Java Multithreaded Download Example

Project structure:

Filedownload.java:

Package Com.wl.download;import Java.io.file;import Java.io.filenotfoundexception;import java.io.IOException;import Java.io.randomaccessfile;import Java.text.decimalformat;import Org.apache.http.httpresponse;import Org.apache.http.client.clientprotocolexception;import Org.apache.http.client.httpclient;import Org.apache.http.client.methods.httpget;import Com.wl.util.downloadthread;import com.wl.util.HttpClientFactory; public class FileDownload {public static void main (string[] args) {Long startTime = System.currenttimemillis (); System.out.println (StartTime); String Srcfileurl = "Http://172.16.2.40:80/2014/12/gpfqpfvlwsvka2mj39pn.mprx"; String Destfilepath = "g:/download/destfile.mprx";//Gets the file size long fileSize = Getremotefilesize (srcfileurl);/** * File size to download per thread (self-tuning) *///long unitsize = 1024;  Multithreading too much stuck your computer no problem long unitsize = 1024 * 1024 * 2; Download file size = 535.66M;  23559 Millisecond//long unitsize = 1024 * 1024 * 50; Download file size = 535.66M;  35726 Millisecond//long unitsize = fileSize; Download filesize = 535.66M; Time used = 52865 millisecond//Create destination file and specify size CreateFile (Destfilepath, fileSize);//Open several threads to download long threadcount = fileSize/ unitsize;//Write file location long offset = 0;if (fileSize <= unitsize) {//If the remote file size is less than or equal to unitsizedownloadthread downloadthread = NE W Downloadthread (Srcfileurl, Destfilepath, offset, fileSize);  Thread t = new thread (downloadthread); t.setpriority (ten); T.start (); try {t.join (); The method functions: The main thread (here is the threads that the main function executes) waits for the download thread to end} catch (Interruptedexception e) {}}else{for (int i = 1; I <= threadcount; i++) { Downloadthread downloadthread = new Downloadthread (Srcfileurl, Destfilepath, offset, unitsize); Thread t = new thread (downloadthread); t.setpriority (ten); T.start (); offset = offset + unitsize;} if (fileSize% unitsize! = 0) {//If not divisible, you need to create another thread to download the remaining bytes Downloadthread downloadthread = new Downloadthread (Srcfileurl, DE Stfilepath, offset, filesize-unitsize * threadcount); Thread t = new thread (downloadthread); t.setpriority (ten); T.start (); try {t.join ();///The method acts: the main thread (here is the one that the main function executes) waits for all The main thread produces the end of the download thread} catch (Interruptedexception e) {}}}long endTime = System.currenttimemillis (); System.out.println (EndTime);  System.out.println ("Download File size =" + filesize2string (fileSize) + "; Time used = "+ (endtime-starttime) +" millisecond ");} /** * Get file size */private static long getremotefilesize (String srcfileurl) {HttpClient HttpClient = Httpclientfactory.getins Tance (). Gethttpclient (); HttpGet httpget = new HttpGet (srcfileurl);//Send request, return response HttpResponse response = null;try {response = Httpclient.execute (htt Pget);} catch (Clientprotocolexception e) {} catch (IOException e) {}long result = Response.getentity (). Getcontentlength (); return result;}  /** * Create a file of the specified size * @param fileName * @param fileSize */private static void CreateFile (String fileName, long fileSize) {file NewFile = new File (fileName), if (Newfile.exists ()) Newfile.delete (); Randomaccessfile RAF = null;try {RAF = new Randomaccessfile (newFile, "RW"); Raf.setlength (fileSize);} catch ( FileNotFoundException e) {} catch (IOException e) {} finally {try {if (RAF! = null) {Raf.close ()}} catch (IOException e) {}}}/** * Get size String * @param totalsize * @return */private S        Tatic string filesize2string (Long totalsize) {string filetotalsize= "";    DecimalFormat df = new DecimalFormat ("0.00");    if (TotalSize <1024) {filetotalsize=totalsize+ "B";    }else if (totalsize <1048576) {Filetotalsize=df.format ((float) totalsize/1024) + "K";    }else if (totalsize <1073741824) {Filetotalsize=df.format (float) totalsize/1048576) + "M";    }else{Filetotalsize=df.format ((float) totalsize/1073741824) + "G"; } return filetotalsize;}}

Downloadthread.java

Package Com.wl.util;import Java.io.bufferedinputstream;import Java.io.ioexception;import Java.net.httpurlconnection;import Java.net.url;public class Downloadthread implements Runnable {private String URL = null;//file to download private String file = null;//Local storage path private long offset = 0;//offset private Long length = 0;//number of bytes allocated to this thread pub Lic downloadthread (string url, string file, long offset, long length) {This.url = Url;this.file = File;this.offset = OFFSE t;this.length = length;} public void Run () {Bufferedinputstream bis = null; Saveitemfile Saveitemfile = null;try {httpurlconnection httpurlconnection = (httpurlconnection) New URL ( This.url.replace ("", "%20")). OpenConnection (); Httpurlconnection.setrequestmethod ("GET"); Httpurlconnection.setrequestproperty ("RANGE", "bytes=" + This.offset + "-" + (This.offset + this.length-1)); bis = new Buf Feredinputstream (Httpurlconnection.getinputstream ()); saveitemfile = new Saveitemfile (file,offset); byte[] Buff = new Byte[1024*8];while (length = bis.read (Buff)) > 0 && Offset < offset+length) {//write to file contents, return the last written length offset + = saveitemfile.write (buff, 0, (i            NT) length); }} catch (IOException e) {} finally {try {if (bis! = null) {Bis.close ()} if (saveitemfile!=null) {saveitemfile.close ();}} catch (IOException e) {}}}}

Httpclientfactory.java:

Package Com.wl.util;import Java.util.concurrent.timeunit;import Org.apache.http.httpversion;import Org.apache.http.client.httpclient;import Org.apache.http.conn.scheme.plainsocketfactory;import Org.apache.http.conn.scheme.scheme;import Org.apache.http.conn.scheme.schemeregistry;import Org.apache.http.conn.ssl.sslsocketfactory;import Org.apache.http.impl.client.defaulthttpclient;import Org.apache.http.impl.conn.poolingclientconnectionmanager;import Org.apache.http.params.basichttpparams;import Org.apache.http.params.coreconnectionpnames;import Org.apache.http.params.httpparams;import Org.apache.http.params.httpprotocolparams;public class Httpclientfactory {private HttpClient HttpClient = null;/** * A unique instance of this class may exist */private static httpclientfactory m_instance;/** * Static Factory method * * @return return a single instance of the Readconfigation class */public s Tatic httpclientfactory getinstance () {if (null = = m_instance) {m_instance = new httpclientfactory ();} return m_instance;} Private Httpclientfactory () {//Set component parameters, version of HTTP protocol,1.1/1.0/0.9httpparams params = new Basichttpparams (); Httpprotocolparams.setversion (params, httpversion.http_1_1); Httpprotocolparams.setuseragent (params, "httpcomponents/1.1"); Httpprotocolparams.setuseexpectcontinue (params, true);//Set connection Timeout int request_timeout = 30 * 1000; Set request Timeout 10 seconds int so_timeout = 10 * 1000; Set wait data timeout time 10 seconds//Httpconnectionparams.setconnectiontimeout (params, request_timeout);// Httpconnectionparams.setsotimeout (params, so_timeout);p Arams.setparameter (coreconnectionpnames.connection_ Timeout,request_timeout);p arams.setparameter (Coreconnectionpnames.so_timeout, so_timeout);// Set the Access protocol Schemeregistry Schreg = new Schemeregistry (); Schreg.register ("http", 80, Plainsocketfactory.getsocketfactory ())); Schreg.register ("https", 443, Sslsocketfactory.getsocketfactory ()));//multi-connected thread-Safe manager poolingclientconnectionmanager PCCM = new Poolingclientconnectionmanager (Schreg);p Ccm.setdefaultmaxperroute (50); Maximum number of parallel links per host pccm.setmaxtotal (100); Client total parallel link Maximum number HttpclieNT = new Defaulthttpclient (PCCM, params); Httpclient.getconnectionmanager (). Closeidleconnections (10, Timeunit.seconds);} Public Defaulthttpclient gethttpclient () {return (defaulthttpclient) httpClient;}}

Saveitemfile.java:

Package Com.wl.util;import Java.io.ioexception;import Java.io.randomaccessfile;public class SaveItemFile {//Store file PR        Ivate Randomaccessfile Itemfile;    Public Saveitemfile () throws IOException {This ("", 0); }/** * @param name file path, name * @param POS Write point location position * @throws IOException */Public SaveItem File (String name, long Pos) throws IOException {itemfile = new Randomaccessfile (name, "RW");//readable writable//in the specified PO    The s position begins writing data Itemfile.seek (POS); }/** * <b>function:</b> Sync method Write file * @author Hoojo * @createDate 2011-9-26 12:21:22 * @param buff Buffer array * @param start position * @param length * @return */public int write (byte[] buff, int        Start, int length) {int i =-1;            try {itemfile.write (buff, start, length);        i = length;        } catch (IOException e) {e.printstacktrace ();    } return i; } public void Close() throws IOException {if (itemfile! = null) {itemfile.close (); }    }}

Pom.xml

<project xmlns= "http://maven.apache.org/POM/4.0.0" xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance" xsi: schemalocation= "http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd" >    < modelversion>4.0.0</modelversion>  <groupId>com.filedownload</groupId>  < artifactid>filedownload</artifactid>  <version>0.0.1-SNAPSHOT</version>    < dependencies>    <dependency>         <groupId>org.apache.httpcomponents</groupId>         < Artifactid>com.springsource.org.apache.httpcomponents.httpclient</artifactid>         <version> 4.2.1</version>     </dependency>    </dependencies></project>

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Multi-threaded upload to be continued .....

Java Multithreaded Download Example