ExtJs的store默认是异步的，但有时候我们必须要发送同步请求才能满足需求，比如在多线程中，要实现同步很简单，只需继承Ext.data.proxy.Ajax，重写的同步类如下：

Ext.define('Ext.ux.data.proxy.Ajax', {      extend: 'Ext.data.proxy.Ajax',      async:true,      doRequest: function(operation, callback, scope) {          var writer  = this.getWriter(),              request = this.buildRequest(operation);            if (operation.allowWrite()) {              request = writer.write(request);          }          Ext.apply(request, {              async         : this.async,              binary        : this.binary,              headers       : this.headers,              timeout       : this.timeout,              scope         : this,              callback      : this.createRequestCallback(request, operation, callback, scope),              method        : this.getMethod(request),              disableCaching: false           });          Ext.Ajax.request(request);          return request;      }  });

使用的时候，只需修改代理即可,async：false表示同步，true为异步:

proxy: Ext.create("Ext.ux.data.proxy.Ajax",{                  async:false,                  url:" ",                  reader: {                      type: 'json',                      root: 'root'                }          })