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斷點(diǎn)續(xù)傳和下載原理分析用法
文章來(lái)源：365jz.com 點(diǎn)擊數(shù)：499 更新時(shí)間：2018-10-27 10:26 參與評(píng)論
斷點(diǎn)續(xù)傳：指的是在上傳/下載時(shí)，將任務(wù)（一個(gè)文件或壓縮包）人為的劃分為幾個(gè)部分，每一個(gè)部分采用一個(gè)線程進(jìn)行上傳/下載，如果碰到網(wǎng)絡(luò)故障，可以從已經(jīng)上傳/下載的部分開始繼續(xù)上傳/下載未完成的部分，而沒(méi)有必要從頭開始上傳/下載?？梢怨?jié)省時(shí)間，提高速度。
斷點(diǎn)續(xù)傳和斷點(diǎn)下載都是用的RandomAccessFile, 它具有移動(dòng)指定的文件大小的位置的功能seek 。
斷點(diǎn)續(xù)傳的用途
有時(shí)用戶上傳/下載文件需要?dú)v時(shí)數(shù)小時(shí)，萬(wàn)一線路中斷，不具備斷點(diǎn)續(xù)傳的 HTTP/FTP 服務(wù)器或下載軟件就只能從頭重傳，比較好的 HTTP/FTP 服務(wù)器或下載軟件具有斷點(diǎn)續(xù)傳能力，允許用戶從上傳/下載斷線的地方繼續(xù)傳送，這樣大大減少了用戶的煩惱。
常見的支持?jǐn)帱c(diǎn)續(xù)傳的上傳/下載軟件：QQ 旋風(fēng)、迅雷、快車、電驢、酷6、土豆、優(yōu)酷、百度視頻、新浪視頻、騰訊視頻、百度云等。
在 Linux/Unix 系統(tǒng)下，常用支持?jǐn)帱c(diǎn)續(xù)傳的 FTP 客戶端軟件是 lftp。
斷點(diǎn)續(xù)傳是由服務(wù)器給客戶端一個(gè)已經(jīng)上傳的位置標(biāo)記position，然后客戶端再將文件指針移動(dòng)到相應(yīng)的position，通過(guò)輸入流將文件剩余部分讀出來(lái)傳輸給服務(wù)器
斷點(diǎn)下載 是由客戶端告訴服務(wù)器已經(jīng)下載的大小，然后服務(wù)器會(huì)將指針移動(dòng)到相應(yīng)的position，繼續(xù)讀出，把文件返回給客戶端。 當(dāng)然為了下載的更快一下，也可以多線程下載，那么基本實(shí)現(xiàn)就是給每個(gè)線程分配固定的字節(jié)的文件，分別去讀
下面是用自己編的一個(gè)"瀏覽器"來(lái)傳遞請(qǐng)求信息給 Web 服務(wù)器，要求從 2000070 字節(jié)開始。
GET /down.zip HTTP/1.0
User-Agent: NetFox
RANGE: bytes=2000070-
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
仔細(xì)看一下就會(huì)發(fā)現(xiàn)多了一行 RANGE: bytes=2000070-
這一行的意思就是告訴服務(wù)器 down.zip 這個(gè)文件從 2000070 字節(jié)開始傳，前面的字節(jié)不用傳了。
服務(wù)器收到這個(gè)請(qǐng)求以后，返回的信息如下：
206
Content-Length=106786028
Content-Range=bytes 2000070-106786027/106786028
Date=Mon, 30 Apr 2001 12:55:20 GMT
ETag=W/"02ca57e173c11:95b"
Content-Type=application/octet-stream
Server=Microsoft-IIS/5.0
Last-Modified=Mon, 30 Apr 2001 12:55:20 GMT
和前面服務(wù)器返回的信息比較一下，就會(huì)發(fā)現(xiàn)增加了一行：
Content-Range=bytes 2000070-106786027/106786028
返回的代碼也改為 206 了，而不再是 200 了。
知道了以上原理，就可以進(jìn)行斷點(diǎn)續(xù)傳的編程了。
首先是文件上傳，這個(gè)要用到服務(wù)器
關(guān)鍵代碼：
FileServer.java
Java代碼
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PushbackInputStream;
import java.io.RandomAccessFile;
import java.net.ServerSocket;
import java.net.Socket;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import util.FileLogInfo;
import util.StreamTool;
public class FileServer {
private ExecutorService executorService;//線程池
private int port;//監(jiān)聽端口
private boolean quit = false;//退出
private ServerSocket server;
private Map<Long, FileLogInfo> datas = new HashMap<Long, FileLogInfo>();//存放斷點(diǎn)數(shù)據(jù),以后改為數(shù)據(jù)庫(kù)存放
public FileServer(int port)
{
this.port = port;
//創(chuàng)建線程池，池中具有(cpu個(gè)數(shù)*50)條線程
executorService = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors() * 50);
}
/**
* 退出
*/
public void quit()
{
this.quit = true;
try
{
server.close();
}catch (IOException e)
{
e.printStackTrace();
}
}
/**
* 啟動(dòng)服務(wù)
* @throws Exception
*/
public void start() throws Exception
{
server = new ServerSocket(port);//實(shí)現(xiàn)端口監(jiān)聽
while(!quit)
{
try
{
Socket socket = server.accept();
executorService.execute(new SocketTask(socket));//為支持多用戶并發(fā)訪問(wèn)，采用線程池管理每一個(gè)用戶的連接請(qǐng)求
}catch (Exception e)
{
e.printStackTrace();
}
}
}
private final class SocketTask implements Runnable
{
private Socket socket = null;
public SocketTask(Socket socket)
{
this.socket = socket;
}
@Override
public void run()
{
try
{
System.out.println("FileServer accepted connection "+ socket.getInetAddress()+ ":"+ socket.getPort());
//得到客戶端發(fā)來(lái)的第一行協(xié)議數(shù)據(jù)：Content-Length=143253434;filename=xxx.3gp;sourceid=
//如果用戶初次上傳文件，sourceid的值為空。
InputStream inStream = socket.getInputStream();
String head = StreamTool.readLine(inStream);
System.out.println("FileServer head:"+head);
if(head!=null)
{
//下面從協(xié)議數(shù)據(jù)中提取各項(xiàng)參數(shù)值
String[] items = head.split(";");
String filelength = items[0].substring(items[0].indexOf("=")+1);
String filename = items[1].substring(items[1].indexOf("=")+1);
String sourceid = items[2].substring(items[2].indexOf("=")+1);
//生成資源id，如果需要唯一性，可以采用UUID
long id = System.currentTimeMillis();
FileLogInfo log = null;
if(sourceid!=null && !"".equals(sourceid))
{
id = Long.valueOf(sourceid);
//查找上傳的文件是否存在上傳記錄
log = find(id);
}
File file = null;
int position = 0;
//如果上傳的文件不存在上傳記錄,為文件添加跟蹤記錄
if(log==null)
{
//設(shè)置存放的位置與當(dāng)前應(yīng)用的位置有關(guān)
File dir = new File("c:/temp/");
if(!dir.exists()) dir.mkdirs();
file = new File(dir, filename);
//如果上傳的文件發(fā)生重名，然后進(jìn)行改名
if(file.exists())
{
filename = filename.substring(0, filename.indexOf(".")-1)+ dir.listFiles().length+ filename.substring(filename.indexOf("."));
file = new File(dir, filename);
}
save(id, file);
}
// 如果上傳的文件存在上傳記錄,讀取上次的斷點(diǎn)位置
else
{
System.out.println("FileServer have exits log not null");
//從上傳記錄中得到文件的路徑
file = new File(log.getPath());
if(file.exists())
{
File logFile = new File(file.getParentFile(), file.getName()+".log");
if(logFile.exists())
{
Properties properties = new Properties();
properties.load(new FileInputStream(logFile));
//讀取斷點(diǎn)位置
position = Integer.valueOf(properties.getProperty("length"));
}
}
}
//***************************上面是對(duì)協(xié)議頭的處理，下面正式接收數(shù)據(jù)***************************************
//向客戶端請(qǐng)求傳輸數(shù)據(jù)
OutputStream outStream = socket.getOutputStream();
String response = "sourceid="+ id+ ";position="+ position+ "%";
//服務(wù)器收到客戶端的請(qǐng)求信息后，給客戶端返回響應(yīng)信息：sourceid=1274773833264;position=position
//sourceid由服務(wù)生成，唯一標(biāo)識(shí)上傳的文件，position指示客戶端從文件的什么位置開始上傳
outStream.write(response.getBytes());
RandomAccessFile fileOutStream = new RandomAccessFile(file, "rwd");
//設(shè)置文件長(zhǎng)度
if(position==0) fileOutStream.setLength(Integer.valueOf(filelength));
//移動(dòng)文件指定的位置開始寫入數(shù)據(jù)
fileOutStream.seek(position);
byte[] buffer = new byte[1024];
int len = -1;
int length = position;
//從輸入流中讀取數(shù)據(jù)寫入到文件中，并將已經(jīng)傳入的文件長(zhǎng)度寫入配置文件，實(shí)時(shí)記錄文件的最后保存位置
while( (len=inStream.read(buffer)) != -1)
{
fileOutStream.write(buffer, 0, len);
length += len;
Properties properties = new Properties();
properties.put("length", String.valueOf(length));
FileOutputStream logFile = new FileOutputStream(new File(file.getParentFile(), file.getName()+".log"));
//實(shí)時(shí)記錄文件的最后保存位置
properties.store(logFile, null);
logFile.close();
}
//如果長(zhǎng)傳長(zhǎng)度等于實(shí)際長(zhǎng)度則表示長(zhǎng)傳成功
if(length==fileOutStream.length()){
delete(id);
}
fileOutStream.close();
inStream.close();
outStream.close();
file = null;
}
}
catch (Exception e)
{
e.printStackTrace();
}
finally{
try
{
if(socket!=null && !socket.isClosed()) socket.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
}
/**
* 查找在記錄中是否有sourceid的文件
* @param sourceid
* @return
*/
public FileLogInfo find(Long sourceid)
{
return datas.get(sourceid);
}
/**
* 保存上傳記錄，日后可以改成通過(guò)數(shù)據(jù)庫(kù)存放
* @param id
* @param saveFile
*/
public void save(Long id, File saveFile)
{
System.out.println("save logfile "+id);
datas.put(id, new FileLogInfo(id, saveFile.getAbsolutePath()));
}
/**
* 當(dāng)文件上傳完畢，刪除記錄
* @param sourceid
*/
public void delete(long sourceid)
{
System.out.println("delete logfile "+sourceid);
if(datas.containsKey(sourceid)) datas.remove(sourceid);
}
}由于在上面的流程圖中已經(jīng)進(jìn)行了詳細(xì)的分析，我在這兒就不講了，只是在存儲(chǔ)數(shù)據(jù)的時(shí)候服務(wù)器沒(méi)有用數(shù)據(jù)庫(kù)去存儲(chǔ)，這兒只是為了方便，所以要想測(cè)試斷點(diǎn)上傳，服務(wù)器是不能停的，否則數(shù)據(jù)就沒(méi)有了，在以后改進(jìn)的時(shí)候應(yīng)該用數(shù)據(jù)庫(kù)去存儲(chǔ)數(shù)據(jù)。
文件上傳客戶端：
關(guān)鍵代碼：
UploadActivity.java
Java代碼
package com.hao;
import java.io.File;
import java.util.List;
import com.hao.upload.UploadThread;
import com.hao.upload.UploadThread.UploadProgressListener;
import com.hao.util.ConstantValues;
import com.hao.util.FileBrowserActivity;
import android.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.res.Resources;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
/**
*
* @author Administrator
*
*/
public class UploadActivity extends Activity implements OnClickListener{
private static final String TAG = "SiteFileFetchActivity";
private Button download, upload, select_file;
private TextView info;
private static final int PROGRESS_DIALOG = 0;
private ProgressDialog progressDialog;
private UploadThread uploadThread;
private String uploadFilePath = null;
private String fileName;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.upload);
initView();
}
private void initView(){
download = (Button) findViewById(R.id.download);
download.setOnClickListener(this);
upload = (Button) findViewById(R.id.upload);
upload.setOnClickListener(this);
info = (TextView) findViewById(R.id.info);
select_file = (Button) findViewById(R.id.select_file);
select_file.setOnClickListener(this);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// TODO Auto-generated method stub
super.onActivityResult(requestCode, resultCode, data);
if (resultCode == RESULT_OK) {
if (requestCode == 1) {
Uri uri = data.getData(); // 接收用戶所選文件的路徑
info.setText("select: " + uri); // 在界面上顯示路徑
uploadFilePath = uri.getPath();
int last = uploadFilePath.lastIndexOf("/");
uploadFilePath = uri.getPath().substring(0, last+1);
fileName = uri.getLastPathSegment();
}
}
}
protected Dialog onCreateDialog(int id) {
switch(id) {
case PROGRESS_DIALOG:
progressDialog = new ProgressDialog(UploadActivity.this);
progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
progressDialog.setButton("暫停", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
uploadThread.closeLink();
dialog.dismiss();
}
});
progressDialog.setMessage("正在上傳...");
progressDialog.setMax(100);
return progressDialog;
default:
return null;
}
}
/**
* 使用Handler給創(chuàng)建他的線程發(fā)送消息，
* 匿名內(nèi)部類
*/
private Handler handler = new Handler()
{
@Override
public void handleMessage(Message msg)
{
//獲得上傳長(zhǎng)度的進(jìn)度
int length = msg.getData().getInt("size");
progressDialog.setProgress(length);
if(progressDialog.getProgress()==progressDialog.getMax())//上傳成功
{
progressDialog.dismiss();
Toast.makeText(UploadActivity.this, getResources().getString(R.string.upload_over), 1).show();
}
}
};
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Resources r = getResources();
switch(v.getId()){
case R.id.select_file:
Intent intent = new Intent();
//設(shè)置起始目錄和查找的類型
intent.setDataAndType(Uri.fromFile(new File("/sdcard")), "*/*");//"*/*"表示所有類型，設(shè)置起始文件夾和文件類型
intent.setClass(UploadActivity.this, FileBrowserActivity.class);
startActivityForResult(intent, 1);
break;
case R.id.download:
startActivity(new Intent(UploadActivity.this, SmartDownloadActivity.class));
break;
case R.id.upload:
if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED))//判斷SDCard是否存在
{
if(uploadFilePath == null){
Toast.makeText(UploadActivity.this, "還沒(méi)設(shè)置上傳文件", 1).show();
}
System.out.println("uploadFilePath:"+uploadFilePath+" "+fileName);
//取得SDCard的目錄
File uploadFile = new File(new File(uploadFilePath), fileName);
Log.i(TAG, "filePath:"+uploadFile.toString());
if(uploadFile.exists())
{
showDialog(PROGRESS_DIALOG);
info.setText(uploadFile+" "+ConstantValues.HOST+":"+ConstantValues.PORT);
progressDialog.setMax((int) uploadFile.length());//設(shè)置長(zhǎng)傳文件的最大刻度
uploadThread = new UploadThread(UploadActivity.this, uploadFile, ConstantValues.HOST, ConstantValues.PORT);
uploadThread.setListener(new UploadProgressListener() {
@Override
public void onUploadSize(int size) {
// TODO Auto-generated method stub
Message msg = new Message();
msg.getData().putInt("size", size);
handler.sendMessage(msg);
}
});
uploadThread.start();
}
else
{
Toast.makeText(UploadActivity.this, "文件不存在", 1).show();
}
}
else
{
Toast.makeText(UploadActivity.this, "SDCard不存在！", 1).show();
}
break;
}
}
}UploadThread.java
Java代碼
package com.hao.upload;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.RandomAccessFile;
import java.net.Socket;
import android.content.Context;
import android.util.Log;
import com.hao.db.UploadLogService;
import com.hao.util.StreamTool;
public class UploadThread extends Thread {
private static final String TAG = "UploadThread";
/*需要上傳文件的路徑*/
private File uploadFile;
/*上傳文件服務(wù)器的IP地址*/
private String dstName;
/*上傳服務(wù)器端口號(hào)*/
private int dstPort;
/*上傳socket鏈接*/
private Socket socket;
/*存儲(chǔ)上傳的數(shù)據(jù)庫(kù)*/
private UploadLogService logService;
private UploadProgressListener listener;
public UploadThread(Context context, File uploadFile, final String dstName,final int dstPort){
this.uploadFile = uploadFile;
this.dstName = dstName;
this.dstPort = dstPort;
logService = new UploadLogService(context);
}
public void setListener(UploadProgressListener listener) {
this.listener = listener;
}
/**
* 模擬斷開連接
*/
public void closeLink(){
try{
if(socket != null) socket.close();
}catch(IOException e){
e.printStackTrace();
Log.e(TAG, "close socket fail");
}
}
@Override
public void run() {
// TODO Auto-generated method stub
try {
// 判斷文件是否已有上傳記錄
String souceid = logService.getBindId(uploadFile);
// 構(gòu)造拼接協(xié)議
String head = "Content-Length=" + uploadFile.length()
+ ";filename=" + uploadFile.getName() + ";sourceid="
+ (souceid == null ? "" : souceid) + "%";
// 通過(guò)Socket取得輸出流
socket = new Socket(dstName, dstPort);
OutputStream outStream = socket.getOutputStream();
outStream.write(head.getBytes());
Log.i(TAG, "write to outStream");
InputStream inStream = socket.getInputStream();
// 獲取到字符流的id與位置
String response = StreamTool.readLine(inStream);
Log.i(TAG, "response:" + response);
String[] items = response.split(";");
String responseid = items[0].substring(items[0].indexOf("=") + 1);
String position = items[1].substring(items[1].indexOf("=") + 1);
// 代表原來(lái)沒(méi)有上傳過(guò)此文件，往數(shù)據(jù)庫(kù)添加一條綁定記錄
if (souceid == null) {
logService.save(responseid, uploadFile);
}
RandomAccessFile fileOutStream = new RandomAccessFile(uploadFile, "r");
// 查找上次傳送的最終位置，并從這開始傳送
fileOutStream.seek(Integer.valueOf(position));
byte[] buffer = new byte[1024];
int len = -1;
// 初始化上傳的數(shù)據(jù)長(zhǎng)度
int length = Integer.valueOf(position);
while ((len = fileOutStream.read(buffer)) != -1) {
outStream.write(buffer, 0, len);
// 設(shè)置長(zhǎng)傳數(shù)據(jù)長(zhǎng)度
length += len;
listener.onUploadSize(length);
}
fileOutStream.close();
outStream.close();
inStream.close();
socket.close();
// 判斷上傳完則刪除數(shù)據(jù)
if (length == uploadFile.length())
logService.delete(uploadFile);
} catch (Exception e) {
e.printStackTrace();
}
}
public interface UploadProgressListener{
void onUploadSize(int size);
}
}
下面是多線程下載
SmartDownloadActivity.java
Java代碼
package com.hao;
import java.io.File;
import com.hao.R;
import com.hao.R.id;
import com.hao.R.layout;
import com.hao.download.SmartFileDownloader;
import com.hao.download.SmartFileDownloader.SmartDownloadProgressListener;
import com.hao.util.ConstantValues;
import android.app.Activity;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
/**
*
* @author Administrator
*
*/
public class SmartDownloadActivity extends Activity {
private ProgressBar downloadbar;
private TextView resultView;
private String path = ConstantValues.DOWNLOAD_URL;
SmartFileDownloader loader;
private Handler handler = new Handler() {
@Override
// 信息
public void handleMessage(Message msg) {
switch (msg.what) {
case 1:
int size = msg.getData().getInt("size");
downloadbar.setProgress(size);
float result = (float) downloadbar.getProgress() / (float) downloadbar.getMax();
int p = (int) (result * 100);
resultView.setText(p + "%");
if (downloadbar.getProgress() == downloadbar.getMax())
Toast.makeText(SmartDownloadActivity.this, "下載成功", 1).show();
break;
case -1:
Toast.makeText(SmartDownloadActivity.this, msg.getData().getString("error"), 1).show();
break;
}
}
};
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.download);
Button button = (Button) this.findViewById(R.id.button);
Button closeConn = (Button) findViewById(R.id.closeConn);
closeConn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(loader != null){
finish();
}else{
Toast.makeText(SmartDownloadActivity.this, "還沒(méi)有開始下載，不能暫停", 1).show();
}
}
});
downloadbar = (ProgressBar) this.findViewById(R.id.downloadbar);
resultView = (TextView) this.findViewById(R.id.result);
resultView.setText(path);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
download(path, ConstantValues.FILE_PATH);
} else {
Toast.makeText(SmartDownloadActivity.this, "沒(méi)有SDCard", 1).show();
}
}
});
}
// 對(duì)于UI控件的更新只能由主線程(UI線程)負(fù)責(zé)，如果在非UI線程更新UI控件，更新的結(jié)果不會(huì)反映在屏幕上，某些控件還會(huì)出錯(cuò)
private void download(final String path, final File dir) {
new Thread(new Runnable() {
@Override
public void run() {
try {
loader = new SmartFileDownloader(SmartDownloadActivity.this, path, dir, 3);
int length = loader.getFileSize();// 獲取文件的長(zhǎng)度
downloadbar.setMax(length);
loader.download(new SmartDownloadProgressListener() {
@Override
public void onDownloadSize(int size) {// 可以實(shí)時(shí)得到文件下載的長(zhǎng)度
Message msg = new Message();
msg.what = 1;
msg.getData().putInt("size", size);
handler.sendMessage(msg);
}
});
} catch (Exception e) {
Message msg = new Message();// 信息提示
msg.what = -1;
msg.getData().putString("error", "下載失敗");// 如果下載錯(cuò)誤，顯示提示失??！
handler.sendMessage(msg);
}
}
}).start();// 開始
}
}這個(gè)單個(gè)的下載線程
SmartDownloadThread.java
Java代碼
package com.hao.download;
import java.io.File;
import java.io.InputStream;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;
import android.util.Log;
/**
* 線程下載
* @author Administrator
*
*/
public class SmartDownloadThread extends Thread {
private static final String TAG = "SmartDownloadThread";
private File saveFile;
private URL downUrl;
private int block;
/* *下載開始位置 */
private int threadId = -1;
private int downLength;
private boolean finish = false;
private SmartFileDownloader downloader;
public SmartDownloadThread(SmartFileDownloader downloader, URL downUrl,
File saveFile, int block, int downLength, int threadId) {
this.downUrl = downUrl;
this.saveFile = saveFile;
this.block = block;
this.downloader = downloader;
this.threadId = threadId;
this.downLength = downLength;
}
@Override
public void run() {
if (downLength < block) {// 未下載完成
try {
HttpURLConnection http = (HttpURLConnection) downUrl
.openConnection();
http.setConnectTimeout(5 * 1000);
http.setRequestMethod("GET");
http.setRequestProperty("Accept","image/gif, image/jpeg, image/pjpeg, image/pjpeg, application/x-shockwave-flash, 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, */*");
http.setRequestProperty("Accept-Language", "zh-CN");
http.setRequestProperty("Referer", downUrl.toString());
http.setRequestProperty("Charset", "UTF-8");
int startPos = block * (threadId - 1) + downLength;// 開始位置
int endPos = block * threadId - 1;// 結(jié)束位置
http.setRequestProperty("Range", "bytes=" + startPos + "-" + endPos);// 設(shè)置獲取實(shí)體數(shù)據(jù)的范圍
http.setRequestProperty("User-Agent","Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.2; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)");
http.setRequestProperty("Connection", "Keep-Alive");
InputStream inStream = http.getInputStream();
byte[] buffer = new byte[1024];
int offset = 0;
print("Thread " + this.threadId + " start download from position " + startPos);
RandomAccessFile threadfile = new RandomAccessFile(this.saveFile, "rwd");
threadfile.seek(startPos);
while ((offset = inStream.read(buffer, 0, 1024)) != -1) {
threadfile.write(buffer, 0, offset);
downLength += offset;
downloader.update(this.threadId, downLength);
downloader.saveLogFile();
downloader.append(offset);
}
threadfile.close();
inStream.close();
print("Thread " + this.threadId + " download finish");
this.finish = true;
} catch (Exception e) {
this.downLength = -1;
print("Thread " + this.threadId + ":" + e);
}
}
}
private static void print(String msg) {
Log.i(TAG, msg);
}
/**
* 下載是否完成
* @return
*/
public boolean isFinish() {
return finish;
}
/**
* 已經(jīng)下載的內(nèi)容大小
* @return 如果返回值為-1,代表下載失敗
*/
public long getDownLength() {
return downLength;
}
}總得下載線程
SmartFileDownloader.java
Java代碼
package com.hao.download;
import java.io.File;
import java.io.RandomAccessFile;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import com.hao.db.DownloadFileService;
import android.content.Context;
import android.util.Log;
/**
* 文件下載主程序
* @author Administrator
*
*/
public class SmartFileDownloader {
private static final String TAG = "SmartFileDownloader";
private Context context;
private DownloadFileService fileService;
/* 已下載文件長(zhǎng)度 */
private int downloadSize = 0;
/* 原始文件長(zhǎng)度 */
private int fileSize = 0;
/*原始文件名*/
private String fileName;
/* 線程數(shù) */
private SmartDownloadThread[] threads;
/* 本地保存文件 */
private File saveFile;
/* 緩存各線程下載的長(zhǎng)度 */
private Map<Integer, Integer> data = new ConcurrentHashMap<Integer, Integer>();
/* 每條線程下載的長(zhǎng)度 */
private int block;
/* 下載路徑 */
private String downloadUrl;
/**
* 獲取文件名
*/
public String getFileName(){
return this.fileName;
}
/**
* 獲取線程數(shù)
*/
public int getThreadSize() {
return threads.length;
}
/**
* 獲取文件大小
* @return
*/
public int getFileSize() {
return fileSize;
}
/**
* 累計(jì)已下載大小
* @param size
*/
protected synchronized void append(int size) {
downloadSize += size;
}
/**
* 更新指定線程最后下載的位置
* @param threadId 線程id
* @param pos 最后下載的位置
*/
protected void update(int threadId, int pos) {
this.data.put(threadId, pos);
}
/**
* 保存記錄文件
*/
protected synchronized void saveLogFile() {
this.fileService.update(this.downloadUrl, this.data);
}
/**
* 構(gòu)建文件下載器
* @param downloadUrl 下載路徑
* @param fileSaveDir 文件保存目錄
* @param threadNum 下載線程數(shù)
*/
public SmartFileDownloader(Context context, String downloadUrl,
File fileSaveDir, int threadNum) {
try {
this.context = context;
this.downloadUrl = downloadUrl;
fileService = new DownloadFileService(this.context);
URL url = new URL(this.downloadUrl);
if (!fileSaveDir.exists()) fileSaveDir.mkdirs();
this.threads = new SmartDownloadThread[threadNum];
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-flash, 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("Referer", downloadUrl);
conn.setRequestProperty("Charset", "UTF-8");
conn.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.2; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)");
conn.setRequestProperty("Connection", "Keep-Alive");
conn.connect();
printResponseHeader(conn);
if (conn.getResponseCode() == 200) {
this.fileSize = conn.getContentLength();// 根據(jù)響應(yīng)獲取文件大小
if (this.fileSize <= 0)
throw new RuntimeException("Unkown file size ");
fileName = getFileName(conn);
this.saveFile = new File(fileSaveDir, fileName);/* 保存文件 */
Map<Integer, Integer> logdata = fileService.getData(downloadUrl);
if (logdata.size() > 0) {
for (Map.Entry<Integer, Integer> entry : logdata.entrySet())
data.put(entry.getKey(), entry.getValue());
}
//劃分每個(gè)線程下載文件長(zhǎng)度
this.block = (this.fileSize % this.threads.length) == 0 ? this.fileSize / this.threads.length
: this.fileSize / this.threads.length + 1;
if (this.data.size() == this.threads.length) {
for (int i = 0; i < this.threads.length; i++) {
this.downloadSize += this.data.get(i + 1);
}
print("已經(jīng)下載的長(zhǎng)度" + this.downloadSize);
}
} else {
throw new RuntimeException("server no response ");
}
} catch (Exception e) {
print(e.toString());
throw new RuntimeException("don't connection this url");
}
}
/**
* 獲取文件名
*/
private String getFileName(HttpURLConnection conn) {
String filename = this.downloadUrl.substring(this.downloadUrl.lastIndexOf('/') + 1);//鏈接的最后一個(gè)/就是文件名
if (filename == null || "".equals(filename.trim())) {// 如果獲取不到文件名稱
for (int i = 0;; i++) {
String mine = conn.getHeaderField(i);
print("ConnHeader:"+mine+" ");
if (mine == null)
break;
if ("content-disposition".equals(conn.getHeaderFieldKey(i).toLowerCase())) {
Matcher m = Pattern.compile(".*filename=(.*)").matcher(mine.toLowerCase());
if (m.find())
return m.group(1);
}
}
filename = UUID.randomUUID() + ".tmp";// 默認(rèn)取一個(gè)文件名
}
return filename;
}
/**
* 開始下載文件
*
* @param listener
* 監(jiān)聽下載數(shù)量的變化,如果不需要了解實(shí)時(shí)下載的數(shù)量,可以設(shè)置為null
* @return 已下載文件大小
* @throws Exception
*/
public int download(SmartDownloadProgressListener listener)
throws Exception {
try {
RandomAccessFile randOut = new RandomAccessFile(this.saveFile, "rw");
if (this.fileSize > 0)
randOut.setLength(this.fileSize);
randOut.close();
URL url = new URL(this.downloadUrl);
if (this.data.size() != this.threads.length) {
this.data.clear();// 清除數(shù)據(jù)
for (int i = 0; i < this.threads.length; i++) {
this.data.put(i + 1, 0);
}
}
for (int i = 0; i < this.threads.length; i++) {
int downLength = this.data.get(i + 1);
if (downLength < this.block && this.downloadSize < this.fileSize) { // 該線程未完成下載時(shí),繼續(xù)下載
this.threads[i] = new SmartDownloadThread(this, url,
this.saveFile, this.block, this.data.get(i + 1), i + 1);
this.threads[i].setPriority(7);
this.threads[i].start();
} else {
this.threads[i] = null;
}
}
this.fileService.save(this.downloadUrl, this.data);
boolean notFinish = true;// 下載未完成
while (notFinish) {// 循環(huán)判斷是否下載完畢
Thread.sleep(900);
notFinish = false;// 假定下載完成
for (int i = 0; i < this.threads.length; i++) {
if (this.threads[i] != null && !this.threads[i].isFinish()) {
notFinish = true;// 下載沒(méi)有完成
if (this.threads[i].getDownLength() == -1) {// 如果下載失敗,再重新下載
this.threads[i] = new SmartDownloadThread(this,
url, this.saveFile, this.block, this.data.get(i + 1), i + 1);
this.threads[i].setPriority(7);
this.threads[i].start();
}
}
}
if (listener != null)
listener.onDownloadSize(this.downloadSize);
}
fileService.delete(this.downloadUrl);
} catch (Exception e) {
print(e.toString());
throw new Exception("file download fail");
}
return this.downloadSize;
}
/**
* 獲取Http響應(yīng)頭字段
*
* @param http
* @return
*/
public static Map<String, String> getHttpResponseHeader(
HttpURLConnection http) {
Map<String, String> header = new LinkedHashMap<String, String>();
for (int i = 0;; i++) {
String mine = http.getHeaderField(i);
if (mine == null)
break;
header.put(http.getHeaderFieldKey(i), mine);
}
return header;
}
/**
* 打印Http頭字段
*
* @param http
*/
public static void printResponseHeader(HttpURLConnection http) {
Map<String, String> header = getHttpResponseHeader(http);
for (Map.Entry<String, String> entry : header.entrySet()) {
String key = entry.getKey() != null ? entry.getKey() + ":" : "";
print(key + entry.getValue());
}
}
// 打印日志
private static void print(String msg) {
Log.i(TAG, msg);
}
public interface SmartDownloadProgressListener {
public void onDownloadSize(int size);
}
}如對(duì)本文有疑問(wèn)，請(qǐng)?zhí)峤坏浇涣髡搲?，廣大熱心網(wǎng)友會(huì)為你解答！！ 點(diǎn)擊進(jìn)入論壇
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