保存当前 ImageView 状态以关闭和重新打开应用程序

Question

我正在尝试制作一个应用程序，我可以在其中拍摄某物的照片，然后将该照片设置为 ImageView，我已经成功了。下一步是能够将图片保存在 imageView 中，这样即使关闭并重新打开应用程序，图片也保持不变。我正在使用 SharedPrefrences 来存储其他一些值，但我找不到将它用于图像的方法。这是我的代码：


package com.example.pongrknare;

import android.content.Intent;
import android.content.SharedPreferences;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.media.Image;
import android.provider.MediaStore;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Base64;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.ImageView;
import android.widget.Switch;
import android.widget.TextView;

import java.io.IOException;

public class MainActivity extends AppCompatActivity {

   private ImageView imageView1;
   private ImageView imageView2;
   private ImageView imageView3;
   private ImageView imageView4;
   private ImageView imageView5;
   private ImageView imageView6;
   private TextView textView1;
   private TextView textView2;
   private TextView textView3;
   private TextView textView4;
   private TextView textView5;
   private TextView textView6;
   private Switch undoSwitch;
   private int nr = 1;
   private int p1 = 0;
   private int p2 = 0;
   private int p3 = 0;
   private int p4 = 0;
   private int p5 = 0;
   private int p6 = 0;


   public static final String SHARED_PREFS = "sharedPrefs";
   public static final String P1 = "P1_value";
   public static final String P2 = "P2_value";
   public static final String P3 = "P3_value";
   public static final String P4 = "P4_value";
   public static final String P5 = "P5_value";
   public static final String P6 = "P6_value";


   private static final int REQUEST_IMAGE_CAPTURE = 101;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.activity_main);
        imageView1 = findViewById(R.id.imageView1);
        imageView2 = findViewById(R.id.imageView2);
        imageView3 = findViewById(R.id.imageView3);
        imageView4 = findViewById(R.id.imageView4);
        imageView5 = findViewById(R.id.imageView5);
        imageView6 = findViewById(R.id.imageView6);
        textView1 = findViewById(R.id.textView1);
        textView2 = findViewById(R.id.textView2);
        textView3 = findViewById(R.id.textView3);
        textView4 = findViewById(R.id.textView4);
        textView5 = findViewById(R.id.textView5);
        textView6 = findViewById(R.id.textView6);

       undoSwitch = findViewById(R.id.undoSwitch);

       loadData();
       update_text();

}

   public void takePicture1(View view) {
       Intent imageTakeIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

       nr = 1;

       if(imageTakeIntent.resolveActivity(getPackageManager()) != null){
           startActivityForResult(imageTakeIntent,REQUEST_IMAGE_CAPTURE);
       }
   }
   public void takePicture2(View view) {
       Intent imageTakeIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

       nr = 2;

       if(imageTakeIntent.resolveActivity(getPackageManager()) != null){
           startActivityForResult(imageTakeIntent,REQUEST_IMAGE_CAPTURE);
       }
   }
   public void takePicture3(View view) {
       Intent imageTakeIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

       nr = 3;

       if(imageTakeIntent.resolveActivity(getPackageManager()) != null){
           startActivityForResult(imageTakeIntent,REQUEST_IMAGE_CAPTURE);
       }
   }
   public void takePicture4(View view) {
       Intent imageTakeIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

       nr = 4;

       if(imageTakeIntent.resolveActivity(getPackageManager()) != null){
           startActivityForResult(imageTakeIntent,REQUEST_IMAGE_CAPTURE);
       }
   }
   public void takePicture5(View view) {
       Intent imageTakeIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

       nr = 5;

       if(imageTakeIntent.resolveActivity(getPackageManager()) != null){
           startActivityForResult(imageTakeIntent,REQUEST_IMAGE_CAPTURE);
       }
   }
   public void takePicture6(View view) {
       Intent imageTakeIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

       nr = 6;

       if(imageTakeIntent.resolveActivity(getPackageManager()) != null){
           startActivityForResult(imageTakeIntent,REQUEST_IMAGE_CAPTURE);
       }
   }

   @Override
   public boolean onCreateOptionsMenu(Menu menu) {
       MenuInflater inflater = getMenuInflater();
       inflater.inflate(R.menu.reset_menu, menu);

       return true;
   }
   @Override
   public boolean onOptionsItemSelected(MenuItem item) {

       switch (item.getItemId()){
           case R.id.ja1:
               p1 = 0;
               p2 = 0;
               p3 = 0;
               p4 = 0;
               p5 = 0;
               p6 = 0;
               update_text();
               return true;
           case R.id.ja2:

               imageView1.setImageResource(R.color.colorImage);
               imageView2.setImageResource(R.color.colorImage);
               imageView3.setImageResource(R.color.colorImage);
               imageView4.setImageResource(R.color.colorImage);
               imageView5.setImageResource(R.color.colorImage);
               imageView6.setImageResource(R.color.colorImage);




               return true;

       }



       return super.onOptionsItemSelected(item);
   }

   private void update_text(){

       textView1.setText("" + p1);
       textView2.setText("" + p2);
       textView3.setText("" + p3);
       textView4.setText("" + p4);
       textView5.setText("" + p5);
       textView6.setText("" + p6);

   }


   @Override
  protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {


     if (nr==1) {
         Bundle extras = data.getExtras();
         Bitmap imageBitmap1 = (Bitmap) extras.get("data");
         imageView1.setImageBitmap(imageBitmap1);
         saveData();
     } else if(nr == 2){
         Bundle extras = data.getExtras();
         Bitmap imageBitmap2 = (Bitmap) extras.get("data");
         imageView2.setImageBitmap(imageBitmap2);
         saveData();
     }else if(nr == 3){
         Bundle extras = data.getExtras();
         Bitmap imageBitmap3 = (Bitmap) extras.get("data");
         imageView3.setImageBitmap(imageBitmap3);
         saveData();
     }else if(nr == 4){
         Bundle extras = data.getExtras();
         Bitmap imageBitmap4 = (Bitmap) extras.get("data");
         imageView4.setImageBitmap(imageBitmap4);
         saveData();
     }else if(nr == 5){
         Bundle extras = data.getExtras();
         Bitmap imageBitmap5 = (Bitmap) extras.get("data");
         imageView5.setImageBitmap(imageBitmap5);
         saveData();
     }else if(nr == 6){
         Bundle extras = data.getExtras();
         Bitmap imageBitmap6 = (Bitmap) extras.get("data");
         imageView6.setImageBitmap(imageBitmap6);
         saveData();
     }else{
         return;
     }
   }

   public void count1(View view) {
       if (undoSwitch.isChecked()== false) {
           p1++;
       }else if(p1> 0){
           p1--;
       }

       textView1.setText(""+p1);
       saveData();
   }
   public void count2(View view) {

       if (undoSwitch.isChecked()== false) {
           p2++;
       }else if(p2>0){
           p2--;
       }
       textView2.setText(""+p2);
       saveData();
   }
   public void count3(View view) {

       if (undoSwitch.isChecked()== false) {
           p3++;
       }else if(p3>0){
           p3--;
       }

       textView3.setText(""+p3);
       saveData();
   }
   public void count4(View view) {

       if (undoSwitch.isChecked()== false) {
           p4++;
       }else if(p4>0){
           p4--;
       }

       textView4.setText(""+p4);
       saveData();
   }
   public void count5(View view) {

       if (undoSwitch.isChecked()== false) {
           p5++;
       }else if(p5>0){
           p5--;
       }

       textView5.setText(""+p5);
       saveData();
   }
   public void count6(View view) {

       if (undoSwitch.isChecked()== false) {
           p6++;
       }else if(p6>0){
           p6--;
       }

       textView6.setText(""+p6);
       saveData();
   }

   public void saveData(){

       SharedPreferences sharedPreferences = getSharedPreferences(SHARED_PREFS, MODE_PRIVATE);
       SharedPreferences.Editor editor = sharedPreferences.edit();

       editor.putInt(P1, p1);
       editor.putInt(P2, p2);
       editor.putInt(P3, p3);
       editor.putInt(P4, p4);
       editor.putInt(P5, p5);
       editor.putInt(P6, p6);


       editor.apply();

   }

   public void loadData(){

       SharedPreferences sharedPreferences = getSharedPreferences(SHARED_PREFS, MODE_PRIVATE);

       p1 = sharedPreferences.getInt(P1, 0);
       p2 = sharedPreferences.getInt(P2, 0);
       p3 = sharedPreferences.getInt(P3, 0);
       p4 = sharedPreferences.getInt(P4, 0);
       p5 = sharedPreferences.getInt(P5, 0);
       p6 = sharedPreferences.getInt(P6, 0);

   }

}

Answer 1

您可以将照片保存到app图片目录如下

1.生成镜像文件：

private File createImageFile() throws IOException {
    String timestamp = new SimpleDateFormat("yyyyMMdd_Hms").format(new Date());
    String fileName = "JPEG_" + timestamp + "_";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File photoImage = File.createTempFile(fileName, ".jpg", storageDir);

    // Store this value in field to use later
    picture1Path = photoImage.getAbsolutePath();
    return photoImage;
}

将图像文件 Uri 添加到 IMAGE_CAPTURE 意图中：

private void takePicture1() {
Intent imageTakeIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
File photoFile = null;

try {
    photoFile = createImageFile();
} catch (IOException e) {
    Log.e(MainActivity.class.getSimpleName(), e.getMessage(), e);
}

// Add file Uri to intent
if (photoFile != null) {
    Uri photoUri = FileProvider.getUriForFile(
            this,"com.your_app_package.fileprovider", photoFile);
    imageTakeIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoUri);
}

if(imageTakeIntent.resolveActivity(getPackageManager()) != null){
    startActivityForResult(imageTakeIntent,REQUEST_IMAGE_CAPTURE);
}

}

如果图像捕获成功，将图像 Uri 保存到共享首选项：

@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == REQUEST_IMAGE_CAPTURE) {
    if (resultCode == Activity.RESULT_OK) {
        setPic();
        // Save imageUri
        preferences.edit().putString("image1Uri", currentPhotoPath).apply();
    }
}

}

private void setPic() {
// load and display pic
Bitmap bitmap = BitmapFactory.decodeFile(currentPhotoPath);
imageView1.setImageBitmap(bitmap);
}

4.然后设置FileProvider：

在应用内manifest.xml标签内：

        <provider
        android:name="androidx.core.content.FileProvider"
        android:authorities="com.your_app_package.fileprovider"
        android:exported="false"
        android:grantUriPermissions="true">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/file_paths" />

    </provider>

还包括 WRITE_EXTERNAL_STORAGE 权限。

创建 "file_paths.xml" 并添加：

    <paths>
        <external-files-path name="my_images" path="/"/>
    </paths>

然后在 onCreate 中从首选项加载图像文件 Uri 并显示：

        currentPhotoPath = preferences.getString("image1Uri", null);
    if (currentPhotoPath != null) {
        setPic();
    }

保存当前 ImageView 状态以关闭和重新打开应用程序

Saving current ImageView state for closing and reopening a app

android

android-studio

imageview

save

sharedpreferences