Php 为什么从Web服务器下载照片后会引发NullPointerException？

我正在从Web服务器下载一张照片。以下是在网页url中显示照片的PHP代码：

<?php
$rep = $_GET['dossierClient'];
    if (file_exists($rep))
    {
        $myDirectory = opendir($rep);

        while($entryName = readdir($myDirectory)) {
            $dirArray[] = $entryName;
        }

        closedir($myDirectory);

        $indexCount = count($dirArray);

        sort($dirArray);

        for($index=0; $index < $indexCount; $index++) 
        {
            if (substr("$dirArray[$index]", 0, 1) != ".")
            {
                print("<img src=$rep/$dirArray[$index] />");
                //print("\n");
            }
        }
    }
?>

这里的图像引用了LWUIT图像。 downloadImage方法的代码为：

private Image downloadImage(String url) throws IOException
    {
        Image img = null;
        byte[] rawImg = null;
        try
        {
            String imageData = getDataFromUrl(url);
            rawImg = imageData.getBytes();
            putPhotoToPhone(rawImg);
            img = Image.createImage(rawImg, 0, rawImg.length );
        }
        catch(Exception e1) {
            e1.printStackTrace();
        }

        return img;
    }
    public String getDataFromUrl(String url) throws IOException {

        StringBuffer b = new StringBuffer();
        InputStream is = null;
        HttpConnection c = null;

        long len = 0 ;
        int ch = 0;
        c = (HttpConnection)Connector.open(url);
        is = c.openInputStream();
        len = c.getLength();
        if( len != -1)
        {
            for(int i =0 ; i < len ; i++ )
            {
                if((ch = is.read()) != -1)
                {
                    b.append((char) ch);
                }
            }
        }
        else
        {
            while ((ch = is.read()) != -1)
            {
                len = is.available() ;
                b.append((char)ch);
            }
        }
        is.close();
        c.close();
        return b.toString();
    }
private void putPhotoToPhone(byte[] rawImg)
    {
        FileConnection fcDir, fcFile;
        int photoId, photoNextCounter;
        String fileName;
        OutputStream os;
        if (rawImg != null)
        {
            try {
                fcDir = (FileConnection) Connector.open("file:///"+pRoot+photoDirectory+"/", Connector.READ_WRITE);
                if(!fcDir.exists())
                    fcDir.mkdir();

                if (vPhotosName.isEmpty())
                    photoNextCounter = 1;
                else
                    photoNextCounter = 1;
                    //photoNextCounter = getNextImageCounter(fcDir, String.valueOf(backForm.vPhotosName.elementAt(backForm.vPhotosName.size()-1)));

                fileName = "photo_downloaded_" + photoNextCounter + ".png";
                fcFile = (FileConnection) Connector.open("file:///"+pRoot+photoDirectory+"/"+fileName, Connector.READ_WRITE);
                if(!fcFile.exists())
                    fcFile.create();
                os = fcFile.openOutputStream();
                os.write(rawImg);
                os.close();
                fcFile.close();
                fcDir.close();

                try {
                    photoId = rsImage.addRecord(rawImg, 0, rawImg.length);
                    vRawPhotoIDs.addElement(new Integer(photoId));
                }
                catch (RecordStoreException ex) {}
                vPhotosName.addElement(fileName);
            }
            catch (Exception e) {}
        }
    }

---

那么如何正确下载呢？

最有可能的情况是，您的图像无法下载，从而导致在调用该null参数上的image.getWidth时，传递给create缩略图的参数为null和NPE

---

如果您检查控制台，我猜您使用emulator进行调试，您可能会注意到来自e1.printStackTrace的堆栈跟踪；在下载图像的方法。检查它告诉您的信息，并尝试找出下载中出现的问题

我在浏览器的地址栏中键入了以下内容：，我得到了一个显示照片的正确网页。我右键点击了这个页面，我得到了它的源代码，它给出了：我想你刚刚回答了你自己的问题。downloadphoto.php提供的不是图像，而是包含标记和图像真实路径的html。我用模拟器对其进行了调试，是image.createImage造成了问题。@AndyFrédéric你知道image.createImage中有什么问题吗？例外还是零拉维姆？还是长度参数？还有什么？我找到了解决办法！！！我的错误在于url值的设置：我在谷歌上搜索了j2me下载照片，发现了一个教程，其中展示了设置url的方法。就是这样,；所以我在代码中设置url的方式是错误的。现在，在设置正确的url后，它可以正常工作！！！谢谢

private Image downloadImage(String url) throws IOException
    {
        Image img = null;
        byte[] rawImg = null;
        try
        {
            String imageData = getDataFromUrl(url);
            rawImg = imageData.getBytes();
            putPhotoToPhone(rawImg);
            img = Image.createImage(rawImg, 0, rawImg.length );
        }
        catch(Exception e1) {
            e1.printStackTrace();
        }

        return img;
    }
    public String getDataFromUrl(String url) throws IOException {

        StringBuffer b = new StringBuffer();
        InputStream is = null;
        HttpConnection c = null;

        long len = 0 ;
        int ch = 0;
        c = (HttpConnection)Connector.open(url);
        is = c.openInputStream();
        len = c.getLength();
        if( len != -1)
        {
            for(int i =0 ; i < len ; i++ )
            {
                if((ch = is.read()) != -1)
                {
                    b.append((char) ch);
                }
            }
        }
        else
        {
            while ((ch = is.read()) != -1)
            {
                len = is.available() ;
                b.append((char)ch);
            }
        }
        is.close();
        c.close();
        return b.toString();
    }
private void putPhotoToPhone(byte[] rawImg)
    {
        FileConnection fcDir, fcFile;
        int photoId, photoNextCounter;
        String fileName;
        OutputStream os;
        if (rawImg != null)
        {
            try {
                fcDir = (FileConnection) Connector.open("file:///"+pRoot+photoDirectory+"/", Connector.READ_WRITE);
                if(!fcDir.exists())
                    fcDir.mkdir();

                if (vPhotosName.isEmpty())
                    photoNextCounter = 1;
                else
                    photoNextCounter = 1;
                    //photoNextCounter = getNextImageCounter(fcDir, String.valueOf(backForm.vPhotosName.elementAt(backForm.vPhotosName.size()-1)));

                fileName = "photo_downloaded_" + photoNextCounter + ".png";
                fcFile = (FileConnection) Connector.open("file:///"+pRoot+photoDirectory+"/"+fileName, Connector.READ_WRITE);
                if(!fcFile.exists())
                    fcFile.create();
                os = fcFile.openOutputStream();
                os.write(rawImg);
                os.close();
                fcFile.close();
                fcDir.close();

                try {
                    photoId = rsImage.addRecord(rawImg, 0, rawImg.length);
                    vRawPhotoIDs.addElement(new Integer(photoId));
                }
                catch (RecordStoreException ex) {}
                vPhotosName.addElement(fileName);
            }
            catch (Exception e) {}
        }
    }

public Image createThumbnail(Image image) {
        int sourceWidth = image.getWidth();
        int sourceHeight = image.getHeight();
        int thumbWidth = 50;
        int thumbHeight = -1;

        if (thumbHeight == -1) {
            thumbHeight = thumbWidth * sourceHeight / sourceWidth;
        }
        Image thumb = image.scaled(thumbWidth, thumbHeight);
        return thumb;
    }