java - 文件未找到异常 :/storage/emulated/0/JsonParseTutorialCache: open failed: ENOENT (No such file or directory)

Question

我正在使用 GridView 加载包含图像的 json 数据。当我构建项目时发生了一些异常

AndroidManifest.xml:

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

文件缓存类:

public class FileCache {

private File cacheDir;

public FileCache(Context context) {
    // Find the dir to save cached images
    if (android.os.Environment.getExternalStorageState().equals(
            android.os.Environment.MEDIA_MOUNTED))
        cacheDir = new File(
                android.os.Environment.getExternalStorageDirectory(),
                "JsonParseTutorialCache");
    else
        cacheDir = context.getCacheDir();
    if (!cacheDir.exists())
        cacheDir.mkdirs();
}

public File getFile(String url) throws IOException {
    String filename = String.valueOf(url.hashCode());
    // String filename = URLEncoder.encode(url);
    File f = new File(cacheDir, filename);
    f.createNewFile();
    return f;
}

public void clear() {
    File[] files = cacheDir.listFiles();
    if (files == null)
        return;
    for (File f : files)
        f.delete();
 }

日志:

W/System.err: java.io.IOException: open failed: ENOENT (No such file or directory)
W/System.err:     at java.io.File.createNewFile(File.java:939)
W/System.err:     at    com.totoroads.android.app.FileCache.getFile(FileCache.java:33) 
W/System.err:     at com.totoroads.android.app.ImageLoader.getBitmap(ImageLoader.java:64)
W/System.err:     at com.totoroads.android.app.ImageLoader.access$000(ImageLoader.java:29)
W/System.err:     at com.totoroads.android.app.ImageLoader$PhotosLoader.run(ImageLoader.java:155)
W/System.err:     at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:423)
W/System.err:     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
W/System.err:     at java.lang.Thread.run(Thread.java:818)
W/System.err: Caused by: android.system.ErrnoException: open failed: ENOENT (No such file or directory)
W/System.err:     at libcore.io.Posix.open(Native Method)
W/System.err:     at libcore.io.BlockGuardOs.open(BlockGuardOs.java:186)
W/System.err:     at java.io.File.createNewFile(File.java:932)
W/System.err:   ... 9 more

我想在 GridView 上下载、读取和显示图片，如何解决这些异常？

Answer 1

在我的例子中，它是:

如果以 Android 10(API 级别 29)或更高版本为目标，请在应用的 AndroidManifest 文件中将 requestLegacyExternalStorage 的值设置为 true。

<manifest ... >
<application android:requestLegacyExternalStorage="true" ... >