How to encode URL in Java ME

Comments

26 Sep
2009

Article Review by kalki (20090926)

This article demonstrate an example of URL encoding. When MIDlet send request using get method its become crucial to encode the URL.At the server end the appended data at the end of URL must be converted to meaningful information as sent by client.

Code Example is perfectly working and runs successfully.To do URL encoding the given code is ready to be executed.

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This article explains how to encode a URL in Java ME.

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Created: senthilkumar05 (28 Dec 2007)

Last edited: hamishwillee (06 Feb 2012)

// The following methods are used to encode the URL String,
 
//This method returns the encoded URL string.
 
public static String urlEncode(String s) {
    StringBuffer sbuf = new StringBuffer();
    int len = s.length();
    for (int i = 0; i < len; i++) {
        int ch = s.charAt(i);
        if ('A' <= ch && ch <= 'Z') { // 'A'..'Z'
            sbuf.append((char)ch);
        } else if ('a' <= ch && ch <= 'z') { // 'a'..'z'
            sbuf.append((char)ch);
        } else if ('0' <= ch && ch <= '9') { // '0'..'9'
            sbuf.append((char)ch);
        } else if (ch == ' ') { // space
            sbuf.append('+');
        } else if (ch == '-' || ch == '_'   //these characters don't need encoding
                || ch == '.' || ch == '*') {
            sbuf.append((char)ch);
        } else if (ch <= 0x007f) { // other ASCII
            sbuf.append(hex(ch));
        } else if (ch <= 0x07FF) { // non-ASCII <= 0x7FF
            sbuf.append(hex(0xc0 | (ch >> 6)));
            sbuf.append(hex(0x80 | (ch & 0x3F)));
        } else { // 0x7FF < ch <= 0xFFFF
            sbuf.append(hex(0xe0 | (ch >> 12)));
            sbuf.append(hex(0x80 | ((ch >> 6) & 0x3F)));
            sbuf.append(hex(0x80 | (ch & 0x3F)));
        }
    }
    return sbuf.toString();
}
 
//get the encoded value of a single symbol, each return value is 3 characters long
static String hex(int sym)
 {
     return(hex.substring(sym*3, sym*3 + 3));
 }
 
// Hex constants concatenated into a string, messy but efficient
final static String hex = 
"%00%01%02%03%04%05%06%07%08%09%0a%0b%0c%0d%0e%0f%10%11%12%13%14%15%16%17%18%19%1a%1b%1c%1d%1e%1f" + 
"%20%21%22%23%24%25%26%27%28%29%2a%2b%2c%2d%2e%2f%30%31%32%33%34%35%36%37%38%39%3a%3b%3c%3d%3e%3f" + 
"%40%41%42%43%44%45%46%47%48%49%4a%4b%4c%4d%4e%4f%50%51%52%53%54%55%56%57%58%59%5a%5b%5c%5d%5e%5f" + 
"%60%61%62%63%64%65%66%67%68%69%6a%6b%6c%6d%6e%6f%70%71%72%73%74%75%76%77%78%79%7a%7b%7c%7d%7e%7f" + 
"%80%81%82%83%84%85%86%87%88%89%8a%8b%8c%8d%8e%8f%90%91%92%93%94%95%96%97%98%99%9a%9b%9c%9d%9e%9f" +
"%a0%a1%a2%a3%a4%a5%a6%a7%a8%a9%aa%ab%ac%ad%ae%af%b0%b1%b2%b3%b4%b5%b6%b7%b8%b9%ba%bb%bc%bd%be%bf" +
"%c0%c1%c2%c3%c4%c5%c6%c7%c8%c9%ca%cb%cc%cd%ce%cf%d0%d1%d2%d3%d4%d5%d6%d7%d8%d9%da%db%dc%dd%de%df" +
"%e0%e1%e2%e3%e4%e5%e6%e7%e8%e9%ea%eb%ec%ed%ee%ef%f0%f1%f2%f3%f4%f5%f6%f7%f8%f9%fa%fb%fc%fd%fe%ff";