function createXmlHttp() { 
    var xmlHttp; 
    try { // Firefox, Opera 8.0+, Safari 
      xmlHttp = new XMLHttpRequest(); 
    } 
    catch (e) { 
      try {// Internet Explorer 
        xmlHttp = new ActiveXObject("Msxml2.XMLHTTP"); 
      } 
      catch (e) { 
        try { 
          xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); 
        } 
        catch (e) { } 
      } 
    } 

    return xmlHttp; 

  } 


  function infoCheck(){
    var ename=document.getElementById("ename").value;
    var password=document.getElementById("password").value;
    var pwdConfirm=document.getElementById("pwdConfirm").value;
    if(password!=pwdConfirm){
      alert("兩次密碼不統(tǒng)一");
      return ;
    }
    //驗(yàn)證登錄用戶名是否存在，類似的可以驗(yàn)證手機(jī)號(hào)什么的
    // 1.創(chuàng)建異步對(duì)象 
    var xhr = createXmlHttp(); 
    xhr.onreadystatechange = function () { 
      if (xhr.readyState === 4 && xhr.status === 200) { 

      //  var data = new Function("return" + xhr.responseText)()//反序列化 
      var val=xhr.responseText;
        if(val==1){
          document.getElementById("ch").innerHTML="重新設(shè)置名字";
          document.getElementById("ename").focus();
          return;
        }else{
          document.getElementById("ch").innerHTML="";
        }
      } 
    } 

    xhr.open("post", 'LoginController/checkEname?ename='+escape(encodeURIComponent(ename)), true);  
    //發(fā)送 
    xhr.send(null); 
  } 

  <filter>
    <filter-name>encodingFilter</filter-name>
    <filter-class>
        org.springframework.web.filter.CharacterEncodingFilter
      </filter-class>
    <init-param>
     <param-name>encoding</param-name>
     <param-value>utf-8</param-value>
    </init-param>
    <init-param>
     <param-name>forceEncoding</param-name>
     <param-value>true</param-value>
    </init-param>
   </filter>
   <filter-mapping>
    <filter-name>encodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
   </filter-mapping>

   提交的時(shí)候
   剩下的 小部分的亂碼可以用編碼在解碼的方式獲得正確數(shù)據(jù)
   編碼:'LoginController/checkEname?ename='+escape(encodeURIComponent(ename))
   解碼:try {
      String str=URLDecoder.decode(ename, "utf-8");
       ename=URLDecoder.decode(ename, "utf-8");
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
    }
    后面寫(xiě)入數(shù)據(jù)庫(kù)的時(shí)候亂碼問(wèn)題,我個(gè)人先創(chuàng)數(shù)據(jù)庫(kù)編碼是utf8,項(xiàng)目的編碼也是utf-8,避免其他的編碼問(wèn)題發(fā)生，在連接數(shù)據(jù)庫(kù)的URL也加上
url=jdbc:mysql://localhost:3306/ssm?useUnicode=true&characterEncoding=utf8
目前碰到的亂碼問(wèn)題已經(jīng)解決（除開(kāi)ajax返回?cái)?shù)據(jù)亂碼，這個(gè)目前沒(méi)找到解決方案）

<form action="LoginController/register" method="post" id="form">
姓名:<input type="text" name="name" id="name"><br>
登錄名:<input type="text" name="ename" id="ename" onblur="infoCheck()"> <font id="ch" name="ch"></font><br>
密碼:<input type="password" name="password" id="password"><br>
密碼確定:<input type="password" name="pwdConfirm" id="pwdConfirm"><br>
<input type="button" value="注冊(cè)" onclick="submitInfo()" >
</form>

function submitInfo(){
    var name=document.getElementById("name").value;
    var ename=document.getElementById("ename").value;
    var password=document.getElementById("password").value;
    var pwdConfirm=document.getElementById("pwdConfirm").value;
    //針對(duì)空格和制表符的""能做到過(guò)濾
    name=name.replace(/(^\s*)|(\s*$)/g, "");
    ename=ename.replace(/(^\s*)|(\s*$)/g, "");
    password=password.replace(/(^\s*)|(\s*$)/g, "");
    pwdConfirm=pwdConfirm.replace(/(^\s*)|(\s*$)/g, "");
    if(name.length==0||name==" "||name.langth=="undefined") {
    //alert(name.langth);
    //alert(111);
    alert("姓名為必填項(xiàng)");
    return ;
    }
    if(ename.length==0||ename=="  "||ename.langth=="undefined") {
    alert("登錄名為必填項(xiàng)");
    return ;
    }
    if(password.length==0||password==" "||password.langth=="undefined") {
    alert("密碼為必填項(xiàng)");
    return;
    }
    if(password!=pwdConfirm){
      alert("兩次密碼不統(tǒng)一");
      return ;
    }
     document.getElementById("form").submit();
  }