JsonApi.java

package JsonClient.Java;

import java.net.MalformedURLException;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;

import JsonClient.Java.urlstuff.UrlHelper;

/**
 * High-level JSON API
 * 
 * @author justin nelson
 * 
 */
public class JsonApi {

	// holds parameters that will always be passed into the url
	private Map<String, String> constantParameters;

	private JsonClient client;
	private String baseUrl;

	/**
	 * Create a new JsonApi given a base URL for the API and the JsonClient to use.
	 * 
	 * @param baseUrl
	 *            the base url for the API
	 * @param client
	 *            the JsonCLient to pass requests to.
	 */
	public JsonApi(String baseUrl, JsonClient client) {
		if (client == null)
			throw new NullPointerException("JsonClient must not be null");
		if (baseUrl == null || baseUrl.trim().length() == 0)
			throw new IllegalArgumentException("The base url must not be null or empty.");
		this.baseUrl = baseUrl;
		this.client = client;
		this.constantParameters = new HashMap<String, String>();
	}

	public void addConstantParameter(String param, String value) {
		constantParameters.put(param, value);
	}

	public void clearConstantParams() {
		constantParameters.clear();
	}

	/**
	 * Call an API's GET method
	 * 
	 * @param methodName
	 *            The name of the method. Use null or "" for no method name (use the base URL)
	 * @param parameters
	 *            the parameters for this method
	 * @param returnType
	 *            the type that this method should return
	 * @return an object of type returnType. Can safely be cast.
	 * @throws ApiException
	 *             If an error occurred during the call.
	 */
	public Object callGetMethod(String methodName, Map<String, String> parameters,
			Class<?> returnType) throws ApiException {
		if (returnType == null)
			throw new NullPointerException("Return type must not be null");
		String url = new UrlHelper(baseUrl, methodName, mergeMaps(parameters, constantParameters))
				.toUrl();
		Object result = client.makeGetRequest(url, returnType);
		return result;
	}

	/**
	 * Call an API's GET method
	 * 
	 * @param fullUrl
	 *            the full last part of a url
	 * @param returnType
	 *            the type this method should return.
	 * @return an object of type returnType
	 * @throws ApiException
	 */
	public Object callGetMethod(String fullUrl, Class<?> returnType) throws ApiException {
		if (returnType == null)
			throw new NullPointerException("Return type must not be null");
		String url;
		try {
			UrlHelper hlpr = UrlHelper.parseUrl(baseUrl + "/" + fullUrl);
			hlpr.setParams(mergeMaps(constantParameters, hlpr.getParams()));
			url = hlpr.toUrl();
		} catch (MalformedURLException e) {
			throw new ApiException(e);
		}
		Object result = client.makeGetRequest(url, returnType);
		return result;
	}

	/**
	 * Call an API's GET method
	 * 
	 * @param methodName
	 *            The name of the method. Use null or "" for no method name (use the base URL)
	 * @param parameters
	 *            the parameters for this method
	 * @param inputData
	 *            the data to pass into the request
	 * @param returnType
	 *            the type that this method should return
	 * @return an object of type returnType. Can safely be cast.
	 * @throws ApiException
	 *             If an error occurred during the call.
	 */
	public Object callPostMethod(String methodName, Map<String, String> parameters,
			Object inputData, Class<?> returnType) throws ApiException {
		if (returnType == null)
			throw new NullPointerException("Return type must not be null");
		String url = new UrlHelper(baseUrl, methodName, mergeMaps(parameters, constantParameters))
				.toUrl();
		return client.makePostRequest(url, inputData, returnType);
	}

	/**
	 * Call an API's POST method
	 * 
	 * @param fullUrl
	 *            The full last part of a url (After the tld)
	 * @param inputData
	 *            the data to POST to the server
	 * @param returnType
	 *            the type this method should return
	 * @return an object of type returnType
	 * @throws ApiException
	 */
	public Object callPostMethod(String fullUrl, Object inputData, Class<?> returnType)
			throws ApiException {
		if (returnType == null)
			throw new NullPointerException("Return type must not be null");
		String url;
		try {
			UrlHelper hlpr = UrlHelper.parseUrl(baseUrl + "/" + fullUrl);
			hlpr.setParams(mergeMaps(constantParameters, hlpr.getParams()));
			url = hlpr.toUrl();
		} catch (MalformedURLException e) {
			throw new ApiException(e);
		}
		return client.makePostRequest(url, inputData, returnType);
	}

	private static Map<String, String> mergeMaps(Map<String, String> m1, Map<String, String> m2) {
		if (m1 == null && m2 == null) {
			return new HashMap<String, String>();
		}
		if (m1 == null) {
			return m2;
		}
		if (m2 == null) {
			return m1;
		}
		Map<String, String> result = new HashMap<String, String>();
		for (Entry<String, String> entry : m1.entrySet()) {
			result.put(entry.getKey(), entry.getValue());
		}
		for (Entry<String, String> entry : m2.entrySet()) {
			result.put(entry.getKey(), entry.getValue());
		}
		return result;
	}
}