Android中实现自定义的拍照应用

可以参考：http://www.android-doc.com/guide/topics/media/camera.html

一、添加相应的权限

<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" /><!-- 拍照的功能 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

<activity
android:name=".MainActivity"
android:label="@string/app_name"
android:screenOrientation="landscape"><!-- 写死横屏 -->
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

二、布局文件的配置

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<FrameLayout
android:id="@+id/camera_preview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1"
/>

<Button
android:id="@+id/button_capture"
android:text="Capture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
/>
</LinearLayout>

三、系统关键代码和注释

创建预览类CameraPreview：

import java.io.IOException;

import android.content.Context;
import android.hardware.Camera;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

/** A basic Camera preview class */
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
public static final String TAG = "camera";
private SurfaceHolder mHolder;
private Camera mCamera;

public CameraPreview(Context context, Camera camera) {
super(context);
mCamera = camera;

// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
//获取surfaceview的控制器
mHolder = getHolder();
//创建侦听
mHolder.addCallback(this);
// deprecated setting, but required on Android versions prior to 3.0
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

public void surfaceCreated(SurfaceHolder holder) {
// The Surface has been created, now tell the camera where to draw the preview.
try {
//设置摄像头预览界面在holder对应的那个surfaceview
mCamera.setPreviewDisplay(holder);
//开始预览
mCamera.startPreview();
} catch (IOException e) {
Log.d(TAG, "Error setting camera preview: " + e.getMessage());
}
}

public void surfaceDestroyed(SurfaceHolder holder) {
// empty. Take care of releasing the Camera preview in your activity.
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.

if (mHolder.getSurface() == null){
// preview surface does not exist
return;
}

// stop preview before making changes
try {
mCamera.stopPreview();
} catch (Exception e){
// ignore: tried to stop a non-existent preview
}

// set preview size and make any resize, rotate or
// reformatting changes here

// start preview with new settings
try {
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();

} catch (Exception e){
Log.d(TAG, "Error starting camera preview: " + e.getMessage());
}
}
}

主类MainActivity：

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

import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.Camera.AutoFocusCallback;
import android.hardware.Camera.PictureCallback;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;

public class MainActivity extends Activity {

private Camera mCamera;
private CameraPreview mPreview;

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

if(checkCameraHardware(this)){
// Create an instance of Camera
//创建摄像头实例
mCamera = getCameraInstance();
} else {
return;
}

// Create our Preview view and set it as the content of our activity.
//创建预览类的对象
mPreview = new CameraPreview(this, mCamera);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
//把预览类设置为帧布局的子节点
preview.addView(mPreview);

//给按钮设置监听
Button captureButton = (Button) findViewById(R.id.button_capture);
captureButton.setOnClickListener(
new View.OnClickListener() {
@Override
public void onClick(View v) {
//设置聚焦
mCamera.autoFocus(new AutoFocusCallback() {

@Override
public void onAutoFocus(boolean success, Camera camera) {
//进行拍照
mCamera.takePicture(null, null, mPicture);
}
});

}
}
);
}

/** 检测手机是否有摄像头 */
private boolean checkCameraHardware(Context context) {
if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){
// this device has a camera
return true;
} else {
// no camera on this device
return false;
}
}

/** 一个获取摄像头对象的安全实例 */
public static Camera getCameraInstance(){
Camera c = null;
try {
c = Camera.open(); //获取第一个后置摄像头的实例
}
catch (Exception e){
// Camera is not available (in use or does not exist)
}
return c; // returns null if camera is unavailable
}

private PictureCallback mPicture = new PictureCallback() {

//拍照时会调用此方法
//data：照片的字节数组
@Override
public void onPictureTaken(byte[] data, Camera camera) {

try {
File pictureFile = new File("sdcard/mr.jpg");
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
Log.d(CameraPreview.TAG, "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d(CameraPreview.TAG, "Error accessing file: " + e.getMessage());
} finally {
//拍照完成后重新进入预览
camera.startPreview();
}
}
};

}

显示效果：