怎么点击按钮后调用系统相机拍照，并且获取照片路径的完整代码

这是一个简单的示例代码，可以通过点击按钮调用系统相机拍照，然后获取照片路径：

public class MainActivity extends AppCompatActivity {
    private static final int REQUEST_IMAGE_CAPTURE = 1;
    private String currentPhotoPath;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

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

    private void dispatchTakePictureIntent() {
        Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
            File photoFile = null;
            try {
                photoFile = createImageFile();
            } catch (IOException ex) {
                // Error occurred while creating the File
                ex.printStackTrace();
            }
            // Continue only if the File was successfully created
            if (photoFile != null) {
                Uri photoURI = FileProvider.getUriForFile(this,
                        "com.example.android.fileprovider",
                        photoFile);
                takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
                startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
            }
        }
    }

    private File createImageFile() throws IOException {
        // Create an image file name
        String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String imageFileName = "JPEG_" + timeStamp + "_";
        File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
        File image = File.createTempFile(
                imageFileName,  /* prefix */
                ".jpg",         /* suffix */
                storageDir      /* directory */
        );

        // Save a file: path for use with ACTION_VIEW intents
        currentPhotoPath = image.getAbsolutePath();
        return image;
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK) {
            // Image captured and saved to fileUri specified in the Intent
            Toast.makeText(this, "Image saved to " + currentPhotoPath, Toast.LENGTH_SHORT).show();
        }
    }
}

其中，我们首先设置了一个按钮，当用户点击按钮时，我们调用了`dispatchTakePictureIntent()`方法，该方法通过`MediaStore.ACTION_IMAGE_CAPTURE`意图调用系统相机应用程序。如果相机应用程序可用，我们创建一个临时文件来保存照片，并将其URI（`photoURI`）传递给相机应用程序。当用户拍摄照片并保存时，我们通过`onActivityResult()`方法获取照片的路径。