利用XMLBean轻轻松松读写XML

一、关于XML解析

  XML在Java应用程序里变得越来越重要, 广泛应用于数据存储和
交换. 比如我们常见的配置文件,都是以XML方式存储的. XML还应用
于Java Message Service和Web Services等技术作为数据交换.
因此,正确读写XML文档是XML应用的基础.
  Java提供了SAX和DOM两种方式用于解析XML,但即便如此,要读写一个
稍微复杂的XML,也不是一件容易的事.

二、XMLBean简介

    Hibernate已经成为目前流行的面向Java环境的对象/关系数据库映射工具.
在Hibernate等对象/关系数据库映射工具出现之前,对数据库的操作是
通过JDBC来实现的,对数据库的任何操作,开发人员都要自己写SQL语句
来实现. 对象/关系数据库映射工具出现后,对数据库的操作转成对
JavaBean的操作,极大方便了数据库开发. 所以如果有一个类似的工具能够
实现将对XML的读写转成对JavaBean的操作,将会简化XML的读写,即使对XML
不熟悉的开发人员也能方便地读写XML. 这个工具就是XMLBean.

三、准备XMLBean和XML文档

   XMLBean是Apache的一个开源项目,可以从http://www.apache.org下载,
最新的版本是2.3.0. 解压后目录如下:
xmlbean2.3.0
     +---bin
     +---docs
     +---lib
     +---samples
     +---schemas
其他设置参照前一篇： 使用Eclipse开发XMLBeans项目
另外还要准备一个XML文档(customers.xml),
在本文的例子里,我们将对这个文档进行读写操作. 文档源码如下:

<?xml version="1.0" encoding="UTF-8"?> <Customers xmlns="http://xmlbeans.apache.org/samples/template/xmlbean"> <customer> <id>1</id> <gender>female</gender> <firstname>Jessica</firstname> <lastname>Lim</lastname> <phoneNumber>1234567</phoneNumber> <address> <primaryAddress> <postalCode>350106</postalCode> <addressLine1>#25-1</addressLine1> <addressLine2>SHINSAYAMA 2-CHOME</addressLine2> </primaryAddress> <billingAddress> <receiver>Ms Danielle</receiver> <postalCode>350107</postalCode> <addressLine1>#167</addressLine1> <addressLine2>NORTH TOWER HARBOUR CITY</addressLine2> </billingAddress> </address> </customer> <customer> <id>2</id> <gender>male</gender> <firstname>David</firstname> <lastname>Bill</lastname> <phoneNumber>808182</phoneNumber> <address> <primaryAddress> <postalCode>319087</postalCode> <addressLine1>1033 WS St.</addressLine1> <addressLine2>Tima Road</addressLine2> </primaryAddress> <billingAddress> <receiver>Mr William</receiver> <postalCode>672993</postalCode> <addressLine1>1033 WS St.</addressLine1> <addressLine2>Tima Road</addressLine2> </billingAddress> </address> </customer> </Customers>

这是一个客户的数据模型,每个客户都有客户编号(ID),姓名,性别(gender),
电话号码(phoneNumber)和地址,其中地址有两个: 首要地址(PrimaryAddress)
和帐单地址(BillingAddress),每个地址有邮编,地址1,和地址2组成.
其中帐单地址还有收件人(receiver).

四、XMLBean使用步骤

    和其他面向Java环境的对象/关系数据库映射工具的使用步骤一样,
在正式使用XMLBean前,我们要作两个准备.

    1. 生成XML Schema文件

       什么是XML Schema文件? 正常情况下,每个XML文件都有一个Schema文件,
       XML Schema文件是一个XML的约束文件,它定义了XML文件的结构和元素.
       以及对元素和结构的约束. 通俗地讲,如果说XML文件是数据库里的记录,
       那么Schema就是表结构定义.

       为什么需要这个文件? XMLBean需要通过这个文件知道一个XML文件的
       结构以及约束,比如数据类型等. 利用这个Schema文件,XMLBean将会产生
       一系列相关的Java Classes来实现对XML的操作. 而作为开发人员,则是
       利用XMLBean产生的Java Classes来完成对XML的操作而不需要SAX或DOM.

       怎样产生这个Schema文件呢? 如果对于熟悉XML的开发人员,可以自己来
       写这个Schema文件,对于不熟悉XML的开发人员,可以通过一些工具来完成.
       比较有名的如XMLSPY和Stylus Studio都可以通过XML文件来生成Schema
       文件. 加入我们已经生成这个Schema文件(customer.xsd):

<?xml version="1.0" encoding="UTF-8"?> <xs:schema targetNamespace="http://xmlbeans.apache.org/samples/template/xmlbean" xmlns:po="http://xmlbeans.apache.org/samples/template/xmlbean" xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified"> <xs:element name="Customers"> <xs:complexType> <xs:sequence> <xs:element maxOccurs="unbounded" name="customer" type="po:customerType" /> </xs:sequence> </xs:complexType> </xs:element> <xs:complexType name="customerType"> <xs:sequence> <xs:element name="id" type="xs:int" /> <xs:element name="gender" type="xs:string" /> <xs:element name="firstname" type="xs:string" /> <xs:element name="lastname" type="xs:string" /> <xs:element name="phoneNumber" type="xs:string" /> <xs:element name="address" type="po:addressType" /> </xs:sequence> </xs:complexType> <xs:complexType name="addressType"> <xs:sequence> <xs:element name="primaryAddress" type="po:primaryAddressType" /> <xs:element name="billingAddress" type="po:billingAddressType" /> </xs:sequence> </xs:complexType> <xs:complexType name="primaryAddressType"> <xs:sequence> <xs:element name="postalCode" type="xs:string" /> <xs:element name="addressLine1" type="xs:string" /> <xs:element name="addressLine2" type="xs:string" /> </xs:sequence> </xs:complexType> <xs:complexType name="billingAddressType"> <xs:sequence> <xs:element name="receiver" type="xs:string" /> <xs:element name="postalCode" type="xs:string" /> <xs:element name="addressLine1" type="xs:string" /> <xs:element name="addressLine2" type="xs:string" /> </xs:sequence> </xs:complexType> </xs:schema>

2. 利用ANT工具来生成Java Classes
ANT文件可以参照下面文件作成：
<!-- Copyright 2004 The Apache Software Foundation Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. --> <project name="SampleTemplate" default="build"> <property environment="env"/> <path id="SampleTemplate.path"> <path refid="xmlbeans.path"/> <fileset dir="lib" includes="*.jar"/> <pathelement path="build/classes"/> </path> <target name="init" depends = "clean"> <property name="xmlbeans.home" value="${env.XMLBEANS_HOME}"/> <echo message="xmlbeans.home: ${xmlbeans.home}"/> <!-- check for xbean.jar from binary distribution --> <available property="xmlbeans.lib" value="${xmlbeans.home}/lib" file="${xmlbeans.home}/lib/xbean.jar" /> <!-- check for xbean.jar compiled from source --> <available property="xmlbeans.lib" value="${xmlbeans.home}/build/lib" file="${xmlbeans.home}/build/lib/xbean.jar" /> <fail message="Set XMLBEANS_HOME in your enviornment." unless="xmlbeans.lib"/> <echo message="xmlbeans.lib: ${xmlbeans.lib}"/> <path id="xmlbeans.path"> <fileset dir="${xmlbeans.lib}" includes="*.jar"/> </path> <taskdef name="xmlbean" classname="org.apache.xmlbeans.impl.tool.XMLBean" classpathref="xmlbeans.path"/> </target> <!-- ========================== clean ==== --> <target name="clean"> <delete dir="build"/> <delete file="lib/schemas.jar"/> <delete dir="XMLBeansSrc"/> <mkdir dir="XMLBeansSrc"/> </target> <!-- ========================== build ==== --> <target name="build" depends="init,schemas.jar,SampleTemplate.classes"> </target> <target name="schemas.check"> <uptodate property="schemas.notRequired" targetfile="lib/schemas.jar"> <srcfiles dir="schemas" includes="**/*.xsd"/> </uptodate> </target> <target name="schemas.jar" depends="init,schemas.check" unless="schemas.notRequired"> <xmlbean schema="schemas" destfile="lib/schemas.jar" srcgendir="XMLBeansSrc" classpathref="xmlbeans.path" debug="on" /> </target> <target name="SampleTemplate.classes" depends="init"> <mkdir dir="build/classes"/> <javac srcdir="src" destdir="build/classes" classpathref="SampleTemplate.path" debug="on" source="1.5" /> </target> <!-- ========================== run ==== --> <target name="run" depends="init,build"> <echo message="============================== running SampleTemplate"/> <java classname="org.apache.xmlbeans.samples.template.SampleTemplate" classpathref="SampleTemplate.path" fork="true"> <arg line="xml/hello.xml"/> <arg line="xml/bad.xml"/> </java> </target> <!-- ========================== test ==== --> <target name="test" depends="init,build"> <echo message="============================== testing SampleTemplate"/> <java classname="org.apache.xmlbeans.samples.template.SampleTemplateTest" classpathref="SampleTemplate.path" fork="true"> <arg line="xml/hello.xml"/> <arg line="xml/bad.xml"/> </java> </target> </project>

 其实, 生成的Java源代码没有多大作用,我们要的是jar文件.我们先看一下生成文件一览：
XMLBeansSrc/org/apache/xmlbeans/samples/template/xmlbean下生成的Classes.
 CustomersDocument.java                          -- 整个XML文档的Java Class映射
 CustomerType.java                                     -- 节点sustomer的映射
 AddressType.java                                         -- 节点address的映射
 BillingAddressType.java                               -- 节点billingAddress的映射
 PrimaryAddressType.java                                -- 节点primaryAddress的映射
XMLBeansSrc/org/apache/xmlbeans/samples/template/xmlbean/impl下生成的Classes是上面文件的接口类.

       好了,到此我们所有的准备工作已经完成了. 下面就开始进入重点：利用刚才生成的jar文件读写XML.

五、利用XMLBean读XML文件
六、利用XMLBean写XML文件
七、利用XMLBean修改XML文件
八、利用XMLBean删除一个customer

 

    新建一个Java Class: CustomerXMLBean.  源码如下:

package com.sample.reader; import java.io.File; import org.apache.xmlbeans.XmlOptions; import org.apache.xmlbeans.samples.template.xmlbean.AddressType; import org.apache.xmlbeans.samples.template.xmlbean.BillingAddressType; import org.apache.xmlbeans.samples.template.xmlbean.CustomerType; import org.apache.xmlbeans.samples.template.xmlbean.CustomersDocument; import org.apache.xmlbeans.samples.template.xmlbean.PrimaryAddressType; public class CustomerXMLBean ...{ private String filename = null; public CustomerXMLBean(String filename) ...{ super(); this.filename = filename; } public void customerReader() ...{ try ...{ File xmlFile = new File(filename); CustomersDocument doc = CustomersDocument.Factory.parse(xmlFile); CustomerType[] customers = doc.getCustomers().getCustomerArray(); for (int i = 0; i < customers.length; i++) ...{ CustomerType customer = customers[i]; println("Customer#" + i); println(" Customer ID:" + customer.getId()); println(" First name:" + customer.getFirstname()); println(" Last name:" + customer.getLastname()); println(" Gender:" + customer.getGender()); println(" PhoneNumber:" + customer.getPhoneNumber()); // Primary // address PrimaryAddressType primaryAddress = customer.getAddress() .getPrimaryAddress(); println(" PrimaryAddress:"); println(" PostalCode:" + primaryAddress.getPostalCode()); println(" AddressLine1:" + primaryAddress.getAddressLine1()); println(" AddressLine2:" + primaryAddress.getAddressLine2()); // Billing address BillingAddressType billingAddress = customer.getAddress() .getBillingAddress(); println(" BillingAddress:"); println(" Receiver:" + billingAddress.getReceiver()); println(" PostalCode:" + billingAddress.getPostalCode()); println(" AddressLine1:" + billingAddress.getAddressLine1()); println(" AddressLine2:" + billingAddress.getAddressLine2()); } } catch (Exception ex) ...{ ex.printStackTrace(); } } public void createCustomer() ...{ try ...{ // Create Document CustomersDocument doc = CustomersDocument.Factory.newInstance(); // Add new customer CustomerType customer = doc.addNewCustomers().addNewCustomer(); // set customer info customer.setId(3); customer.setFirstname("Jessica"); customer.setLastname("Lim"); customer.setGender("female"); customer.setPhoneNumber("1234567"); // Add new address AddressType address = customer.addNewAddress(); // Add new // PrimaryAddress PrimaryAddressType primaryAddress = address.addNewPrimaryAddress(); primaryAddress.setPostalCode("350106"); primaryAddress.setAddressLine1("#25-1"); primaryAddress.setAddressLine2("SHINSAYAMA 2-CHOME"); // Add new // BillingAddress BillingAddressType billingAddress = address.addNewBillingAddress(); billingAddress.setReceiver("Ms Danielle"); billingAddress.setPostalCode("350107"); billingAddress.setAddressLine1("#167"); billingAddress.setAddressLine2("NORTH TOWER HARBOUR CITY"); File xmlFile = new File(filename); doc.save(xmlFile); } catch (Exception ex) ...{ ex.printStackTrace(); } } private void insertCustomer() ...{ try ...{ File xmlFile = new File(filename); // Create Document CustomersDocument doc = CustomersDocument.Factory.parse(xmlFile); // Add new customer CustomersDocument.Customers customer = doc.getCustomers(); CustomerType importCustomer = customer.addNewCustomer(); // set customer info importCustomer.setId(3); importCustomer.setFirstname("Jessica3"); importCustomer.setLastname("Lim"); importCustomer.setGender("female"); importCustomer.setPhoneNumber("1234567"); // Add new address AddressType address = importCustomer.addNewAddress(); // Add new PrimaryAddress PrimaryAddressType primaryAddress = address.addNewPrimaryAddress(); primaryAddress.setPostalCode("350106"); primaryAddress.setAddressLine1("#25-1"); primaryAddress.setAddressLine2("SHINSAYAMA 2-CHOME"); // Add new BillingAddress BillingAddressType billingAddress = address.addNewBillingAddress(); billingAddress.setReceiver("Ms Danielle"); billingAddress.setPostalCode("350107"); billingAddress.setAddressLine1("#167"); billingAddress.setAddressLine2("NORTH TOWER HARBOUR CITY"); importCustomer = customer.insertNewCustomer(1); // set customer info importCustomer.setId(4); importCustomer.setFirstname("Jessica4"); importCustomer.setLastname("Lim"); importCustomer.setGender("female"); importCustomer.setPhoneNumber("1234567"); // Add new address address = importCustomer.addNewAddress(); // Add new PrimaryAddress primaryAddress = address.addNewPrimaryAddress(); primaryAddress.setPostalCode("350106"); primaryAddress.setAddressLine1("#25-1"); primaryAddress.setAddressLine2("SHINSAYAMA 2-CHOME"); // Add new BillingAddress billingAddress = address.addNewBillingAddress(); billingAddress.setReceiver("Ms Danielle"); billingAddress.setPostalCode("350107"); billingAddress.setAddressLine1("#167"); billingAddress.setAddressLine2("NORTH TOWER HARBOUR CITY"); XmlOptions xmlOptions = new XmlOptions(); xmlOptions.setSavePrettyPrint(); doc.save(xmlFile, xmlOptions); } catch (Exception ex) ...{ ex.printStackTrace(); } } public void updateCustomer(int id, String lastname) ...{ try ...{ File xmlFile = new File(filename); CustomersDocument doc = CustomersDocument.Factory.parse(xmlFile); CustomerType[] customers = doc.getCustomers().getCustomerArray(); for (int i = 0; i < customers.length; i++) ...{ CustomerType customer = customers[i]; if (customer.getId() == id) ...{ customer.setLastname(lastname); break; } } doc.save(xmlFile); } catch (Exception ex) ...{ ex.printStackTrace(); } } public void deleteCustomer(int id) ...{ try ...{ File xmlFile = new File(filename); CustomersDocument doc = CustomersDocument.Factory.parse(xmlFile); CustomerType[] customers = doc.getCustomers().getCustomerArray(); for (int i = 0; i < customers.length; i++) ...{ CustomerType customer = customers[i]; if (customer.getId() == id) ...{ customer.setNil(); break; } } doc.save(xmlFile); } catch (Exception ex) ...{ ex.printStackTrace(); } } private void println(String str) ...{ System.out.println(str); } public static void main(String[] args) ...{ String filename = "xml/customers.xml"; CustomerXMLBean customerXMLBean = new CustomerXMLBean(filename); customerXMLBean.customerReader(); filename = "xml/customers2.xml"; customerXMLBean = new CustomerXMLBean(filename); customerXMLBean.createCustomer(); filename = "xml/customersForUpdate.xml"; customerXMLBean = new CustomerXMLBean(filename); customerXMLBean.updateCustomer(2, "test"); filename = "xml/customersForDeleteAndInsert.xml"; customerXMLBean = new CustomerXMLBean(filename); customerXMLBean.deleteCustomer(2); customerXMLBean.insertCustomer(); } }

怎么样,是不是很轻松? XMLBean的威力.

  
    九、查询XML

    除了本文在以上讲述的,利用XMLBean能轻轻松松完成XML的读写操作外,结合XPath和XQuery,
   XMLBean还能完成象SQL查询数据库一样方便地查询XML数据. 关于XML查询以及如何创建XML数据库, 我将在另一篇文章里讨论.

 

十、结束语
    XMLBean能帮助我们轻易读写XML,这将有助于我们降低XML的学习和使用,有了这个基础,
    开发人员将为学习更多地XML相关技术和Web Services,JMS等其他J2EE技术打下良好地基础.

本文参考文献：叶枫 利用XMLBean轻轻松松读写XML
http://blog.matrix.org.cn/page/叶枫