sencha touch中textfield限制输入字数

首先重写textfield方法，添加maxLength属性

Ext.form.TextField.prototype.initValue = function()
{
    if(this.value !== undefined){
        this.setValue(this.value);
    }else if(this.el.dom.value.length > 0){
        this.setValue(this.el.dom.value);
    }
    this.el.dom.size = this.size;
    if (!isNaN(this.maxLength) && (this.maxLength *1) > 0 && (this.maxLength != Number.MAX_VALUE)) {
        this.el.dom.maxLength = this.maxLength *1;
    }
};

然后在用的地方添加maxLength属性

{
	            xtype: 'textfield',
	            name: 'realname',
	            label: '<span style="color:#ff0000;float:none;">*</span>姓名',
	            labelWidth : '30%',
	            maxLength : 4,
	            placeHolder : '请输入姓名',
	        },