android – 如何使用共享首选项保存图像路径

我有一个活动,打开另一个活动,以获得相机画廊图片.图片返回到我原来的活动并在imageView中休息.这工作正常.如何保存图像,以便用户稍后返回或杀死应用程序时图像仍然存在.我知道我应该使用共享首选项来获取图像路径而不是保存图像本身,但我只是不知道如何做到这一点.

活动A.

private ImageView im1;
private String selectedImagePath;
private static final int SELECT_PICTURE = 1;

public void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (resultCode == RESULT_OK) {
    if (requestCode == SELECT_PICTURE) {
    Uri selectedImageUri = data.getData();
    selectedImagePath = getPath(selectedImageUri);
    System.out.println("Image Path : " + selectedImagePath);
    im1.setImageURI(selectedImageUri);
    }}}
public String getPath(Uri uri) {
    String[] projection = { MediaStore.Images.Media.DATA };
    Cursor cursor = managedQuery(uri, projection, null, null, null);
    int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
    cursor.moveToFirst();
    return cursor.getString(column_index);
    };
   ((Button)dialogView.findViewById(R.id.button3))
   .setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
    Intent intent = new Intent();
    intent.setType("image/*");
    intent.setAction(Intent.ACTION_GET_CONTENT);
    startActivityForResult(Intent.createChooser(intent,"Select Picture"), SELECT_PICTURE);
    }});

活动B.

Button send = (Button) findViewById(R.id.send);
    send.setOnClickListener(new OnClickListener() {
 public void onClick(View v) {              
            Intent intent=new Intent();
            setResult(RESULT_OK, intent);
            Bundle bundle=new Bundle();
            bundle.putInt("image",R.id.showImg);
            intent.putExtras(bundle);
            finish();

 public void onActivityResult(int requestCode, int resultCode, Intent data) {
         if (resultCode == RESULT_OK) {
         if (requestCode == SELECT_PICTURE) {
            Uri selectedImageUri = data.getData();
            selectedImagePath = getPath(selectedImageUri);
            System.out.println("Image Path : " + selectedImagePath);
            img.setImageURI(selectedImageUri);
        }}}

public String getPath(Uri uri) {
    String[] projection = { MediaStore.Images.Media.DATA };
    Cursor cursor = managedQuery(uri, projection, null, null, null);
    int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
    cursor.moveToFirst();
    return cursor.getString(column_index);
    }

使用图像覆盖Activity中的onPause()方法(以了解为什么onPause,检查活动图的生命周期： http://developer.android.com/reference/android/app/Activity.html),如下所示：

@Override
protected void onPause() {
    SharedPrefrences sp = getSharedPreferences("AppSharedPref", 0); // Open SharedPreferences with name AppSharedPref
    Editor editor = sp.edit();
    editor.putString("ImagePath", selectedImagePath); // Store selectedImagePath with key "ImagePath". This key will be then used to retrieve data.         
    editor.commit();
    super.onPause();
}

这意味着每当此Activity进入后台时,图像路径将保存在名称为AppSharedPref的SharedPreferences中 – 此名称可以是您喜欢的任何名称,但在检索数据时需要使用相同的名称.

然后在同一个Activity中覆盖onResume()方法,以便在Activity到达前台时检索图像路径：

@Override
protected void onResume() {
    SharedPreferences sp = getSharedPreferences("AppSharedPref", 0);
    selectedImagePath = settings.getString("ImagePath", "");
    super.onResume();
}

您可能还想使用覆盖其他方法,例如根据图表的onStart(),但我留给您.