest versions and information
How to contribute
Money! Just kidding you can contribute by downloading, using, and giving feedback on the program That way I can determine which path to take with the application and which features to prioritize or not Graphics is also where I need lots of help I am left brained and can not draw a good stick figure to save my life If you can help with graphics or anything else, please let me know Also talk to me, I am bored I have no job at the moment so I can use the company
Features
Able to upload/download from server/computer
Connect to FTP sites using login
Connect using other ports besides 21
Delete, rename, and CHMOD a file
History
12/10/2003 - Version 011a
12/07/2003 - Version 010a

某公司面试题java11使用并发多线程加速下载文件,如何写
Java多线程可以提高下载的效率,尤其是在需要下载大量或者文件时。通过多线程技术,可以把大量的下载任务分解成多个子任务,每个子任务独立运行在一个单独的线程中,从而可以并发地下载多张或者文件,从而大大提高了下载速度。
然而,多线程下载也存在一些问题,比如线程间的协调、资源共享、锁竞争等等,如果处理不当,可能会导致程序出现死锁、并发冲突等问题,甚至会降低程序的运行效率。因此,在编写多线程下载程序时,需要注意线程的安全性、同步机制、资源管理等方面的问题,以确保程序的稳定性和性能。同时,还需要考虑网络带宽、服务器限制等因素,避免过度占用网络资源,给其他用户造成影响。

多线程下载导致cpu占用过高
先建一个用于下载文件的多线程类,通常要指明下载文件的位置(URL)和文件名以及保存到本地的路径
public class FileDownloader implements Runnable
{
private static File file;//要下载的文件
private static String url;//文件所在URL
private static File storagePath;//保存路径
public static void initialize(File file, String url, File storagePath)//初始化静态字段,初始化的代码不用我写吧
}
然后,指明同步块,目的是让各个线程共享一个文件资源,那样它们可以知道同一个文件的下载状况(即获取其他线程下载文件到哪个位置,以防重复下载)
public synchronized void fileDownload()//此方法用于下载文件,一般的Java程序员都会写,实在不会我可以帮你补上
或者
public void fileDownload(){
synchronized(file){
synchronized(url){
synchronized(storagePath){
}}}}//给每个字段加上同步块
run()方法的实现就以自己的喜好去写吧,只要里面调用了fileDownload()方法就行。
public void run(){
…
fileDownload();//下载文件
…
}
然后,在主类的main方法中创建一个多线程数组:
Runnable[] fds=new FileDownloader[线程数量];//fds为file_downloaders缩写
Thread[] threads=new Thread[线程数量];
最后使用循环把所有的线程逐一启动。
for(int i=0;i<线程数量;i++){
threads[i]=new Thread(fds[i]);
threads[i]start();
}
为什么要准许多线程下载?
我们在使用电脑的时候,当电脑CPU占用率过高,会感觉到电脑变的非常卡。操作电脑很久都不会有反应,严重的话直接死机。那么有哪些原因会导致cpu占用率过高?下面本篇文章就来带大家了解一下,希望对大家有所帮助。
影响电脑CPU占用率过高的原因很多,有软件导致的,有硬件本身导致的。下面就给大家分析下CPU占用率过高的几种原因:
1、驱动没有经过认证
很多对电脑不是很懂的用户,在给电脑安装驱动的时候,尤其是显卡驱动,没有安装官方驱动,安装的是测试版驱动。很多测试版驱动都不规范,在系统运行的时候非常占用CPU资源。
2、病毒、木马、流氓软件
系统如果感染了病毒、木马,它们会在电脑后台不断的运行复制,导致一直占用CPU资源,电脑系统出现严重卡顿。
而,流氓软件是介于病毒和正规软件之间的软件。如果电脑中有流氓软件,会不经用户许可,自动运行,占用CPU资源等等。
此时,就需要使用杀毒、强力卸载软件来进行杀毒和软件的卸载,
3、运行大型程序(如游戏)
有时候CPU运行率高是一些大型程序导致的,比如占CPU高的大型游戏啊,正常原因有两种,第一种是编写的程序不符合导致CPU运行率飚高。
4、启动软件程序过多
很多朋友喜欢同时启动多个软件,比如一下次打开几十个浏览器窗口。要知道每打开一个浏览器窗口都会占用一部分CPU资源。
5、磁盘碎片过多
有时候经会对电脑的软件安装或者卸载,当文件在安装和卸载的时候,会使硬盘中的数据排列非常分散或者断断续续的,让电脑在查找时速度变慢,就造成大量的使用CPU。
所以要常把系统的垃圾清理掉,清理之后要对磁盘碎片进行整理。6、系统服务项未优化
电脑系统默认设置的服务项有很多多余服务会长期占用CPU资源,需要进行优化。
7、CPU老化
其实电脑的系统软件都在不断的升级,WIN从32位已经到了64位。这样就导致对CPU的要求越来越高。如果你使用单核赛扬级CPU来运行WIN7,那CPU基本不能支持。
这时就需要更换CPU。
多线程下载就是为了解决下载速度慢的问题,但前提是路由器没有做限制或者用其它的限制软件!多线程就相当于你多个连接下载!一般的下载软件都是多线程下载!至于下载速度也得看你连接的服务器的限制,有的网站不支持多线程下载,得用单线程!
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