经过大量研究，我找到了这个解决方案。为了清楚起见，我为这个问题创建了一个完整的应用程序，其目的是打开相机点击照片并将图像设置为 ImageView 的 ImageBitmap。这个问题中询问的代码从第二个块开始，即 setView() 方法，它位于 onCreate() 方法下面，然后我们有 onActivityResult() 方法
这是应用程序的演示。
下面我附上了 MainActivity.java 文件
package com.cr7.opencamera;
import android.Manifest;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.util.Log;
import android.widget.Button;
import android.widget.ImageView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import java.io.IOException;
public class MainActivity extends AppCompatActivity {
private Button buttonCaptureImageFromCamera;
private Uri imageUri;
private ImageView imageViewCameraImage;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Button that will open the camera
buttonCaptureImageFromCamera = findViewById(R.id.buttonCaptureImageFromCamera);
// ImageView that will store the image
imageViewCameraImage = findViewById(R.id.imageViewCameraImage);
askPermission();
}
这是获取图像的 Uri 所需要的，这里 imageUri 是一个全局变量，因此它可以在 onActivityResult() 方法中使用
// Sets OnClickListener for the button if storage permission is given
private void setView() {
buttonCaptureImageFromCamera.setOnClickListener(v -> {
String fileName = "new-photo-name.jpg";
// Create parameters for Intent with filename
ContentValues values = new ContentValues();
values.put(MediaStore.Images.Media.TITLE, fileName);
values.put(MediaStore.Images.Media.DESCRIPTION, "Image capture by camera");
imageUri =
getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
values);
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
startActivityForResult(intent, 1231);
});
}
这是 onActivityResult 方法。这里我使用了 imageUri，即 Uri 类型的全局变量，它在上面的 setView() 方法中的按钮的 OnClickListener 中初始化。
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == 1231 && resultCode == Activity.RESULT_OK) {
try {
ContentResolver cr = getContentResolver();
try {
// Creating a Bitmap with the image Captured
Bitmap bitmap = MediaStore.Images.Media.getBitmap(cr, imageUri);
// Setting the bitmap as the image of the
imageViewCameraImage.setImageBitmap(bitmap);
} catch (IOException e) {
e.printStackTrace();
}
} catch (IllegalArgumentException e) {
if (e.getMessage() != null)
Log.e("Exception", e.getMessage());
else
Log.e("Exception", "Exception");
e.printStackTrace();
}
}
}
剩余代码...
// Asking user for storage permission
public void askPermission() {
// Checking if the permissions are not granted.
if (
ContextCompat.checkSelfPermission(
this,
android.Manifest.permission.WRITE_EXTERNAL_STORAGE
) != PackageManager.PERMISSION_GRANTED ||
ContextCompat.checkSelfPermission(
this,
android.Manifest.permission.READ_EXTERNAL_STORAGE
) != PackageManager.PERMISSION_GRANTED
) {
// If not granted requesting Read and Write storage
ActivityCompat.requestPermissions(this, /*You can ask for multiple request by adding
more permissions to the string*/new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE,
Manifest.permission.READ_EXTERNAL_STORAGE}, 60);
} else {
// If permissions are granted we proceed by setting an OnClickListener for the button
// which helps the user pick the image
setView();
}
}
// This method is called after the permissions have been asked i.e. the dialog that says
// allow or deny
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
@NonNull int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
// Now by default we assume that the permission has not been granted
boolean allPermissionsGranted = false;
// Now we check if the permission was granted
if ( requestCode == 60 && grantResults.length > 0) {
// If all the permissions are granted allPermissionsGranted is set to true else false
allPermissionsGranted = grantResults[0] == PackageManager.PERMISSION_GRANTED
&&
grantResults[1] == PackageManager.PERMISSION_GRANTED;
}
// If permissions are granted we call the setView Method which prompts the user to pick
// an Image either by the clicking it now or picking from the gallery
if ( allPermissionsGranted ) {
setView();
}
}
}
这些代码块是按顺序排列的，也就是说，如果你合并所有这些块，你会得到完整的 MainActivity.java 类。
如果你想实现这个应用程序，你需要创建一个布局文件，其中包含一个 ID 为“imageViewCameraImage”的 ImageView 和一个 ID 为“buttonCaptureImageFromCamera”的按钮。
希望这会有所帮助。我知道这很长，我通过写这篇文章让它更长。
问候，
乔尔