Android使用系统相机进行拍照的步骤

<Button
 android:id="@+id/button"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_marginTop="4dp"
 android:text="take phone"
 app:layout_constraintEnd_toEndOf="parent"
 app:layout_constraintHorizontal_bias="0.281"
 app:layout_constraintStart_toStartOf="parent"
 app:layout_constraintTop_toTopOf="parent" />

 <ImageView
 android:id="@+id/imageView"
 android:layout_width="wrap_content"
 android:layout_height="wrap_content"
 android:layout_marginTop="29dp"
 app:layout_constraintEnd_toEndOf="parent"
 app:layout_constraintStart_toStartOf="parent"
 app:layout_constraintTop_toBottomOf="@+id/button"
 app:srcCompat="@mipmap/ic_launcher_round" />

 private Uri imageUri;
 private ImageView imageView;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 imageView = findViewById(R.id.imageView);

 Button button = findViewById(R.id.button);
 button.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {

  //创建一个File对象。getExternalCacheDir()获取应用的缓存目录，outputImage.jpg是照片名称
  File outputImage = new File(getExternalCacheDir(),"outputImage.jpg");
  try{  
  //创建一个空文件  
   outputImage.createNewFile();
  }catch (IOException e){
   e.printStackTrace();
  }

  //不同的安卓版本对用不同的获取Uri的方法
  if (Build.VERSION.SDK_INT>=24){
   imageUri =FileProvider.getUriForFile(MainActivity.this,"huan",outputImage);
  }else{
   imageUri = Uri.fromFile(outputImage);
  }

  //启动相机的对应Activity
  Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
  intent.putExtra(MediaStore.EXTRA_OUTPUT,imageUri);
  startActivityForResult(intent,1);
  }
 });

 @Override
 protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
 if (requestCode == 1) {
  if (resultCode == RESULT_OK)
  try {
   Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
   imageView.setImageBitmap(bitmap);
  } catch (FileNotFoundException e) {
   e.printStackTrace();
  }
 }
 }

<provider
  android:name="android.support.v4.content.FileProvider"
  android:authorities="huan"
  android:exported="false"
  android:grantUriPermissions="true">
  <meta-data
  android:name="android.support.FILE_PROVIDER_PATHS"
  android:resource="@xml/file_paths" />
 </provider>

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
 <external-path
 name="my_image"
 path="/"/>
</paths>