无法从Dropbox的下载文件 [英] cannot download file from dropbox
本文介绍了无法从Dropbox的下载文件的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我上传和下载Dropbox的从一个文件中。当我上传的文件是正确上传的。当我下载一个文件并打开它，该文件是零字节。谁能告诉我，为什么发生这种情况？ 下载code：
尝试{
文件localFile =新的文件（localFilePath）;
文件fileSelected =新的文件（dropboxPath）;
如果（！localFile.exists（））{
localFile.createNewFile（）;
} 其他 {
//拷贝（fileSelected，localFile）;
//mApi.copy("/Test/test.png，/sdcard/testfile.png）;
的BufferedInputStream BR = NULL;
的BufferedOutputStream体重= NULL;
DropboxInputStream的fd;
尝试 {
FD = mApi.getFileStream（fileSelected.getPath（），NULL）;
BR =新的BufferedInputStream（FD）;
体重=新的BufferedOutputStream（新的FileOutputStream（localFile））;
byte []的缓冲区=新的字节[4096];
INT读取;
而（真）{
读= br.read（缓冲区）;
如果（读＆LT; = 0）{
打破;
}
bw.write（缓冲，0，读）;
}
}赶上（DropboxException E）{
e.printStackTrace（）;
}赶上（FileNotFoundException异常E）{
// TODO自动生成的catch块
e.printStackTrace（）;
}赶上（IOException异常E）{
e.printStackTrace（）;
} 最后 {
如果（BW！= NULL）{
尝试 {
bw.close（）;
如果（BR！= NULL）{
br.close（）;
}
}赶上（IOException异常E）{
e.printStackTrace（）;
}
}
}
} / *
其他 {
showToast（文件已存在）;
} * /
}
赶上（IOException异常E）{
showToast（异常）;
e.printStackTrace（）;
}
赶上（例外五）{
showToast（异常）;
e.printStackTrace（）;
}
解决方案
/ *
*版权所有（C）2010 - 11年度的Dropbox公司
*
*特此授权，免费的，任何人
*获得该软件副本及相关文档
*文件（软件），以处理本软件不
*限制，包括但不限于使用权，
*复制，修改，合并，发布，分发，再许可和/或出售
*拷贝软件，并允许个人向谁
*软件附有这样做，受到以下
*条件：
*
*以上版权声明和本许可通告
*包括在所有副本或实质性部分的软件。
*
*本软件按原样，没有任何形式的担保，
* EX $ P $干燥综合征或暗示，包括但不限于的担保
*适销性，适用于某种特定用途的
*不侵权。在任何情况下，作者或版权所有
*持有人承担任何索赔，损失或其他责任，
*无论是因执行合同，侵权还是其他原因，
* FROM，淘汰或与本软件或使用，或
*在软件的其他交易。
* /
包codelynks.easydropbox;
进口android.app.ProgressDialog;
进口android.content.Context;
进口android.content.DialogInterface;
进口android.content.DialogInterface.OnClickListener;
进口android.graphics.drawable.Drawable;
进口android.os.AsyncTask;
进口android.widget.Toast;
进口com.dropbox.client2.DropboxAPI;
进口com.dropbox.client2.DropboxAPI.Entry;
进口com.dropbox.client2.ProgressListener;
进口com.dropbox.client2.exception.DropboxException;
进口com.dropbox.client2.exception.DropboxIOException;
进口com.dropbox.client2.exception.DropboxParseException;
进口com.dropbox.client2.exception.DropboxPartialFileException;
进口com.dropbox.client2.exception.DropboxServerException;
进口com.dropbox.client2.exception.DropboxUnlinkedException;
进口java.io.FileNotFoundException;
进口java.io.FileOutputStream中;
进口java.io.IOException异常;
/ **
*在这里我们得到的元数据目录和下载文件的
*后台线程，试图表现出典型的异常处理和流量
*控制一个应用程序，从下载Dropbox的文件。
* /
公共类下载扩展的AsyncTask＆LT;虚空龙，布尔＆GT; {
私人语境mContext;
私人最终ProgressDialog mDialog;
私人DropboxAPI＆LT;＆GT; MAPI;
私人字符串的mpath;
私人绘制对象mDrawable;
私人的FileOutputStream mFos;
私人布尔mCanceled;
私人龙mFileLen;
私人字符串mErrorMsg;
私人字符串mDownloadpath;
//注意，由于我们使用一个单一的文件名这里为了简单起见，就
//将无法使用此code两个同时下载。
私人最终静态字符串映像文件=dbroulette.png;
公共下载（上下文的背景下，DropboxAPI＆LT;＆GT; API，
字符串dropboxPath，字符串downloadpath）{
//我们设置的背景下这种方式使我们不小心泄露活动
mContext = context.getApplicationContext（）;
MAPI = API;
的mpath = dropboxPath;
mDownloadpath = downloadpath;
mDialog =新ProgressDialog（上下文）;
mDialog.setMax（100）;
mDialog.setMessage（下载文件）;
mDialog.setProgressStyle（ProgressDialog.STYLE_HORIZONTAL）;
mDialog.setProgress（0）;
mDialog.setButton（ProgressDialog.BUTTON_POSITIVE，取消，新OnClickListener（）{
公共无效的onClick（DialogInterface对话，诠释它）{
mCanceled = TRUE;
mErrorMsg =取消;
//这将通过关闭取消getThumbnail操作
//其流
如果（mFos！= NULL）{
尝试 {
mFos.close（）;
}赶上（IOException异常E）{
}
}
}
}）;
mDialog.show（）;
mDialog.setCanceledOnTouchOutside（假）;
}
@覆盖
保护布尔doInBackground（空... PARAMS）{
尝试 {
如果（mCanceled）{
返回false;
}
//获取元数据目录
项的dirent = mApi.metadata（的mpath，1000，空，真，空）;
如果（dirent.isDir）{
//这不是一个目录，或者有没有在这
mErrorMsg =目录不能下载;
返回false;
}
如果（mCanceled）{
返回false;
}
尝试 {
mFos =新的FileOutputStream（mDownloadpath）;
}赶上（FileNotFoundException异常E）{
mErrorMsg =无法创建本地文件存储图像;
返回false;
}
mApi.getFile（的mpath，空，mFos，新ProgressListener（）{
@覆盖
众长progressInterval（）{
返回500;
}
@覆盖
公共无效onProgress（长为arg0，长ARG1）{
mFileLen = ARG1; //文件总长度
publishProgress（将arg0）; //下载的文件长度
}
}）;
如果（mCanceled）{
返回false;
}
//我们必须有一个合法的图片
返回true;
}赶上（DropboxUnlinkedException E）{
//该AuthSession未正确验证或用户未链接。
}赶上（DropboxPartialFileException E）{
//我们取消了操作
mErrorMsg =下载已取消;
}赶上（DropboxServerException E）{
//服务器端异常。这些都是会发生什么的例子，
//但是我们不与他们在这里做什么特别的。
如果（e.error == DropboxServerException._304_NOT_MODIFIED）{
//不会发生，因为我们不通过修订中的元数据
}否则，如果（e.error == DropboxServerException._401_UNAUTHORIZED）{
//未经授权的，所以我们应该取消它们的链接。您可能要
//自动注销用户在这种情况下。
}否则，如果（e.error == DropboxServerException._403_FORBIDDEN）{
//不允许访问此
}否则，如果（e.error == DropboxServerException._404_NOT_FOUND）{
//路径未找到（或如果它是缩略图，不能
//缩略图）
}否则，如果（e.error == DropboxServerException._406_NOT_ACCEPTABLE）{
//太多的条目返回
}否则，如果（e.error == DropboxServerException._415_UNSUPPORTED_MEDIA）{
//不能缩略
}否则，如果（e.error == DropboxServerException._507_INSUFFICIENT_STORAGE）{
// 用户超出配额
} 其他 {
//别的东西
}
//这得到了Dropbox的错误，翻译成用户的语言
mErrorMsg = e.body.userError;
如果（mErrorMsg == NULL）{
mErrorMsg = e.body.error;
}
}赶上（DropboxIOException E）{
//发生的时间，可能要自动重试。
mErrorMsg =网络错误重试。;
}赶上（DropboxParseException E）{
//可能是由于Dropbox的服务器重新启动后，应重试
mErrorMsg =。Dropbox的错误重试。;
}赶上（DropboxException E）{
// 未知错误
mErrorMsg =未知错误重试。;
}
返回false;
}
@覆盖
保护无效onProgressUpdate（长...进度）{
INT百分比=（INT）（100.0 *（双）进展[0] / mFileLen + 0.5）;
mDialog.setProgress（百分比）;
}
@覆盖
保护无效onPostExecute（布尔结果）{
mDialog.dismiss（）;
如果（结果）{
showToast（下载完成）;
//现在我们把它设置图像
//mView.setImageDrawable(mDrawable）;
} 其他 {
//无法下载它，所以显示错误
showToast（mErrorMsg）;
}
}
私人无效showToast（弦乐味精）{
吐司错误= Toast.makeText（mContext，味精，Toast.LENGTH_LONG）;
error.show（）;
}
}
通话一样跟着后台线程
下载=新的下载（背景下，马皮，drop_box_file_path，sdcard_path_to_store）;
download.execute（）;
其中，MAPI是DropboxAPI参考
I am uploading and downloading a file from dropbox. when I upload a file it uploads it correctly. when I download a file and open it, the file is zero bytes. can someone tell me why this is happening? download code:
try{
File localFile = new File(localFilePath);
File fileSelected = new File(dropboxPath);
if (!localFile.exists()) {
localFile.createNewFile();
} else {
//copy(fileSelected, localFile);
//mApi.copy("/Test/test.png", "/sdcard/testfile.png");
BufferedInputStream br = null;
BufferedOutputStream bw = null;
DropboxInputStream fd;
try {
fd = mApi.getFileStream(fileSelected.getPath(), null);
br = new BufferedInputStream(fd);
bw = new BufferedOutputStream(new FileOutputStream(localFile));
byte[] buffer = new byte[4096];
int read;
while (true) {
read = br.read(buffer);
if (read <= 0) {
break;
}
bw.write(buffer, 0, read);
}
} catch (DropboxException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (bw != null) {
try {
bw.close();
if (br != null) {
br.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}/*
else {
showToast("File already exists");
}*/
}
catch (IOException e) {
showToast("Exception");
e.printStackTrace();
}
catch (Exception e) {
showToast("Exception");
e.printStackTrace();
}
解决方案
/*
* Copyright (c) 2010-11 Dropbox, Inc.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
package codelynks.easydropbox;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.graphics.drawable.Drawable;
import android.os.AsyncTask;
import android.widget.Toast;
import com.dropbox.client2.DropboxAPI;
import com.dropbox.client2.DropboxAPI.Entry;
import com.dropbox.client2.ProgressListener;
import com.dropbox.client2.exception.DropboxException;
import com.dropbox.client2.exception.DropboxIOException;
import com.dropbox.client2.exception.DropboxParseException;
import com.dropbox.client2.exception.DropboxPartialFileException;
import com.dropbox.client2.exception.DropboxServerException;
import com.dropbox.client2.exception.DropboxUnlinkedException;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
/**
* Here we show getting metadata for a directory and downloading a file in a
* background thread, trying to show typical exception handling and flow of
* control for an app that downloads a file from Dropbox.
*/
public class Download extends AsyncTask<Void, Long, Boolean> {
private Context mContext;
private final ProgressDialog mDialog;
private DropboxAPI<?> mApi;
private String mPath;
private Drawable mDrawable;
private FileOutputStream mFos;
private boolean mCanceled;
private Long mFileLen;
private String mErrorMsg;
private String mDownloadpath;
// Note that, since we use a single file name here for simplicity, you
// won't be able to use this code for two simultaneous downloads.
private final static String IMAGE_FILE_NAME = "dbroulette.png";
public Download(Context context, DropboxAPI<?> api,
String dropboxPath, String downloadpath) {
// We set the context this way so we don't accidentally leak activities
mContext = context.getApplicationContext();
mApi = api;
mPath = dropboxPath;
mDownloadpath = downloadpath;
mDialog = new ProgressDialog(context);
mDialog.setMax(100);
mDialog.setMessage("Downloading File");
mDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
mDialog.setProgress(0);
mDialog.setButton(ProgressDialog.BUTTON_POSITIVE, "Cancel", new OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
mCanceled = true;
mErrorMsg = "Canceled";
// This will cancel the getThumbnail operation by closing
// its stream
if (mFos != null) {
try {
mFos.close();
} catch (IOException e) {
}
}
}
});
mDialog.show();
mDialog.setCanceledOnTouchOutside(false);
}
@Override
protected Boolean doInBackground(Void... params) {
try {
if (mCanceled) {
return false;
}
// Get the metadata for a directory
Entry dirent = mApi.metadata(mPath, 1000, null, true, null);
if (dirent.isDir) {
// It's not a directory, or there's nothing in it
mErrorMsg = "Directory Can't be download";
return false;
}
if (mCanceled) {
return false;
}
try {
mFos = new FileOutputStream(mDownloadpath);
} catch (FileNotFoundException e) {
mErrorMsg = "Couldn't create a local file to store the image";
return false;
}
mApi.getFile(mPath, null, mFos, new ProgressListener() {
@Override
public long progressInterval() {
return 500;
}
@Override
public void onProgress(long arg0, long arg1) {
mFileLen = arg1;//Total File Length
publishProgress(arg0);//Downloaded File Length
}
});
if (mCanceled) {
return false;
}
// We must have a legitimate picture
return true;
} catch (DropboxUnlinkedException e) {
// The AuthSession wasn't properly authenticated or user unlinked.
} catch (DropboxPartialFileException e) {
// We canceled the operation
mErrorMsg = "Download canceled";
} catch (DropboxServerException e) {
// Server-side exception. These are examples of what could happen,
// but we don't do anything special with them here.
if (e.error == DropboxServerException._304_NOT_MODIFIED) {
// won't happen since we don't pass in revision with metadata
} else if (e.error == DropboxServerException._401_UNAUTHORIZED) {
// Unauthorized, so we should unlink them. You may want to
// automatically log the user out in this case.
} else if (e.error == DropboxServerException._403_FORBIDDEN) {
// Not allowed to access this
} else if (e.error == DropboxServerException._404_NOT_FOUND) {
// path not found (or if it was the thumbnail, can't be
// thumbnailed)
} else if (e.error == DropboxServerException._406_NOT_ACCEPTABLE) {
// too many entries to return
} else if (e.error == DropboxServerException._415_UNSUPPORTED_MEDIA) {
// can't be thumbnailed
} else if (e.error == DropboxServerException._507_INSUFFICIENT_STORAGE) {
// user is over quota
} else {
// Something else
}
// This gets the Dropbox error, translated into the user's language
mErrorMsg = e.body.userError;
if (mErrorMsg == null) {
mErrorMsg = e.body.error;
}
} catch (DropboxIOException e) {
// Happens all the time, probably want to retry automatically.
mErrorMsg = "Network error. Try again.";
} catch (DropboxParseException e) {
// Probably due to Dropbox server restarting, should retry
mErrorMsg = "Dropbox error. Try again.";
} catch (DropboxException e) {
// Unknown error
mErrorMsg = "Unknown error. Try again.";
}
return false;
}
@Override
protected void onProgressUpdate(Long... progress) {
int percent = (int) (100.0 * (double) progress[0] / mFileLen + 0.5);
mDialog.setProgress(percent);
}
@Override
protected void onPostExecute(Boolean result) {
mDialog.dismiss();
if (result) {
showToast("Downloading Finished");
// Set the image now that we have it
//mView.setImageDrawable(mDrawable);
} else {
// Couldn't download it, so show an error
showToast(mErrorMsg);
}
}
private void showToast(String msg) {
Toast error = Toast.makeText(mContext, msg, Toast.LENGTH_LONG);
error.show();
}
}
Call the background thread like followed
Download download = new Download(context, mApi, drop_box_file_path, sdcard_path_to_store);
download.execute();
Where, mApi is the reference of DropboxAPI
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