Android:从服务器下载文件无法解码流
我正在尝试使用android模拟器从服务器下载图像。似乎下载正常，但我无法获取下载的图像。我收到以下错误：Android:从服务器下载文件无法解码流,android,download,Android,Download,我正在尝试使用android模拟器从服务器下载图像。似乎下载正常，但我无法获取下载的图像。我收到以下错误： Unable to decode stream: java.io.FileNotFoundException: /storage/sdcard/downloadedfile.jpg: open failed: ENOENT (No such file or directory) 这是我使用的代码： public class DownloadActivity extends Activit
Unable to decode stream: java.io.FileNotFoundException: /storage/sdcard/downloadedfile.jpg: open failed: ENOENT (No such file or directory)
public class DownloadActivity extends Activity {
// button to show progress dialog
Button btnShowProgress;
// Progress Dialog
private ProgressDialog pDialog;
ImageView my_image;
// Progress dialog type (0 - for Horizontal progress bar)
public static final int progress_bar_type = 0;
// File url to to download
private static String file_url = `"http://10.0.2.2:8080/TestAndroid/DownloadServlet/Desert.jpg";`
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// show progress bar button
btnShowProgress = (Button) findViewById(R.id.btnProgressBar);
// Image view to show image after downloading
my_image = (ImageView) findViewById(R.id.my_image);
/**
* Show Progress bar click event
* */
btnShowProgress.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// starting new Async Task
new DownloadFileFromURL().execute(file_url);
}
});
}
/**
* Showing Dialog
* */
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case progress_bar_type: // we set this to 0
pDialog = new ProgressDialog(this);
pDialog.setMessage("Downloading file. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setMax(100);
pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
pDialog.setCancelable(true);
pDialog.show();
return pDialog;
default:
return null;
}
}
/**
* Background Async Task to download file
* */
class DownloadFileFromURL extends AsyncTask<String, String, String> {
/**
* Before starting background thread
* Show Progress Bar Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
showDialog(progress_bar_type);
}
/**
* Downloading file in background thread
* */
@Override
protected String doInBackground(String... f_url) {
int count;
try {
URL url = new URL(f_url[0]);
URLConnection conection = url.openConnection();
conection.connect();
// this will be useful so that you can show a tipical 0-100% progress bar
int lenghtOfFile = conection.getContentLength();
// download the file
InputStream input = new BufferedInputStream(url.openStream(), 8192);
// Output stream
// OutputStream output = new FileOutputStream("/sdcard/downloadedfile.jpg");
byte data[] = new byte[1024];
long total = 0;
long startTotalTime = System.currentTimeMillis();
long passedTime =0;
long previosTime=0;
while ((count = input.read(data)) != -1) {
total += count;
long endtTime = System.currentTimeMillis();
long passed;
passedTime =endtTime - startTotalTime;
// passed=passedTime -previosTime ;
// previosTime = passed ;
// publishing the progress....
// After this onProgressUpdate will be called
publishProgress(""+(int)((total*100)/lenghtOfFile));
Log.i("log_lenghtOfFile",lenghtOfFile+"" );
Log.i("log_total",total+"" );
Log.i("log_ourcentage",(int)((total*100)/lenghtOfFile)+"" );
Log.i("log_passed_time",passedTime +"" );
calculDebitdescendant( total, lenghtOfFile);
// Log.i("log_Debit",passedTime +"" );
// writing data to file
// output.write(data, 0, count);
}
long endTotalTime = System.currentTimeMillis();
Log.i("log_Total_passed_time",endTotalTime-startTotalTime +"" );
// flushing output
// output.flush();
// closing streams
// output.close();
input.close();
} catch (Exception e) {
Log.e("Error***: ", e.getMessage());
}
return null;
}
public void calculDebitdescendant(long bytesAvailable,long TotalSize){
long bytesAvailable1 = bytesAvailable;
long TotalSize1 = TotalSize;
Log.i("bytesAvailable",bytesAvailable1 +"fonction");
Log.i("log_ourcentage",(int)(((TotalSize1-bytesAvailable1 )*100)/TotalSize1 )+"% " );
}
/**
* Updating progress bar
* */
protected void onProgressUpdate(String... progress) {
// setting progress percentage
pDialog.setProgress(Integer.parseInt(progress[0]));
}
/**
* After completing background task
* Dismiss the progress dialog
* **/
@Override
protected void onPostExecute(String file_url) {
// dismiss the dialog after the file was downloaded
dismissDialog(progress_bar_type);
// Displaying downloaded image into image view
// Reading image path from sdcard
String imagePath = Environment.getExternalStorageDirectory().toString() + "/downloadedfile.jpg";
Log.i("imagePath", imagePath);
// setting downloaded into image view
my_image.setImageDrawable(Drawable.createFromPath(imagePath));
}
}
公共类下载活动扩展活动{
//显示进度对话框的按钮
按钮BTN显示进度；
//进度对话框
私人对话；
图像查看我的图像；
//进度对话框类型（0-用于水平进度条）
公共静态最终整数进度条类型=0；
//要下载的文件url
私有静态字符串文件_url=`”http://10.0.2.2:8080/TestAndroid/DownloadServlet/Desert.jpg";`
@凌驾
创建时的公共void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
//显示进度条按钮
btnShowProgress=（按钮）findViewById（R.id.btnProgressBar）；
//图像视图，用于在下载后显示图像
my_image=（ImageView）findViewById（R.id.my_image）；
/**
*显示进度条单击事件
* */
btnShowProgress.setOnClickListener（新视图.OnClickListener（）{
@凌驾
公共void onClick（视图v）{
//启动新的异步任务
新建DownloadFileFromURL（）.execute（文件url）；
}
});
}
/**
*显示对话框
* */
@凌驾
受保护的对话框onCreateDialog（int id）{
开关（id）{
案例进度条类型：//我们将其设置为0
pDialog=新建进度对话框（此对话框）；
setMessage（“正在下载文件，请稍候…”）；
pDialog.setUndeterminate（假）；
pDialog.setMax（100）；
pDialog.setProgressStyle（ProgressDialog.STYLE_水平）；
pDialog.setCancelable（真）；
pDialog.show（）；
返回pDialog；
违约：
返回null；
}
}
/**
*要下载文件的后台异步任务
* */
类DownloadFileFromURL扩展异步任务{
/**
*在启动后台线程之前
*显示进度条对话框
* */
@凌驾
受保护的void onPreExecute（）{
super.onPreExecute（）；
显示对话框（进度条类型）；
}
/**
*在后台线程中下载文件
* */
@凌驾
受保护的字符串doInBackground（字符串…f_url）{
整数计数；
试一试{
URL=新URL（f_URL[0]）；
URLConnection conconnection=url.openConnection（）；
conconnect.connect（）；
//这将非常有用，以便您可以显示典型的0-100%进度条
int lenghtOfFile=conconnect.getContentLength（）；
//下载该文件
InputStream输入=新的BufferedInputStream（url.openStream（），8192）；
//输出流
//OutputStream output=新文件OutputStream（“/sdcard/downloaddedfile.jpg”）；
字节数据[]=新字节[1024]；
长总计=0；
long startTotalTime=System.currentTimeMillis（）；
long passedTime=0；
长时间=0；
而（（计数=输入。读取（数据））！=-1）{
总数+=计数；
long-endtTime=System.currentTimeMillis（）；
早已过去；
passedTime=endtTime-startTotalTime；
//已通过=已通过时间-前置时间；
//previosTime=已通过；
//发布进度。。。。
//在此之后，将调用onProgressUpdate
出版进度（“+（int）（（总计*100）/长度文档））；
Log.i（“Log_lenghtOfFile”，lenghtOfFile+”）；
Log.i（“Log_total”，total+”）；
Log.i（“Log_ourcentage”，int）（（总计*100）/长办公室）+”）；
Log.i（“Log_passed_time”，passedTime+”）；
计算子代（总长度、长度）；
//Log.i（“Log_Debit”，passedTime+）；
//将数据写入文件
//输出.写入（数据，0，计数）；
}
long-endTotalTime=System.currentTimeMillis（）；
Log.i（“Log_Total_passed_time”，endTotalTime startTotalTime+”）；
//冲洗输出
//output.flush（）；
//合流
//output.close（）；
input.close（）；
}捕获（例外e）{
Log.e（“错误***：”，e.getMessage（））；
}
返回null；
}
public void calculdebitsubstant（长字节可用，长总大小）{
long bytesAvailable 1=字节数Available；
长TotalSize1=总尺寸；
Log.i（“bytesAvailable”，bytesAvailable1+“fonction”）；
Log.i（“Log_ourcentage”，（int）（（TotalSize1-bytesAvailable1）*100）/TotalSize1）+“%”；
}
/**
*更新进度条
* */
受保护的void onProgressUpdate（字符串…进度）{
//设置进度百分比
pDialog.setProgress（Integer.parseInt（progress[0]））；
}
/**
*完成后台任务后
*关闭进度对话框
* **/
@凌驾
受保护的void onPostExecute（字符串文件\u url）{
//下载文件后关闭对话框
解雇对话框（进度条类型）；
//在图像视图中显示下载的图像
//从SD卡读取图像路径
字符串imagePath=Environment.getExternalStorageDirectory（）.toString（）+“/downloadedfile.jpg”；
Log.i（“imagePath”，imagePath）；
//设置已下载到图像视图中
my_image.setImageDrawable（Drawable.createFromPath（imagePath））；
}
}
如果有人知道错误的来源，请告诉我。谢谢。我编辑了代码，我可以从服务器下载一张图片到模拟器的SD卡。我刚刚启用了写入功能（我将它们放在注释中）
公共类下载活动扩展活动{
//显示进度的按钮
public class DownloadActivity extends Activity {
// button to show progress dialog
Button btnShowProgress;
// Progress Dialog
private ProgressDialog pDialog;
ImageView my_image;
// Progress dialog type (0 - for Horizontal progress bar)
public static final int progress_bar_type = 0;
// File url to to download
// private static String file_url = "http://192.168.1.106:8080/TestAndroid/DownloadServlet/Desert.jpg";
private static String file_url = "http://10.0.2.2:8080/TestAndroid/DownloadServlet/Desert.jpg";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// show progress bar button
btnShowProgress = (Button) findViewById(R.id.btnProgressBar);
// Image view to show image after downloading
my_image = (ImageView) findViewById(R.id.my_image);
/**
* Show Progress bar click event
* */
btnShowProgress.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// starting new Async Task
new DownloadFileFromURL().execute(file_url);
}
});
}
/**
* Showing Dialog
* */
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case progress_bar_type: // we set this to 0
pDialog = new ProgressDialog(this);
pDialog.setMessage("Downloading file. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setMax(100);
pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
pDialog.setCancelable(true);
pDialog.show();
return pDialog;
default:
return null;
}
}
/**
* Background Async Task to download file
* */
class DownloadFileFromURL extends AsyncTask<String, String, String> {
/**
* Before starting background thread
* Show Progress Bar Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
showDialog(progress_bar_type);
}
/**
* Downloading file in background thread
* */
@Override
protected String doInBackground(String... f_url) {
int count;
try {
URL url = new URL(f_url[0]);
URLConnection conection = url.openConnection();
conection.connect();
// this will be useful so that you can show a tipical 0-100% progress bar
int lenghtOfFile = conection.getContentLength();
// download the file
InputStream input = new BufferedInputStream(url.openStream(), 8192);
// Output stream
OutputStream output = new FileOutputStream("/sdcard/downloadedfile.jpg");
byte data[] = new byte[1024];
long total = 0;
long startTotalTime = System.currentTimeMillis();
long passedTime =0;
long previosTime=0;
while ((count = input.read(data)) != -1) {
total += count;
long endtTime = System.currentTimeMillis();
long passed;
passedTime =endtTime - startTotalTime;
// passed=passedTime -previosTime ;
// previosTime = passed ;
// publishing the progress....
// After this onProgressUpdate will be called
publishProgress(""+(int)((total*100)/lenghtOfFile));
Log.i("log_lenghtOfFile",lenghtOfFile+"" );
Log.i("log_total",total+"" );
Log.i("log_ourcentage",(int)((total*100)/lenghtOfFile)+"" );
Log.i("log_passed_time",passedTime +"" );
calculDebitdescendant( total, lenghtOfFile);
// Log.i("log_Debit",passedTime +"" );
// writing data to file
output.write(data, 0, count);
}
long endTotalTime = System.currentTimeMillis();
Log.i("log_Total_passed_time",endTotalTime-startTotalTime +"" );
// flushing output
output.flush();
// closing streams
output.close();
input.close();
} catch (Exception e) {
Log.e("Error***: ", e.getMessage());
}
return null;
}
public void calculDebitdescendant(long bytesAvailable,long TotalSize){
long bytesAvailable1 = bytesAvailable;
long TotalSize1 = TotalSize;
Log.i("bytesAvailable",bytesAvailable1 +"fonction");
Log.i("log_ourcentage",(int)(((TotalSize1-bytesAvailable1 )*100)/TotalSize1 )+"% " );
}
/**
* Updating progress bar
* */
protected void onProgressUpdate(String... progress) {
// setting progress percentage
pDialog.setProgress(Integer.parseInt(progress[0]));
}
/**
* After completing background task
* Dismiss the progress dialog
* **/
@Override
protected void onPostExecute(String file_url) {
// dismiss the dialog after the file was downloaded
dismissDialog(progress_bar_type);
// Displaying downloaded image into image view
// Reading image path from sdcard
String imagePath = Environment.getExternalStorageDirectory().toString() + "/downloadedfile.jpg";
Log.i("imagePath", imagePath);
Log.i("isExternalStorageWritable", isExternalStorageWritable() + "true" );
// setting downloaded into image view
my_image.setImageDrawable(Drawable.createFromPath(imagePath));
}
}
public boolean isExternalStorageWritable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
Log.i("isExternalStorageWritable", "true" );
return true;
}
return false;
}