ajax发送post数据，php获取不到

通过ajax发送post数据，php无法获取

加下面一行代码试试，一段要加在send()方法前面

xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded;charset=utf-8"); 

<input type="text" name="name" value="" id="inp"><span id="s"></span>

	var inp=document.getElementById('inp');
	inp.onblur=function(){
		var xhr=new XMLHttpRequest();
		xhr.onreadystatechange=function(){
			if(xhr.readyState==4){
				console.log(xhr.responseText);
				if(xhr.responseText==1){
                    document.getElementById('s').innerHTML="<font color='red'>不可用</font>";
				}else{
                     document.getElementById('s').innerHTML="<font color='green'>可用</font>";
				}
			}
		}
		xhr.open('post','http://127.0.0.1/cheshi/0002.php');
		xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded;charset=utf-8"); 
		xhr.send('name='+inp.value+'&sex="男"');
        
	}

<?php
     if($_POST['name']=='admin'){
     	echo 1;
     }else{
          echo $_POST['sex'];
     }
?>