HttpURLConnection实现文件断点续传

首先

client端：

[java] view plain copy print?

1. HttpURLConnection conn = null;  
2.         BufferedInputStream fin = null;  
3.         BufferedOutputStream out = null;  
4.         URL reqUrl;  
5.         try {  
6.             reqUrl = new URL("http://<ip>:<port>/Emergency/phone/attachmentUpload");  
7.             conn = (HttpURLConnection) reqUrl.openConnection();  
8.             conn.setConnectTimeout(3000);  
9.             conn.setRequestMethod("PUT");  
10.             if(isCommit){  
11.                 conn.setRequestProperty("isCommit", "true");  
12.             }else{  
13.                 conn.setRequestProperty("isCommit", "false");  
14.             }  
15.             conn.setRequestMethod("PUT");  
16.             conn.setRequestProperty("Content-Type", "binary/octet-stream");  
17.             conn.setRequestProperty("offset", StringUtil.toString(offset));  
18.             conn.setDoOutput(true);  
19.             conn.setDoInput(true);  
20.             // 1M的chunk缓冲  
21.             conn.setChunkedStreamingMode(1024*1024);  
22.             out = new BufferedOutputStream(conn.getOutputStream());  
23.             fin = new BufferedInputStream(new FileInputStream(file));  
24.             byte[] buf = new byte[bufferSizeUpload];  
25.             int len = -1;  
26.             long currentUploadSize = offset;  
27.             fin.skip(offset);  
28.             while ((len = fin.read(buf)) != -1&currentUploadSize<offset+uploadSize) {  
29.                 if(offset+uploadSize-currentUploadSize<bufferSizeUpload){  
30.                     len = Integer.parseInt(StringUtil.toString(offset+uploadSize-currentUploadSize));  
31.                 }  
32.                 if(len>0){  
33.                     if(out!=null){  
34.                         out.write(buf, 0, len);  
35.                         out.flush();  
36.                     }  
37.                 }  
38.                 currentUploadSize += len;  
39.             }  
40.         } catch (SocketTimeoutException e) {  
41.             e.printStackTrace();  
42.         } catch(IOException e){  
43.             e.printStackTrace();  
44.         } finally {  
45.             try {  
46.                 if (fin != null) {  
47.                     fin.close();  
48.                     fin = null;  
49.                 }  
50.                 if (out != null) {  
51.                     out.close();  
52.                     out = null;  
53.                 }  
54.                 if (conn != null) {  
55.                     conn.disconnect();  
56.                     conn = null;  
57.                 }  
58.             } catch (IOException ioe) {  
59.                 ioe.printStackTrace();  
60.                 throw new RuntimeException("Release resource failed.");  
61.             }  
62.         }  

HttpURLConnection conn = null;BufferedInputStream fin = null;BufferedOutputStream out = null;URL reqUrl;try {reqUrl = new URL("http://<ip>:<port>/Emergency/phone/attachmentUpload");conn = (HttpURLConnection) reqUrl.openConnection();conn.setConnectTimeout(3000);conn.setRequestMethod("PUT");if(isCommit){conn.setRequestProperty("isCommit", "true");}else{conn.setRequestProperty("isCommit", "false");}conn.setRequestMethod("PUT");conn.setRequestProperty("Content-Type", "binary/octet-stream");conn.setRequestProperty("offset", StringUtil.toString(offset));conn.setDoOutput(true);conn.setDoInput(true);// 1M的chunk缓冲conn.setChunkedStreamingMode(1024*1024);out = new BufferedOutputStream(conn.getOutputStream());fin = new BufferedInputStream(new FileInputStream(file));byte[] buf = new byte[bufferSizeUpload];int len = -1;long currentUploadSize = offset;fin.skip(offset);while ((len = fin.read(buf)) != -1&currentUploadSize<offset+uploadSize) {if(offset+uploadSize-currentUploadSize<bufferSizeUpload){len = Integer.parseInt(StringUtil.toString(offset+uploadSize-currentUploadSize));}if(len>0){if(out!=null){out.write(buf, 0, len);out.flush();}}currentUploadSize += len;}} catch (SocketTimeoutException e) {e.printStackTrace();} catch(IOException e){e.printStackTrace();} finally {try {if (fin != null) {fin.close();fin = null;}if (out != null) {out.close();out = null;}if (conn != null) {conn.disconnect();conn = null;}} catch (IOException ioe) {ioe.printStackTrace();throw new RuntimeException("Release resource failed.");}}

如上所示：url参数通过setRequestProperty方法放在请求头中 ，而文件流放在 body 中。

同时需要注意 HttpURLConnection.setChunkedStreamingMode 此方法保证每次文件流达到指定大小就发送一次，避免了放在缓存并一次性传输中可能遇到的数据缺失。

http://blog.csdn.net/z69183787/article/details/8186918 可参考

服务端：

[java] view plain copy print?

1. public String underUpload() throws IOException{  
2.         String data = request.getHeader("data");   
3.         String userInfo = request.getHeader("userInfo");   
4.         userInfo = new String(userInfo.getBytes("iso-8859-1"),"GBK");  
5.         //System.out.println(data);  
6.         //System.out.println(userInfo);  
7.         Map<String,String> data_map = gson.fromJson(data,attachVo.data_map.getClass());  
8.         if(data_map!=null) attachVo.data_map=data_map;  
9.         attachVo.user = gson.fromJson(userInfo,attachVo.user.getClass());  
10.         apiService.attachUpload(attachVo,new BufferedInputStream(request.getInputStream()));  
11.         //response.setStatus(200);  
12.         return null;  
13.     }  

public String underUpload() throws IOException{String data = request.getHeader("data"); String userInfo = request.getHeader("userInfo"); userInfo = new String(userInfo.getBytes("iso-8859-1"),"GBK");//System.out.println(data);//System.out.println(userInfo);Map<String,String> data_map = gson.fromJson(data,attachVo.data_map.getClass());if(data_map!=null) attachVo.data_map=data_map;attachVo.user = gson.fromJson(userInfo,attachVo.user.getClass());apiService.attachUpload(attachVo,new BufferedInputStream(request.getInputStream()));//response.setStatus(200);return null;}

使用的是ssh架构 ，通过getHeader 得到 url参数，通过getInputStream得到文件流，同时还要控制好编码，以防中文乱码。

至于断点续传，基本思想是通过信息头的部分 传递每次传输的文件大小，与服务器端的文件大小匹配。并通过

[java] view plain copy print?

1. RandomAccessFile raFile = new RandomAccessFile(uploadFile.getAbsolutePath(), "rw");  
2.         raFile.seek(uploadFile.length());  

RandomAccessFile raFile = new RandomAccessFile(uploadFile.getAbsolutePath(), "rw");raFile.seek(uploadFile.length());

方法进行根据传输大小实时进行文件读写。

[java] view plain copy print?

1. public static void saveFile(String destFilePathStr,String destFileName){  
2.         try {  
3.             File destFilePath = new File(destFilePathStr);  
4.             if(!destFilePath.exists()){  
5.                 destFilePath.mkdirs();  
6.                 destFilePath = null;  
7.             }  
8.             File destFile = new File(destFilePathStr+"//"+destFileName);  
9.             if(!destFile.exists()){  
10.                 destFile.createNewFile();  
11.             }  
12.       
13.         } catch (Exception e) {  
14.             e.printStackTrace();  
15.         }  
16.     }  
17.       
18.     public static long uploadFile(String offset,String destFileName,BufferedInputStream bis)   
19.     throws IOException{  
20.         File uploadFile = new File(destFileName);  
21.         int len = 0;  
22.         byte[] bt = new byte[1024];  
23.         RandomAccessFile raFile = new RandomAccessFile(uploadFile.getAbsolutePath(), "rw");  
24.         raFile.seek(uploadFile.length());  
25.         while ((len = bis.read(bt)) > 0){  
26.             raFile.write(bt, 0, len);  
27.         }  
28.         long l = raFile.length();  
29.         try {  
30.              if(bis != null)  
31.                  bis.close();  
32.              if (raFile != null)  
33.                  raFile.close();  
34.                
35.         } catch (IOException e) {  
36.             l = 0;  
37.             e.printStackTrace();  
38.         }  
39.         return l ;  
40.     }  

public static void saveFile(String destFilePathStr,String destFileName){try {File destFilePath = new File(destFilePathStr);if(!destFilePath.exists()){destFilePath.mkdirs();destFilePath = null;}File destFile = new File(destFilePathStr+"//"+destFileName);if(!destFile.exists()){destFile.createNewFile();}} catch (Exception e) {e.printStackTrace();}}public static long uploadFile(String offset,String destFileName,BufferedInputStream bis) throws IOException{File uploadFile = new File(destFileName);int len = 0;byte[] bt = new byte[1024];RandomAccessFile raFile = new RandomAccessFile(uploadFile.getAbsolutePath(), "rw");raFile.seek(uploadFile.length());    while ((len = bis.read(bt)) > 0){    raFile.write(bt, 0, len);    }    long l = raFile.length();    try {     if(bis != null)     bis.close();     if (raFile != null)     raFile.close();     } catch (IOException e) {l = 0;    e.printStackTrace();}return l ;}

首先创建一个空文件，接下来根据每次接收的文件流及文件长度 写入文件。