我想从网址加载照片并保存在我的Android应用程序的外部存储中，但在运行应用程序时出现 NetworkOnMainThreadException 问题。我正在尝试使用Universal Image Loader加载图像和存储到外部存储目录。谢谢。
这是我的代码
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_post);
dbhelper = new MyDbHelper(this);
dbhelper.onOpen(db);
imageLoader = ImageLoader.getInstance();
ImageLoader.getInstance().init(ImageLoaderConfiguration.createDefault(CustomActionActivity.this));
options = new DisplayImageOptions.Builder()
.cacheInMemory(true)
.cacheOnDisk(true)
.considerExifParams(true)
.bitmapConfig(Bitmap.Config.RGB_565)
.build();
Loaddata();
new LosdImages().execute();
}
private class LosdImages extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... arg0) {
Loaddata();
return null;
}
}
public void Loaddata() {
db = dbhelper.getWritableDatabase();
Cursor cursor = db.rawQuery("select * from ActivityObjectList", null);
if (cursor.moveToFirst())
{
do {
imageName = cursor.getString(cursor.getColumnIndex("imageaudioPath"));
Log.e("imageName "," = "+imageName);
String fileUrl = namespace + "/DownloadFile/FilePathMobile/ATTACHMENT/FileName/"+imageName;
download_PngFileImgLoader(fileUrl, imageName);
Log.e("imageName ", " DownLoaded Succecively !!! = " + imageName);
pics.add(imageName);
}
while (cursor.moveToNext());
}
cursor.close();
}
void download_PngFileImgLoader(String fileUrl, String ImageName) {
newFolder = new File(Environment.getExternalStorageDirectory().getPath() + File.separator + "classnkk_images");
File fileForImage = new File(newFolder, ImageName);
try {
InputStream sourceStream;
File cachedImage = imageLoader.getInstance().getDiscCache().get(fileUrl);
if (cachedImage != null && cachedImage.exists()) { // if image was cached by UIL
sourceStream = new FileInputStream(cachedImage);
} else { // otherwise - download image
ImageDownloader downloader = new BaseImageDownloader(getApplicationContext());
sourceStream = downloader.getStream(fileUrl, null);
}
if (sourceStream != null) {
try {
OutputStream targetStream = new FileOutputStream(fileForImage);
try {
IoUtils.copyStream(sourceStream, targetStream, null);
} finally {
targetStream.close();
}
} finally {
sourceStream.close();
}
}
} catch (IOException ie) {
ie.printStackTrace();
}
}
}
这是我的错误日志
Process: com.example.tazeen.classnkk, PID: 3409
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tazeen.classnkk/com.example.tazeen.classnkk.CustomActionActivity}: android.os.NetworkOnMainThreadException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2329)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2389)
at android.app.ActivityThread.access$900(ActivityThread.java:147)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1296)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5254)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:898)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:693)
Caused by: android.os.NetworkOnMainThreadException
at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1147)
at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:110)
at libcore.io.IoBridge.connectErrno(IoBridge.java:154)
at libcore.io.IoBridge.connect(IoBridge.java:122)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:183)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:456)
at java.net.Socket.connect(Socket.java:882)
at com.android.okhttp.internal.Platform.connectSocket(Platform.java:139)
at com.android.okhttp.Connection.connect(Connection.java:148)
at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:276)
at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:211)
at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:373)
at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:323)
at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponseCode(HttpURLConnectionImpl.java:491)
at com.nostra13.universalimageloader.core.download.BaseImageDownloader.getStreamFromNetwork(BaseImageDownloader.java:117)
at com.nostra13.universalimageloader.core.download.BaseImageDownloader.getStream(BaseImageDownloader.java:88)
at com.example.tazeen.classnkk.CustomActionActivity.download_PngFileImgLoader(CustomActionActivity.java:128)
at com.example.tazeen.classnkk.CustomActionActivity.Loaddata(CustomActionActivity.java:108)
at com.example.tazeen.classnkk.CustomActionActivity.onCreate(CustomActionActivity.java:84)
at android.app.Activity.performCreate(Activity.java:5933)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2282)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2389)
at android.app.ActivityThread.access$900(ActivityThread.java:147)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1296)
答案 0 :(得分：2)
我的建议是使用Glide他们有缓存，错误处理等等
简单易用
File b = new File(Environment.getExternalStorageDirectory(),
"DCIM/Camera/IMG_20151028_192555.jpg");
Glide.with(MainActivity.this).load(c).
error(R.drawable.empty_pic).
placeholder(R.drawable.empty_pic).into(image2);
请参阅此link
答案 1 :(得分：2)
您必须在AsyncTask中编写网络操作，而不是在主Thread
删除此行格式 onCreate() ，您已在AsyncTask中调用。
Loaddata();
答案 2 :(得分：1)
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_post);
dbhelper = new MyDbHelper(this);
dbhelper.onOpen(db);
imageLoader = ImageLoader.getInstance();
ImageLoader.getInstance().init(ImageLoaderConfiguration.createDefault(CustomActionActivity.this));
options = new DisplayImageOptions.Builder()
.cacheInMemory(true)
.cacheOnDisk(true)
.considerExifParams(true)
.bitmapConfig(Bitmap.Config.RGB_565)
.build();
new LosdImages().execute();
}
private class LosdImages extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... arg0) {
Loaddata();
return null;
}
public void Loaddata() {
db = dbhelper.getWritableDatabase();
Cursor cursor = db.rawQuery("select * from ActivityObjectList", null);
if (cursor.moveToFirst())
{
do {
imageName = cursor.getString(cursor.getColumnIndex("imageaudioPath"));
Log.e("imageName "," = "+imageName);
String fileUrl = namespace + "/DownloadFile/FilePathMobile/ATTACHMENT/FileName/"+imageName;
download_PngFileImgLoader(fileUrl, imageName);
Log.e("imageName ", " DownLoaded Succecively !!! = " + imageName);
pics.add(imageName);
}
while (cursor.moveToNext());
}
cursor.close();
}
void download_PngFileImgLoader(String fileUrl, String ImageName) {
newFolder = new File(Environment.getExternalStorageDirectory().getPath() + File.separator + "classnkk_images");
File fileForImage = new File(newFolder, ImageName);
try {
InputStream sourceStream;
File cachedImage = imageLoader.getInstance().getDiscCache().get(fileUrl);
if (cachedImage != null && cachedImage.exists()) { // if image was cached by UIL
sourceStream = new FileInputStream(cachedImage);
} else { // otherwise - download image
ImageDownloader downloader = new BaseImageDownloader(getApplicationContext());
sourceStream = downloader.getStream(fileUrl, null);
}
if (sourceStream != null) {
try {
OutputStream targetStream = new FileOutputStream(fileForImage);
try {
IoUtils.copyStream(sourceStream, targetStream, null);
} finally {
targetStream.close();
}
} finally {
sourceStream.close();
}
}
} catch (IOException ie) {
ie.printStackTrace();
}
}
}
}
我在代码中做了一些更改，导致NetworkMainThreadException。希望它能起作用
答案 3 :(得分：0)
您需要在班级中添加StrictMode.ThreadPolicy。
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_post);
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
.....
}