package downutil;
import java.net.URL;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.lang.Thread;
import org.omg.CORBA_2_3.portable.InputStream;
public class DownUtil {
private String path;
private String targetFile;
private int threadNum;
private DownThread[] threads;
private int fileSize;
public DownUtil(String path, String targetFile, int threadNum) {
this.path = path;
this.threadNum = threadNum;
//此处DownThread类不能用,以下如此,亦不能实例化
threads = (DownThread[]) new DownThread(threadNum);
this.targetFile = targetFile;
}
public void download() throws Exception {
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(5 * 1000);
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept",
"image/gif,image/jpeg,image/pjpeg,image/pjpeg," + "application/x-shockwave-falsh,application/xaml+xml,"
+ "application/vnd.ms-xpsdocument,application/x-ms-xbap,"
+ "application/x-ms-application,application/vnd.ms-excel,"
+ "application/vnd.ms-powerpoint,application/msword,*/*");
conn.setRequestProperty("Accept-Language", "zh-CN");
;
conn.setRequestProperty("Charset", "UTF-8");
conn.setRequestProperty("Connection", "Keep-Alive");
fileSize = conn.getContentLength();
conn.disconnect();
int currentPartSize = fileSize / threadNum + 1;
RandomAccessFile file = new RandomAccessFile(targetFile, "rw");
file.setLength(fileSize);
;
file.close();
for (int i = 0; i < threadNum; i++) {
int startPos = i * currentPartSize;
RandomAccessFile currentPart = new RandomAccessFile(targetFile, "rw");
currentPart.seek(startPos);
;
//此处如此DownTread
threads[i] = new DownThread(startPos, currentPartSize, currentPart);
((Thread) threads[i]).start();
}
}
public double getCompleteRate() {
int sumSize = 0;
for (int i = 0; i < threadNum; i++) {
//此处length报错,不知啥问题
sumSize += threads[i].length;
}
return sumSize * 1.0 / fileSize;
//此处DownThread不知啥问题
private class DownThread extends Thread {
private int startPos;
private int currentPartSize;
private RandomAccessFile currentPart;
public int length;
public DownThread(int startPos, int currentPartSize, RandomAccessFile currentPart) {
this.startPos = startPos;
this.currentPartSize = currentPartSize;
this.currentPart = currentPart;
}
public void run() {
try {
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(5 * 1000);
conn.setRequestMethod("GET");
conn.setRequestProperty("Accept",
"image/gif,image/jpeg,image/pjpeg,image/pjpeg,"
+ "applicaton/x-shockwave-flash,application/xaml+xml,"
+ "spplication/vnd.ms-xpsdocument,application/x-ms-xbap,"
+ "application/x-ms-application,application/vnd.ms-excel,"
+ "appplication/vnd.ms-powerpoint,application/mswerd,*/*");
conn.setRequestProperty("Accept-Language", "zh-CN");
conn.setRequestProperty("Charset", "UTF-8");
java.io.InputStream inStream = conn.getInputStream();
inStream.skip(this.startPos);
byte[] buffer = new byte[1024];
int hasRead = 0;
while (length < currentPartSize && (hasRead = inStream.read(buffer)) != -1)
;
{
currentPart.write(buffer, 0, hasRead);
length += hasRead;
currentPart.close();
inStream.close();
}
} catch (Exception e) {
e.printStackTrace();
}
};
}
}
public static class MultiThreadDown {
public static void main(String[] args) throws Exception {
final DownUtil downUtil = new DownUtil(
"http://www.crazyit.org/" + "attachments/month_1403/1403202355ff6cc9a4fbf6f14a.png", "ios.png", 4);
downUtil.download();
new Thread(() -> {
while (downUtil.getCompleteRate() < 1) {
System.out.println("已完成:" + downUtil.getCompleteRate());
try {
Thread.sleep(1000);
} catch (Exception ex) {
}
}
}).start();
}
}
}