从 JSON url 下载图像不起作用。 [关闭]

Posted 2023-05-07

【中文标题】从 JSON url 下载图像不起作用。 [关闭]

【英文标题】：Download image from JSON url is not working. [closed]

【发布时间】：2017-08-13 06:26:12

【问题描述】：

当我插入 SD 卡时它的工作。

如何将其保存到我的内部存储中？

我从 Url 下载了图像，并希望在插入 sd 卡时将其显示到我的手机上。 但是我的三星 Galaxy S6 edge plus 没有 SD 卡，因此无法下载图像。如何将图像保存到内部存储而不是外部存储中。

package com.example.makdia.tuntuninews;

import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;

import android.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.content.Intent;
import android.graphics.drawable.Drawable;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class ViewImage extends AppCompatActivity 


    Button btnShowProgress;
    String _id;
    // Progress Dialog
    private ProgressDialog pDialog;
    ImageView my_image;
    // Progress dialog type (0 - for Horizontal progress bar)
    public static final int progress_bar_type = 0;
    String _photo;
    // File url to download
    public static String file_url;

    TextView id, name;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_view_image);

        id = (TextView) findViewById(R.id.photoid);
        name = (TextView) findViewById(R.id.photoname);


        _id = getIntent().getStringExtra("MyID");
        file_url = getIntent().getStringExtra("MyPhoto");
        final String _name = getIntent().getStringExtra("MyName");

        id.setText("PhotoID = "+_id);
        name.setText("PhotoName = "+_name +" "+file_url+ "\n\n");


        btnShowProgress = (Button) findViewById(R.id.btnProgressBar);
        // Image view to show image after downloading
        my_image = (ImageView) findViewById(R.id.my_image);
        /**
         * Show Progress bar click event
         * */
        btnShowProgress.setOnClickListener(new View.OnClickListener() 

            @Override
            public void onClick(View v) 
                // starting new Async Task
                new DownloadFileFromURL().execute(file_url);
            
        );



    

    /**
     * Showing Dialog
     * */
    @Override
    protected Dialog onCreateDialog(int id) 
        switch (id) 
            case progress_bar_type: // we set this to 0
                pDialog = new ProgressDialog(this);
                pDialog.setMessage("Downloading file. Please wait...");
                pDialog.setIndeterminate(false);
                pDialog.setMax(100);
                pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                pDialog.setCancelable(true);
                pDialog.show();
                return pDialog;
            default:
                return null;
        
    

    /**
     * Background Async Task to download file
     * */
    class DownloadFileFromURL extends AsyncTask<String, String, String> 

        /**
         * Before starting background thread
         * Show Progress Bar Dialog
         * */
        @Override
        protected void onPreExecute() 
            super.onPreExecute();
            showDialog(progress_bar_type);
        

        /**
         * Downloading file in background thread
         * */
        @Override
        protected String doInBackground(String... f_url) 
            int count;
            try 
                URL url = new URL(f_url[0]);
                URLConnection conection = url.openConnection();
                conection.connect();
                // this will be useful so that you can show a tipical 0-100% progress bar
                int lenghtOfFile = conection.getContentLength();

                // download the file
                InputStream input = new BufferedInputStream(url.openStream(), 8192);

                // Output stream
                OutputStream output = new FileOutputStream("/sdcard/"+_id+".jpg");

                byte data[] = new byte[1024];

                long total = 0;

                while ((count = input.read(data)) != -1) 
                    total += count;
                    // publishing the progress....
                    // After this onProgressUpdate will be called
                    publishProgress(""+(int)((total*100)/lenghtOfFile));

                    // writing data to file
                    output.write(data, 0, count);
                

                // flushing output
                output.flush();

                // closing streams
                output.close();
                input.close();

             catch (Exception e) 
                Log.e("Error: ", e.getMessage());
            

            return null;
        

        /**
         * Updating progress bar
         * */
        protected void onProgressUpdate(String... progress) 
            // setting progress percentage
            pDialog.setProgress(Integer.parseInt(progress[0]));
        

        /**
         * After completing background task
         * Dismiss the progress dialog
         * **/
        @Override
        protected void onPostExecute(String file_url) 
            // dismiss the dialog after the file was downloaded
            dismissDialog(progress_bar_type);

            // Displaying downloaded image into image view
            // Reading image path from sdcard
            String imagePath = Environment.getExternalStorageDirectory().toString() +"/"+_id+".jpg";
            // setting downloaded into image view
            my_image.setImageDrawable(Drawable.createFromPath(imagePath));
        

    

【参考方案1】：

替换：

OutputStream output = new FileOutputStream("/sdcard/"+_id+".jpg");

与：

FileOutputStream outputStream = openFileOutput(_id+".jpg", Context.MODE_PRIVATE);

注意：在保存文件之前为存储添加运行时权限。希望这会有所帮助。

【讨论】：

它不起作用兄弟。可能是它6.0的问题。它说 storage/emulated/0/11.jpg 无法打开访问被拒绝

你能告诉我堆栈跟踪吗？你没有为存储添加运行时权限吗？

是的，既然你提到了它。我添加了运行时权限，现在它可以工作了:)

我认为这是一个正确答案并按下绿色按钮 :)

谢谢，我已经编辑了答案。