通过从Camera拍照获取onActivityResult中的null

Question

我在我的应用程序中创建了一个使用相机拍照的类。 此类将使用相机拍摄照片并将其存储在具有唯一名称的文件夹中。 但是，当我想在onActivityResult方法中获取图片路径时，总是会得到null的data ！

这是我班的相机：

public class Camera{

  private Activity activity;
  private SystemTools systemTools;


  public Camera(Context context) {

    this.activity = (Activity) context;
    systemTools = new SystemTools();
  }

  /**
   * This Method will take a picture with camera for us
   */

  public void takePicture() {

    boolean cameraAvailable = systemTools.device_isHardwareFeatureAvailable(activity, PackageManager.FEATURE_CAMERA);

    if (cameraAvailable &&
      systemTools.system_isIntentAvailable(activity, MediaStore.ACTION_IMAGE_CAPTURE)) {

      Intent takePicIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

      //We prepare the intent to store the taken picture
      try {

        File outputDir = systemTools.storage_getExternalPublicFolder("ReportsAttachments", true);
        File outFile = systemTools.storage_createUniqueFileName("cameraPic", ".jpg", outputDir);

        takePicIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(outFile));

      } catch (Exception e) {
        Toast.makeText(activity, "در دریافت تصویر اشکالی رخ داده است ، لطفا دوباره تلاش کنید.", Toast.LENGTH_SHORT).show();
      }

      activity.startActivityForResult(takePicIntent, App.REQUEST_IMAGE_CAPTURE);


    } else {
      if (cameraAvailable) {
        Toast.makeText(activity, "برنامه ی دوربین دستگاه خراب است.", Toast.LENGTH_SHORT).show();

      } else {
        Toast.makeText(activity, "دسترسی به دوربین سیستم امکان پذیر نمی باشد.", Toast.LENGTH_SHORT).show();
      }
    }
  }
}

我在使用相机的Activity中设置了onActivityResult()方法。 像这样：

 @Override
  public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    try {
      if (requestCode == App.REQUEST_IMAGE_CAPTURE) {
        if (resultCode == Activity.RESULT_OK && data != null) {
          Log.i("ATTACH", "In Result");

          Bitmap bmp = (Bitmap) data.getExtras().get("data");
          ByteArrayOutputStream stream = new ByteArrayOutputStream();

          // CALL THIS METHOD TO GET THE URI FROM THE BITMAP
          Uri selectedImage = getImageUri(this, bmp);
          String realPath = getRealPathFromURI(selectedImage);
          selectedImage = Uri.parse(realPath);
          presenter.onNewAttachmentRequest(selectedImage.getPath());


        }
      }
    } catch (Exception e) {
      Log.i("ATTACH", e + "  Something went wrong");
    }
  }

这可以正常工作，并且在SD_Card上可以使用pictre，但是当我想获取图片的路径时，我不能，因为onActivityResult “ data”一直都是null！ 此代码在哪里出问题？

谢谢。

Answer 1

takePicIntent.putExtra（MediaStore.EXTRA_OUTPUT，Uri.fromFile（outFile））;

如您所见，您已经将File Uri传递给了意图，即Camera应用程序将在此路径上写入所拍摄的图像，并且不会返回位图。 只需在您的类中将此路径保存为全局路径，然后在onActivityResult（）中使用即可。 您需要添加它，因为相机应用程序取决于设备。

takePicIntent.putExtra（“ return-data”，false）;

Answer 2

当我想获取图片的路径时

您已经有了图片的路径。 它是outFile 。 将其保存在字段中，并在配置更改时保留它。 另外，由于Uri.fromFile()在Android 7.0+上无法很好地工作，因此请考虑切换到FileProvider ，就像我在此示例项目的以下活动中所做的那样：

/***
 Copyright (c) 2008-2017 CommonsWare, LLC
 Licensed under the Apache License, Version 2.0 (the "License"); you may not
 use this file except in compliance with the License. You may obtain a copy
 of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required
 by applicable law or agreed to in writing, software distributed under the
 License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
 OF ANY KIND, either express or implied. See the License for the specific
 language governing permissions and limitations under the License.

 Covered in detail in the book _The Busy Coder's Guide to Android Development_
 https://commonsware.com/Android
 */

package com.commonsware.android.camcon;

import android.Manifest;
import android.app.Activity;
import android.content.ActivityNotFoundException;
import android.content.ClipData;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.ResolveInfo;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.provider.MediaStore;
import android.support.v4.content.FileProvider;
import android.widget.Toast;
import java.io.File;
import java.util.List;

public class MainActivity extends Activity {
  private static final String EXTRA_FILENAME=
    "com.commonsware.android.camcon.EXTRA_FILENAME";
  private static final String FILENAME="CameraContentDemo.jpeg";
  private static final int CONTENT_REQUEST=1337;
  private static final String AUTHORITY=
    BuildConfig.APPLICATION_ID+".provider";
  private static final String PHOTOS="photos";
  private File output=null;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    if (savedInstanceState==null) {
      output=new File(new File(getFilesDir(), PHOTOS), FILENAME);

      if (output.exists()) {
        output.delete();
      }
      else {
        output.getParentFile().mkdirs();
      }

      Intent i=new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
      Uri outputUri=FileProvider.getUriForFile(this, AUTHORITY, output);

      i.putExtra(MediaStore.EXTRA_OUTPUT, outputUri);

      if (Build.VERSION.SDK_INT>=Build.VERSION_CODES.LOLLIPOP) {
        i.addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
      }
      else if (Build.VERSION.SDK_INT>=Build.VERSION_CODES.JELLY_BEAN) {
        ClipData clip=
          ClipData.newUri(getContentResolver(), "A photo", outputUri);

        i.setClipData(clip);
        i.addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
      }
      else {
        List<ResolveInfo> resInfoList=
          getPackageManager()
            .queryIntentActivities(i, PackageManager.MATCH_DEFAULT_ONLY);

        for (ResolveInfo resolveInfo : resInfoList) {
          String packageName = resolveInfo.activityInfo.packageName;
          grantUriPermission(packageName, outputUri,
            Intent.FLAG_GRANT_WRITE_URI_PERMISSION);
        }
      }

      try {
        startActivityForResult(i, CONTENT_REQUEST);
      }
      catch (ActivityNotFoundException e) {
        Toast.makeText(this, R.string.msg_no_camera, Toast.LENGTH_LONG).show();
        finish();
      }
    }
    else {
      output=(File)savedInstanceState.getSerializable(EXTRA_FILENAME);
    }
  }

  @Override
  protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);

    outState.putSerializable(EXTRA_FILENAME, output);
  }

  @Override
  protected void onActivityResult(int requestCode, int resultCode,
                                  Intent data) {
    if (requestCode == CONTENT_REQUEST) {
      if (resultCode == RESULT_OK) {
        Intent i=new Intent(Intent.ACTION_VIEW);
        Uri outputUri=FileProvider.getUriForFile(this, AUTHORITY, output);

        i.setDataAndType(outputUri, "image/jpeg");
        i.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);

        try {
          startActivity(i);
        }
        catch (ActivityNotFoundException e) {
          Toast.makeText(this, R.string.msg_no_viewer, Toast.LENGTH_LONG).show();
        }

        finish();
      }
    }
  }
}