client-java: handle server HTTP errors (#3762)

* client-java: handle server HTTP errors

* Update SeaweedWrite.java

other/java/client/src/main/java/seaweedfs/client/SeaweedWrite.java

@@ -149,6 +149,13 @@ public class SeaweedWrite {
         CloseableHttpResponse response = SeaweedUtil.getClosableHttpClient().execute(post);
 
         try {
+            if (response.getStatusLine().getStatusCode() / 100 != 2) {
+                if (response.getEntity().getContentType() != null && response.getEntity().getContentType().getValue().equals("application/json")) {
+                    throw new IOException(EntityUtils.toString(response.getEntity(), "UTF-8"));
+                } else {
+                    throw new IOException(response.getStatusLine().getReasonPhrase());
+                }
+            }
 
             String etag = response.getLastHeader("ETag").getValue();