?http://blog.csdn.net/jason0539/article/details/10125017

android之相機開發?

分類：?android 基礎知識2013-08-20 22:32?9774人閱讀?評論(2)?收藏?舉報 Android

在android中應用相機功能，一般有兩種：一種是直接調用系統相機，一種自己寫的相機。
我將分別演示兩種方式的使用：

第一種：是使用Intent跳轉到系統相機,action為:android.media.action.STILL_IMAGE_CAMERA
關鍵代碼：

[java]?view plaincopyprint?

Intent?intent?=?new?Intent();?//調用照相機??????

intent.setAction("android.media.action.STILL_IMAGE_CAMERA");??????

startActivity(intent);??????

例子:

[java]?view plaincopyprint?

import?android.app.Activity;??????

import?android.content.Intent;??????

import?android.os.Bundle;??????

public?class?CameraTest_2?extends?Activity?{??????

????/**?Called?when?the?activity?is?first?created.?*/??????

????@Override??????

????public?void?onCreate(Bundle?savedInstanceState)?{??????

????????super.onCreate(savedInstanceState);??????

????????setContentView(R.layout.main);??????

????????Intent?intent?=?new?Intent();?//調用照相機??????

?????????intent.setAction("android.media.action.STILL_IMAGE_CAMERA");???????

????????startActivity(intent);??????

????}??????

}??????

想要測試的，可以直接新建一個項目，并且把主activity的代碼換成上面的，然后運行，我測試了一下，上面這個代碼并不
需要權限，畢竟只是調用系統自帶的程序。
當然網上還有一些其他相關的調用方法，只要設置對了action,那么系統就會調用系統自帶的相機.

第二種:
（1）首先我們要自己創建一個照相界面，必須考慮用什么控件顯示照相機中的預覽效果，顯然android已經幫我們做好了選擇，那就是SurfaceView

控制SurfaceView需要一個surfaceHolder,他是系統提供的一個用來設置SurfaceView的一個對象，可以通過surfaceView.getHolder()這個方法來獲得.

Camera提供一個setPreviewDisplay(SurfaceHolder)的方法來連接surfaceHolder,并通過他來控制surfaceView.

而我們則使用android的Camera類提供了startPreview()和stopPreview()來開啟和關閉預覽.
關系如下：
Camera -- -->SurfaceHolder------>SurfaceView.

（2）知道怎么預覽了，當然也要知道怎么開啟相機.Camera.open()這是個靜態方法，如果相機沒有別人用著，則會返回一個 相機引用，如果被人用著，則會拋出異常。很奇怪的是，這個方法，不能隨便放，如放在構造方法或者onCreate()方法中，都會照成沒有預覽效果.

（3）
SurfaceHolder.Callback,這是個holder用來顯示surfaceView 數據的接口,他分別必須實現3個方法
surfaceCreated()這個方法是surface 被創建后調用的
surfaceChanged()這個方法是當surfaceView發生改變后調用的
surfaceDestroyed()這個是當surfaceView銷毀時調用的.
surfaceHolde通過addCallBack()方法將響應的接口綁定到他身上.
surfaceHolder還必須設定一個setType()方法，查看api的時候，發現這個方法已經過時，但是不寫，又會報錯

（4）
我用以上知識寫了一個MySurfaceView類，他繼承于SurfaceView,并在里面實現了照相機的預覽功能.這個我覺得最簡單的照相機預覽代碼:
MySurfaceView.java:

[java]?view plaincopyprint?

import?java.io.IOException;??????

import?android.content.Context;??????

import?android.graphics.PixelFormat;??????

import?android.hardware.Camera;??????

import?android.util.Log;??????

import?android.view.SurfaceHolder;??????

import?android.view.SurfaceView;??????

public?class?MySurfaceView?extends?SurfaceView?implements?SurfaceHolder.Callback{??????

????SurfaceHolder?holder;??????

????Camera?myCamera;??????

????public?MySurfaceView(Context?context)??????

????{??????

????????super(context);??????

????????holder?=?getHolder();//獲得surfaceHolder引用??????

?????????holder.addCallback(this);??????

????????holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);//設置類型????????

????}??

????@Override??????

????public?void?surfaceCreated(SurfaceHolder?holder)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????if(myCamera?==?null)??????

????????{??????

????????????myCamera?=?Camera.open();//開啟相機,不能放在構造函數中，不然不會顯示畫面.??????

????????????try?{??????

????????????????myCamera.setPreviewDisplay(holder);??????

????????????}?catch?(IOException?e)?{??????

????????????????//?TODO?Auto-generated?catch?block??????

????????????????e.printStackTrace();??????

????????????}??????

????????}?????????????

????}??????

????@Override??????

????public?void?surfaceChanged(SurfaceHolder?holder,?int?format,?int?width,??????

????????????int?height)?{??????

????????myCamera.startPreview();??????????????

????}??????

????????@Override??????

????public?void?surfaceDestroyed(SurfaceHolder?holder)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????myCamera.stopPreview();//停止預覽??????

?????????myCamera.release();//釋放相機資源??????

?????????myCamera?=?null;??????

????????Log.d("ddd",?"4");????????

????}??????

}??????

主activity代碼:

[java]?view plaincopyprint?

import?android.app.Activity;??????

import?android.os.Bundle;??????

import?android.view.View;??????

import?android.view.View.OnClickListener;??????

public?class?CameraTest_3?extends?Activity??{??????

????/**?Called?when?the?activity?is?first?created.?*/??????

????MySurfaceView?mySurface;??????

????@Override??????

????public?void?onCreate(Bundle?savedInstanceState)?{??????

????????super.onCreate(savedInstanceState);??????

????????mySurface?=?new?MySurfaceView(this);??????

????????setContentView(mySurface);??????

????}??????

}??????

而且必須給應用添加權限:

[html]?view plaincopyprint?

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

(5)能夠預覽了，接下來就是拍照了，拍照用到了一個camera.tackPiture()這個方法,這個方法，有三個參數分別是
ShutterCallBack shutter,PictureCallBack raw,PictureCallBack jpeg.
下面是對他們的實現

[java]?view plaincopyprint?

private?ShutterCallback?shutter?=?new?ShutterCallback()?{??????

??????????

????@Override??????

????public?void?onShutter()?{??????

????????//?TODO?Auto-generated?method?stub??????

????????Log.d("ddd",?"shutter");??????????

????}??????

};??????

private?PictureCallback?raw?=?new?PictureCallback()?{??????

??????????

????@Override??????

????public?void?onPictureTaken(byte[]?data,?Camera?camera)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????Log.d("ddd",?"raw");????????

????}??????

};??????

private?PictureCallback?jpeg?=?new?PictureCallback()?{??????

??????????

????@Override??????

????public?void?onPictureTaken(byte[]?data,?Camera?camera)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????Log.d("ddd","jpeg");????????

????}??????

};??????

當開始拍照時，會依次調用shutter的onShutter()方法，raw的onPictureTaken方法,jpeg的onPictureTaken方法.
三個參數的作用是shutter--拍照瞬間調用，raw--獲得沒有壓縮過的圖片數據，jpeg---返回jpeg的圖片數據
當你不需要對照片進行處理，可以直接用null代替.
注意，當調用camera.takePiture方法后，camera關閉了預覽，這時需要調用startPreview()來重新開啟預覽。

我用以上知識，加到上面的那個例子，就形成了下面的代碼：
MySurfaceView.java:

[java]?view plaincopyprint?

package?jason.camera;??????

import?java.io.IOException;??????

import?android.content.Context;??????

import?android.graphics.PixelFormat;??????

import?android.hardware.Camera;??????

import?android.hardware.Camera.PictureCallback;??????

import?android.hardware.Camera.ShutterCallback;??????

import?android.util.Log;??????

import?android.view.SurfaceHolder;??????

import?android.view.SurfaceView;??????

public?class?MySurfaceView?extends?SurfaceView?implements?SurfaceHolder.Callback{??????

????SurfaceHolder?holder;??????

????Camera?myCamera;??????

????private?ShutterCallback?shutter?=?new?ShutterCallback()?{??????

??????????????

????????@Override??????

????????public?void?onShutter()?{??????

????????????//?TODO?Auto-generated?method?stub??????

????????????Log.d("ddd",?"shutter");??????

??????????????????

????????}??????

????};??????

????private?PictureCallback?raw?=?new?PictureCallback()?{??????

??????????????

????????@Override??????

????????public?void?onPictureTaken(byte[]?data,?Camera?camera)?{??????

????????????//?TODO?Auto-generated?method?stub??????

????????????Log.d("ddd",?"raw");??????

??????????????????

????????}??????

????};??????

????private?PictureCallback?jpeg?=?new?PictureCallback()?{??????

??????????????

????????@Override??????

????????public?void?onPictureTaken(byte[]?data,?Camera?camera)?{??????

????????????//?TODO?Auto-generated?method?stub??????

????????????Log.d("ddd","jpeg");??????

??????????????????

????????}??????

????};??????

????public?MySurfaceView(Context?context)??????

????{??????

????????super(context);??????

????????holder?=?getHolder();//獲得surfaceHolder引用??????

?????????holder.addCallback(this);??????

????????holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);//設置類型????????

????}??????

????public?void?tackPicture()??????

????{??????

????????myCamera.takePicture(null,null,null);??????

????}??????

????public?void?voerTack()??????

????{??????

????????myCamera.startPreview();??????

????}??????

????@Override??????

????public?void?surfaceChanged(SurfaceHolder?holder,?int?format,?int?width,??????

????????????int?height)?{??????

????????myCamera.startPreview();??????????????

????}??????

????@Override??????

????public?void?surfaceCreated(SurfaceHolder?holder)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????if(myCamera?==?null)??????

????????{??????

????????????myCamera?=?Camera.open();//開啟相機,不能放在構造函數中，不然不會顯示畫面.??????

????????????try?{??????

????????????????myCamera.setPreviewDisplay(holder);??????

????????????}?catch?(IOException?e)?{??????

????????????????//?TODO?Auto-generated?catch?block??????

????????????????e.printStackTrace();??????

????????????}??????

????????}?????????????

????}??????

????@Override??????

????public?void?surfaceDestroyed(SurfaceHolder?holder)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????myCamera.stopPreview();//停止預覽??????

?????????myCamera.release();//釋放相機資源??????

?????????myCamera?=?null;??????

??????????????????

????}??????

}??????

主activity:

[java]?view plaincopyprint?

import?android.app.Activity;??????

import?android.os.Bundle;??????

import?android.view.View;??????

import?android.view.View.OnClickListener;??????

public?class?CameraTest_3?extends?Activity?implements?OnClickListener??{??????

????/**?Called?when?the?activity?is?first?created.?*/??????

????MySurfaceView?mySurface;??????

????boolean?isClicked?=?false;??????

????@Override??????

????public?void?onCreate(Bundle?savedInstanceState)?{??????

????????super.onCreate(savedInstanceState);??????

????????mySurface?=?new?MySurfaceView(this);??????

????????setContentView(mySurface);??????

????????mySurface.setOnClickListener(this);??????

????}??????

????@Override??????

????public?void?onClick(View?v)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????if(!isClicked)??????

????????{??????

????????????mySurface.tackPicture();??????

????????????isClicked?=?true;??????

????????}else??????

????????{??????

????????????mySurface.voerTack();??????

????????????isClicked?=?false;??????

??????????????????

????????}??????

??????????????

????}??????

這樣就是實現了拍照的功能，那么怎樣要圖片保存呢？那么這是就需要在那個參數中的jpeg的
方法里面進行處理了，那個方法的data參數，就是相片的數據。
我們通過BitmapFactory.decodeByteArray(data, 0, data.length)來獲得圖片并通過io處理，將圖片保存到想要保存的位置
下面這段代碼，是將照片保存到/sdcard/wjh.jpg;并把一些沒有用到的代碼全部刪掉，剩下一些必須的代碼

[java]?view plaincopyprint?

package?java.camera;??????

import?java.io.BufferedInputStream;??????

import?java.io.BufferedOutputStream;??????

import?java.io.File;??????

import?java.io.FileOutputStream;??????

import?java.io.IOException;??????

import?java.io.OutputStream;??????

import?android.content.Context;??????

import?android.graphics.Bitmap;??????

import?android.graphics.BitmapFactory;??????

import?android.graphics.PixelFormat;??????

import?android.hardware.Camera;??????

import?android.hardware.Camera.PictureCallback;??????

import?android.hardware.Camera.ShutterCallback;??????

import?android.util.Log;??????

import?android.view.SurfaceHolder;??????

import?android.view.SurfaceView;??????

public?class?MySurfaceView?extends?SurfaceView?implements?SurfaceHolder.Callback{??????

????SurfaceHolder?holder;??????

????Camera?myCamera;??????

????private?PictureCallback?jpeg?=?new?PictureCallback()?{??????

??????????????

????????@Override??????

????????public?void?onPictureTaken(byte[]?data,?Camera?camera)?{??????

????????????//?TODO?Auto-generated?method?stub??????

????????????try??????

????????????{??????

????????????????Bitmap?bm?=?BitmapFactory.decodeByteArray(data,?0,?data.length);??????

????????????????File?file?=?new?File("/sdcard/wjh.jpg");??????

????????????????BufferedOutputStream?bos???????

????????????????=?new?BufferedOutputStream(new?FileOutputStream(file));??????

????????????????bm.compress(Bitmap.CompressFormat.JPEG,100,bos);??????

????????????????bos.flush();??????

????????????????bos.close();??????

????????????}catch(Exception?e)??????

????????????{??????

????????????????e.printStackTrace();??????

????????????}??????

????????}??????

????};??????

????public?MySurfaceView(Context?context)??????

????{??????

????????super(context);??????

????????holder?=?getHolder();//獲得surfaceHolder引用??????

?????????holder.addCallback(this);??????

????????holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);//設置類型????????

????}??????

????public?void?tackPicture()??????

????{??????

????????myCamera.takePicture(null,null,jpeg);??????

????}??????

????public?void?voerTack()??????

????{??????

????????myCamera.startPreview();??????

????}??????

????@Override??????

????public?void?surfaceChanged(SurfaceHolder?holder,?int?format,?int?width,??????

????????????int?height)?{??????

????????myCamera.startPreview();??????????????

????}??????

????@Override??????

????public?void?surfaceCreated(SurfaceHolder?holder)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????if(myCamera?==?null)??????

????????{??????

????????????myCamera?=?Camera.open();//開啟相機,不能放在構造函數中，不然不會顯示畫面.??????

????????????try?{??????

????????????????myCamera.setPreviewDisplay(holder);??????

????????????}?catch?(IOException?e)?{??????

????????????????//?TODO?Auto-generated?catch?block??????

????????????????e.printStackTrace();??????

????????????}??????

????????}?????????????

????}??????

????@Override??????

????public?void?surfaceDestroyed(SurfaceHolder?holder)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????myCamera.stopPreview();//停止預覽??????

????????myCamera.release();//釋放相機資源??????

????????myCamera?=?null;??????

????}??????

}??????

注意，這是必須添加在sd卡上寫數據的權限

[html]?view plaincopyprint?

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

(7)能夠拍照了，這下子要考慮如何讓圖片更好看了，這顯然是專業人士的強項，但是我們在程序上，也可以做一些處理，
向上面的那些，因為我直接把surfaceView當做整體布局，就可能出現屏幕被拉開了，不是很好看，所以這時，就可以不要把
surfaceView弄成整體布局，把他弄到一個布局管理器，再設置相關的參數.
這時需要注意的是有些參數不能隨便亂設
如以下代碼:

[java]?view plaincopyprint?

Camera.Parameters?parames?=?myCamera.getParameters();//獲得參數對象??

parames.setPictureFormat(PixelFormat.JPEG);//設置圖片格式??

parames.setPreviewSize(640,480);//這里面的參數只能是幾個特定的參數，否則會報錯.(176*144,320*240,352*288,480*360,640*480)??

myCamera.setParameters(parames);??

還有自動對焦，當然有些手機沒有這個功能，自動對焦是通過autoFocus()這個方法調用一個自動對焦的接口，并在里面進行處理。
注意，這個方法必須在startPreview()和stopPreview()中間。
AutoFocusCallback是自動對焦的接口，實現它必須實現public void onAutoFocus(boolean success, Camera camera)這個方法，
所以我們可以將拍照方法放在這里面，然后對焦后再進行拍攝。。效果會好很多。
注意自動對焦需要添加

[html]?view plaincopyprint?

<uses-feature?android:name="android.hardware.camera.autofocus"?/>??

?

下面是主要代碼,直接貼出來了

[java]?view plaincopyprint?

import?java.io.BufferedOutputStream;??????

import?java.io.File;??????

import?java.io.FileOutputStream;??????

import?java.io.IOException;??????

import?android.app.Activity;??????

import?android.content.pm.ActivityInfo;??????

import?android.graphics.Bitmap;??????

import?android.graphics.BitmapFactory;??????

import?android.graphics.PixelFormat;??????

import?android.hardware.Camera;??????

import?android.hardware.Camera.AutoFocusCallback;??????

import?android.hardware.Camera.PictureCallback;??????

import?android.os.Bundle;??????

import?android.view.SurfaceHolder;??????

import?android.view.SurfaceView;??????

import?android.view.View;??????

import?android.view.Window;??????

import?android.view.SurfaceHolder.Callback;??????

import?android.view.View.OnClickListener;??????

public?class?CameraTest_4?extends?Activity?implements??????

Callback,?OnClickListener,?AutoFocusCallback{??????

????SurfaceView?mySurfaceView;//surfaceView聲明??????

????SurfaceHolder?holder;//surfaceHolder聲明??????

????Camera?myCamera;//相機聲明??????

????String?filePath="/sdcard/wjh.jpg";//照片保存路徑??????

????boolean?isClicked?=?false;//是否點擊標識??????

????//創建jpeg圖片回調數據對象??????

????PictureCallback?jpeg?=?new?PictureCallback()?{??????

??????????????

????????@Override??????

????????public?void?onPictureTaken(byte[]?data,?Camera?camera)?{??????

????????????//?TODO?Auto-generated?method?stub??????

????????????try??????

????????????{//?獲得圖片??????

????????????Bitmap?bm?=?BitmapFactory.decodeByteArray(data,?0,?data.length);??????

????????????File?file?=?new?File(filePath);??????

????????????BufferedOutputStream?bos?=??????

????????????????new?BufferedOutputStream(new?FileOutputStream(file));??????

????????????bm.compress(Bitmap.CompressFormat.JPEG,?100,?bos);//將圖片壓縮到流中??????

????????????bos.flush();//輸出??????

????????????bos.close();//關閉??????

????????????}catch(Exception?e)??????

????????????{??????

????????????????e.printStackTrace();??????

????????????}??????

??????????????????

????????}??????

????};??????

????/**?Called?when?the?activity?is?first?created.?*/??????

????@Override??????

????public?void?onCreate(Bundle?savedInstanceState)?{??????

????????super.onCreate(savedInstanceState);??????

????????requestWindowFeature(Window.FEATURE_NO_TITLE);//無標題?????????????????

????????//設置拍攝方向??????

????????this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);??????

????????setContentView(R.layout.main);??????

????????//獲得控件??????

????????mySurfaceView?=?(SurfaceView)findViewById(R.id.surfaceView1);??????

????????//獲得句柄??????

????????holder?=?mySurfaceView.getHolder();??????

????????//添加回調??????

????????holder.addCallback(this);??????

????????//設置類型??????

????????holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);??????

????????//設置監聽??????

????????mySurfaceView.setOnClickListener(this);??????

????}??????

????@Override??????

????public?void?surfaceChanged(SurfaceHolder?holder,?int?format,?int?width,??????

????????????int?height)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????//設置參數并開始預覽??????

????????Camera.Parameters?params?=?myCamera.getParameters();??????

????????params.setPictureFormat(PixelFormat.JPEG);??????

????????params.setPreviewSize(640,480);??????

????????myCamera.setParameters(params);??????

????????myCamera.startPreview();??????

??????????????

????}??????

????@Override??????

????public?void?surfaceCreated(SurfaceHolder?holder)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????//開啟相機??????

????????if(myCamera?==?null)??????

????????{??????

????????????myCamera?=?Camera.open();??????

????????????try?{??????

????????????????myCamera.setPreviewDisplay(holder);??????

????????????}?catch?(IOException?e)?{??????

????????????????//?TODO?Auto-generated?catch?block??????

????????????????e.printStackTrace();??????

????????????}??????

????????}??????

??????????????

????}??????

????@Override??????

????public?void?surfaceDestroyed(SurfaceHolder?holder)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????//關閉預覽并釋放資源??????

????????myCamera.stopPreview();??????

????????myCamera.release();??????

????????myCamera?=?null;??????

??????????????

????}??????

????@Override??????

????public?void?onClick(View?v)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????if(!isClicked)??????

????????{??????

????????????myCamera.autoFocus(this);//自動對焦??????

????????????isClicked?=?true;??????

????????}else??????

????????{??????

????????????myCamera.startPreview();//開啟預覽??????

????????????isClicked?=?false;??????

????????}??????

??????????????

????}??????

????@Override??????

????public?void?onAutoFocus(boolean?success,?Camera?camera)?{??????

????????//?TODO?Auto-generated?method?stub??????

????????if(success)??????

????????{??????

????????????//設置參數,并拍照??????

????????????Camera.Parameters?params?=?myCamera.getParameters();??????

????????????params.setPictureFormat(PixelFormat.JPEG);??????

????????????params.setPreviewSize(640,480);??????

????????????myCamera.setParameters(params);??????

????????????myCamera.takePicture(null,?null,?jpeg);??????

????????}??????

??????????????

????}??????

}??????

main.xml:

[html]?view plaincopyprint?

<linearlayout?xmlns:android="http://schemas.android.com/apk/res/android"?????

????androidrientation="vertical"??????

????android:layout_width="fill_parent"??????

????android:layout_height="fill_parent"??????

????>??????

????<surfaceview?android:id="@+id/surfaceView1"?????

?????android:layout_width="640px"??????

?????android:layout_height="480px"??????

?????android:layout_gravity="center">??????

AndroidManifest.xml:

[html]?view plaincopyprint?

<?xml?version="1.0"?encoding="utf-8"?>????

<manifest?xmlns:android="http://schemas.android.com/apk/res/android"????

??????package="com.wjh.camera"????

??????android:versionCode="1"????

??????android:versionName="1.0">????

????<uses-sdk?android:minSdkVersion="7"?/>????

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

????<uses-feature?android:name="android.hardware.camera.autofocus"?/>????

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

????<application?android:icon="@drawable/icon"?android:label="@string/app_name">????

????????<activity?android:name=".CameraTest_4"????

??????????????????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>????

</manifest>????

?

PS:其實自己去實現相機的必要性不大,大部分應用都是直接調用系統的相機,畢竟相機是涉及到一些比較專業的成像知識.

轉載于:https://www.cnblogs.com/qingchen1984/p/4766395.html

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