Multi-thread download in Android

Public class mainactivity extends activity {// declare the control // path and number of threads private edittext et_url, et_num; // progress bar public static progressbar pb_thread; // display progress operation private textview TV _pb; // The number of threads public static int threadnum = 3; // the size of each thread to download public int blocksize; public static int threadcount; // The number of // accessed pathpublic string path; public static Boolean flag = true; // record progress bar value public static int pb_count = 0; public static handler; public static final int textvalue = 1; public static int pb_num = 0; public static int size = 0; @ overrideprotected void oncreate (bundle savedinstancestate) {super. oncreate (savedinstancestate); setcontentview (R. layout. activity_main); et_url = (edittext) findviewbyid (R. id. et_path); et_num = (edittext) findviewbyid (R. id. et_threadnum); pb_thread = (progressbar) findviewbyid (R. id. pb_down); TV _pb = (textview) findviewbyid (R. id. TV _pb); handler = new handler () {@ overridepublic void handlemessage (Message MSG) {super. handlemessage (MSG); Switch (MSG. what) {Case textvalue: system. out. println ("-----------------------" + mainactivity. pb_count + "//" + mainactivity. size); // change textviewpb_num = (mainactivity. pb_count * 100)/mainactivity. size; TV _pb.settext ("the current progress is +" + pb_num + "%"); break; default: Break ;}}}@ overridepublic Boolean oncreateoptionsmenu (menu) {// inflate the menu; this adds items to the action bar if it is present. // getmenuinflater (). inflate (R. menu. down, menu); Return true;} // download public void download (view v) {// change the variable value: mainactivity. flag = true; mainactivity. pb_count = 0; Path = et_url.gettext (). tostring (); string threadnum_et = et_num.gettext (). tostring (); If (textutils. isempty (PATH) | textutils. isempty (threadnum_et) {toast. maketext (this, "cannot be blank", toast. length_long ). show (); return;} toast. maketext (this, "url:" + path + "--" + threadnum_et, toast. length_long ). show (); // convert to the number threadnum = integer. valueof (threadnum_et); New thread (New runnable () {@ overridepublic void run () {try {// create a URL object url = new URL (PATH ); // create the httpurlconnection object httpurlconnection = (httpurlconnection) URL. openconnection (); // sets the method for sending a request to httpurlconnection. setrequestmethod ("get"); // sets whether the request has timed out. setconnecttimeout (5000); // sets httpurlconnection. setrequestproperty ("User-Agent", "Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0)"); // whether the response is successful if (httpurlconnection. getresponsecode () = 200) {// get the file size = httpurlconnection. getcontentlength (); system. out. println ("file size" + size); // set the maximum value of the progress bar pb_thread.setmax (size ); // create a file // save it to the SD card. // first, determine whether sdcardif (environment. getexternalstoragestate (). equals (environment. media_mounted) {// get the sdcard file directory object file sdfile = environment. getexternalstoragedirectory (); // create a file object file = new file (sdfile, "youdao.exe"); randomaccessfile accessfile = new randomaccessfile (file, "RWD "); // set the file size accessfile. setlength (size); // the size of blocksize = size/threadnum downloaded by each thread; // enable three threads to operate the file for (INT I = 1; I <= threadnum; I ++) {// 1 2 3 // calculate the start position of each thread int startsize = (I-1) * blocksize; // The end position int endsize = (I) * blocksize; // if (I = threadnum) when the thread is the last thread {// determine whether the file size is greater than the calculated end position if (size> endsize) {// The end position is equal to the file size endsize = size;} // creates a random reading randomaccessfile threadaccessfile = new randomaccessfile (file, "RWD") for each thread "); new thread (New downloadthread (I, threadaccessfile, startsize, endsize, PATH )). start () ;}}} catch (malformedurlexception e) {// todo auto-generated catch blocke. printstacktrace ();} catch (ioexception e) {// todo auto-generated catch blocke. printstacktrace ();}}}). start () ;}// pause the public void downpause (view v) {toast. maketext (this, "Suspend", toast. length_long ). show (); this. flag = false ;}}

Public class downloadthread implements runnable {// encapsulation of the downloaded file public randomaccessfile accessfile; // the starting position of the file downloaded by the thread public int startsize; Public int endsize; // File Download path Public String path; Public int threadid; // The thread ID public downloadthread (INT threadid, randomaccessfile accessfile, int startsize, int endsize, string path) {This. threadid = threadid; this. accessfile = accessfile; this. startsize = startsize; thi S. endsize = endsize; this. path = path ;}@ overridepublic void run () {// execute the run method try {// create a file to the SD card // first determine whether sdcardif (environment. getexternalstoragestate (). equals (environment. media_mounted) {// get the sdcard file directory object file sdfile = environment. getexternalstoragedirectory (); file threadfile = new file (sdfile, threadid + ". TXT "); If (threadfile. exists () {// read the content of the file // create the input stream object of the file fileinputstream FS = new fileinpu Tstream (threadfile); // use the tool class to read byte data [] = streamtools. istodata (FCM); // convert it to string threadlen = new string (data); If (threadlen! = NULL )&&(! "". Equals (threadlen) {startsize = integer. valueof (threadlen); // solves the error of 416bug if (startsize> endsize) {startsize = endsize-1 ;}}} // create a file // create a URL object url = new URL (PATH); // create an httpurlconnection object httpurlconnection = (httpurlconnection) URL. openconnection (); // sets the request header httpurlconnection. setrequestmethod ("get"); // sets whether the request has timed out. setconnecttimeout (5000); // sets httpurlconnecti On. setrequestproperty ("User-Agent", "Mozilla/5.0 (compatible; MSIE 10.0; Windows NT 6.2; Trident/6.0)"); // key settings httpurlconnection. setrequestproperty ("range", "bytes =" + startsize + "-" + endsize); // output the current thread system. out. println ("current thread" + threadid + "Download start position:" + startsize + "Download end position:" + endsize ); // response successful // set the start position of the random File Read accessfile. seek (startsize); // obtain the corresponding Stream object inputstream is = httpurlconnection. getinputstream (); // Create the output stream object byte buffer [] = new byte [1024]; int Len = 0; int threadtotal = 0; // Save the record/while (LEN = is. read (buffer ))! =-1) {accessfile. write (buffer, 0, Len); threadtotal + = Len; // record the length you write. // XML file // change the progress bar: setprogressbar (LEN ); // record the length of the downloaded file fileoutputstream Fos = new fileoutputstream (threadfile); FOS. write (threadtotal + ""). getbytes (); FOS. flush (); FOS. close (); // send the handler message mainactivity. handler. sendemptymessage (mainactivity. textvalue); If (! Mainactivity. flag) {return ;}} accessfile. close (); is. close (); system. out. println (threadid + "thread execution completed"); // thread operation synchronized (mainactivity. class) {mainactivity. threadcount ++; If (mainactivity. threadcount> = mainactivity. threadnum) {for (INT I = 1; I <= mainactivity. threadnum; I ++) {// obtain the file deletefile = new file (sdfile, I + ". TXT "); If (deletefile. exists () {// Delete deletefile. delete () ;}}}} catch (malformedurlexception e) {// todo auto-generated catch blocke. printstacktrace ();} catch (ioexception e) {// todo auto-generated catch blocke. printstacktrace () ;}} public synchronized void setprogressbar (INT Len) {mainactivity. pb_count + = Len; mainactivity. pb_thread.setprogress (mainactivity. pb_count );}}

Public class streamtools {public static byte [] istodata (inputstream is) throws ioexception {// bytearrayoutputstream BOPS = new bytearrayoutputstream (); // The cache for reading Data byte buffer [] = new byte [1024]; // The read length record int Len = 0; // read while cyclically (LEN = is. read (buffer ))! =-1) {BOPs. write (buffer, 0, Len);} // converts the read content to a byte array byte data [] = BOPs. tobytearray (); BOPs. flush (); BOPs. close (); is. close (); return data ;}}

Complete source code please visit: http://download.csdn.net/detail/chrp99/5616629