简单的Android摄像头应用程序 - 旋转导致NullPointerException异常 [英] Simple Android Camera App - Rotation causes NullPointerException
问题描述
我是新的Android开发，并用相机玩弄。我只是想创建一个简单的应用程序，将拍摄照片时使用本机摄像头的应用程序，并给我回的图像文件的路径。
我有工作正常，但我已经打了一个奇怪的错误。当我轻点按钮来启动相机，如果我改变屏幕的方向，而在摄像头的应用程序，而不用切换回我退出相机（pressing完成按钮之前，当我问我想夺回与否），它会导致抛出NullPointerException。
我在一个有点不知所措的我在这里就如何计算这一个，所以任何信息将是有益的！
下面是code我到目前为止有：
包com.CameraTest;
进口android.app.Activity;
进口android.content.ContentValues;
进口android.content.Intent;
进口android.database.Cursor;
进口android.net.Uri;
进口android.os.Bundle;
进口android.provider.MediaStore;
进口android.view.View;
进口android.widget.Button;
进口android.widget.TextView;
公共类CameraTestActivity扩展活动
{
私有静态最终诠释CAMERA_PIC_REQUEST = 1234;
保护乌里mCapturedImageURI;
受保护的TextView TextView的;
保护Button按钮;
/ **第一次创建活动时调用。 * /
@覆盖公共无效的onCreate（包savedInstanceState）
{
super.onCreate（savedInstanceState）;
的setContentView（R.layout.main）;
按钮=（按钮）findViewById（R.id.button1）;
TextView的=（的TextView）findViewById（R.id.textView1）;
如果（savedInstanceState！= NULL）{
textview.setText（savedInstanceState.getString（TextView中））;
}
button.setOnClickListener（新View.OnClickListener（）
{
公共无效的onClick（视图查看）
{
字符串文件名=temp.jpg;
ContentValues值=新ContentValues（）;
values.put（MediaStore.Images.Media.TITLE，文件名）;
mCapturedImageURI = getContentResolver（）插入（MediaStore.Images.Media.EXTERNAL_CONTENT_URI，值）。
意向意图=新的意图（MediaStore.ACTION_IMAGE_CAPTURE）;
intent.putExtra（MediaStore.EXTRA_OUTPUT，mCapturedImageURI）;
startActivityForResult（意向，CAMERA_PIC_REQUEST）;
}
}）;
}
@覆盖保护无效的onSaveInstanceState（包outState）
{
super.onSaveInstanceState（outState）;
outState.putString（TextView的，textview.getText（）的toString（））;
}
保护无效onActivityResult（INT申请code，INT结果code，意图数据）
{
super.onActivityResult（要求code，因此code，数据）;
如果（要求code == CAMERA_PIC_REQUEST和放大器;＆安培;结果code == -1）
{
的String []投影= {MediaStore.Images.Media.DATA};
光标光标= managedQuery（this.mCapturedImageURI，投影，NULL，NULL，NULL）;
INT column_index_data = cursor.getColumnIndexOrThrow（MediaStore.Images.Media.DATA）;
cursor.moveToFirst（）;
字符串capturedImageFilePath = cursor.getString（column_index_data）;
this.textview.setText（文件路径：+ capturedImageFilePath）;
}
}
}
你必须改变你的清单文件
在你的清单只需更换低于code
＆LT;活动机器人：名称=。CameraTestActivity
机器人：标签=@字符串/ APP_NAME机器人：configChanges =keyboardHidden |定位＆GT;
您code
＆LT;活动机器人：名称=。CameraTestActivity
机器人：标签=@字符串/ APP_NAME＆GT;
I'm new to Android development and was playing around with the camera. I just wanted to create a simple app that would take a photo using the native camera app and give me back the file path of that image.
I have that working fine, but I've hit a strange error. When I tap the button to launch the camera, if I change the orientation of the screen while in the camera app, and don't switch back before I exit the camera (pressing the Done button when I'm asked if I want to retake or not), it causes a NullPointerException to be thrown.
I'm at a bit of a loss here as to how to figure this one out, so any information would be helpful!
Here is the code I have so far:
package com.CameraTest;
import android.app.Activity;
import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class CameraTestActivity extends Activity
{
private static final int CAMERA_PIC_REQUEST = 1234;
protected Uri mCapturedImageURI;
protected TextView textview;
protected Button button;
/** Called when the activity is first created. */
@Override public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
button = (Button) findViewById(R.id.button1);
textview = (TextView) findViewById(R.id.textView1);
if (savedInstanceState != null) {
textview.setText(savedInstanceState.getString("textview"));
}
button.setOnClickListener(new View.OnClickListener()
{
public void onClick(View view)
{
String fileName = "temp.jpg";
ContentValues values = new ContentValues();
values.put(MediaStore.Images.Media.TITLE, fileName);
mCapturedImageURI = getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
intent.putExtra(MediaStore.EXTRA_OUTPUT, mCapturedImageURI);
startActivityForResult(intent, CAMERA_PIC_REQUEST);
}
});
}
@Override protected void onSaveInstanceState(Bundle outState)
{
super.onSaveInstanceState(outState);
outState.putString("textview", textview.getText().toString());
}
protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == CAMERA_PIC_REQUEST && resultCode == -1)
{
String[] projection = { MediaStore.Images.Media.DATA};
Cursor cursor = managedQuery(this.mCapturedImageURI, projection, null, null, null);
int column_index_data = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
cursor.moveToFirst();
String capturedImageFilePath = cursor.getString(column_index_data);
this.textview.setText("File Path:" + capturedImageFilePath);
}
}
}
you have to change your manifest file
in your manifest just replace below code
<activity android:name=".CameraTestActivity"
android:label="@string/app_name" android:configChanges="keyboardHidden|orientation">
with your code
<activity android:name=".CameraTestActivity"
android:label="@string/app_name">
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