Prerender Java

Are you using backbone, angular, emberjs, etc, but you're unsure about the SEO implications?

Use this java filter that prerenders a javascript-rendered page using an external service and returns the HTML to the search engine crawler for SEO.

Note: If you are using a # in your urls, make sure to change it to #!. View Google's ajax crawling protocol

Note: Make sure you have more than one webserver thread/process running because the prerender service will make a request to your server to render the HTML.

1:Add this line to your web.xml:

<filter>
      <filter-name>prerender</filter-name>
      <filter-class>com.github.greengerong.PreRenderSEOFilter</filter-class>
      <init-param>
          <param-name>prerenderServiceUrl</param-name>
          <param-value>http://localhost:3000</param-value>
      </init-param>
      <init-param>
          <param-name>crawlerUserAgents</param-name>
          <param-value>me</param-value>
      </init-param>
  </filter>
  <filter-mapping>
      <filter-name>prerender</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>

2:add dependency on your project pom:

<dependency>
  <groupId>com.github.greengerong</groupId>
  <artifactId>prerender-java</artifactId>
  <version>1.6.4-SNAPSHOT</version>
</dependency>

How it works

1. Check to make sure we should show a prerendered page
   1. Check if the request is from a crawler (_escaped_fragment_ or agent string)
   2. Check to make sure we aren't requesting a resource (js, css, etc...)
   3. (optional) Check to make sure the url is in the whitelist
   4. (optional) Check to make sure the url isn't in the blacklist
2. Make a GET request to the prerender service(phantomjs server) for the page's prerendered HTML
3. Return that HTML to the crawler

Customization

crawlerUserAgents

example: someproxy,someproxy1

whitelist

blacklist

forwardedURLHeader

Important for servers behind reverse proxy that need the public url to be used for pre-rendering. We usually set the original url in an http header which is added by the reverse proxy (similar to the more standard x-forwarded-proto and x-forwarded-for)

Using your own prerender service

If you've deployed the prerender service on your own, set the PRERENDER_SERVICE_URL environment variable so that this package points there instead. Otherwise, it will default to the service already deployed at http://prerender.herokuapp.com

$ export PRERENDER_SERVICE_URL=<new url>

Or on heroku:

$ heroku config:add PRERENDER_SERVICE_URL=<new url>

As an alternative, you can pass prerender_service_url in the options object during initialization of the middleware

 config filter init param with "prerenderServiceUrl";

prerender service token

If you want to use token with the prerender service, you can config it.

 config filter init param with "prerenderToken";

prerender event handler

If you want to cache the caching, analytics, log or others, you can config it. It should be instance of "com.github.greengerong.PreRenderEventHandler"

 config filter init param with "preRenderEventHandler";

Testing

If you want to make sure your pages are rendering correctly:

1. Open the Developer Tools in Chrome (Cmd + Atl + J)
2. Click the Settings gear in the bottom right corner.
3. Click "Overrides" on the left side of the settings panel.
4. Check the "User Agent" checkbox.
5. Choose "Other..." from the User Agent dropdown.
6. Type googlebot into the input box.
7. Refresh the page (make sure to keep the developer tools open).

License

The MIT License (MIT)