保存当前 ImageView 状态以关闭和重新打开应用

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，然后将该图片设置为ImageView，我已经成功了。 下一步是能够将图片保存在 imageView 中，以便即使在关闭并重新打开应用程序时图片也保持不变。我正在使用 SharedPrefrences 来存储一些其他值，但我找不到将其用于图像的方法。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应用程序图片目录，如下所示

1. 生成图像文件：

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;
}

2. 将图像文件 Uri 添加到IMAGE_CAPTURE意图：

   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);
   }
   

   }

3. 如果图像捕获成功，则将图像 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.然后设置文件提供程序：

在应用清单中.xml在标记内：

<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 从首选项加载图像文件 Uri 并显示：

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