最近项目中需要在界面中点击按钮拍照，但不展示预览界面（吐槽：什么鬼需求），本来以为比较简单，但在实现时遇到几个问题，在此记录下

本人的实现思路是将预览界面的大小设置为一个宽高都为1px的界面就可以了
一开始的代码

Camera camera;
    private void takePhoto(){

        if (camera == null)
            camera  = Camera.open();
        if (camera != null) {
            SurfaceView surfaceView = new SurfaceView(this);
            //设置预览
            try {
                camera.setPreviewDisplay(surfaceView.getHolder());
            } catch (IOException e) {
                e.printStackTrace();
            }
            camera.startPreview();
            camera.takePicture(null, null, new Camera.PictureCallback() {
                @Override
                public void onPictureTaken(byte[] data, Camera camera) {
                    try {
                        File file = getFile();
                        if (file == null) {
                            return;
                        }
                        FileOutputStream fos = new FileOutputStream(file);
                        fos.write(data);
                        fos.close();
                        Log.e("PhotoHandler", "图片保存完成");
                    } catch (Exception error) {
                        error.printStackTrace();
                    }
                    camera.stopPreview();
                }
            });
        }
    }
    private String FILE_PATH = Environment
            .getExternalStorageDirectory().getAbsolutePath()
            + "/testImage/";
    private File getFile() {
        File f = new File(FILE_PATH);
        if (!f.exists()) {
           f.mkdirs();
        }

        String timeStamp = new SimpleDateFormat("yyyy-MM-dd  HH:mm:ss").format(new Date());
        File file;
        file = new File(FILE_PATH,
                "IMG_" + timeStamp + ".jpg");
        try {
            if (!file.exists()) {
                file.createNewFile();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return file;
    }

报错:Caused by: java.lang.RuntimeException: takePicture failed

百度了下找到解决方法
问题是在相机实例上开始预览后，需要一些时间才能拍照

camera.startPreview();
        camera.setOneShotPreviewCallback(new Camera.PreviewCallback() {
            @Override
            public void onPreviewFrame(byte[] data, Camera camera) {
                camera.takePicture(null, null, new Camera.PictureCallback() {
                    @Override
                    public void onPictureTaken(byte[] data, Camera camera) {
               // do something you want with your picture and stop preview
                        camera.stopPreview();
                    }
                });

将takePicture方法放在setOneShotPreviewCallback回调中解决问题

又遇见问题 调用后没反应,回调中也没走
后来发现是SurfaceView 问题，直接new的话就会有这个问题，在xml文件中声明就没有问题（暂时不知道原因，哪位大佬知道麻烦告知，谢谢）

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffff">
    <SurfaceView
        android:id="@+id/sview"
        android:layout_width="1px"
        android:layout_height="1px"/>

    <ImageView
        android:layout_margin="5dp"
        android:id="@+id/button"
        android:layout_centerInParent="true"
        android:layout_width="30dp"
        android:layout_height="30dp"
        android:background="@mipmap/ic_launcher_round"/>
</RelativeLayout>


Camera camera;
private SurfaceView surfaceview;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_test);
        surfaceview = findViewById(R.id.sview);
        ImageView button = findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                takePhoto();
            }
        });
    }
    private void takePhoto(){

        if (camera == null)
            camera  = Camera.open();
        if (camera != null) {
//            SurfaceView surfaceView = new SurfaceView(this);
            //设置预览
            try {
                camera.setPreviewDisplay(surfaceview.getHolder());
            } catch (IOException e) {
                e.printStackTrace();
            }
          .......
        }
    }

最终实现需求