Solr 4.9.0 Tomcat SEVERE: Error filterStart

Error

SEVERE: Error filterStart

Solution:

For Solr Version  4.9.0

These jars are required in tomcat/7.0.23/lib/ directory-

slf4j-api-1.7.6.jar
slf4j-log4j12-1.7.6.jar

Url encode an HTTP GET Solr request and parse json using gson java library

Make a request to the SOLR webserver and parse the json string to Java classes using the code snippets below.
The JSON to be parsed-

	{
	"responseHeader": {
	"status": 0,
	"QTime": 1,
	"params": {
	"q": "searchterm1 OR searchterm2",
	"q.op": "AND",
	"wt": "json",
	"rows": "10000",
	"version": "2.2"
	}
	},
	"response": {
	"numFound": 2,
	"start": 0,
	"docs": [
	{
	"name": "searchterm1",
	"id": "1"
	},
	{
	"name": "searchterm2",
	"id": "2"
	}
	]
	}
	}

view raw Solr.json hosted with ❤ by GitHub

The corresponding Java classes-

	public class Documents {
	private String name;
	private String id;
	@Override
	public String toString() {
	return id+":"+name;
	}
	public String getName() {
	return name;
	}
	public String getID() {
	return id;
	}
	}
	public class Results {
	private String numFound;
	private ArrayList<Documents> docs;
	@Override
	public String toString() {
	return numFound +" - " + docs.toString();
	}
	public ArrayList<Documents> getDocs(){
	return docs;
	}
	public String getNumFound() {
	return numFound;
	}
	}
	public class Response {
	private Results response;
	@Override
	public String toString() {
	return response.toString();
	}
	}

view raw Classes.java hosted with ❤ by GitHub

Code snippet to make a web server call and parse using gson-

	String REQUEST_URL = "properties/select/?q=" + criteria
	+ "&q.op=AND&rows=10&version=2.2&wt=json";
	try {
	URL url = new URL(webServer + "properties/select/?q="
	+ URLEncoder.encode(criteria, "UTF-8")
	+ "&q.op=AND&rows=10&version=2.2&wt=json");
	BufferedReader in = new BufferedReader(
	new InputStreamReader(url.openStream()));
	String inputLine;
	while ((inputLine = in.readLine()) != null) {
	jsonString = inputLine;
	}
	in.close();
	//Create gson
	Gson gson = new GsonBuilder().create();
	Response r = gson.fromJson(jsonString, Response.class);
	LOG.info("MyGSON:" + r.toString());
	} catch (IOException e) {
	e.getMessage();
	e.printStackTrace();
	} catch (Exception e) {
	e.getMessage();
	e.printStackTrace();
	}

view raw ParseGson.java hosted with ❤ by GitHub

The Java classes must have the same variable names as the Json's keys. Notice how nested Json elements are handled.