android中的多媒体应用camera

MainActivity.java

package com.amaker.ch11.app;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.view.KeyEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class MainActivity extends Activity {
    // 声明拍照界面组件SurfaceView
    private SurfaceView surfaceView;
    // 声明界面控制组件SurfaceHolder
    private SurfaceHolder surfaceHolder;
    // 声明照相机
    private Camera camera;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        // 实例化拍照界面组件
        surfaceView = (SurfaceView)findViewById(R.id.preview);
        // 从SurfaceView中获得SurfaceHolder
        surfaceHolder = surfaceView.getHolder();
        // 为SurfaceHolder 添加回调
        surfaceHolder.addCallback(surfaceCallback);
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }
    
    // 响应按键事件
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if(keyCode==KeyEvent.KEYCODE_CAMERA||keyCode==KeyEvent.KEYCODE_SEARCH){
            takePic();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }
    // 拍照方法
    private void takePic(){
        // 停止预览
        camera.stopPreview();
        // 拍照
        camera.takePicture(null,null, pictureCallback);
    }
    // 照片回调
    Camera.PictureCallback pictureCallback = new Camera.PictureCallback() {
        @Override
        public void onPictureTaken(byte[] data, Camera camera) {
            new SavePictureTask().execute(data);
            camera.startPreview();
        }
    };
    
    // 保存照片任务类
    class SavePictureTask extends AsyncTask<byte[],String,String>{
        @Override
        protected String doInBackground(byte[]... params) {
            // 创建文件
            File picture = new File(Environment.getExternalStorageDirectory(),"picture.jpg");
            // 如果文件存在删除掉
            if(picture.exists())picture.delete();
            try {
                // 获得文件输出流
                FileOutputStream  fos = new FileOutputStream(picture.getPath());
                // 写到该文件
                fos.write(params[0]);
                // 关闭文件流
                fos.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }
    }
    // SurfaceHodler 回调，处理打开相机，关闭相机以及照片尺寸的改变
    SurfaceHolder.Callback surfaceCallback = new SurfaceHolder.Callback() {
        @Override
        public void surfaceCreated(SurfaceHolder holder) {
            // 打开相机
            camera = Camera.open();
            try {
                // 设置预览
                camera.setPreviewDisplay(holder);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        
        @Override
        public void surfaceChanged(SurfaceHolder holder, int format, int width,
                int height) {
            // 获得相机参数
            Camera.Parameters parameters = camera.getParameters();
            // 设置照片大小
            parameters.setPreviewSize(width, height);
            // 设置照片格式
            parameters.setPictureFormat(PixelFormat.JPEG);
            // 设置相机参数
            camera.setParameters(parameters);
            // 开始预览
            camera.startPreview();
        }
        
        @Override
        public void surfaceDestroyed(SurfaceHolder holder) {
            // 停止预览
            camera.stopPreview();
            // 释放相机资源
            camera.release();
            camera = null;
        }
    };
}

main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.view.SurfaceView xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/preview"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  >
</android.view.SurfaceView>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.amaker.ch11.app"
      android:versionCode="1"
      android:versionName="1.0">
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".MainActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
    <uses-sdk android:minSdkVersion="3" />

</manifest>