java什么时候用到多线程 Java多线程下载

Java多线程下载  

　　同时下载多个文件 不过单文件没有多线程的下载并且没有断点续传功能 继续完善:

　　view plaincopy to clipboardprint?    package util file;

　　public class Files {

　　/***         * 获取应用程序的根目录         * @return 应用程序根目录         */        public static String getSysPath(){        return  System getProperty( user dir );        }

　　}

　　package util file;

　　public class Files {

　　/***         * 获取应用程序的根目录         * @return 应用程序根目录         */        public static String getSysPath(){     return  System getProperty( user dir );        }

　　}view plaincopy to clipboardprint?

　　view plaincopy to clipboardprint?    <PRE class=csharp name= code >package re crawl;

　　import java io File;    import java io FileOutputStream;    import java io IOException;    import java io InputStream;    import HttpURLConnection;    import URL;

　　import re Http;

　　public class WebSpider implements Runnable{

　　private Http = new Http();

　　private String webAddress = ;        private String destFile = ;

　　public void setWebAddress(String webAddress){        this webAddress = webAddress;        }

　　public void setDestFile (String destFile){        this destFile = destFile;        }

　　public boolean download() throws IOException InterruptedException {

　　HttpURLConnection Conn = null;

　　try {            URL url = new URL(webAddress);

　　Conn = (HttpURLConnection) url openConnection();            ( GET );            ( User Agent Mozilla/ (Windows; U; Windows NT ; zh CN; rv: ) Gecko/ Firefox/ );            InputStream in = ();            String fileType = fileType(());            System out println(fileType);            FileOutputStream out = new FileOutputStream(new File(destFile + fileType));            int chByte = in read();            while (chByte != ) {            out write(chByte);            //System out println(chByte);            chByte = in read();            }        } catch (Exception ex) {            System out println(ex toString());        } finally {            ();        }        return true;        }

　　public void run() {        try {            //System out println(Thread currentThread() getName());            download();        } catch (IOException e) {            e printStackTrace();        } catch (InterruptedException e) {            e printStackTrace();        }        }    }    </PRE>

　　view plaincopy to clipboardprint?package re crawl;     import java io File;   import java io FileOutputStream;   import java io IOException;   import java io InputStream;   import HttpURLConnection;   import URL;     import re Http;     public class WebSpider implements Runnable{              private Http = new Http();         private String webAddress = ;       private String destFile = ;              public void setWebAddress(String webAddress){       this webAddress = webAddress;       }              public void setDestFile (String destFile){       this destFile = destFile;       }              public boolean download() throws IOException InterruptedException {         HttpURLConnection Conn = null;         try {           URL url = new URL(webAddress);                    Conn = (HttpURLConnection) url openConnection();           ( GET );           ( User Agent Mozilla/ (Windows; U; Windows NT ; zh CN; rv: ) Gecko/ Firefox/ );           InputStream in = ();           String fileType = fileType(());           System out println(fileType);           FileOutputStream out = new FileOutputStream(new File(destFile + fileType));           int chByte = in read();           while (chByte != ) {           out write(chByte);           //System out println(chByte);           chByte = in read();           }       } catch (Exception ex) {           System out println(ex toString());       } finally {           ();       }       return true;       }         public void run() {       try {           //System out println(Thread currentThread() getName());           download();           } catch (IOException e) {           e printStackTrace();       } catch (InterruptedException e) {           e printStackTrace();       }       }   }  package re crawl;

　　import java io File;    import java io FileOutputStream;    import java io IOException;    import java io InputStream;    import HttpURLConnection;    import URL;

　　import re Http;

　　public class WebSpider implements Runnable{

　　private Http = new Http();

　　private String webAddress = ;        private String destFile = ;

　　public void setWebAddress(String webAddress){     this webAddress = webAddress;        }

　　public void setDestFile (String destFile){     this destFile = destFile;        }

　　public boolean download() throws IOException InterruptedException {

　　HttpURLConnection Conn = null;

　　try {         URL url = new URL(webAddress);

　　Conn = (HttpURLConnection) url openConnection();         ( GET );         ( User Agent Mozilla/ (Windows; U; Windows NT ; zh CN; rv: ) Gecko/ Firefox/ );         InputStream in = ();         String fileType = fileType(());         System out println(fileType);         FileOutputStream out = new FileOutputStream(new File(destFile + fileType));         int chByte = in read();         while (chByte != ) {      out write(chByte);      //System out println(chByte);      chByte = in read();         }     } catch (Exception ex) {         System out println(ex toString());     } finally {         ();     }     return true;        }

　　public void run() {     try {         //System out println(Thread currentThread() getName());         download();     } catch (IOException e) {         e printStackTrace();     } catch (InterruptedException e) {         e printStackTrace();     }        }    }

　　view plaincopy to clipboardprint?    <PRE class=csharp name= code >package re crawl;

　　import java io IOException;

　　import util file Files;

　　public class Crawl {

　　/**         * @param args         * @throws IOException         * @throws InterruptedException         */        public static void main(String[] args) throws IOException InterruptedException {

　　long begin = System currentTimeMillis();        WebSpider spider = new WebSpider();        WebSpider spider = new WebSpider();        spider setWebAddress( );        spider setDestFile(Files getSysPath() + / + spider );

　　spider setWebAddress( );        spider setDestFile(Files getSysPath() + / + spider );

　　Thread t = new Thread(spider );        Thread t = new Thread(spider );        t start();        t start();

　　t join();        t join();

　　System out println( the end );        System out println(System currentTimeMillis() begin);        }