一个jaxb的例子看java object和xml之间的转换
这段时间在研究o/x mapping，即Java object和xml之间的转换以及xml文件验证的问题，自己也动手开发了一个小的演示例子，如下所示：
--------开发环境-----
1.jdk1.5
2.jwsdp2.0（Java Web Services Developer Pack 2.0， sun的官网上有的下）
3.程序中需要用到的jar包：
%jwsdp2.0安装目录下%/jaxb/lib/jaxb-api.jar
%jwsdp2.0安装目录下%/jaxb/lib/jaxb-impl.jar
%jwsdp2.0安装目录下%/sjsxp/lib/jsr173_api.jar
%jwsdp2.0安装目录下%/jwsdp-shared/lib/activation.jar
4.开发工具：eclipse3.2
---------------------
定义一个XML schema文件--library.xsd
<?xml version="1.0" encoding="UTF-8"?><xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified" attributeFormDefault="unqualified"><xs:element name="librarys" type="librarys"/><xs:complexType name="librarys"><xs:sequence><xs:element name="library" minOccurs="1" maxOccurs="unbounded"><xs:complexType><xs:sequence><xs:element name="name" type="xs:string"/><xs:element name="layer" type="xs:int"/><xs:element name="row" type="xs:int"/><xs:element name="book" type="book"/></xs:sequence></xs:complexType></xs:element></xs:sequence></xs:complexType><xs:complexType name="book"><xs:sequence><xs:element name="bookID" type="xs:string"/><xs:element name="bookName" type="xs:string"/><xs:element name="borrowDate" type="xs:date"/><xs:element name="user" type="user"/></xs:sequence><xs:attribute name="description" type="xs:string"/></xs:complexType><xs:complexType name="user"><xs:sequence><xs:element name="userID" type="xs:string"/><xs:element name="userName" type="xs:string"/><xs:element name="userAge" type="xs:int"/></xs:sequence></xs:complexType></xs:schema>
再定义jwsdp的xjc工具的binding文件---binding.xjb
<jxb:bindings version="1.0" xmlns:jxb="http://java.sun.com/xml/ns/jaxb" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <jxb:bindings schemaLocation="library.xsd" node="/xs:schema"><!-- schemaLocation属性是xsd文件的相对路径 --> <jxb:globalBindings fixedAttributeAsConstantProperty="true" collectionType="java.util.ArrayList" typesafeEnumBase="xs:NCName" choiceContentProperty="false" typesafeEnumMemberName="generateError" enableFailFastCheck="false" generateIsSetMethod="false" underscoreBinding="asCharInWord"/> <jxb:schemaBindings> <jxb:package name="com.cuishen.o_x_mapping.object"/> <!-- 这里是生成的JAVA类文件存放包名 --> <jxb:nameXmlTransform> <jxb:elementName suffix="Element"/></jxb:nameXmlTransform> </jxb:schemaBindings> <!-- 这里是定义xsd中一个复合类型与Java类的映射（如果要修改才定义，不修改则不需要） --> <jxb:bindings node="//xs:complexType[@name='librarys']"> <jxb:class name="Librarys"/> </jxb:bindings> <jxb:bindings node="//xs:complexType[@name='book']"> <jxb:class name="Book"/> <!-- 这里是定义复合类型的一个元素名称与Java类中属性的映射（如果要修改才定义，不修改则不需要） --> <jxb:bindings node=".//xs:element[@name='bookID']"> <jxb:property name="id"/> </jxb:bindings> </jxb:bindings> <jxb:bindings node="//xs:complexType[@name='user']"> <jxb:class name="User"/> <!-- 这里是定义复合类型的一个元素名称与Java类中属性的映射（如果要修改才定义，不修改则不需要） --> <jxb:bindings node=".//xs:element[@name='userID']"> <jxb:property name="id"/> </jxb:bindings> </jxb:bindings> </jxb:bindings></jxb:bindings>
注意！binding文件的编码格式要用UTF-8，如果直接把代码粘到eclipse里编码格式就不是UTF-8了，这时xjc工具就要报错了，解决办法就是把这个文件用UltraEdit工具转一下。
可以通过binding文件和xsd文件用jaxb自带的xjc工具自动生成java object，是不是很棒啊^_^
现在写o/x mapping的测试主类----Main.java
package com.cuishen.o_x_mapping;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream;import java.net.MalformedURLException;import java.net.URL;import java.util.GregorianCalendar;import java.util.List;import javax.xml.XMLConstants;import javax.xml.bind.JAXBContext;import javax.xml.bind.JAXBElement;import javax.xml.bind.JAXBException;import javax.xml.bind.Marshaller;import javax.xml.bind.Unmarshaller;import javax.xml.bind.ValidationEvent;import javax.xml.bind.ValidationEventHandler;import javax.xml.bind.ValidationEventLocator;import javax.xml.datatype.DatatypeConfigurationException;import javax.xml.datatype.DatatypeFactory;import javax.xml.datatype.XMLGregorianCalendar;import javax.xml.validation.Schema;import javax.xml.validation.SchemaFactory;import com.cuishen.o_x_mapping.object.Book;import com.cuishen.o_x_mapping.object.Librarys;import com.cuishen.o_x_mapping.object.User;import com.cuishen.o_x_mapping.object.ObjectFactory;import com.cuishen.o_x_mapping.utils.FileUtils;;/** * o/x mapping测试主类 * @author cuishen * @date 2008-4-2 * @version 1.0 */public class Main {public static void object2xml() {try {JAXBContext context = JAXBContext.newInstance("com.cuishen.o_x_mapping.object");Librarys libs = new Librarys();List<Librarys.Library> libList = libs.getLibrary();User usr = createUser("1011", 28, "cuishen");Book book = createBook("成长比成功更重要", getDate(), "成功励志书", "88-91-211", usr);libList.add(createLibrary("上海图书馆", 2, 4, book));usr = createUser("1017", 22, "sanmao");book = createBook("七龙珠", getDate(), "漫画", "34-16-310", usr);libList.add(createLibrary("徐汇图书馆", 3, 11, book));// create an element for marshallingJAXBElement<Librarys> element = (new ObjectFactory()).createLibrarys(libs);Marshaller m = context.createMarshaller();m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);m.setProperty("jaxb.encoding", "gbk");m.marshal(element, System.out);File xmlFile = FileUtils.makeFile(getXmPath());OutputStream ot = new FileOutputStream(xmlFile);m.marshal(element, ot);} catch (JAXBException e) {e.printStackTrace();} catch (FileNotFoundException e) {e.printStackTrace();} catch (MalformedURLException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}}public static void xml2object(Unmarshaller u) {try {//JAXBContext jc = JAXBContext.newInstance( "com.cuishen.o_x_mapping.object" );//Unmarshaller u = jc.createUnmarshaller();// unmarshal a po instance document into a tree of Java content// objects composed of classes from the com.cuishen.o_x_mapping.object package.JAXBElement poe = (JAXBElement)u.unmarshal(new FileInputStream(getXmPath()));Librarys librarys = (Librarys)poe.getValue();List libList = librarys.getLibrary();for(int i = 0; i < libList.size(); i++) {Librarys.Library lib = (Librarys.Library)libList.get(i);System.out.println("librarys ==> ");System.out.println("===> library :");System.out.println("=========> layer " + lib.getLayer());System.out.println("=========> name " + lib.getName());System.out.println("=========> row " + lib.getRow());System.out.println("=========> book :");Book book = lib.getBook();System.out.println("=============> id " + book.getId());System.out.println("=============> borrowDate " + book.getBorrowDate());System.out.println("=============> name " + book.getBookName());System.out.println("=============> desc " + book.getDescription());System.out.println("=============> user :");User usr = book.getUser();System.out.println("==================> userID " + usr.getId());System.out.println("==================> userName " + usr.getUserName());System.out.println("==================> Age " + usr.getUserAge()); }} catch( JAXBException je ) {je.printStackTrace();} catch( IOException ioe ) {ioe.printStackTrace();}}/** * 对xml文件解组时的验证 * @return boolean */public static Unmarshaller validate() {// create a JAXBContext capable of handling classes generated into// the com.cuishen.o_x_mapping.object packageJAXBContext jc;Unmarshaller u = null;try {jc = JAXBContext.newInstance( "com.cuishen.o_x_mapping.object" );u = jc.createUnmarshaller();SchemaFactory sf = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);try {Schema schema = sf.newSchema(new File(getXSDPath()));u.setSchema(schema);u.setEventHandler(new ValidationEventHandler() {public boolean handleEvent(ValidationEvent ve) {if (ve.getSeverity() == ValidationEvent.WARNING || ve.getSeverity() != ValidationEvent.WARNING) {ValidationEventLocator vel = ve.getLocator();System.out.println("Line:Col[" + vel.getLineNumber() + ":" + vel.getColumnNumber() + "]:" + ve.getMessage());return false;}return true;}});} catch (org.xml.sax.SAXException se) {System.out.println("Unable to validate due to following error.");se.printStackTrace();} catch (MalformedURLException e) {e.printStackTrace();}} catch (JAXBException e) {e.printStackTrace();}return u;}private static String getXmPath() throws MalformedURLException {String xmlPath = FileUtils.extractDirPath(FileUtils.extractDirPath(Main.class.getClassLoader().getResource(".").toString()));xmlPath = FileUtils.makeFilePath(xmlPath, "src/com/cuishen/o_x_mapping/xml/library.xml");URL url = new URL(xmlPath);return url.getPath();}private static String getXSDPath() throws MalformedURLException {String xsdPath = FileUtils.extractDirPath(FileUtils.extractDirPath(Main.class.getClassLoader().getResource(".").toString()));xsdPath = FileUtils.makeFilePath(xsdPath, "library.xsd");URL url = new URL(xsdPath);System.out.println("xsd path ==========> " + url.getPath());return url.getPath();}public static void main(String args[]) {System.out.println("======== object to xml ...");object2xml();System.out.println("======== xml to object ...");xml2object(validate());}public static Librarys.Library createLibrary(String name, int layer, int row, Book book) {Librarys.Library library = new Librarys.Library();library.setName(name);library.setLayer(layer);library.setRow(row);library.setBook(book);return library;}public static Book createBook(String name, XMLGregorianCalendar date, String desc, String id, User usr) {Book book = new Book();book.setBookName(name);book.setBorrowDate(date);book.setDescription(desc);book.setId(id);book.setUser(usr);return book;}public static User createUser(String id, int age, String name) {User usr = new User();usr.setId(id);usr.setUserAge(age);usr.setUserName(name);return usr;}private static XMLGregorianCalendar getDate() {try {return DatatypeFactory.newInstance().newXMLGregorianCalendar(new GregorianCalendar());} catch (DatatypeConfigurationException e) {throw new Error(e);}}}以上代码的核心是xml文件的编组和解组，用到了接口javax.xml.bind.Marshaller(Marshaller 类负责管理将 Java 内容树序列化回 XML 数据的过程,它提供了基本的编组方法marshal), 以及接口javax.xml.bind.Unmarshaller(Unmarshaller 类管理将 XML 数据反序列化为新创建的 Java 内容树的过程，并可在解组时有选择地验证 XML 数据。它针对各种不同的输入种类提供各种重载的 unmarshal 方法。), 至于xml文件的验证是在解组的时候，调用方法unmarshal会触发验证的机制，验证xml文件是否符合schema的规范。
下面定义build.xml，用ant工具来完成整个项目的编译和运行，方便快捷，^_^
<project basedir="." default="run"> <!--这里是jwsdp的安装目录 --> <property name="jwsdp.home" value="d:\Sun\jwsdp-2.0"/> <!--这里是log4j的安装目录 --> <property name="log4j.home" value="D:\conserv\o-x-mapping\implement\lib"/> <path id="xjc.classpath"> <pathelement path="src"/> <pathelement path="bin"/> <pathelement path="lib"/> <pathelement path="schemas"/> <!--for use with bundled ant--> <fileset dir="${jwsdp.home}" includes="jaxb/lib/*.jar"/> <fileset dir="${jwsdp.home}" includes="sjsxp/lib/*.jar"/> <fileset dir="${jwsdp.home}" includes="jwsdp-shared/lib/activation.jar"/> <fileset dir="${jwsdp.home}" includes="jwsdp-shared/lib/resolver.jar"/> <fileset dir="${log4j.home}" includes="log4j-1.2.5.jar"/> </path> <taskdef name="xjc" classname="com.sun.tools.xjc.XJCTask"><classpath refid="xjc.classpath" /> </taskdef> <!--compile Java source files--> <target name="compile" description="Compile all Java source files"> <echo message="Compiling the schema..." /> <!-- mkdir dir="src" /--> <xjc schema="library.xsd" binding="binding.xjb" destdir="src"/> <echo message="Compiling the java source files..." /> <mkdir dir="bin" /> <javac destdir="bin" debug="on"> <src path="src" /> <classpath refid="xjc.classpath" /> </javac> </target> <target name="run" depends="compile" description="Run the sample app"> <echo message="Running the sample application..." /> <java classname="com.cuishen.o_x_mapping.Main" fork="true"> <classpath refid="xjc.classpath" /> </java> </target> </project>我已经将演示项目的完整代码打包上传到附件了，测试通过，方便网友们下载，有不足之处愿与大家切磋
<xs:element name="ForecastPartner"> <xs:complexType> <xs:sequence minOccurs="1" maxOccurs="unbounded"> <xs:element ref="GlobalPartnerReferenceTypeCode" /> <xs:element ref="PartnerDescription" /> </xs:sequence> </xs:complexType> </xs:element>
@XmlAccessorType(XmlAccessType.FIELD)@XmlType(name = "", propOrder = { "globalPartnerReferenceTypeCodeAndPartnerDescription"})@XmlRootElement(name = "ForecastPartner")public class ForecastPartner { @XmlElements({ @XmlElement(name = "PartnerDescription", required = true, type = PartnerDescription.class), @XmlElement(name = "GlobalPartnerReferenceTypeCode", required = true, type = String.class) }) protected List<Object> globalPartnerReferenceTypeCodeAndPartnerDescription; /** * Gets the value of the globalPartnerReferenceTypeCodeAndPartnerDescription property. * * <p> * This accessor method returns a reference to the live list, * not a snapshot. Therefore any modification you make to the * returned list will be present inside the JAXB object. * This is why there is not a <CODE>set</CODE> method for the globalPartnerReferenceTypeCodeAndPartnerDescription property. * * <p> * For example, to add a new item, do as follows: * <pre> * getGlobalPartnerReferenceTypeCodeAndPartnerDescription().add(newItem); * </pre> * * * <p> * Objects of the following type(s) are allowed in the list * {@link PartnerDescription } * {@link String } * * */ public List<Object> getGlobalPartnerReferenceTypeCodeAndPartnerDescription() { if (globalPartnerReferenceTypeCodeAndPartnerDescription == null) { globalPartnerReferenceTypeCodeAndPartnerDescription = new ArrayList<Object>(); } return this.globalPartnerReferenceTypeCodeAndPartnerDescription; }}