其实我是android的新手，我正在制作一个小型的Android应用程序，我可以捕获一张照片并将其上传到网络服务器，我找到了一些示例代码来实现它。
问题在于，当我启动应用程序时，它在横向或纵向上都很有效，但如果我将方向从横向更改为纵向或从纵向更改为横向，则会崩溃。
以下是Eclipse的日志：
04-26 13:04:36.380: I/dalvikvm(887): threadid=3: reacting to signal
3 04-26 13:04:36.510: I/dalvikvm(887): Wrote stack traces to '/data/anr/traces.txt'
04-26 13:04:36.880: I/dalvikvm(887): threadid=3: reacting to signal 3
04-26 13:04:36.890: I/dalvikvm(887): Wrote stack traces to '/data/anr/traces.txt'
04-26 13:04:37.180: D/gralloc_goldfish(887): Emulator without GPU emulation detected.
04-26 13:04:37.390: I/dalvikvm(887): threadid=3: reacting to signal 3
04-26 13:04:37.530: I/dalvikvm(887): Wrote stack traces to '/data/anr/traces.txt'
04-26 13:07:26.370: D/HEE(887): /mnt/sdcard/neosoft/ocr/photo/IMG_20130426_130726.jpg
04-26 13:07:27.840: D/dalvikvm(887): GC_FOR_ALLOC freed 128K, 3% free 9168K/9415K, paused 404ms
04-26 13:07:44.929: D/AndroidRuntime(887): Shutting down VM
04-26 13:07:44.929: W/dalvikvm(887): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
04-26 13:07:44.990: E/AndroidRuntime(887): FATAL EXCEPTION: main
04-26 13:07:44.990: E/AndroidRuntime(887): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.atakephoto1/com.example.atakephoto1.Photo1Activity}: java.lang.NullPointerException
04-26 13:07:44.990: E/AndroidRuntime(887): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
04-26 13:07:44.990: E/AndroidRuntime(887): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
04-26 13:07:44.990: E/AndroidRuntime(887): at android.app.ActivityThread.handleRelaunchActivity(ActivityThread.java:3351)
04-26 13:07:44.990: E/AndroidRuntime(887): at android.app.ActivityThread.access$700(ActivityThread.java:123)
04-26 13:07:44.990: E/AndroidRuntime(887): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1151)
04-26 13:07:44.990: E/AndroidRuntime(887): at android.os.Handler.dispatchMessage(Handler.java:99)
04-26 13:07:44.990: E/AndroidRuntime(887): at android.os.Looper.loop(Looper.java:137)
04-26 13:07:44.990: E/AndroidRuntime(887): at android.app.ActivityThread.main(ActivityThread.java:4424)
04-26 13:07:44.990: E/AndroidRuntime(887): at java.lang.reflect.Method.invokeNative(Native Method)
04-26 13:07:44.990: E/AndroidRuntime(887): at java.lang.reflect.Method.invoke(Method.java:511)
04-26 13:07:44.990: E/AndroidRuntime(887): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
04-26 13:07:44.990: E/AndroidRuntime(887): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
04-26 13:07:44.990: E/AndroidRuntime(887): at dalvik.system.NativeStart.main(Native Method)
04-26 13:07:44.990: E/AndroidRuntime(887): Caused by: java.lang.NullPointerException
04-26 13:07:44.990: E/AndroidRuntime(887): at com.example.atakephoto1.Photo1Activity.onCreate(Photo1Activity.java:139)
04-26 13:07:44.990: E/AndroidRuntime(887): at android.app.Activity.performCreate(Activity.java:4465)
04-26 13:07:44.990: E/AndroidRuntime(887): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
04-26 13:07:44.990: E/AndroidRuntime(887): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
04-26 13:07:44.990: E/AndroidRuntime(887): ... 12 more 04-26 13:07:45.751: I/dalvikvm(887): threadid=3: reacting to signal 3
04-26 13:07:45.760: I/dalvikvm(887): Wrote stack traces to '/data/anr/traces.txt'
这是我的java代码：
package com.example.atakephoto1;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.pm.PackageManager;
import android.content.res.Configuration;
import android.graphics.ImageFormat;
import android.hardware.Camera;
import android.hardware.Camera.AutoFocusCallback;
import android.hardware.Camera.Parameters;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.Size;
import android.util.Log;
import android.view.Menu;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.FrameLayout;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
public class Photo1Activity extends Activity {
//private AutoFocusCallback myAutoFocusCallback = null;
public static String image_file_path;
public static String php_upload_url;
public static String photoPath;
String TAG="tag";
private Camera mCamera;
private CameraPreview mPreview;
public static final int MEDIA_TYPE_IMAGE = 1;
public static final int MEDIA_TYPE_VIDEO = 2;
SQLiteDatabase db;
public String db_name = "config";
public String table_name = "config";
NewListDataSQL helper = new NewListDataSQL(Photo1Activity.this, db_name);
AutoFocusCallback myAutoFocusCallback = new AutoFocusCallback() {
public void onAutoFocus(boolean success, Camera camera) {
}
};
public static boolean exists(String URLName){
try {
HttpURLConnection.setFollowRedirects(false);
HttpURLConnection con =
(HttpURLConnection) new URL(URLName).openConnection();
con.setRequestMethod("HEAD");
return (con.getResponseCode() == HttpURLConnection.HTTP_OK);
}
catch (Exception e) {
e.printStackTrace();
return false;
}
}
protected void alertbox(String title, String mymessage) {
new AlertDialog.Builder(this)
.setMessage(mymessage)
.setTitle(title)
.setCancelable(true)
.setNeutralButton(android.R.string.cancel,
new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton){}
})
.show();
}
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
// some work that needs to be done on orientation change
}
@Override
public void onCreate(Bundle savedInstanceState) {
requestWindowFeature(Window.FEATURE_NO_TITLE);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_photo1);
db = helper.getReadableDatabase();
Cursor cursor = db.rawQuery("select value from config where name='image_save_path'", null);
int rows_num = cursor.getCount();
if(rows_num != 0) {
cursor.moveToFirst();
for(int i=0; i<rows_num; i++) {
String strCr = cursor.getString(0);
photoPath = strCr;
cursor.moveToNext();
}
}
cursor.close();
Cursor cursor_php = db.rawQuery("select value from config where name='php_upload_url'", null);
int rows_num_php = cursor_php.getCount();
if(rows_num_php != 0) {
cursor_php.moveToFirst();
for(int i=0; i<rows_num_php; i++) {
String strCr = cursor_php.getString(0);
php_upload_url = strCr;
cursor_php.moveToNext();
}
}
cursor_php.close();
// Create an instance of Camera
mCamera = getCameraInstance();
//final Camera.Parameters parameters = mCamera.getParameters();
Parameters parameters = mCamera.getParameters();
List<Size> sizes = parameters.getSupportedPictureSizes();
Camera.Size size = sizes.get(0);
for(int i=0;i<sizes.size();i++)
{
if(sizes.get(i).width > size.width)
size = sizes.get(i);
}
parameters.setPictureSize(size.width, size.height);
parameters.setPictureFormat(ImageFormat.JPEG);
parameters.setFlashMode(Parameters.FLASH_MODE_AUTO);
parameters.setFocusMode(Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
parameters.setSceneMode(Parameters.SCENE_MODE_AUTO);
parameters.setWhiteBalance(Parameters.WHITE_BALANCE_AUTO);
parameters.setExposureCompensation(0);
parameters.setPictureFormat(ImageFormat.JPEG);
parameters.setJpegQuality(100);
List<String> focusModes = parameters.getSupportedFocusModes();
if (focusModes.contains(Parameters.FOCUS_MODE_AUTO)){
parameters.setFocusMode(Parameters.FOCUS_MODE_AUTO);
}
mCamera.setParameters(parameters);
// 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);
final FrameLayout frame01 = (FrameLayout) findViewById(R.id.camera_preview);
frame01.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
mCamera.autoFocus(myAutoFocusCallback);
}
});
// Add a listener to the Capture button
final Button captureButton = (Button) findViewById(R.id.button_capture);
captureButton.setOnClickListener(
new View.OnClickListener() {
public void onClick(View v) {
// get an image from the camera
captureButton.setEnabled(false);
mCamera.autoFocus(myAutoFocusCallback);
mCamera.takePicture(null, null, mPicture);
}
}
);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_photo1, menu);
return true;
}
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;
}
}
/** A safe way to get an instance of the Camera object. */
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
}
/** A basic Camera preview class */
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
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.
}
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());
}
}
}
private PictureCallback mPicture = new PictureCallback() {
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
if (pictureFile == null){
Log.d(TAG, "Error creating media file, check storage permissions: ");
//e.getMessage());
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
image_file_path = pictureFile.getPath();
Log.d("HEE",pictureFile.getPath());
FileUploadTask fileuploadtask = new FileUploadTask();
fileuploadtask.execute();
mCamera.startPreview();
final Button captureButton = (Button) findViewById(R.id.button_capture);
captureButton.setEnabled(true);
} catch (FileNotFoundException e) {
Log.d(TAG, "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d(TAG, "Error accessing file: " + e.getMessage());
}
}
};
/** Create a file Uri for saving an image or video */
private static Uri getOutputMediaFileUri(int type){
return Uri.fromFile(getOutputMediaFile(type));
}
/** Create a File for saving an image or video */
private static File getOutputMediaFile(int type){
// To be safe, you should check that the SDCard is mounted
// using Environment.getExternalStorageState() before doing this.
String filepath = Environment.getExternalStorageDirectory().getPath();
File mediaStorageDir = new File(filepath, photoPath );
if(!mediaStorageDir.exists()){
Log.d("HERE",photoPath );
try
{
mediaStorageDir.mkdirs();
Log.d("HERE","after");
} catch (Exception e) {
Log.d("HERE",e.getMessage().toString());
}
}
// Create a media file name
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
if (type == MEDIA_TYPE_IMAGE){
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"IMG_"+ timeStamp + ".jpg");
} else if(type == MEDIA_TYPE_VIDEO) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator +
"VID_"+ timeStamp + ".mp4");
} else {
return null;
}
return mediaFile;
}
class FileUploadTask extends AsyncTask<Object, Integer, Void> {
private ProgressDialog dialog = null;
HttpURLConnection connection = null;
DataOutputStream outputStream = null;
DataInputStream inputStream = null;
String pathToOurFile = image_file_path;
String urlServer = php_upload_url;
String lineEnd = "\r\n";
String twoHyphens = "--";
String boundary = "*****";
File uploadFile = new File(pathToOurFile);
long totalSize = uploadFile.length(); // Get size of file, bytes
@Override
protected void onPreExecute() {
dialog = new ProgressDialog(Photo1Activity.this);
dialog.setMessage("Uploading...");
dialog.setIndeterminate(false);
dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
dialog.setProgress(0);
dialog.show();
}
@Override
protected Void doInBackground(Object... arg0) {
long length = 0;
int progress;
int bytesRead, bytesAvailable, bufferSize;
byte[] buffer;
int maxBufferSize = 256 * 1024;
try {
FileInputStream fileInputStream = new FileInputStream(new File(pathToOurFile));
URL url = new URL(urlServer);
connection = (HttpURLConnection) url.openConnection();
// Set size of every block for post
connection.setChunkedStreamingMode(256 * 1024);// 256KB
// Allow Inputs & Outputs
connection.setDoInput(true);
connection.setDoOutput(true);
connection.setUseCaches(false);
// Enable POST method
connection.setRequestMethod("POST");
connection.setRequestProperty("Connection", "Keep-Alive");
connection.setRequestProperty("Charset", "UTF-8");
connection.setRequestProperty("Content-Type",
"multipart/form-data;boundary=" + boundary);
outputStream = new DataOutputStream(
connection.getOutputStream());
outputStream.writeBytes(twoHyphens + boundary + lineEnd);
outputStream
.writeBytes("Content-Disposition: form-data; name=\"uploadedfile\";filename=\""
+ pathToOurFile + "\"" + lineEnd);
outputStream.writeBytes(lineEnd);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
buffer = new byte[bufferSize];
// Read file
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
while (bytesRead > 0) {
outputStream.write(buffer, 0, bufferSize);
length += bufferSize;
progress = (int) ((length * 100) / totalSize);
publishProgress(progress);
bytesAvailable = fileInputStream.available();
bufferSize = Math.min(bytesAvailable, maxBufferSize);
bytesRead = fileInputStream.read(buffer, 0, bufferSize);
}
outputStream.writeBytes(lineEnd);
outputStream.writeBytes(twoHyphens + boundary + twoHyphens
+ lineEnd);
publishProgress(100);
// Responses from the server (code and message)
// int serverResponseCode = connection.getResponseCode();
// String serverResponseMessage = connection.getResponseMessage();
fileInputStream.close();
outputStream.flush();
outputStream.close();
} catch (Exception ex) {
}
return null;
}
@Override
protected void onProgressUpdate(Integer... progress) {
dialog.setProgress(progress[0]);
}
@Override
protected void onPostExecute(Void result) {
try {
dialog.dismiss();
// TODO Auto-generated method stub
} catch (Exception e) {
}
}
}
}
答案 0 :(得分：1)
尝试使用
清单文件中的＆LT;活动名称=＆＃34; .YourActivity＆＃34; 机器人：configChanges =＆＃34;取向|屏幕尺寸＆＃34; /＆GT;
通过声明这个android将管理自己的活动状态。可能它会停止崩溃活动。
答案 1 :(得分：1)
将以下内容添加到清单中的活动中。
<activity
android:name=".YourActivity"
android:configChanges="orientation|keyboardHidden|screenSize">
</activity>
在YourActivity.java中
附加以下代码：
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
}
如果这仍然不起作用，请告诉我。
答案 2 :(得分：0)
尝试在活动的清单文件中添加以下属性
android:configChanges="keyboardHidden|orientation"
答案 3 :(得分：0)
确保调用Camera.release（）以在onPause（）中释放相机 并使用Camera.reconnect（）
在onResume（）中重新打开相机