多執行緒下載時HTTP response code: 416 解決方案
阿新 • • 發佈:2019-02-03
今天用java寫的多執行緒下載報錯,找了很久,發現是第一次請求伺服器時響應碼正常,開啟多執行緒部分的響應碼為416,響應碼對應的意思可以去這裡看看點選開啟連結。主要意思就是public void setRequestProperty (String field, String newValue)出現了錯誤,設定的下載位元組範圍和訪問檔案大小有出入,要麼就是上面確認各個執行緒的下載範圍出現問題,要麼就是該語句沒用對。將之前的每個執行緒下載位元組範圍都打印出來發現沒問題。後來檢視setRequestProperty相關資料發現是setRequestProperty("Range", "bytes:" + threadStart + "-" + threadEnd)這裡出錯了,bytes後面應該是=號而不是:
附上沒有完成斷點下載的多執行緒下載程式碼.
(我用的是某馬的74期的視訊學習的,而他的程式碼用的是:卻可以執行,有點鬱悶,,還有他的getFileName()方法中獲取/的索引後沒有+1就擷取檔名得到的是/feiq.exe, 那也是錯誤的,後面執行時會報錯拒絕訪問)
package com.lyle.study; import java.io.File; import java.io.InputStream; import java.io.RandomAccessFile; import java.net.HttpURLConnection; import java.net.URL; public class UpDownload1 { public static String path = "http://192.168.56.1:8080/itheima74/feiq.exe"; public static int threadCount = 3; public static void main(String[] args) { try { URL url = new URL(path); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); connection.setConnectTimeout(1000 * 10); if (connection.getResponseCode() == 200) { long length = connection.getContentLength(); RandomAccessFile randomAccessFile = new RandomAccessFile(new File(getFileName()), "rw"); randomAccessFile.setLength(length); randomAccessFile.close(); long threadSize = length / threadCount; for (int i = 0; i < threadCount; i++) { int threadId = i; long threadStart = threadId * threadSize; long threadEnd = (threadId == threadCount - 1 ? length - 1 : (threadId + 1) * threadSize - 1); new DoThreadOpen(threadStart, threadEnd).start(); } } } catch (Exception e) { e.printStackTrace(); } } public static class DoThreadOpen extends Thread { private long threadStart; private long threadEnd; public DoThreadOpen(long threadStart, long threadEnd) { this.threadEnd = threadEnd; this.threadStart = threadStart; } @Override public void run() { try { URL url = new URL(path); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); connection.setRequestMethod("GET"); connection.setConnectTimeout(1000 * 10); connection.setRequestProperty("Range", "bytes=" + threadStart + "-" + threadEnd); int code = connection.getResponseCode(); if (code == 206) { InputStream inputStream = connection.getInputStream(); RandomAccessFile randomAccessFile = new RandomAccessFile( new File(getFileName()), "rw"); randomAccessFile.seek(threadStart); byte[] buffer = new byte[1024]; int len; while ((len = inputStream.read(buffer)) != -1) { randomAccessFile.write(buffer, 0, len); } inputStream.close(); randomAccessFile.close(); } } catch (Exception e) { e.printStackTrace(); } } } private static String getFileName() { return path.substring(path.lastIndexOf("/") + 1); } }