Android如何调用外置摄像头

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1、布局文件

2、相应的MainActivity.java的主要代码如下

package com.deepreality.takephotowithusbcamera;import android.Manifest;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.SurfaceTexture;import android.hardware.Camera;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;import android.view.TextureView;import android.view.View;import android.widget.ImageButton;import android.widget.Toast;import com.tbruyelle.rxpermissions2.RxPermissions;import java.io.BufferedOutputStream;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.text.SimpleDateFormat;import java.util.Date;public class MainActivity extends AppCompatActivity implements TextureView.SurfaceTextureListener, View.OnClickListener {    private static final String TAG = MainActivity.class.getSimpleName();    private Camera mCamera;    private ImageButton mPlayButton;    private RxPermissions rxPermissions;    private int permissionNum;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        rxPermissions = new RxPermissions(MainActivity.this);        checkUserAllPermissions();        mPlayButton = (ImageButton) findViewById(R.id.play);        mPlayButton.setOnClickListener(this);        ((TextureView) findViewById(R.id.textureview))                .setSurfaceTextureListener(this);    }    private void takePic() {        if (mCamera != null) {            //调用抓拍摄像头抓拍            mCamera.takePicture(null, null, pictureCallback);        } else {            Log.e("TAG", "请检查摄像头！");        }    }    private Bitmap mBitmap;    public Camera.PictureCallback pictureCallback = new Camera.PictureCallback() {        @Override        public void onPictureTaken(byte[] data, Camera camera) {            Log.i("ygy", "onPictureTaken");            SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//设置日期格式            System.out.println(df.format(new Date()));// new Date()为获取当前系统时间            String picName = df.format(new Date());            Toast.makeText(getApplicationContext(), "正在保存...", Toast.LENGTH_LONG).show();            mBitmap = BitmapFactory.decodeByteArray(data, 0, data.length);            File file = new File("/storage/emulated/0/" + picName + ".jpg");            try {                file.createNewFile();                BufferedOutputStream os = new BufferedOutputStream(new FileOutputStream(file));                mBitmap.compress(Bitmap.CompressFormat.JPEG, 100, os);                os.flush();                os.close();                Toast.makeText(getApplicationContext(), "图像保存成功", Toast.LENGTH_LONG).show();            } catch (IOException e) {                e.printStackTrace();            }        }    };    @Override    public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {        mCamera = Camera.open(0);        if (mCamera != null) {            try {                mCamera.setPreviewTexture(surface);                mCamera.startPreview();            } catch (IOException e) {                Log.d("TAG", e.getMessage());            }        }    }    @Override    protected void onStop() {        if (mCamera != null) {            mCamera.stopPreview();            mCamera.release();            mCamera = null;        }        super.onStop();    }    @Override    public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {    }    @Override    public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {        if (mCamera != null) {            mCamera.stopPreview();            mCamera.release();            mCamera = null;        }        return false;    }    @Override    public void onSurfaceTextureUpdated(SurfaceTexture surface) {    }    @Override    public void onClick(View v) {        if (mCamera == null) {            return;        }        takePic();    }    /**     * 检查并获取用户权限     */    private void checkUserAllPermissions() {        rxPermissions                .requestEach(Manifest.permission.WRITE_EXTERNAL_STORAGE,                        Manifest.permission.CAMERA                )                .subscribe(permission -> {                    if (permission.granted) {                    } else if (permission.shouldShowRequestPermissionRationale) {                    } else {}                    permissionNum ++;                    if (permissionNum == 2) {                    }                });    }}

3、注意在清单文件里AndroidManifest.xml添加用户权限

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