Question

我保留了一个处理ListView的学校项目，其中包含托管在服务器上的图像当有人从列表中选择一个图像时，这会在另一个布局中以“原始”尺寸显示，即使这里一切都很顺利但也要问图像显示器何时可以选择将其保存到SD卡中，这是我不能做的部分。

这是我做的代码：

public class MainActivity extends AppCompatActivity {

private ListView listView;
private ProgressDialog progressDialog;
ArrayList asuntos=new ArrayList();
ArrayList imagen=new ArrayList();

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolBar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolBar);
    listView=(ListView) findViewById(R.id.list);
    progressDialog = new ProgressDialog(this);
    progressDialog.setCancelable(false);
    lista o=new lista();
    o.obtenerAvisos();
}

public class lista {

    public void obtenerAvisos() {

        asuntos.clear();
        imagen.clear();

        String tag_string_req = "req_data";

        progressDialog.setMessage("Conectando...");
        showDialog();

        StringRequest strReq = new StringRequest(Request.Method.POST, AppURLs.URL, new Response.Listener<String>() {

            public void onResponse(String response) {

                hideDialog();

                try {

                    JSONArray jsonArray = new JSONArray(response);

                    for (int i = 0; i < jsonArray.length(); i++) {
                        asuntos.add(jsonArray.getJSONObject(i).getString("asunto"));
                        imagen.add(jsonArray.getJSONObject(i).getString("publicacion"));
                    }

                    listView.setAdapter(new ImagenAdaptador(getApplicationContext()));
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        }, new Response.ErrorListener() {

            public void onErrorResponse(VolleyError error) {

                Toast.makeText(getApplicationContext(), error.getMessage(), Toast.LENGTH_LONG).show();
                hideDialog();
            }
        }) {

            protected Map<String, String> getParams() {

                Map<String, String> params = new HashMap<String, String>();
                params.put("tag", "data");
                return params;
            }

        };
        AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
    }
}

private void showDialog() {

    if (!progressDialog.isShowing())
        progressDialog.show();
}

private void hideDialog() {

    if (progressDialog.isShowing())
        progressDialog.dismiss();
}

public class ImagenAdaptador extends BaseAdapter {

    Context ctx;
    LayoutInflater layoutInflater;
    SmartImageView smartImageView;
    TextView tvasunto;

    public ImagenAdaptador(Context applicationContext) {

        this.ctx=applicationContext;
        layoutInflater=(LayoutInflater)ctx.getSystemService(LAYOUT_INFLATER_SERVICE);
    }

    public int getCount() {
        return imagen.size();
    }

    public Object getItem(int position) {
        return position;
    }


    public long getItemId(int position) {
        return position;
    }


    public View getView(int position, View convertView, ViewGroup parent) {

        ViewGroup viewGroup=(ViewGroup) layoutInflater.inflate(R.layout.activity_main_items,null);
        smartImageView=(SmartImageView)viewGroup.findViewById(R.id.imagen1);
        tvasunto=(TextView) viewGroup.findViewById(R.id.tvAsunto);
        final String urlfinal="http://192.168.43.45/InfoTec/publicaciones/"+imagen.get(position).toString();
        Rect rect=new Rect(smartImageView.getLeft(), smartImageView.getTop(), smartImageView.getRight(), smartImageView.getBottom());
        smartImageView.setImageUrl(urlfinal, rect);
        tvasunto.setText(asuntos.get(position).toString());

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Intent intent = new Intent(MainActivity.this, Visor.class);
                intent.putExtra("arg", asuntos.get(position).toString());
                intent.putExtra("arg2",imagen.get(position).toString());
                startActivity(intent);
            }
        });
        return viewGroup;
    }
}
}

这部分有效，但这个课程就是问题：

public class Visor extends AppCompatActivity {

TextView tvasunto2;
SmartImageView smartImageView2;
Button descarga;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_visor);
    String original=getIntent().getStringExtra("arg");
    String imgOriginal=getIntent().getStringExtra("arg2");
    tvasunto2=(TextView) findViewById(R.id.tvAsunto2);
    smartImageView2=(SmartImageView) findViewById(R.id.imagen2);
    descarga=(Button) this.findViewById(R.id.button);

    tvasunto2.setText(original);
    String url="http://192.168.43.45/InfoTec/publicaciones/"+imgOriginal;
    Rect rect=new Rect(smartImageView2.getLeft(), smartImageView2.getTop(), smartImageView2.getRight(), smartImageView2.getBottom());
    smartImageView2.setImageUrl(url,rect);

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

        }
    });
}
}

如果显示所选图像，但现在不显示如何在下载按钮的情况下处理数据会有什么解决方案？

Answer 1

首先，您需要获取您的位图。您已经可以将它作为对象Bitmap，或者您可以尝试从ImageView获取它，例如：

im=img.resize((height,width), Image.ANTIALIAS);
im=np.array(im);
im=im.ravel();

然后你必须从SD卡到达目录（File对象），例如：

BitmapDrawable drawable = (BitmapDrawable) mImageView1.getDrawable();
Bitmap bitmap = drawable.getBitmap();

接下来，为图像存储创建特定文件：

File sdCardDirectory = Environment.getExternalStorageDirectory();

之后，由于其方法压缩，您只需编写位图，例如：

File image = new File(sdCardDirectory, "test.png");

最后，如果需要，只需处理布尔结果。如：

boolean success = false;

// Encode the file as a PNG image.
FileOutputStream outStream;
try {

    outStream = new FileOutputStream(image);
    bitmap.compress(Bitmap.CompressFormat.PNG, 100, outStream); 
    /* 100 to keep full quality of the image */

    outStream.flush();
    outStream.close();
    success = true;
} catch (FileNotFoundException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
}

请勿忘记在您的清单中添加以下权限：

if (success) {
    Toast.makeText(getApplicationContext(), "Image saved with success",
            Toast.LENGTH_LONG).show();
} else {
    Toast.makeText(getApplicationContext(),
            "Error during image saving", Toast.LENGTH_LONG).show();
}

Answer 2

最好创建一个对话框让用户选择他们想要存储照片的位置。请记住，有大量 Android 设备，它们可能会有所不同。

Android Studio：将图像保存在SD卡中

2 个答案: