Using jquery and servlet to implement cross domain submission requests sample points

  This article mainly introduces examples of Cross-domain submission requests using jquery and servlet, which can be referenced by friends in the following

Principle: JavaScript Ajax cannot be cross-domain, but it can be done across domains by issuing a request to a servlet in the local area. The remote structure is then returned to the client. This will allow Ajax to cross the domain. In the back, and then send a PHP version, please pay attention AH. Here is the code   JS code:   NOTE: In the post mode, param1 and param2 are sent to the remote parameter values, can have more than one.     Code as follows://get mode function Reqeustcrossdomainproxyget () {    var url = "http://www.baidu.com";/ Remote Request address     var param = {' requesturl ': url, ' typedata ': ' JSON '};     var data = Getcrossdomainproxyremote (param, "json"); //post mode function Reqeustcrossdomainproxypost (param1,param2) {    var url = apiserver+ "/api/lucene/query"; & nbsp   var param = {' requesturl ': url, ' typedata ': ' JSON ', ' param1 ':p aram1, ' param2 ':p aram2};     var data = Getcrossdomainproxyremote (param, "json"); }  /**  * JS sends a POST request to a servlet in this address, all parameters about the remote request.  * is sent here to the servlet  * @param param remote Request parameters  * @param rtype js return type (temporarily unavailable)  * @return  */func tion Getcrossdomainproxyremote (param,rtype) {    var url = "/cross/proxy";//servlet URL address    VAR returndata;     $.ajax ({        url:url,type: ' POST ', Datatype:rtype,timeout:40000,data:param, async: False         Error:function (response,error) {alert (response.status);},    ,     Success:function (data) {Returndata=data;}    });     return returndata; }       Java code:     Code as follows: public class Corssdomainproxy extends HttpServlet {      public void Doget (HttpServletRequest req, HttpServletResponse resp)             throws Serv Letexception, IOException {        This.dopost (req, resp);         }       public void DoPost (HttpServletRequest req, HttpServletResponse resp)           &NB Sp Throws Servletexception, IOException {        Boolean requesttype = false;//mark Remote request type, default to get way         PrintWriter out = Resp.getwriter ();         Enumeration keys = Req.getparameternames ()//Remove all parameters incoming by client         Arrayli st<string> params = new arraylist<string> ();         String url=null;         while (keys.hasmoreelements ()) {            String key = (string ) keys.nextelement ();            /**              * If there are several representations within the request parameter, this parameter does not participate in the remote request              */            if (key.equals ("Requesturl")) {//Determine if parameter is, remote request address                 URL = req.getparameter (key);     &NBSP ;      }else if (key.equals ("Typedata")) {//Judging request data type, temporarily not used              } else if (key.equals ("ReturnType")) {//Judgment request return type, temporarily not used              }else{&NBSp               Params.add (key)//Other add parameter list, here is the parameter of participating remote request         &NBSP ;       RequestType = true;//modification tag, table request for a post mode            ,     &NB Sp  }           HttpClient client = new HttpClient ();         HttpMethod method = null;         if (RequestType) {//Judging request mode, and instantiating HttpMethod object, True:post,false:get         & nbsp   method = new Utf8postmethod (URL);             for (String name:params) {//Iteration post parameter, join to request           & nbsp     String _value = req.getparameter (name);                 ((Postmethod) method) Setparameter (Name,_value);                    }else{            m Ethod = new GetMethod (URL);   &nbsp    }                Client.executemethod (method);//Execute request     & nbsp   String bodystr = method.getresponsebodyasstring ()//return result         OUT.PRINTLN (BODYSTR); Return results to client    }      /**      * internal class, convert URL string to UTF-8      * @author Administrator      *      */    private static class Utf8postmethod extends Postm Ethod {          public utf8postmethod (String URL) {            &NB Sp Super (URL);         }          @Override         PU Blic String Getrequestcharset () {              return "UTF-8";      &NBS P  }     }  }