java - 无法看到图像(Imageloader.java)

Question

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)

Answer 1

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" />