Android拍照保存

1、拍照是在安卓开发中常用到的一个功能，所以需要熟练掌握

2、实现的功能是：拍照、保存到指定文件夹、照片可以命名

3、先获得读取文件夹的权限：

List permissionList = new ArrayList<>();
if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.
        permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
    permissionList.add(Manifest.permission.WRITE_EXTERNAL_STORAGE);
}
if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.
        permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
    permissionList.add(Manifest.permission.CAMERA);
}
if (!permissionList.isEmpty()) {
    String[] permissions = permissionList.toArray(new String[permissionList.size()]);
    ActivityCompat.requestPermissions(MainActivity.this, permissions, 1);
}

 4、新建FileProvider，不然会报错Unable to get provider androidx.core.content.FileProvider: java.lang.IllegalArgumentException: Missing android.support.FILE_PROVIDER_PATHS meta-data，先建一个xml文件夹：

 然后写入元数据：

5、完整代码：

package com.example.myapplication;

import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.core.content.FileProvider;

import android.Manifest;
import android.annotation.SuppressLint;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private String currentPhotoPath;
    private ImageView imageView;
    static final int REQUEST_TAKE_PHOTO = 1;

    private void dispatchTakePictureIntent() {
        Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        // Ensure that there's a camera activity to handle the intent
        if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
            // Create the File where the photo should go
            File photoFile = null;
            photoFile = createImageFile();
            // Continue only if the File was successfully created
            if (photoFile != null) {
                Uri photoURI;
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                    /*7.0以上要通过FileProvider将File转化为Uri*/
                    photoURI = FileProvider.getUriForFile(this, "com.example.myapplication.fileprovider", photoFile);
                } else {
                    /*7.0以下则直接使用Uri的fromFile方法将File转化为Uri*/
                    photoURI = Uri.fromFile(photoFile);
                }
                takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
                startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
            }
        }
    }

    private File createImageFile() {
        // Create an image file name
        @SuppressLint("SimpleDateFormat") String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String imageFileName = "JPEG_" + timeStamp;
        File storageDir = new File(Environment.getExternalStorageDirectory(), "AAAAA");
        if (!storageDir.exists())
            storageDir.mkdirs();
        File currentImageFile = new File(storageDir, imageFileName + ".jpg");
        if (!currentImageFile.exists()) {
            try {
                currentImageFile.createNewFile();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        // Save a file: path for use with ACTION_VIEW intents
        currentPhotoPath = currentImageFile.getAbsolutePath();
        return currentImageFile;
    }

    //添加到相册
    private void galleryAddPic() {
        Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
        File f = new File(currentPhotoPath);
        Uri contentUri = Uri.fromFile(f);
        mediaScanIntent.setData(contentUri);
        this.sendBroadcast(mediaScanIntent);
    }

    @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) {
                dispatchTakePictureIntent();
            }
        });

        List permissionList = new ArrayList<>();
        if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.
                permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            permissionList.add(Manifest.permission.WRITE_EXTERNAL_STORAGE);
        }
        if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.
                permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
            permissionList.add(Manifest.permission.CAMERA);
        }
        if (!permissionList.isEmpty()) {
            String[] permissions = permissionList.toArray(new String[permissionList.size()]);
            ActivityCompat.requestPermissions(MainActivity.this, permissions, 1);
        }
    }

    //返回结果
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == REQUEST_TAKE_PHOTO && resultCode == RESULT_OK) {
            galleryAddPic();
            //如果写入本地//takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);data就会变成null
            if (data != null) {
                Bundle bundle = data.getExtras();
                Bitmap bitmap = (Bitmap) bundle.get("data");
                imageView.setImageBitmap(bitmap);
            } else {
                Toast.makeText(MainActivity.this, "data is null", Toast.LENGTH_LONG).show();
                //本地读
                File file = new File(currentPhotoPath);
                Uri uri = Uri.fromFile(file);
                try {
                    Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri));
                    imageView.setImageBitmap(bitmap);

                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                }
            }

        }

        super.onActivityResult(requestCode, resultCode, data);

    }
}