J2ME Network Programming (httpconnection) __ Programming

1, What is the difference between ' HTTP connection ' and ' socket connection '?
If you are choose to use "Socket connection", Opera Mini would keep an open connection to the Opera Mini servers. This means that pages'll load quicker, and the Opera Mini servers can push updates (for example new bookmarks through Op ERA Link) directly to Opera Mini on your phone.

If you are choose "HTTP Connection", Opera Mini has to establish a connection to the Opera Mini servers every time you load a Page. New updates to Opera Mini would also the not being pushed to the phone until a new page is loaded. Note:not all phone models and mobile networks allow socket connections. If you are have problems with your connection, try to use "HTTP connection" instead.

2, when the use of HTTP connection in j2me,you Needn ' t set a connection property, then by default it's set to keep-a Live (MIDP uses a subset of HTTP 1.1, which has persistent connections by default).

3, client, server interaction example code

Server (C #):

Public partial class CheckVersion:System.Web.UI.Page {private string version = "1.2.0";//Latest version private String URL = "HT Tp://****.jad "; Latest version download address private soft_version SV = new Soft_version (); protected void Page_Load (object sender, EventArgs e) {if (request.querystring["brand"]!= null) && Request.query string["model"]!= null) {if (request.querystring["ver"]!= null) {sv. Getnewversion (request.querystring["brand"). ToString (), request.querystring["model"]. ToString (), out version, out URL); if (version!= request.querystring["ver"). ToString ()) {Response.ContentType = "text/html"; Response.AddHeader ("content-length", url. ToCharArray (). Length.tostring ()); Response.Write (URL); else {String SS = ""; Response.ContentType = "text/html"; Response.AddHeader ("Content-length", SS. ToCharArray (). Length.tostring ()); Response.Write (ss); }} else {String SS = ""; Response.ContentType = "text/html"; Response.AddHeader ("Content-length", SS. ToCharArray (). Length.tostring ()); Response.wRite (ss); } } }

Client (J2ME):

/** * http send request, return response * @author Jessica Tang */public class SendRequest {/** * send request, return response * @param strrequest to serve The data sent by the service * @param serverurl server URL * @return responsecode+ content Value/public static string Send (String strrequest,string serveru RL) {String message= ""; try {httpconnection HC = (httpconnection) connector.open (ServerURL, connector.read_write);//settings please The method is POST Hc.setrequestmethod (httpconnection.post); Send data to server outputstream OS = Hc.openoutputstream (); byte[] Request_body = Strrequest.getbytes (); for (int i = 0; i < request_body.length i++) {os.write (request_body[i);} os.flush (); Os.close (); OS = null; Read response code from server: 200-Normal message = String.valueof (Hc.getresponsecode ()); Reading data from the server InputStream is = Hc.openinputstream (); Read data int ch; while (ch = is.read ())!=-1) {message = message + (char) ch;;} is.close (); is = null; Hc.close (); Close Httpconnection Connection HC = NULL; catch (Exception e) {e.printstacktrace ();} return message; } }

/** * Check if there is a new version * @author Jessica Tang */private void CheckNew () {String str = sendrequest.send ("CheckNew", Locale.get ("U Rl.checknew ")); if (Str.trim (). Equals ("200")) {//is the latest Version//#style notificationalert Alert alert = new Alert ("Hint", "the version is already up to date.") ", null, alerttype.info); Display.setcurrent (alert); }else{try {this.platformrequest (str);} catch (Connectionnotfoundexception e) {//#style notificationalert Alert alert = New Alert ("Prompt", "version update failed.") ", null, alerttype.error); Display.setcurrent (alert); } } }

Appendix: Common Response Headers and their meaning