利用JQuery和Servlet实现跨域提交请求示例分享

//GET方式
function reqeustCrossDomainProxyGet(){
    var url = "http://www.baidu.com";//远程请求地址
    var param = {'requesturl':url,'typedata':'JSON'};
    var data = getCrossDomainProxyRemote(param,"json");
}
//Post方式
function reqeustCrossDomainProxyPost(param1,param2){
    var url = apiServer+"/api/lucene/query";
    var param = {'requesturl':url,'typedata':'JSON','param1':param1,'param2':param2};
    var data = getCrossDomainProxyRemote(param,"json");
}

/**
 * JS向本址的一个Servlet发送POST请求，所有关于远程请求的参数。
 * 在此处参POST方式发送给Servlet
 * @param param 远程请求参数
 * @param rtype JS返回类型（暂时没有用到）
 * @return
 */
function getCrossDomainProxyRemote(param,rtype){
    var url = "/cross/proxy";//Servlet的URL地址
    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;
}

public class CorssDomainProxy extends HttpServlet {
    
    public void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        this.doPost(req, resp);    
    }
    
    public void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        boolean requestType = false;//标记远程请求类型，默认为GET方式
        PrintWriter out = resp.getWriter();
        Enumeration keys = req.getParameterNames();//取出客户端传入的所有参数名
        ArrayList<String> params = new ArrayList<String>();
        String url=null;
        while (keys.hasMoreElements()){
            String key = (String) keys.nextElement();
            /**
             * 如果请求参数内有如下几种表示，这此参数不参与远程请求
             */
            if(key.equals("requesturl")){//判断参数是否是，远程请求地址
                url = req.getParameter(key);
            }else if(key.equals("typedata")){//判断请求数据类型，暂时没有用到
                
            }else if(key.equals("returntype")){//判断请求返回类型，暂时没有用到
                
            }else{
                params.add(key);//其它加入参数列表，此处为参与远程请求的参数
                requestType = true;//修改标记，表求远程请求为POST方式
            }
        }
        
        HttpClient client = new HttpClient();
        HttpMethod method = null;
        if(requestType){//判断请求方式，并实例化HttpMethod对象，true:POST,false:GET
            method = new UTF8PostMethod(url);
            for(String name : params){//迭代POST参数，加入到请求中
                String _value = req.getParameter(name);
                ((PostMethod)method).setParameter(name,_value);
            }
        }else{
            method = new GetMethod(url);
        }      
        client.executeMethod(method);//执行请求
        String bodystr = method.getResponseBodyAsString();//返回结果
        out.println(bodystr);//将结果返回给客户端
    }
    
    /**
     * 内部类，转换URL字符串为UTF-8
     * @author Administrator
     *
     */
    private static class UTF8PostMethod extends PostMethod {
        public UTF8PostMethod(String url) {
            super(url);
        }
        @Override
        public String getRequestCharSet() {
            return "UTF-8";
        }
    }
    
}