<?php

    header("Content-Type:text/html; charset=utf-8");

    echo "<div class='comment'><h6>{$_REQUEST['username']}:</h6><p class='para'>{$_REQUEST['content']}</p></div>";

?>

  .post 返回xml数据

  $(function(){

       $("#send").click(function(){

            $.post("post2.php", {

                        username :  $("#username").val() ,

                        content :  $("#content").val()

                    }, function (data, textStatus){

                        var username = $(data).find("comment").attr("username");

                        var content = $(data).find("comment content").text();

                        var txtHtml = "<div class='comment'><h6>"+username+":</h6><p class='para'>"+content+"</p></div>";

                        $("#resText").html(txtHtml); // 把返回的数据添加到页面上

                    },"xml");

       })

    })

php 文件

<?php

    header("Content-Type:text/xml; charset=utf-8");

    echo "<?xml version='1.0' encoding='utf-8'?>".

         "<comments>".

         "<comment username='{$_REQUEST['username'] }' >".

         "<content>{$_REQUEST['content']}</content>".

         "</comment>".

         "</comments>";

?>

 .post 返回json数据实现

 $(function(){

       $("#send").click(function(){

            $.post("post3.php", {

                        username :  $("#username").val() ,

                        content :  $("#content").val()

                    }, function (data, textStatus){

                        var username = data.username;

                        var content = data.content;

                        var txtHtml = "<div class='comment'><h6>"+username+":</h6><p class='para'>"+content+"</p></div>";

                        $("#resText").html(txtHtml); // 把返回的数据添加到页面上

                    },"json");

       })

    })
php文件

<?php

    header("Content-Type:text/html; charset=utf-8");

    echo "{ \"username\" : \"{$_REQUEST['username']}\" , \"content\" : \"{$_REQUEST['content']}\"}"

?>

.load注意是
    $(function(){

       $("#send").click(function(){

              $("#resText").load("post1.php",{

                        username :  $("#username").val() ,

                        content :  $("#content").val()

              })

       })

    })

<?php

    header("Content-Type:text/html; charset=utf-8");

    echo "<div class='comment'><h6>{$_REQUEST['username']}:</h6><p class='para'>{$_REQUEST['content']}</p></div>";

?>