调用相机拍照

AndroidManifest.xml

<application
        <!--适配7.0+拍照返回 Start-->
        <provider
            android:name="android.support.v4.content.FileProvider"
            android:authorities="${applicationId}.fileProvider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/provider_path" />
        </provider>
        <!--适配7.0+拍照返回 End-->
</application>

build.gradle

    implementation "org.permissionsdispatcher:permissionsdispatcher:4.7.0"
    annotationProcessor "org.permissionsdispatcher:permissionsdispatcher-processor:4.7.0"

MainActivity.java

package com.shuanghua.takephoto_sample;

import android.Manifest;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.provider.MediaStore;
import android.widget.Button;
import android.widget.ImageView;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.content.FileProvider;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;

import permissions.dispatcher.NeedsPermission;
import permissions.dispatcher.RuntimePermissions;

@RuntimePermissions  //第一步
public class MainActivity extends AppCompatActivity {
    private static final int SCREEN_WIDTH = 120;
    public static final int REQUEST_TAKE_PHOTO_CAMERA = 1;
    public static final int REQUEST_TAKE_PHOTO_GALLERY = 2;
    private ImageView mImageView;
    private Button mButton;
    File imgFile;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mImageView = findViewById(R.id.imageView);
        mButton = findViewById(R.id.button);
        mButton.setOnClickListener(view -> {
            MainActivityPermissionsDispatcher.takePhotoWithPermissionCheck(this); // 第四步
//            pickPhotoFromGallery();
        });
    }

    @NeedsPermission(Manifest.permission.CAMERA) //第二步
    public void takePhoto() {
        Uri imgUri;
        imgFile = new File(getExternalCacheDir(), "output_image.jpg");// getExternalCacheDir 返回当前应用包名下的 cache 目录路径
        if (imgFile.exists()) {
            imgFile.delete();
        } else {
            try {
                imgFile.createNewFile();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (Build.VERSION.SDK_INT < 24) {
            imgUri = Uri.fromFile(imgFile);
        } else {
            imgUri = FileProvider.getUriForFile(this, getPackageName() + ".fileProvider", imgFile);//.fileProvider 也可以改成别的,只是一个标识而已
        }
        // uri=content://com.shuanghua.takephoto_sample.fileProvider/external_files/Android/data/com.shuanghua.takephoto_sample/cache/output_image.jpg
        // file=/storage/emulated/0/Android/data/com.shuanghua.takephoto_sample/cache/output_image.jpg
        Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
        intent.putExtra(MediaStore.EXTRA_OUTPUT, imgUri); // 如果需要拍照的原图 (不需要则将该行注释掉,然后在 ActivityResult 通过 data 获取)
        startActivityForResult(intent, REQUEST_TAKE_PHOTO_CAMERA);// 打开系统相机，同时设置一个 ActivityResult 标记（说明是是从相机页面返回的结果）
    }

    private void pickPhotoFromGallery() {
        Intent intent = new Intent();
        intent.setAction(Intent.ACTION_PICK);
        intent.setData(MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
        startActivityForResult(intent, REQUEST_TAKE_PHOTO_GALLERY);
    }

    /**
     * 采样压缩
     */
    private Bitmap optionsImg(Uri imgUri) throws FileNotFoundException {
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(getContentResolver().openInputStream(imgUri), null, options);
        int width_tmp = options.outWidth, height_tmp = options.outHeight;
        int scale = 2;
        while (true) {
            if (width_tmp / scale < SCREEN_WIDTH) break;
            scale += 2;
        }
        scale /= 2;
        BitmapFactory.Options options2 = new BitmapFactory.Options();
        options2.inSampleSize = scale;
        return BitmapFactory.decodeStream(
                getContentResolver().openInputStream(imgUri), null, options2
        );
    }

    /**
     * 矩阵压缩
     */
    private Bitmap matrixImg(Uri imgUri) throws FileNotFoundException {
        Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imgUri));
        System.out.println("缩放前：" + bitmap.getByteCount());
        Matrix matrix = new Matrix();
        matrix.setScale(0.25f, 0.25f);
        Bitmap bm = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth()
                , bitmap.getHeight(), matrix, true);
        System.out.println("缩放后：" + bm.getByteCount());
        return bm;
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK) {
            switch (requestCode) {
                case REQUEST_TAKE_PHOTO_CAMERA:
                    try {
                        Uri imgUri = Uri.fromFile(imgFile); // File to Uri
                        Bitmap bitmap = matrixImg(imgUri);
                        //Bitmap photo = data.getParcelableExtra("data");// 获取系统压缩过后的图片（压缩后的图片特别小, 大概 2cm X 3cm）
                        mImageView.setImageBitmap(bitmap);
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    }
                    break;
                case REQUEST_TAKE_PHOTO_GALLERY:
                    try {
                        Uri imgUri = data.getData();// 相册页面返回对应图片的 uri
                        Bitmap bitmap = matrixImg(imgUri);
                        mImageView.setImageBitmap(bitmap);
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                    }
                    break;
            }
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode
            , @NonNull String[] permissions, @NonNull int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        MainActivityPermissionsDispatcher.onRequestPermissionsResult(this, requestCode, grantResults); //第三步
    }
}

provider_path.xml

<?xml version="1.0" encoding="utf-8"?>
<paths>
    <external-path
        name="external_files"
        path="." />
</paths>