关于BitmapFactory.decodeStream(is)方法无法正常解码为Bitmap对象的解决方法

关于BitmapFactory.decodeStream(is)方法无法正常解码为Bitmap对象的解决方法

http://blog.csdn.net/andypan1314/article/details/6670320

</pre>在android sdk 1.6版本API帮助文档中，其中关于BitmapFactory.decodeFactory.decodeStream(InputStream is)的帮助文档是这么说明的：<p></p><p></p><pre name="code" class="html">
Bitmap android.graphics.BitmapFactory.decodeStream(InputStream is)

public static Bitmap decodeStream (InputStream is)
Since: API Level 1
Decode an input stream into a bitmap. <strong>If the input stream is null, or cannot be used to decode a bitmap, the function returns null</strong>. The stream's position will be where ever it was after the encoded data was read.

Parameters
is  The input stream that holds the raw data to be decoded into a bitmap.

Returns
The decoded bitmap, or null if the image data could not be decoded.

</pre>在android sdk 1.6版本API帮助文档中，其中关于BitmapFactory.decodeFactory.decodeStream(InputStream is)的帮助文档是这么说明的：<p></p><p></p><pre name="code" class="html"> Bitmap android.graphics.BitmapFactory.decodeStream(InputStream is) public static Bitmap decodeStream (InputStream is) Since: API Level 1 Decode an input stream into a bitmap. <strong>If the input stream is null, or cannot be used to decode a bitmap, the function returns null</strong>. The stream's position will be where ever it was after the encoded data was read. Parameters is The input stream that holds the raw data to be decoded into a bitmap. Returns The decoded bitmap, or null if the image data could not be decoded.

注意黑体字。以下是具体代码：

public static Bitmap bmpFromURL(URL imageURL){

    Bitmap result = null;

    try {

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

        connection.setDoInput(true);

        connection.connect();

        InputStream input = connection.getInputStream();

        result = BitmapFactory.decodeStream(input);


    } catch (IOException e) {


        e.printStackTrace();

    }

    return result;

}

public static Bitmap bmpFromURL(URL imageURL){ Bitmap result = null; try { HttpURLConnection connection = (HttpURLConnection)imageURL .openConnection(); connection.setDoInput(true); connection.connect(); InputStream input = connection.getInputStream(); result = BitmapFactory.decodeStream(input); } catch (IOException e) { e.printStackTrace(); } return result; }后来调试发现，result为null，加之查看帮助文档中的黑体字，
所以在所获得的InputStream不为空的情况下，调用BitmapFactory.decodeStream(is)方法，他也有可能无法解码成bitmap,刚开始我怀疑是本身图片地址有问题，或图片自身格式不正确，但通过浏览器查看，图片显示正常，而且，我是保存了几十张图片，但每次都会有个别几张图片无法正常显示，需要重复下载三四次，才可能保存成功。

后来在一篇文章中才发现，原来这是android 1.6版本的一个bug！

有牛人提出的一个解决办法，我试了试，问题解决了

首先在原方法中改一句：

result = BitmapFactory.decodeStream(new PatchInputStream(input));

result = BitmapFactory.decodeStream(new PatchInputStream(input));
再创建一个类：

public class PatchInputStream extends FilterInputStream{

        protected PatchInputStream(InputStream in) {
            super(in);
            // TODO Auto-generated constructor stub
        }

        public long skip(long n)throws IOException{
            long m=0l;
            while(m<n){
                long _m=in.skip(n-m);
                if(_m==0l){
                    break;
                }
                m+=_m;
            }
            return m;
        }

    }

public class PatchInputStream extends FilterInputStream{ protected PatchInputStream(InputStream in) { super(in); // TODO Auto-generated constructor stub } public long skip(long n)throws IOException{ long m=0l; while(m<n){ long _m=in.skip(n-m); if(_m==0l){ break; } m+=_m; } return m; } }

第二种方法：最终用的是这种方法

InputStream is = httpConn.getInputStream();

InputStream is = httpConn.getInputStream();

if (is == null){
    throw new RuntimeException("stream is null");
}else{
    try {
        byte[] data=readStream(is);
        if(data!=null){
            bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }

    is.close();
}

if (is == null){ throw new RuntimeException("stream is null"); }else{ try { byte[] data=readStream(is); if(data!=null){ bitmap = BitmapFactory.decodeByteArray(data, 0, data.length); } } catch (Exception e) { e.printStackTrace(); } is.close(); }

/*
     * 得到图片字节流 数组大小
     * */
    public static byte[] readStream(InputStream inStream) throws Exception{
        ByteArrayOutputStream outStream = new ByteArrayOutputStream();
        byte[] buffer = new byte[1024];
        int len = 0;
        while( (len=inStream.read(buffer)) != -1){
            outStream.write(buffer, 0, len);
        }
        outStream.close();
        inStream.close();
        return outStream.toByteArray();
    }