android中的多媒體應用camera

MainActivity.java

 

代碼

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 {
// 聲明拍照介面組件SurfaceView
    private SurfaceView surfaceView;
// 聲明介面控制組件SurfaceHolder
    private SurfaceHolder surfaceHolder;
// 聲明照相機
    private Camera camera;

    @Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
// 執行個體化拍照介面組件
        surfaceView = (SurfaceView)findViewById(R.id.preview);
// 從SurfaceView中獲得SurfaceHolder
        surfaceHolder = surfaceView.getHolder();
// 為SurfaceHolder 添加回調
        surfaceHolder.addCallback(surfaceCallback);
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

// 響應按鍵事件
    @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(){
// 停止預覽
        camera.stopPreview();
// 拍照
        camera.takePicture(null,null, pictureCallback);
    }
// 照片回調
    Camera.PictureCallback pictureCallback = new Camera.PictureCallback() {
        @Override
public void onPictureTaken(byte[] data, Camera camera) {
new SavePictureTask().execute(data);
            camera.startPreview();
        }
    };

// 儲存照片任務類
    class SavePictureTask extends AsyncTask<byte[],String,String>{
        @Override
protected String doInBackground(byte[]... params) {
// 建立檔案
            File picture = new File(Environment.getExternalStorageDirectory(),"picture.jpg");
// 如果檔案存在刪除掉
            if(picture.exists())picture.delete();
try {
// 獲得檔案輸出資料流
                FileOutputStream  fos = new FileOutputStream(picture.getPath());
// 寫到該檔案
                fos.write(params[0]);
// 關閉檔案流
                fos.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
return null;
        }
    }
// SurfaceHodler 回調，處理開啟相機，關閉相機以及照片尺寸的改變
    SurfaceHolder.Callback surfaceCallback = new SurfaceHolder.Callback() {
        @Override
public void surfaceCreated(SurfaceHolder holder) {
// 開啟相機
            camera = Camera.open();
try {
// 設定預覽
                camera.setPreviewDisplay(holder);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        @Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// 獲得相機參數
            Camera.Parameters parameters = camera.getParameters();
// 設定照片大小
            parameters.setPreviewSize(width, height);
// 設定照片格式
            parameters.setPictureFormat(PixelFormat.JPEG);
// 設定相機參數
            camera.setParameters(parameters);
// 開始預覽
            camera.startPreview();
        }

        @Override
public void surfaceDestroyed(SurfaceHolder holder) {
// 停止預覽
            camera.stopPreview();
// 釋放相機資源
            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>