diff --git a/webmagic-core/src/main/java/us/codecraft/webmagic/downloader/HttpClientDownloader.java b/webmagic-core/src/main/java/us/codecraft/webmagic/downloader/HttpClientDownloader.java
index 80e7b72..31eebc7 100644
--- a/webmagic-core/src/main/java/us/codecraft/webmagic/downloader/HttpClientDownloader.java
+++ b/webmagic-core/src/main/java/us/codecraft/webmagic/downloader/HttpClientDownloader.java
@@ -7,6 +7,7 @@ import java.util.Map;
 import java.util.Optional;
 
 import org.apache.commons.io.IOUtils;
+import org.apache.http.HttpEntity;
 import org.apache.http.HttpResponse;
 import org.apache.http.client.methods.CloseableHttpResponse;
 import org.apache.http.impl.client.CloseableHttpClient;
@@ -85,13 +86,13 @@ public class HttpClientDownloader extends AbstractDownloader {
             page = handleResponse(request, request.getCharset() != null ? request.getCharset() : task.getSite().getCharset(), httpResponse, task);
 
             onSuccess(page, task);
-            logger.info("downloading page success {}", request.getUrl());
+            logger.info("Download page success: {}", request.getUrl());
 
             return page;
         } catch (IOException e) {
 
             onError(page, task, e);
-            logger.info("download page {} error", request.getUrl(), e);
+            logger.info("Download page error: {}", request.getUrl(), e);
 
             return page;
         } finally {
@@ -111,7 +112,8 @@ public class HttpClientDownloader extends AbstractDownloader {
     }
 
     protected Page handleResponse(Request request, String charset, HttpResponse httpResponse, Task task) throws IOException {
-        byte[] bytes = IOUtils.toByteArray(httpResponse.getEntity().getContent());
+        HttpEntity entity = httpResponse.getEntity();
+        byte[] bytes = entity != null ? IOUtils.toByteArray(entity.getContent()) : new byte[0];;
         String contentType = httpResponse.getEntity().getContentType() == null ? "" : httpResponse.getEntity().getContentType().getValue();
         Page page = new Page();
         page.setBytes(bytes);
diff --git a/webmagic-samples/pom.xml b/webmagic-samples/pom.xml
index d5849ae..035ec72 100644
--- a/webmagic-samples/pom.xml
+++ b/webmagic-samples/pom.xml
@@ -28,7 +28,7 @@
         <dependency>
             <groupId>org.mapdb</groupId>
             <artifactId>mapdb</artifactId>
-            <version>3.0.10</version>
+            <version>3.1.0</version>
         </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>