求救啊安卓httpurlconnection.getinputstream报空指针异常

public Bitmap getBitmapFromURL(String urlString){
Bitmap bitmap ;
InputStream is=null ;
try {
URL url=new URL(urlString);
HttpURLConnection connection=(HttpURLConnection) url.openConnection();
is=new BufferedInputStream(connection.getInputStream());

        bitmap=BitmapFactory.decodeStream(is);

        connection.disconnect();

        return bitmap;
    } catch (java.io.IOException e) {
        e.printStackTrace();
    }finally{
        try {
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return null;

}
这个类出了问题，问题出现在connection.getInputStream()

确定几个东西，1.manifest是否声明了访问网络权限
2.urlstring是否真能访问

connection.setDoInput(true);
设置允许输入

再加上connection.setRequestMethod("POST");或者connection.setRequestMethod("GET");试试

connection.setDoInput(true);