js代码：
<script type="text/javascript">
    $(function(){
        $("#username").blur(function(){
            var name=$("input[name='orgInfo.username']").val(); 
            $.ajax({
                url:"findByName.action",
                data : {orgName : name},
                type : 'post', 
                dataType : 'text', 
                success : function(date) { 
                    if ("exist" == date) {
                        alert('存在该用户');
                    } else { 
                        alert('不存在该用户'+date);
                    } 
                },
            });
        });
        
    });
</script>

private String orgName;
    private String str;
    public String getStr() {
        return str;
    }

    public void setStr(String str) {
        this.str = str;
    }

    public String getOrgName() {
        return orgName;
    }

    public void setOrgName(String orgName) {
        this.orgName = orgName;
    }

    public String findByName() throws IOException{
        OrgInfo info=systemService.getOrgInfoByName(orgName);
        if(info!=null){
            str="exist";
        }else{
            str="noexist";
        }
        System.out.println(str);
        ServletActionContext.getResponse().getWriter().write(str);
        return SUCCESS;
    }