Download baidu map tiles with thread pool

Following the previous article, Baidu Map offline function, here mainly on the download tile map specific methods.

1. Use the all-in-all electronic map to download the tile map with watermarks. Where the folder path is tile/level/x/y.jpg, as shown, all-round electronic map 1.9 Download Baidu Map tile is a black spot.

2. Download the image according to the image URL, get httpurlconnection according to the URL, get the input stream InputStream according to the HttpURLConnection, outputstream out with the output stream = new FileOutputStream (file); Write bytes to file. The code is as follows:

/*** Download Image*/ Public classBaidumapdownload {Static volatileInteger c = 0;//Number of successes    Static volatileInteger fail = 0;//Number of failures
     Public Static voidMain (string[] args)throwsException {String link= "http://online3.map.bdimg.com/onlinelabel/?qt=tile&x={x}&y={y}&z={z}&styles=pl&udt= 20170712&scaler=1&p=1 "; intz = 19;//level        intXmin = 103514;//x Minimum Value        intXmax = 104292;//x Maximum Value        intYmin = 29400;//y Minimum value        intYmax = 30700;//y Maximum value             for(inti = xmin; I <= xmax; i++) {//Loop x                 for(intj = ymin; J <= Ymax; J + +) {//Loop y                    Try {
URL URL=NewURL (Link.replace ("{x}", I + ""). Replace ("{y}", J + ""). Replace ("{z}", z + "")); HttpURLConnection Conn=(HttpURLConnection) url.openconnection (); Conn.setconnecttimeout (100);                        Conn.connect (); InputStream in=Conn.getinputstream (); File dir=NewFile ("d:/mybaidumapdownload1/tiles/" + z + "/" +i); if(!dir.exists ())                        {Dir.mkdirs (); } File File=NewFile ("d:/mybaidumapdownload1/tiles/" + z + "/" + i + "/" + j + ". jpg"); if(!file.exists ())                        {File.createnewfile (); } OutputStream out=Newfileoutputstream (file); byte[] bytes =New byte[1024 * 20]; intLen = 0;  while(len = in.read (bytes))! =-1) {out.write (bytes,0, Len);                        } out.close ();                        In.close (); //System.out.println ("downloaded successfully:" + z + "_" + i + "_" + j + ". jpg");C++; } Catch(Exception e) {System.out.println (E.getmessage ()); Fail++; }
}    //Loop y End}//Loop x EndThread.Sleep (1000); System.out.println ("Total Downloads:" + C + "Zhang"); System.out.println ("Failure:" + fail + "Zhang"); }}

3. The above code can download Baidu pictures, but it is clear that the above code is single-threaded, and will be blocked IO, Baidu map download to the 19th level when there are nearly 1 million tile map. Here is the thread pool Threadpoolexecutor

Optimize the code. It would have been nice to have a two-day plan to cut down the day.

/*** thread pool download picture*/classBdtaskImplementsrunnable{String link; intI//x-coordinate    intJ//y-coordinate    intZ//Zoom Level    Static volatileInteger c = 0;//Number of successes    Static volatileInteger fail = 0;//Number of failures     PublicBdtask (String link,intIintJintz) { This. link =link;  This. i =i;  This. J =J;  This. z =Z; }     Public Static voidMain (string[] args)throwsException {String link= "http://online3.map.bdimg.com/onlinelabel/?qt=tile&x={x}&y={y}&z={z}&styles=pl&udt= 20170712&scaler=1&p=1 "; intz = 12;//level        intXmin = 808;//x Minimum Value        intXmax = 814;//x Maximum Value        intymin = 230;//y Minimum value        intYmax = 239;//y Maximum value //Create thread pool, corepoolsize two threads, max four threads, threads greater than corepoolsize less than maxmumpoolsize wait idle time for 500 milliseconds,        The default value for task queue Linkblockingqueue when not written is the integer default value. Threadpoolexecutor Threadpoolexecutor=NewThreadpoolexecutor (2,4,500, Timeunit.milliseconds,NewLinkedblockingqueue<runnable>());  for(inti = xmin; I <= xmax; i++) {//Loop x             for(intj = ymin; J <= Ymax; J + +) {//Loop yThreadpoolexecutor.execute (NewBdtask (link,i,j,z)); //New Thread (New Bdtask (Link,i,j,z)). Start (); //This method will always create a thread that causes the panic}//Loop y End}//Loop x EndThreadpoolexecutor.shutdown ();//Close the thread pool         while(!threadpoolexecutor.isterminated ()) {}//Keep circulating untilcontinue execution when all tasks are completedSystem.out.println ("Total Download:" + C + "Zhang"); System.out.println ("Failure:" + fail + "Zhang"); }     Public voidrun () {Try{URL URL=NewURL (Link.replace ("{x}", I + ""). Replace ("{y}", J + ""). Replace ("{z}", z + "")); HttpURLConnection Conn=(HttpURLConnection) url.openconnection (); Conn.setconnecttimeout (100);            Conn.connect (); InputStream in=Conn.getinputstream (); File dir=NewFile ("d:/mybaidumapdownload1/tiles/" + z + "/" +i); if(!dir.exists ())            {Dir.mkdirs (); } File File=NewFile ("d:/mybaidumapdownload1/tiles/" + z + "/" + i + "/" + j + ". jpg"); if(!file.exists ())            {File.createnewfile (); } OutputStream out=Newfileoutputstream (file); byte[] bytes =New byte[1024 * 20]; intLen = 0;  while(len = in.read (bytes))! =-1) {out.write (bytes,0, Len);            } out.close ();            In.close (); synchronized(fail) {C++; }        } Catch(Exception e) {System.out.println (E.getmessage ()); synchronized(c) {fail++; }        }    }}

Source

Download baidu map tiles with thread pool