如何使用端点在app engine上检索图像存储以及如何在Android应用程序中显示

我已经上传了应用程序引擎上的图像。我正在使用端点从应用程序引擎检索android应用程序中的图像blob键。我在android应用程序上做一些代码来显示图像。 代码是

URL imageURL = null;
try 
{
    //use our image serve page to get the image URL

    imageURL = new URL("http://yourapp.appspot.com/serveBlob?id=" + o.getImageKey());

} catch (MalformedURLException e) 
{
    e.printStackTrace();
}


try {
     //Decode and resize the image then set as the icon  
     BitmapFactory.Options options = new BitmapFactory.Options();

     options.inJustDecodeBounds = true;

     options.inSampleSize = 1 / 2;

     Bitmap bitmap = BitmapFactor.decodeStream((InputStream) imageURL.getContent());

     Bitmap finImg = Bitmap.createScaledBitmap(bitmap, 50, 50, false);

     icon.setImageBitmap(finImg);

} catch (IOException e) 
{
     e.printStackTrace();
}  

但它给了我

bitmap=null

并抛出空指针异常

从最近4天开始，我就对这一点印象深刻。请帮帮我。

试试这个

Bitmap bitmap = null;
    try {
                HttpURLConnection connection = (HttpURLConnection) imageURL
                        .openConnection();
                connection.setDoInput(true);
                connection.connect();
                InputStream inputStream = connection.getInputStream();

                bitmap = BitmapFactory.decodeStream(inputStream);

                Log.v("bitmap--", "" + bitmap);
                         icon.setImageBitmap(bitmap); 

            } catch (IOException e) {
                e.printStackTrace();
            }

我得到了答案

首先必须在我的项目的应用程序引擎端创建Servlet

Servlet是这样的

public class Serve extends HttpServlet  
{
   private BlobstoreService blobstoreService =BlobstoreServiceFactory.getBlobstoreService();

   public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException
   {
         BlobKey blobKey = new BlobKey(req.getParameter("id"));
         blobstoreService.serve(blobKey, resp);
   }

   public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException
   {
      doGet(req, resp);
   }

}

 URL imageURL = new URL("http://xyz.appspot.com/ServeBlob?id="+blobKey);


    HttpURLConnection connection = (HttpURLConnection) imageURL.openConnection();

    connection.setDoInput(true);

    connection.connect();

    InputStream inputStream = connection.getInputStream();


    Bitmap bitmap = BitmapFactory.decodeStream(inputStream);

ImageView img = (ImageView) findViewById(R.id....);

img.setImageBitmap(bitmap);

然后必须在web.xml中注册servlet

<servlet>
    <servlet-name>Serve</servlet-name>
    <servlet-class>com.xyz.Serve</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>Serve</servlet-name>
    <url-pattern>/ServeBlob</url-pattern>
</servlet-mapping>

xyz

是appspot上的应用程序引擎项目名称。

blobKey

应该是AppEngine上图像存储的blob键

现在像这样将位图传递到图像视图

public class Serve extends HttpServlet  
{
   private BlobstoreService blobstoreService =BlobstoreServiceFactory.getBlobstoreService();

   public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException
   {
         BlobKey blobKey = new BlobKey(req.getParameter("id"));
         blobstoreService.serve(blobKey, resp);
   }

   public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException
   {
      doGet(req, resp);
   }

}

 URL imageURL = new URL("http://xyz.appspot.com/ServeBlob?id="+blobKey);


    HttpURLConnection connection = (HttpURLConnection) imageURL.openConnection();

    connection.setDoInput(true);

    connection.connect();

    InputStream inputStream = connection.getInputStream();


    Bitmap bitmap = BitmapFactory.decodeStream(inputStream);

ImageView img = (ImageView) findViewById(R.id....);

img.setImageBitmap(bitmap);

---

如果能用一种更好、更可读的方式对代码进行格式化，那就太好了。是的，Lipis，我已经用一些格式化方法更新了我的问题。可以吗？你能验证用浏览器从你的imageURL下载图像是否有效吗？如果你能成功地将你的图像检索到你的android应用程序中，你可以查看下面的答案，了解我如何理解1rep人可能会弄错格式。。但为什么还要在答案上继续这个趋势呢？！Tamilan，它仍然得到位图--null，它的工作方式和以前的代码相同。