Question

在我的应用程序中，我正在尝试从我的网站下载文件，但我遇到了一些问题。首先，我似乎无法找出声明URL的正确方法。其次，当我运行应用程序时，当我告诉连接获取InputStream时它会崩溃。我不知道我做错了什么。我一直在网上搜索下午的大部分时间，并尝试了很多方法来解决URL的问题，但没有成功。

我很想知道我做错了什么，所以给予的任何帮助都会非常感激。

package shc_BalloonSat.namespace;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLEncoder;

import org.apache.http.util.ByteArrayBuffer;

import android.util.Log;

public class dl_viewKML
{
    String file_path = "";
    String file_url;
    String file_name;

    void downloadFile()
    {
        try
        {
            String file_name = "data.kml";

            //URL url = new URL("http://space.uah.edu");
            String encodedURL = "http:////"+URLEncoder.encode("www.wktechnologies.com/shc_android_app/", "UTF-8");
            URL url = new URL(encodedURL);
            File file = new File(url + "/" + file_name);

            long startTime = System.currentTimeMillis();
            Log.d("SHC BalloonSat", "Download beginning: ");
            Log.d("SHC BalloonSat", "Download url: " + url);
            Log.d("SHC BalloonSat", "Downloaded file name: " + file_name);

            // Open a connection to the specified URL
            URLConnection conn = url.openConnection();

            // Define InputStreams to read from the URLConnection.
            InputStream is = conn.getInputStream();//crashes here
            BufferedInputStream bis = new BufferedInputStream(is);

            // Read bytes to the Buffer until there is nothing more to read(-1).
            ByteArrayBuffer baf = new ByteArrayBuffer(50);
            int current = 0;
            while ((current = bis.read()) != -1)
            {
                baf.append((byte) current);
            }

            // Convert the Bytes read to a String.
            FileOutputStream fos = new FileOutputStream(file);
            fos.write(baf.toByteArray());
            fos.close();
            Log.d("SHC BalloonSat", "Download ready in: " + ((System.currentTimeMillis() - startTime) / 1000) + " secs.");
            }

            catch (IOException e)
            {
                Log.e("log_tag", "Error: " + e.toString());
            }   
    }
}

Answer 1

无需使用url调用URLEncoder。 URLEncoder.encode用于编码参数：

所以请将您的代码编辑为：

void downloadFile()
{
    try
    {
        String file_name = "data.kml";

        //URL url = new URL("http://space.uah.edu");
        String encodedURL =         "http://"+"www.wktechnologies.com/shc_android_app/data.kml";
        URL url = new URL(encodedURL);

        // Open a connection to the specified URL
        URLConnection conn = url.openConnection();

        // Define InputStreams to read from the URLConnection.
        InputStream is = conn.getInputStream();//crashes here
        BufferedInputStream bis = new BufferedInputStream(is);

        // Read bytes to the Buffer until there is nothing more to read(-1).
        ByteArrayBuffer baf = new ByteArrayBuffer(50);
        int current = 0;
        while ((current = bis.read()) != -1)
        {
            baf.append((byte) current);
        }

        // Convert the Bytes read to a String.
        FileOutputStream fos = new FileOutputStream(file);
        fos.write(baf.toByteArray());
        fos.close();
        Log.d("SHC BalloonSat", "Download ready in: " + ((System.currentTimeMillis() - startTime) / 1000) + " secs.");
    }

    catch (IOException e)
    {
        Log.e("log_tag", "Error: " + e.toString());
    }

}

Answer 2

使用String encodedURL =“http://www.wktechnologies.com/shc_android_app/”; 对于您应用的编码，请参阅RFC3986（http://tools.ietf.org/html/rfc3986#section-3）的第3部分。它告诉您如何编码URI的各个部分。不幸的是，URI的每个部分（主机，路径，查询等）具有略微不同的编码规则。

Answer 3

确保在您的舱单中，您已经宣布了互联网许可。

您可以使用以下

public class dl_viewKML
{

private static final String encodedURL ="http://www.wktechnologies.com/shc_android_app/";
String file_path = "";
String file_url;
String file_name;

void downloadFile()
{
try
{
    String file_name = "data.kml";

    //URL url = new URL("http://space.uah.edu");

    URL url = new URL(encodedURL);
    File file = new File(url + "/" + file_name);

    long startTime = System.currentTimeMillis();
    Log.d("SHC BalloonSat", "Download beginning: ");
    Log.d("SHC BalloonSat", "Download url: " + url);
    Log.d("SHC BalloonSat", "Downloaded file name: " + file_name);

    // Open a connection to the specified URL
    URLConnection conn = url.openConnection();

    // Define InputStreams to read from the URLConnection.
    InputStream is = conn.getInputStream();//crashes here
    BufferedInputStream bis = new BufferedInputStream(is);

    // Read bytes to the Buffer until there is nothing more to read(-1).
    ByteArrayBuffer baf = new ByteArrayBuffer(50);
    int current = 0;
    while ((current = bis.read()) != -1)
    {
        baf.append((byte) current);
    }

    // Convert the Bytes read to a String.
    FileOutputStream fos = new FileOutputStream(file);
    fos.write(baf.toByteArray());
    fos.close();
    Log.d("SHC BalloonSat", "Download ready in: " + ((System.currentTimeMillis() - startTime) / 1000) + " secs.");
}

catch (IOException e)
{
    Log.e("log_tag", "Error: " + e.toString());
}

}

申请网址的正确方法？

3 个答案: