ajax Post 和Get 的访问配置区别

Post   function sendRequest(url) {
        createRequest();
        request.open("POST", "/json/login1", true);
        request.onreadystatechange = updatePage;
        request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
        request.send("uname="+uname+"&psw="+psw);
    }

    function updatePage() {
        if (request.readyState == 4) {
            if (request.status == 200) {
            var res = request.responseXML.getElementsByTagName("res")[0].firstChild.data;
                window.alert(res);
            } else {
                alert("status is" + request.status);
            }
        }
    }
   
   
      function userCheck(){
         uname = document.getElementById("uname").value;
          psw = document.getElementById("psw").value;
        if(uname=="") {
window.alert("用户名不能为空。");
document.getElementById("uname").focus();
return false;
}
else {
sendRequest();
}
     }

Get

    function sendRequest(url) {
        createRequest();
        request.open("GET", url, true);
        request.onreadystatechange = updatePage;
        request.send(null);
    }

    function updatePage() {
        if (request.readyState == 4) {
            if (request.status == 200) {
             var res = request.responseText;
             window.alert(res);
            } else {
                alert("status is" + request.status);
            }
        }
    }
   
   
      function userCheck(){
         var uname = document.getElementById("uname").value;
         var psw = document.getElementById("psw").value;
         if(uname ==""){
                      window.alert("用户名不能为空!");
             document.getElementById("uname").focus();
             return false;
         }   else{
             sendRequest('/json/login?uname='+uname+'&psw='+psw);
         }
     }