introduce configuration for intercepting by default

Author: packowitz

src/main/java/com/github/greengerong/PreRenderSEOFilter.java

@@ -13,7 +13,7 @@
 public class PreRenderSEOFilter implements Filter {
     public static final List<String> PARAMETER_NAMES = Lists.newArrayList("preRenderEventHandler", "proxy", "proxyPort",
             "prerenderToken", "forwardedURLHeader", "crawlerUserAgents", "extensionsToIgnore", "whitelist",
-            "blacklist", "prerenderServiceUrl");
+            "blacklist", "prerenderServiceUrl", "interceptByDefault");
     private PrerenderSeoService prerenderSeoService;
 
     @Override

src/main/java/com/github/greengerong/PrerenderConfig.java

@@ -75,6 +75,14 @@ public String getPrerenderToken() {
     public String getForwardedURLHeader() {
         return config.get("forwardedURLHeader");
     }
+  
+    public boolean isInterceptByDefault() {
+      String interceptByDefault = config.get("interceptByDefault");
+      if(interceptByDefault != null) {
+        return Boolean.parseBoolean(interceptByDefault);
+      }
+      return true;
+    }
 
     public List<String> getCrawlerUserAgents() {
         List<String> crawlerUserAgents = Lists.newArrayList("googlebot", "yahoo", "bingbot", "baiduspider",

src/main/java/com/github/greengerong/PrerenderSeoService.java

@@ -119,18 +119,21 @@ private boolean shouldShowPrerenderedPage(HttpServletRequest request) throws URI
             return true;
         }
 
-        if (StringUtils.isBlank(userAgent)) {
-            log.trace("Request has blank userAgent; intercept: no");
-            return false;
-        }
+        boolean interceptByDefault = prerenderConfig.isInterceptByDefault();
+        if(interceptByDefault) {
+            if (StringUtils.isBlank(userAgent)) {
+                log.trace("Request has blank userAgent; intercept: no");
+                return false;
+            }
 
-        if (!isInSearchUserAgent(userAgent)) {
-            log.trace("Request User-Agent is not a search bot; intercept: no");
-            return false;
+            if (!isInSearchUserAgent(userAgent)) {
+               log.trace("Request User-Agent is not a search bot; intercept: no");
+               return false;
+            }
         }
 
-        log.trace(String.format("Defaulting to request intercept(user-agent=%s): yes", userAgent));
-        return true;
+        log.trace(String.format("Defaulting to request intercept(user-agent=%s): %s", userAgent, interceptByDefault ? "yes" : "no"));
+        return interceptByDefault;
     }
 
     protected HttpGet getHttpGet(String apiUrl) {