java-org.hwo/src/org/hwo/rpc/json/JSONRpcService.java

package org.hwo.rpc.json;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

import org.json.simple.JSONValue;

public class JSONRpcService implements InvocationHandler{

	private String url;
	private Integer nextid;
	
	public JSONRpcService(String url){
		this.url = url;
		this.nextid = 0;
	}
	
	public <T> T createProxy(Class<T> iface){
		T proxy = (T) Proxy.newProxyInstance(iface.getClassLoader(), new Class[]{ iface }, this);
		return proxy;
	}

	@Override
	public Object invoke(Object proxy, Method method, Object[] args)
			throws Throwable {
		
		HashMap<String, Object> req = new HashMap<String, Object>();
		req.put("id", this.nextid++ );
		req.put("method", method.getName());
		req.put("params", Arrays.asList(args));
		
		String reqString = JSONValue.toJSONString(req);
		
		System.err.println(reqString);
		
		URL url = new URL(this.url);
		URLConnection conn = url.openConnection();
		conn.setDoInput(true);
		conn.setDoOutput(true);
		OutputStream out = conn.getOutputStream();
		out.write(reqString.getBytes());
		out.flush();
		out.close();
		
		BufferedReader reader = new BufferedReader(new InputStreamReader( conn.getInputStream()));
		StringBuilder sb = new StringBuilder();
		String line;
		
		while ((line = reader.readLine())!=null) {
			sb.append(line);
		}
		
		System.err.println("Response: " + sb.toString());
		
		Map<String, Object> response = (Map<String, Object>)JSONValue.parse(sb.toString());
		
		if (response.containsKey("error") && (response.get("error") != null)) {
			throw new RuntimeException("JSON-RPC: " + response.get("error"));
		}
		
		return response.get("result");
	}
	
	
}