java opencv读取url中的图片（只有一张，情况特殊），返回Mat形式

采用imdecode函数

String strUrl = "http://...;
InputStream is = null;
ByteArrayOutputStream os = new ByteArrayOutputStream();
URL url = null;
try{
url = new URL(strUrl);
}catch (MalformedURLException e1){
e1.getMessage();
return -1;
}
try{
is = url.openStream();
}catch (IOException e2){
e2.getMessage();
return -1;
}
byte[] buffer = new byte[8192];
try {
int bytesRead = 0;
while((bytesRead = is.read(buffer,0,8192))!=-1){
os.write(buffer,0,bytesRead);
}
}catch (IOException e3){
e3.getMessage();
return -1;
}
try {
is.close();
}catch (IOException e4){
e4.getMessage();
return -1;
}
Mat encoded = new Mat(1, os.size(), CvType.CV_8U);
encoded.put(0, 0, os.toByteArray());
try {
os.close();
}catch (IOException e5){
e5.getMessage();
return -1;
}
//从内存中读，返回Mat形式
Mat decoded = Highgui.imdecode(encoded, -1);
encoded.release();
return decoded;