Java HTTP Get doGet(String theURL, Map nameValuePairs)

Description

do Get

License

Open Source License

Declaration

public static String doGet(String theURL, Map nameValuePairs) throws Exception 

Method Source Code

//package com.java2s;
//License from project: Open Source License 

import java.io.*;
import java.net.*;
import java.util.*;

public class Main {
    public static boolean printHeaders = false;
    public static boolean useStdHeaders = false;
    static final String stdReqHdr[] = {
            //      "Connection", "Keep-Alive",
            "User-Agent", "Mozilla/4.5 [en] (X11; U; SunOS 5.6 sun4u)", "Accept",
            "image/gif, image/x-xbitmap, image/jpeg," + "image/pjpeg, image/png, */*", "Accept-Encoding", "gzip",
            "Accept-Language", "en", "Accept-Charset", "iso-8859-1,*,utf-8" };

    public static String doGet(String theURL, Map nameValuePairs) throws Exception {
        String request = validateURL(theURL);

        if (nameValuePairs != null && nameValuePairs.size() > 0) {
            if (!request.endsWith("?"))
                request += "?";
            request += encodeParams(nameValuePairs);
        }//w ww . j av a2s .c o m

        URL url = new URL(request);
        URLConnection conn = url.openConnection();

        getRequest(conn);
        return readResponse(conn);
    }

    public static String validateURL(String url) {
        if (!url.startsWith("http://"))
            return "http://" + url;
        else
            return url;
    }

    public static String encodeParams(Map nameValuePairs) {
        StringBuffer params = new StringBuffer();
        Iterator nvp = nameValuePairs.keySet().iterator();
        String name, value;
        char ch;

        while (nvp.hasNext()) {
            name = (String) nvp.next();
            value = (String) nameValuePairs.get(name);
            if (value == null)
                value = "null";
            if (nvp.hasNext())
                ch = '&';
            else
                ch = '\n';
            params.append(name + "=" + URLEncoder.encode(value) + ch);
        }

        return params.toString();
    }

    private static void getRequest(URLConnection conn) throws Exception {
        if (useStdHeaders)
            for (int i = 0; i < stdReqHdr.length - 1; i++)
                conn.setRequestProperty(stdReqHdr[i], stdReqHdr[i + 1]);

        conn.setDoOutput(true);
        conn.connect();
    }

    public static String readResponse(URLConnection conn) throws Exception {
        BufferedReader in;
        StringBuffer response = new StringBuffer();
        String line;

        try {
            in = new BufferedReader(new InputStreamReader(conn.getInputStream()));
        } catch (Exception ex) {
            InputStream err = ((HttpURLConnection) conn).getErrorStream();
            if (err == null) {
                System.err.println("Headers: " + getResponseHeaders(conn));
                throw ex;
            }
            in = new BufferedReader(new InputStreamReader(err));
        }

        if (printHeaders)
            response.append(getResponseHeaders(conn));

        while ((line = in.readLine()) != null)
            response.append(line + "\n");

        in.close();

        return response.toString();
    }

    public static String getResponseHeaders(URLConnection conn) {
        StringBuffer headers = new StringBuffer();
        String key;
        int n = 1;

        headers.append("\n----------\n");
        while ((key = conn.getHeaderFieldKey(n)) != null) {
            String value = conn.getHeaderField(n);
            headers.append(key + ": " + value + "\n");
            n++;
        }

        headers.append("----------\n");
        return headers.toString();
    }
}

Related

1. doGET(HttpURLConnection conn)
2. doGet(String url)
3. doGet(String url, HashMap params)
4. doGet(String urlStr)
5. doGet(String urlString)