ExtJs 同步与异步请求

var conn = Ext.lib.Ajax.getConnectionObject().conn;
conn.open("GET", 'your url',false);
conn.send(null);
alert(conn.responseText);

var conn = Ext.lib.Ajax.getConnectionObject().conn;
conn.open("POST", url, false);
conn.send("发送到服务器端的信息");
data = conn.responseText;
alert(data);

var seletedGird = this.grid.getSelectionModel().getSelections();//获得选中的项
var rowid = seletedGird[0].get('id');//获得选中第一项的id列的值
if (rowid == null) {
return "";
}
Ext.Ajax.request({
url:getRootPath()+'/workflow/participatorRule/findUserIdListByRuleId.web',
async: false,   //ASYNC 是否异步( TRUE 异步 , FALSE 同步)
params:{ //需要传递个URL的参数
id:rowid
},
success: function(response, options) {
userIds = response.responseText;
if(userIds==""){
Ext.Msg.alert('错误', '参与者规则下没有挂接用户或岗位');
}

},
failure: function(response, options) {
userIds = response.responseText;
if(userIds==""){
Ext.Msg.alert('错误', '参与者规则下没有挂接用户或岗位');
}
}

});