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Android中创建相机应用教程

  • 时间:2016-09-09
  • 发布:济南Android培训
  • 来源:济南Android培训

在sdk中找到/sdk/docs/guide/topics/media/camera.html#custom-camera,里面有详细的api参考

在清单文件中添加相应的权限:

XML/HTML代码

按照官方文档,分为下面几步:

• Detect and Access Camera - Create code to check for the existence of cameras and request access.

• Create a Preview Class - Create a camera preview class that extends SurfaceView and implements theSurfaceHolder interface. This class previews the live images from the camera.

• Build a Preview Layout - Once you have the camera preview class, create a view layout that incorporates the preview and the user interface controls you want.

• Setup Listeners for Capture - Connect listeners for your interface controls to start image or video capture in response to user actions, such as pressing a button.

• Capture and Save Files - Setup the code for capturing pictures or videos and saving the output.

• Release the Camera - After using the camera, your application must properly release it for use by other applications.

接下来分别实现:

1、检查设备是否有照相机

Java代码

/** 检查设备是否存在照相机 */

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;

}

}

2、得到一个照相机

Java代码

/** 一种安全的方式获取Cameer对象的实例. */

public static Camera getCameraInstance(){

Camera c = null;

try {

c = Camera.open(); // attempt to get a Camera instance

}

catch (Exception e){

// Camera is not available (in use or does not exist)

}

return c; // returns null if camera is unavailable

}

3、新建一个名为CameraPreview的类

Java代码

package com.wuyudong.mycamera;

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 {

private static final String TAG = "CameraPreview";

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.

mHolder = getHolder();

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 {

mCamera.setPreviewDisplay(holder);

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());

}

}

}

4、设置一个预览功能的layout,将原来布局文件中的内容替换成下面的代码

XML/HTML代码

android:orientation="horizontal"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

>

android:id="@+id/camera_preview"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:layout_weight="1"

/>

android:id="@+id/button_capture"

android:text="Capture"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_gravity="center"

/>

5、在清单文件中加入 android:screenOrientation="landscape" 调整相机为横向拍摄

6、在MainActivity中添加

Java代码

public class MainActivity extends Activity {

private Camera mCamera;

private CameraPreview mPreview;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

// Create an instance of Camera

mCamera = getCameraInstance();

// Create our Preview view and set it as the content of our activity.

mPreview = new CameraPreview(this, mCamera);

FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);

preview.addView(mPreview);

}

}

7、实现拍摄按钮的功能

(1)添加拍照回调方法

Java代码

private PictureCallback mPicture = new PictureCallback() {

@Override

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

File pictureFile = new File("/sdcard/" + System.currentTimeMillis()+".jpg");

try {

FileOutputStream fos = new FileOutputStream(pictureFile);

fos.write(data);

fos.close();

} catch (IOException e) {

Log.d("TAG", "Error accessing file: " + e.getMessage());

}

}

};

给拍照按钮添加注册事件:

Java代码

// Add a listener to the Capture button

Button captureButton = (Button) findViewById(R.id.button_capture);

captureButton.setOnClickListener(

new View.OnClickListener() {

@Override

public void onClick(View v) {

// get an image from the camera

mCamera.takePicture(null, null, mPicture);

}

}

);

完整的代码如下:

Java代码

package com.wuyudong.mycamera;

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.sql.Date;

import android.os.Bundle;

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.util.Log;

import android.view.Menu;

import android.view.View;

import android.widget.Button;

import android.widget.FrameLayout;

public class MainActivity extends Activity {

private Camera mCamera;

private CameraPreview mPreview;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

// 创建一个 Camera 的实例

mCamera = getCameraInstance();

// 创建一个预览界面

mPreview = new CameraPreview(this, mCamera);

FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);

preview.addView(mPreview);

// Add a listener to the Capture button

Button captureButton = (Button) findViewById(R.id.button_capture);

captureButton.setOnClickListener(

new View.OnClickListener() {

@Override

public void onClick(View v) {

mCamera.autoFocus(new AutoFocusCallback() { // 对焦

@Override

public void onAutoFocus(boolean success, Camera camera) {

// get an image from the camera

mCamera.takePicture(null, null, mPicture);

}

});

}

}

);

}

/** 检查设备是否存在照相机 */

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;

}

}

/** 一种安全的方式获取Cameer对象的实例. */

public static Camera getCameraInstance() {

Camera c = null;

try {

c = Camera.open(); // attempt to get a Camera instance

} 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() {

@Override

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

File pictureFile = new File("/sdcard/" + System.currentTimeMillis()+".jpg");

try {

FileOutputStream fos = new FileOutputStream(pictureFile);

fos.write(data);

fos.close();

} catch (IOException e) {

Log.d("TAG", "Error accessing file: " + e.getMessage());

}

}

};

protected void onDestory() {

if(mCamera != null) { //释放资源

mCamera.release();

mCamera = null;

}

}

}

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