近期在做毕设，需要用到Android调用摄像头拍摄车牌号，并对车牌号码进行识别。特别记录一下如何调用系统摄像头进行拍照,并将文件保存到本地。

环境：Android Studio
官方指南：Camera|Android Developer

1、首先当然要添加一下调用摄像头需要的权限，以及创建文件需要的权限等

AndroidMainfest.xml

    </application>
    <uses-feature android:name="android.hardware.camera"
        android:required="true" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
        android:maxSdkVersion="18" />

2、添加函数，创建临时文件，用来储存图片
MainActivity.java

    String currentPhotoPath;
    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();
        System.out.println(currentPhotoPath);
        return image;
    }

3、创建函数用来启动摄像头，并储存文件
MainActivity.java

    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;
            try {
                photoFile = createImageFile();
            } catch (IOException ex) {
                // Error occurred while creating the File
            }
            // Continue only if the File was successfully created
            if (photoFile != null) {
                Uri photoURI = FileProvider.getUriForFile(this,
                        "com.example.takephotos.fileprovider",
                        photoFile);

                takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
                startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
            }
        }
    }

4、因为上面使用到privider，因此需要在res下创建xml文件夹、创建文件file_paths.xml,并添加对应的设置
file_paths.xml

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

AndroidMainfest.xml

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

5、在onCreate()中调用dispatchTakePictureIntent()函数
MainActivity.java

        @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mImageView = (ImageView) findViewById(R.id.image);
        dispatchTakePictureIntent();
    }

其保存的文件目录如下：
/storage/emulated/0/Android/data/com.example.takephotos/files/Pictures/JPEG_20190312_2339464476956325377028564.jpg

安卓拍照并且保存本地就到这里完成了。