关于Android接入USB外接摄像头以及控制拍照并保存图片

关于Android接入外接摄像头，首先毋庸置疑的是需要给你的app配置相应的权限

    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

1.首先构建相应的视图view

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="${relativePackage}.${activityClass}" >

    <TextureView 
        android:id="@+id/textureview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    
    <ImageButton
        android:id="@+id/play"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:layout_centerHorizontal="true"
        android:layout_alignParentBottom="true"
        android:background="@drawable/ic_start"
        android:contentDescription="@string/app_name"
        android:layout_marginBottom="10dp"/>
</RelativeLayout>

2.获取到相应的camera对象，并完成拍照进行本地存储

package com.example.onecamera;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Iterator;
import java.util.List;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.SurfaceTexture;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.media.CamcorderProfile;
import android.media.MediaRecorder;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.TextureView;
import android.view.TextureView.SurfaceTextureListener;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageButton;
import android.widget.Toast;

@SuppressWarnings("deprecation")
public class MainActivity extends Activity implements SurfaceTextureListener,
        OnClickListener {
    private static final String TAG = MainActivity.class.getSimpleName();
    private Camera mCamera;
    private ImageButton mPlayButton;
    private boolean isRecord;
    private MediaRecorder mMediaRecorder;
    private CamcorderProfile mProfile;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        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(1);
        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();
    }
}

在完成以上操作之后仍无法调用到摄像头，请注意一下方法：mCamera = Camera.open(1); 这个并不是所有的android系统都是这个，有可能是mCamera = Camera.open(0); 这个根据实际情况来定

如果你做了以上操作成功了，但是移入到项目里面发现并不能行，那么请先检查你的camera是否有预览视图TextureView，如果你在布局文件里面没有放置TextureView来给camera显示，那么可能会导致你的camera无法进行拍照（我就是遇到这个坑，然后一直找不到原因，后来配置了一个宽高1dp的视图放在父布局里面就可以正常使用拍照了）。

demo：http://download.csdn.net/download/d38825/10166750