Android 实现图片保存到本地并调用本地地址显示图片

运行截图

话不多说上代码

public class MainActivity extends AppCompatActivity {
private Button cunn;
private Button xian;
 private ImageView ttt;
//private EditText rrr;
public static final int EXTERNAL_STORAGE_REQ_CODE = 10 ;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    cunn =(Button)findViewById(R.id.cun);
    xian=(Button)findViewById(R.id.xians);
    ttt=(ImageView)findViewById(R.id.tt);
   // rrr=(EditText)findViewById(R.id.rr);
    //final Intent intent = new Intent(MainActivity.this,Download.class);
    final MyDownloadManager myDownloadManager = new MyDownloadManager();
    //final String path= rrr.getText().toString();
    final String path = "https://dss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=2534506313,1688529724&fm=26&gp=0.jpg";
    //final String path1 = "https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=1328477591,2018436166&fm=26&gp=0.jpg";
    //final String dirname ="/sdcard/";
    //final String filename ="rr";
    //final Download download = new Download();
   // final dd d =new dd();
    cunn.setOnClickListener(new View.OnClickListener() {


        @RequiresApi(api = Build.VERSION_CODES.O)
        @Override
        public void onClick(View view) {
            myDownloadManager.addDownloadTask(path);
           // try {
           //    d.ddt(path1,dirname,filename);
           // } catch (IOException e) {
            //   e.printStackTrace();
           // }

        }
    });
    xian.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
          //File file = new File(String.valueOf(myDownloadManager.getDownloadDir()));
            //Bitmap bm = BitmapFactory.decodeFile(myDownloadManager.getDownloadDir()+myDownloadManager.getfileName(path));
           // ttt.setImageBitmap(bm);
            ttt.setImageURI(Uri.fromFile(new File(myDownloadManager.getDownloadDir() +"/"+ myDownloadManager.getfileName(path))));
            //ttt.setImageUri(Uri.fromFile(new File("/sdcard/test.jpg")));
        }
    });



    int permission = ActivityCompat.checkSelfPermission(this,
            Manifest.permission.WRITE_EXTERNAL_STORAGE);

    if (permission != PackageManager.PERMISSION_GRANTED) {
        // 请求权限
        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},
                EXTERNAL_STORAGE_REQ_CODE);
    }
}
public static String MD5(String path)  {
   // URL url = new URL(path);
    //String url = path;

    //String path = Environment.getExternalStorageDirectory().getAbsolutePath();

    //final long startTime = System.currentTimeMillis();

    //String filename=url.substring(url.lastIndexOf("/") + 1);
    String filename ="pp.jpg";
    return filename;
}

 public class MyDownloadManager {
public static final int EXTERNAL_STORAGE_REQ_CODE = 10 ;
private static final int REQUEST_EXTERNAL_STORAGE = 1;
private static String[] PERMISSIONS_STORAGE = {
        Manifest.permission.READ_EXTERNAL_STORAGE,
        Manifest.permission.WRITE_EXTERNAL_STORAGE };

/**
 * Checks if the app has permission to write to device storage
 *
 * If the app does not has permission then the user will be prompted to
 * grant permissions
 *
 * @param activity
 */
public static void verifyStoragePermissions(Activity activity) {
    // Check if we have write permission
    int permission = ActivityCompat.checkSelfPermission(activity,
            Manifest.permission.WRITE_EXTERNAL_STORAGE);

    if (permission != PackageManager.PERMISSION_GRANTED) {
        // We don't have permission so prompt the user
        ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,
                REQUEST_EXTERNAL_STORAGE);
    }

}


private static final String TAG = "MyDownloadManager";
private File downloadDir; // 文件保存路径
private static MyDownloadManager instance; // 单例
private String fileName;

// 单线程任务队列
public static Executor executor;
private static final ThreadFactory sThreadFactory = new ThreadFactory() {
    private final AtomicInteger mCount = new AtomicInteger(1);

    public Thread newThread(Runnable r) {
        return new Thread(r, "MyDownloadManager #" + mCount.getAndIncrement());
    }
};
private static final BlockingQueue<Runnable> sPoolWorkQueue = new LinkedBlockingQueue<>(128);
public static final Executor THREAD_POOL_EXECUTOR = new ThreadPoolExecutor(1, 1, 1,
        TimeUnit.SECONDS, sPoolWorkQueue, sThreadFactory);


public MyDownloadManager() {
    // 初始化下载路径
    downloadDir = new File("/sdcard/");
    if (!downloadDir.exists()) {
        downloadDir.mkdirs();
    }
    executor = new SerialExecutor();
}

/**
 * 顺序执行下载任务
 */
private static class SerialExecutor implements Executor {
    final ArrayDeque<Runnable> mTasks = new ArrayDeque<Runnable>();
    Runnable mActive;

    public synchronized void execute(final Runnable r) {
        mTasks.offer(new Runnable() {
            public void run() {
                try {
                    r.run();
                } finally {
                    scheduleNext();
                }
            }
        });
        if (mActive == null) {
            scheduleNext();
        }
    }

    protected synchronized void scheduleNext() {
        if ((mActive = mTasks.poll()) != null) {
            THREAD_POOL_EXECUTOR.execute(mActive);
        }
    }
}

/**
 * 获取单例对象
 *
 * @return
 */
public static MyDownloadManager getInstance() {
    if (instance == null) {
        instance = new MyDownloadManager();
    }
    return instance;
}

/**
 * 添加下载任务
 *
 * @param path
 */
public void addDownloadTask(final String path) {
    Log.i(TAG, "进入run00");
    executor.execute(new Runnable() {


        @Override
        public void run() {
            Log.i(TAG, "进入run");
            download(path);

        }
    });
}

/**
 * 下载文件
 *
 * @param path
 */
private void download(String path)  {
    String fileName = MainActivity.MD5(path);

    File savePath = new File(downloadDir, fileName); // 下载文件路径
   //File finallyPath = new File(downloadDir, fileName + ".png"); // 下载完成后加入
    if (savePath.exists()) { // 文件存在则已下载
        Log.i(TAG, "file is existed");
        return;
    }
   // 如果是Wifi则开始下载
    if (savePath.exists() && savePath.delete()) { // 如果之前存在文件，证明没有下载完成，删掉重新创建
            savePath = new File(downloadDir, fileName);
            Log.i(TAG, "download 111111");
        }
        Log.i(TAG, "download start");
        try {
            byte[] bs = new byte[1024];
            int len;
            URL url = new URL(path);
            InputStream is = url.openStream();

            OutputStream os = new FileOutputStream(savePath,true);
            Log.i(TAG, "download 22222");


            while ((len = is.read(bs)) != -1) {

                os.write(bs, 0, len);
            }
            is.close();
            os.close();

        } catch (IOException e) {
            e.printStackTrace();
        }
       //if (savePath.renameTo(finallyPath)) { // 下载完成后重命名为
          // Log.i(TAG, "download end");

     //  }


}

/**
 * 添加删除任务
 *
 * @param path
 */
public void addDeleteTask(final String path) {
    executor.execute(new Runnable() {
        @Override
        public void run() {
            delete(path);
        }
    });
}

/**
 * 删除本地文件
 *
 * @param path
 */
private void delete(String path) {
    String fileName = MainActivity.MD5(path);
    File savePath = new File(downloadDir, fileName + ".png");
    Log.i(TAG, savePath.getPath());
    if (savePath.exists()) {
        if (savePath.delete()) {
            Log.i(TAG, "file is deleted");
        }
    }
}

/**
 * 返回下载路径
 *
 * @return
 */
public File getDownloadDir() {
    return downloadDir;
}
public String getfileName(String path){
    String f =MainActivity.MD5(path);
    return f;
}
}

   <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity"
android:orientation="vertical"
       >

  <Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="保存"
android:id="@+id/cun"
/>
  
  
  <Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="显示"
    android:id="@+id/xians"
    />
<ImageView
    android:id="@+id/tt"
    android:layout_width="match_parent"
    android:layout_height="match_parent"/>
 </LinearLayout>

 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
package="com.example.myapplication">
<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.MOUNT_UNMOUNT_FILESYSTEMS"
    tools:ignore="ProtectedPermissions" />



<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme"
    android:requestLegacyExternalStorage="true"
    >
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

 </manifest>

代码中我有很多尝试的地方注释的地方可以忽略或者可以参考

Android 实现图片保存到本地并调用本地地址显示图片

话不多说上代码

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