无法通过默认相机应用程序的意图拍摄照片

Question

我有三节课。一个父类，其中定义了按钮侦听器。第二类用于捕获pic，第三类用于获取pic的路径。但是我遇到了一些麻烦。

Startingactivity.java

 package xxxx.xxxx.xxxx;

import android.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;


public class StartingActivity extends AppCompatActivity {







@Override
protected void onCreate(Bundle savedInstanceState) {
    ActionBar actionBar=getActionBar();
    //actionBar.setTitle();          Put path name here.
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

            new CreateFolder();
   final Captureit captureit=new Captureit();

    Button add,pic,vid,settings;
    add=(Button)findViewById(R.id.addbutton);
    pic=(Button)findViewById(R.id.picbutton);
    vid=(Button)findViewById(R.id.vidbutton);
    settings=(Button)findViewById(R.id.setbutton);


    add.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });

        pic.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                captureit.capturepicture();
            }
        });
        vid.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                captureit.capturevideo();
            }
        });

    settings.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });

 }
 }

Captureit.java

package sagar.mehar.camera2;

import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.Toast;

import java.io.File;
import java.text.SimpleDateFormat;
import java.util.Date;



public class Captureit extends AppCompatActivity{

private static final int CAPTURE_VIDEO_ACTIVITY_REQUEST_CODE=200;
private static final int CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE=100;
public static final int MEDIA_TYPE_IMAGE=1;
public static final int MEDIA_TYPE_VIDEO=2;
private Uri fileUri;
public static CreateFolder createFolder=new CreateFolder();
Intent intent;




protected void onActivityResult(int requestCode, int resultCode, Intent data)
{
    if(requestCode==CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE)
    {
        if(resultCode==RESULT_OK)
        {//Image Captured
            Toast.makeText(this, "Image Captured ", Toast.LENGTH_SHORT).show();
        }
        else if(resultCode==RESULT_CANCELED)
        {//User Cancelled Image capture

        }
        else
        {//Image capture failed.
            Toast.makeText(this,"Image Captured Failed",Toast.LENGTH_SHORT).show();
        }
    }
    if(requestCode==CAPTURE_VIDEO_ACTIVITY_REQUEST_CODE)
    {
        if(resultCode==RESULT_OK)
        {
            Toast.makeText(this,"Video Captured",Toast.LENGTH_SHORT).show();
        }
        else if(resultCode==RESULT_CANCELED)
        {

        }else
        {//Video Capture Failed.
            Toast.makeText(this,"Video Captured Failed",Toast.LENGTH_SHORT).show();
        }
    }
}



public void capturepicture() {

    intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE);
    intent.putExtra(MediaStore.EXTRA_OUTPUT,fileUri);
    this.startActivityForResult(intent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);

}




public void capturevideo()
{
    intent=new Intent(MediaStore.ACTION_VIDEO_CAPTURE);
    fileUri=getOutputMediaFileUri(MEDIA_TYPE_VIDEO);//Create a file to save the video
    intent.putExtra(MediaStore.EXTRA_OUTPUT,fileUri);
    intent.putExtra(MediaStore.EXTRA_VIDEO_QUALITY,1);
    startActivityForResult(intent,CAPTURE_VIDEO_ACTIVITY_REQUEST_CODE);
}
private static Uri getOutputMediaFileUri(int type)
{
    return Uri.fromFile(getOutputMediaFile(type));
}
private static File getOutputMediaFile(int type)
{
    String timeStamp=new SimpleDateFormat("yyyyMMdd__HHmmss").format(new Date());
    File mediaFile;
    if(type==MEDIA_TYPE_IMAGE)
    {
        mediaFile=new File(createFolder.gettPath()+File.separator+"IMG_"+timeStamp+".jpg");
    }
    else if(type==MEDIA_TYPE_VIDEO)
    {
        mediaFile=new File(createFolder.gettPath()+File.separator+"VID_"+timeStamp+".mp4");
    }
    else
    {
        return null;
    }
    return mediaFile;
}

}

第三课正常运作。

清单代码是：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="xxxx.xxxx.xxxx"
>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.CAMERA"/>
<uses-feature android:name="android.hardware.camera2"/>
<uses-permission android:name="android.hardware.CAMERA"/>
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme" >
    <activity android:name=".StartingActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

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

</application>

但是，每当我点击按钮拍摄照片时，应用程序总会崩溃，并提供以下日志。

01-03 11:01:27.568 11291-11291/xxxx.xxxx.xxxx W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x419b9c98)
01-03 11:01:27.568 11291-11291/xxxx.xxxx.xxxx W/dalvikvm: threadid=1: uncaught exception occurred
01-03 11:01:27.568 11291-11291/xxxx.xxxx.xxxx W/System.err: java.lang.NullPointerException
01-03 11:01:27.569 11291-11291/xxxx.xxxx.xxxx W/System.err:     at android.app.Activity.startActivityForResult(Activity.java:3457)
01-03 11:01:27.569 11291-11291/xxxx.xxxx.xxxx W/System.err:     at android.app.Activity.startActivityForResult(Activity.java:3418)
01-03 11:01:27.570 11291-11291/xxxx.xxxx.xxxx W/System.err:     at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:748)
01-03 11:01:27.570 11291-11291/xxxx.xxxx.xxxx W/System.err:     at xxxx.xxxx.xxxx.Captureit.capturepicture(Captureit.java:72)
01-03 11:01:27.570 11291-11291/xxxx.xxxx.xxxx W/System.err:     at xxxx.xxxx.xxxx.StartingActivity$2.onClick(StartingActivity.java:48)
01-03 11:01:27.570 11291-11291/xxxx.xxxx.xxxx W/System.err:     at android.view.View.performClick(View.java:4463)
01-03 11:01:27.570 11291-11291/xxxx.xxxx.xxxx W/System.err:     at android.view.View$PerformClick.run(View.java:18770)
01-03 11:01:27.571 11291-11291/xxxx.xxxx.xxxx W/System.err:     at android.os.Handler.handleCallback(Handler.java:808)
01-03 11:01:27.571 11291-11291/xxxx.xxxx.xxxx W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:103)
01-03 11:01:27.571 11291-11291/xxxx.xxxx.xxxx W/System.err:     at android.os.Looper.loop(Looper.java:193)
01-03 11:01:27.571 11291-11291/xxxx.xxxx.xxxx W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5292)
01-03 11:01:27.571 11291-11291/xxxx.xxxx.xxxx W/System.err:     at java.lang.reflect.Method.invokeNative(Native Method)
01-03 11:01:27.571 11291-11291/xxxx.xxxx.xxxx W/System.err:     at java.lang.reflect.Method.invoke(Method.java:515)
01-03 11:01:27.572 11291-11291/xxxx.xxxx.xxxx W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:824)
01-03 11:01:27.572 11291-11291/xxxx.xxxx.xxxx W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:640)
01-03 11:01:27.572 11291-11291/xxxx.xxxx.xxxx W/System.err:     at dalvik.system.NativeStart.main(Native Method)
01-03 11:01:27.572 11291-11291/xxxx.xxxx.xxxx W/dalvikvm: threadid=1: calling UncaughtExceptionHandler
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime: FATAL EXCEPTION: main
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime: Process: xxxx.xxxx.xxxx, PID: 11291
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime: java.lang.NullPointerException
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at android.app.Activity.startActivityForResult(Activity.java:3457)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at android.app.Activity.startActivityForResult(Activity.java:3418)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:748)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at xxxx.xxxx.xxxx.Captureit.capturepicture(Captureit.java:72)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at xxxx.xxxx.xxxx.StartingActivity$2.onClick(StartingActivity.java:48)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at android.view.View.performClick(View.java:4463)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at android.view.View$PerformClick.run(View.java:18770)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at android.os.Handler.handleCallback(Handler.java:808)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:103)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:193)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5292)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:515)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:824)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:640)
01-03 11:01:27.574 11291-11291/xxxx.xxxx.xxxx E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method)

请帮帮我，我被困了好几个小时。请注意，将Captureit.java的代码移动到startingactivity.java会使应用程序正常工作但代码变得太乱。我只想让它们在不同的课程中工作。

Answer 1

您的第二个文件 - captureit.java - 无法成为活动。只能通过从意图的其他活动中调用startActivity()或startActivityForResult()来创建活动。当您调用new CaptureIt() onCreate()方法时，不会调用其他特定于活动的方法。这意味着活动没有正确的信息来做某些事情 - 比如开始另一项活动。

基本上，您尝试从Android中不存在的活动开始启动相机活动，因此它会抛出NullPointerException。

我建议将其移回同一个文件，直到您了解Android之间的活动之间的移动方式。

您仍然可以将辅助方法（getOutputMediaFile()等）拆分为另一个文件，以保持主活动文件的简单性。但是不要将其作为一项活动而不要从中调用startActivityForResult。