我在 Marsmallow 操作系统中遇到了小问题。我可以使用安卓6.0。但我看不到ImageView。例如:首先，我尝试 5.0 操作系统，一切正常。然后我可以使用6.0但我看不到Imageview？这是怎么回事？我使用 Imageloader.java (因为创建拇指图像。)
6.0 的屏幕截图
5.0 的屏幕截图
Imageloader.java
package com.ufuk.campus;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.widget.ImageView;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Collections;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class ImageLoader {
MemoryCache memoryCache=new MemoryCache();
FileCache fileCache;
private Map<ImageView, String> imageViews=Collections.synchronizedMap(new WeakHashMap<ImageView, String>());
ExecutorService executorService;
public ImageLoader(Context context){
fileCache=new FileCache(context);
executorService=Executors.newFixedThreadPool(5);
}
final int stub_id= R.drawable.image_view;
public void DisplayImage(String url, ImageView imageView)
{
imageViews.put(imageView, url);
Bitmap bitmap=memoryCache.get(url);
if(bitmap!=null)
imageView.setImageBitmap(bitmap);
else
{
queuePhoto(url, imageView);
imageView.setImageResource(stub_id);
}
}
private void queuePhoto(String url, ImageView imageView)
{
PhotoToLoad p=new PhotoToLoad(url, imageView);
executorService.submit(new PhotosLoader(p));
}
private Bitmap getBitmap(String url)
{
File f=fileCache.getFile(url);
//from SD cache
Bitmap b = decodeFile(f);
if(b!=null)
return b;
//from web
try {
Bitmap bitmap=null;
URL imageUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection();
conn.setConnectTimeout(30000);
conn.setReadTimeout(30000);
conn.setInstanceFollowRedirects(true);
InputStream is=conn.getInputStream();
OutputStream os = new FileOutputStream(f);
Utils.CopyStream(is, os);
os.close();
bitmap = decodeFile(f);
return bitmap;
} catch (Exception ex){
ex.printStackTrace();
return null;
}
}
//decodes image and scales it to reduce memory consumption
private Bitmap decodeFile(File f){
try {
//decode image size
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
BitmapFactory.decodeStream(new FileInputStream(f),null,o);
//Find the correct scale value. It should be the power of 2.
final int REQUIRED_SIZE=500;
int width_tmp=o.outWidth, height_tmp=o.outHeight;
int scale=1;
while(true){
if(width_tmp/2<REQUIRED_SIZE || height_tmp/2<REQUIRED_SIZE)
break;
width_tmp/=2;
height_tmp/=2;
scale*=2;
}
//decode with inSampleSize
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize=scale;
return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
} catch (FileNotFoundException e) {}
return null;
}
//Task for the queue
private class PhotoToLoad
{
public String url;
public ImageView imageView;
public PhotoToLoad(String u, ImageView i){
url=u;
imageView=i;
}
}
class PhotosLoader implements Runnable {
PhotoToLoad photoToLoad;
PhotosLoader(PhotoToLoad photoToLoad){
this.photoToLoad=photoToLoad;
}
public void run() {
if(imageViewReused(photoToLoad))
return;
Bitmap bmp=getBitmap(photoToLoad.url);
memoryCache.put(photoToLoad.url, bmp);
if(imageViewReused(photoToLoad))
return;
BitmapDisplayer bd=new BitmapDisplayer(bmp, photoToLoad);
Activity a=(Activity)photoToLoad.imageView.getContext();
a.runOnUiThread(bd);
}
}
boolean imageViewReused(PhotoToLoad photoToLoad){
String tag=imageViews.get(photoToLoad.imageView);
if(tag==null || !tag.equals(photoToLoad.url))
return true;
return false;
}
//Used to display bitmap in the UI thread
class BitmapDisplayer implements Runnable
{
Bitmap bitmap;
PhotoToLoad photoToLoad;
public BitmapDisplayer(Bitmap b, PhotoToLoad p){bitmap=b;photoToLoad=p;}
public void run()
{
if(imageViewReused(photoToLoad))
return;
if(bitmap!=null)
{
photoToLoad.imageView.setImageBitmap(bitmap);
}//else
// photoToLoad.imageView.setImageResource(stub_id);
}
}
public void clearCache() {
memoryCache.clear();
fileCache.clear();
}
}
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.ufuk.campus" >
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />
<uses-permission android:name="android.permission.GET_TASKS" />
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.VIBRATE" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_logo_app"
android:label="@string/app_name"
android:theme="@style/MyMaterialTheme" >
<activity
android:name="com.ufuk.campus.Splash"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.ufuk.campus.MainActivityTab"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
<activity
android:name="com.ufuk.campus.News_List_By_Category"
android:configChanges="orientation|keyboardHidden|screenSize" >
</activity>
<activity
android:name="com.ufuk.campus.News_Detail"
android:configChanges="orientation|keyboardHidden|screenSize" >
</activity>
<activity
android:name="com.ufuk.campus.News_Favorite"
android:configChanges="orientation|keyboardHidden|screenSize" >
</activity>
<activity
android:name="com.ufuk.campus.About_Us"
android:configChanges="orientation|keyboardHidden|screenSize" >
</activity>
<meta-data
android:name="com.google.android.gms.version"
android:value="@integer/google_play_services_version" />
<service android:name="com.parse.PushService" />
<receiver android:name="com.parse.ParseBroadcastReceiver" >
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
<action android:name="android.intent.action.USER_PRESENT" />
</intent-filter>
</receiver>
</application>
</manifest>
list
Logcat
-03 06:58:33.123 1863-10307/com.ufuk.campus W/System.err: java.io.FileNotFoundException: /storage/emulated/0/LazyList/1041555135: open failed: ENOENT (No such file or directory)
01-03 06:58:33.123 1863-10307/com.ufuk.campus W/System.err: at libcore.io.IoBridge.open(IoBridge.java:452)
01-03 06:58:33.123 1863-10307/com.ufuk.campus W/System.err: at java.io.FileOutputStream.<init>(FileOutputStream.java:87)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at java.io.FileOutputStream.<init>(FileOutputStream.java:72)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at com.ufuk.campus.ImageLoader.getBitmap(ImageLoader.java:74)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at com.ufuk.campus.ImageLoader.access$000(ImageLoader.java:24)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at com.ufuk.campus.ImageLoader$PhotosLoader.run(ImageLoader.java:133)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:423)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at java.util.concurrent.FutureTask.run(FutureTask.java:237)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at java.lang.Thread.run(Thread.java:818)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at libcore.io.Posix.open(Native Method)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: at libcore.io.IoBridge.open(IoBridge.java:438)
01-03 06:58:33.124 1863-10307/com.ufuk.campus W/System.err: ... 10 more
01-03 06:58:33.124 1863-10308/com.ufuk.campus W/System.err: Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
01-03 06:58:33.124 1863-10308/com.ufuk.campus W/System.err: at libcore.io.Posix.open(Native Method)
01-03 06:58:33.124 1863-10308/com.ufuk.campus W/System.err: at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
01-03 06:58:33.124 1863-10308/com.ufuk.campus W/System.err: at libcore.io.IoBridge.open(IoBridge.java:438)
01-03 06:58:33.124 1863-10308/com.ufuk.campus W/System.err: ... 10 more
01-03 06:58:33.124 1863-10309/com.ufuk.campus W/System.err: java.io.FileNotFoundException: /storage/emulated/0/LazyList/1041555135: open failed: ENOENT (No such file or directory)
最佳答案
如果缺少此权限，请在 list 中添加此权限，然后尝试:
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
关于java - 无法看到图像(Imageloader.java)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34576313/