plus.net.XMLHttpRequest() post提交json数据，服务器不能接收到，只能是字符串形式

function setAjax(){  
    if(xhr){  
        xhr.abort();  
        xhr=null;  
    }  

    //setHeader('Content-Type', settings.contentType || 'application/x-www-form-urlencoded');  

    var data = {  
            name:55  
        };  
    xhr=new plus.net.XMLHttpRequest();  
    xhr.onreadystatechange=xhrStatechange;  
    xhr.open( "POST", "http://192.168.1.1:7369/axapp/m/status.do" );  
    xhr.setRequestHeader("Content-type", "application/json; charset=utf-8");  
    alert(JSON.stringify(data));  
    //xhr.send('name=4444');  
    //xhr.send(JSON.stringify(data));  
    xhr.send(data);  
}  

服务端PHP  

<?php  
$name = $_POST['name'];  
$a = array('name'=>$name);  
echo json_encode($a);  
?>