设通讯录的数据结构如下：

联系人信息包括姓名、职业、关系、电话等。其中，关系的内容有同学、同事、家人、朋友；电话可以有多个电话号码。每个联系人都有一个“编号”属性作为标识。

编程实现在通讯录的XML文档中查询关系为朋友的联系人的信息。-The data set directory structure is as follows: contact information including name, occupation, relationship, phone. Among them, the relationship between the content of some students, colleagues, family and friends　phone can have multiple phone numbers. Each contact has a " number"　attribute as a logo. Programming XML document in the address book query relations contact information for friends.