resourceutility.java

手机程序在线投票的例子

package com.itpath.examples.voter.util;

import com.itpath.examples.voter.*;

import java.io.*;
import javax.microedition.io.*;
import javax.microedition.lcdui.*;
import java.util.*;

public class ResourceUtility
{
    private static String RESOURCE_URL = "http://www.itpath.com:10001/examples/jsp/";

    private static String LOAD_URL = RESOURCE_URL + "voter.jsp";

	private static String QUESTION = "?";

    public static VoteSummary getVoteSummary()
    {
        String xml = loadVoteResults();

        return convertXMLToVoteSummary( xml);
    }

    private static VoteSummary convertXMLToVoteSummary(String xml)
    {
        InputStreamReader insr = new InputStreamReader( new ByteArrayInputStream(xml.getBytes() ) );

		VoteSummary voteSummary = null;

        try
        {
            voteSummary = XMLUtil.getVoteResults(insr);

        } catch (IOException ioe)
        {}

        return voteSummary;
    }

    public static VoteSummary addEntry(Vote vote)
    {
        StringBuffer requestString = new StringBuffer();

        requestString.append(QUESTION + vote.toRequestString() );

        String xml = backendComms(LOAD_URL, requestString.toString()  );

        return convertXMLToVoteSummary(xml);
    }

    public static String loadVoteResults()
    {
        return backendComms(LOAD_URL, "");
    }

    public static String backendComms(String requestURL, String requeststring)
    {
        HttpConnection hc = null;
        DataInputStream dis = null;
        StringBuffer messagebuffer = new StringBuffer();

        String requestString = requestURL + requeststring;

        try
        {
            // Open up a http connection with the Web server
            // for both send and receive operations
            hc = (HttpConnection) Connector.open(requestString, Connector.READ_WRITE);

            // Set the request method to GET
            hc.setRequestMethod(HttpConnection.GET);

            // Retrieve the response back from the servlet
            dis = new DataInputStream(hc.openInputStream());

            int ch;

            // Check the Content-Length first
            long len = hc.getLength();

            if(len!=-1)
            {
                for(int i = 0;i<len;i++)
                {
                    if((ch = dis.read())!= -1)
                    {
                        messagebuffer.append((char)ch);
                    }
                }
            } else {
                // if the content-length is not available
                while ((ch = dis.read()) != -1)
                {
                    messagebuffer.append((char) ch);
                }
            }
            dis.close();

        } catch (IOException ioe) {
            messagebuffer = new StringBuffer("ERROR!");
        } catch (Exception e){
            e.printStackTrace();
        } finally {
            // Free up i/o streams and http connection
            try {
                if (hc != null) hc.close();
            } catch (IOException ignored) {}
            try {
                if (dis != null) dis.close();
            } catch (IOException ignored) {}
        }
        return messagebuffer.toString();
    }
}