android打开相机拍照和从相册选择图像遇见的坑

android打开相机拍照和从相册选择图像遇见的坑，记录一下
环境：
Android71.2
API25
Android Studi 4.2.1
首先是在manifest声明权限

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.testproject">
    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"/>
    
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:usesCleartextTraffic = "true"
        android:requestLegacyExternalStorage="true"
        android:theme="@style/Theme.TestProject">
        <activity android:name=".MainActivity"
            android:launchMode="standard">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
                <category android:name="android.intent.category.DEFAULT" />
            </intent-filter>
        </activity>

        <provider
            android:name="androidx.core.content.FileProvider"
            android:authorities="com.example.testproject.provider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/file_paths" />
        </provider>

    </application>
    <queries>
        <intent>
            <action android:name="android.media.action.IMAGE_CAPTURE"/>
        </intent>
    </queries>

</manifest>

其中file_paths文件为xml文件，在res目录下的xml文件夹新建一个file_paths.xml文件，里面内容为

<?xml version="1.0" encoding="utf-8"?>
<paths>
    <root-path
        name="root"
        path=""/>
    <files-path
        name="files"
        path="/zlyt"/>
</paths>

下面是请求相机的示例代码

private static final int REQUEST_IMAGE_CAPTURE = 1;
private static final int REQUEST_PHOTO_IMAGE_CAPTURE = 2;

private void requestCameraPermission() {
     //申请权限
        if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.CAMERA)) {
            Snackbar.make(findViewById(android.R.id.content), "Camera permission is needed to take pictures", Snackbar.LENGTH_INDEFINITE).setAction("OK", view -> ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.CAMERA}, 2)).show();
        }
        else {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, 2);
        }
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 2);
        }
        Intent intent = new Intent (MediaStore.ACTION_IMAGE_CAPTURE);
        if (intent.resolveActivity(getPackageManager())!=null){
            startActivityForResult(intent,REQUEST_IMAGE_CAPTURE);
        }
        else{
            Toast.makeText(this, "无法打开相机应用", Toast.LENGTH_SHORT).show();
        }
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK){
            Bundle extras = data.getExtras();
            Bitmap imageBitmap = (Bitmap) extras.get("data");
            showImage.setImageBitmap(imageBitmap);
        }
        else if(requestCode == REQUEST_PHOTO_IMAGE_CAPTURE && resultCode == RESULT_OK){
            Uri photoUri = data.getData();
            String filePath = getRealPathFromURI(this.context,photoUri);
            Log.d("tag","图像路径="+filePath);
            upload(filePath);
            showImage.setImageURI(photoUri);
        }
}
//打开相册
    private void dispatchTakePhotoPictureIntent(){
        Intent photoIntent = new Intent(Intent.ACTION_PICK,MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
        startActivityForResult(photoIntent, REQUEST_PHOTO_IMAGE_CAPTURE);
    }

遇见的问题：
1、相机打开拍完照以后闪退，resultCode不为-1等问题
需要查看manifest里面权限是否给够
2、data返回为null的问题
对于拍照的图像，一种是提前新建Uri文件，使用的时候可以直接使用Uri值，如下所示

        //拍照存放路径
        File fileDir = new File(Environment.getExternalStorageDirectory(),"Pictures") ;
        if (!fileDir.exists()){
            fileDir.getParentFile().mkdir();
        }
        mFilePath = fileDir.getAbsolutePath()+"/IMG_"+System.currentTimeMillis() + ".jpg";

        Intent intent = new Intent (MediaStore.ACTION_IMAGE_CAPTURE);
        if (intent.resolveActivity(getPackageManager())!=null){
            mFileUri = FileProvider.getUriForFile(this.context,"com.example.testproject.provider",new File(mFilePath));
            intent.putExtra(MediaStore.EXTRA_OUTPUT, mFileUri);
            startActivityForResult(intent,REQUEST_IMAGE_CAPTURE);
        }
        else{
            Toast.makeText(this, "无法打开相机应用", Toast.LENGTH_SHORT).show();
        }

另一种是在onActivityResult中处理图像，如下所示

if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK){
            Bundle extras = data.getExtras();
            Bitmap imageBitmap = (Bitmap) extras.get("data");
            showImage.setImageBitmap(imageBitmap);
        }

切记，两种方法不可同时出现，否则会冲突，导致data为null
3、不能获取到拍照的数据可能是权限不够，可以在打开相机之前进行判断，下面是两种申请的方法，可以选择其中一个

        //申请权限
        if (ActivityCompat.shouldShowRequestPermissionRationale(this, Manifest.permission.CAMERA)) {
//            ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.CAMERA}, 1);
            Snackbar.make(findViewById(android.R.id.content), "Camera permission is needed to take pictures", Snackbar.LENGTH_INDEFINITE).setAction("OK", view -> ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.CAMERA}, 2)).show();
        }
        else {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CAMERA}, 2);
        }
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, 2);
        }