Spring的Object/XML映射將對象轉換到XML，或反之亦然。這個過程也被稱為
- XML Marshalling – 轉換對象到XML
- XML UnMarshalling – 轉換XML到對象
在本教學中，我們將介紹如何使用 Spring 的 OXM 來做轉換， Object <--- Spring oxm ---> XML.
注: 為什麼使用 Spring的OXM 有好處？請閱讀本 Spring 對象/XML映射的文章。
1. 一個簡單對象
一個簡單的對象，之後將其轉換成 XML 檔。
package com.zaixian.core.model;
public class Customer {
String name;
int age;
boolean flag;
String address;
//standard getter, setter and toString() methods.
}
3. Marshaller 和 Unmarshaller
這個類將處理通過 Spring 的 OXM 介面的轉換： Marshaller 和 Unmarshaller.
package com.zaixian.core;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
import org.springframework.oxm.Marshaller;
import org.springframework.oxm.Unmarshaller;
public class XMLConverter {
private Marshaller marshaller;
private Unmarshaller unmarshaller;
public Marshaller getMarshaller() {
return marshaller;
}
public void setMarshaller(Marshaller marshaller) {
this.marshaller = marshaller;
}
public Unmarshaller getUnmarshaller() {
return unmarshaller;
}
public void setUnmarshaller(Unmarshaller unmarshaller) {
this.unmarshaller = unmarshaller;
}
public void convertFromObjectToXML(Object object, String filepath)
throws IOException {
FileOutputStream os = null;
try {
os = new FileOutputStream(filepath);
getMarshaller().marshal(object, new StreamResult(os));
} finally {
if (os != null) {
os.close();
}
}
}
public Object convertFromXMLToObject(String xmlfile) throws IOException {
FileInputStream is = null;
try {
is = new FileInputStream(xmlfile);
return getUnmarshaller().unmarshal(new StreamSource(is));
} finally {
if (is != null) {
is.close();
}
}
}
}
4. Spring配置
在 Spring 的 bean 配置檔，注入 CastorMarshaller 作為 XML 綁定框架。
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> <bean id="XMLConverter" class="com.zaixian.core.XMLConverter"> <property name="marshaller" ref="castorMarshaller" /> <property name="unmarshaller" ref="castorMarshaller" /> </bean> <bean id="castorMarshaller" class="org.springframework.oxm.castor.CastorMarshaller" /> </beans>
5. 測試
運行它
package com.zaixian.core;
import java.io.IOException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.zaixian.core.model.Customer;
public class App {
private static final String XML_FILE_NAME = "customer.xml";
public static void main(String[] args) throws IOException {
ApplicationContext appContext = new ClassPathXmlApplicationContext("App.xml");
XMLConverter converter = (XMLConverter) appContext.getBean("XMLConverter");
Customer customer = new Customer();
customer.setName("zaixian");
customer.setAge(28);
customer.setFlag(true);
customer.setAddress("Haikou haidiandao");
System.out.println("Convert Object to XML!");
//from object to XML file
converter.convertFromObjectToXML(customer, XML_FILE_NAME);
System.out.println("Done \n");
System.out.println("Convert XML back to Object!");
//from XML to object
Customer customer2 = (Customer)converter.convertFromXMLToObject(XML_FILE_NAME);
System.out.println(customer2);
System.out.println("Done");
}
}
輸出結果
Convert Object to XML! Done Convert XML back to Object! Customer [name=zaixian, age=28, flag=true, address=Haikou Haidiandao] Done
下麵的 XML 檔“customer.xml”將在專案的根檔夾中生成。
File : customer.xml
<?xml version="1.0" encoding="UTF-8"?> <customer flag="true" age="28"> <address>Haikou Haidiandao</address> <name>zaixian</name> </customer>
XML映射
等等，為什麼flag和age可轉換為屬性？這是一種來控制哪些字段應為屬性或元素的使用的方式？ 當然，您可以使用 Castor XML映射定義對象 和XML之間的關係。
創建以下映射檔，並把它放到你的專案的 classpath。
File : mapping.xml
<mapping> <class name="com.zaixian.core.model.Customer"> <map-to xml="customer" /> <field name="age" type="integer"> <bind-xml name="age" node="attribute" /> </field> <field name="flag" type="boolean"> <bind-xml name="flag" node="element" /> </field> <field name="name" type="string"> <bind-xml name="name" node="element" /> </field> <field name="address" type="string"> <bind-xml name="address" node="element" /> </field> </class> </mapping>
在Spring bean配置檔，上述通過“mappingLocation”注入 mapping.xml 到 CastorMarshaller 。注：這裏需要加入一個 org.springframework.oxm.***.jar 包，這個包函數在 MyEclipse 庫的 Spring 3.0 Web Libaries中。
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> <bean id="XMLConverter" class="com.zaixian.core.XMLConverter"> <property name="marshaller" ref="castorMarshaller" /> <property name="unmarshaller" ref="castorMarshaller" /> </bean> <bean id="castorMarshaller" class="org.springframework.oxm.castor.CastorMarshaller" > <property name="mappingLocation" value="classpath:mapping.xml" /> </bean> </beans>
再次測試，XML檔“customer.xml”將被更新。
File : customer.xml
<?xml version="1.0" encoding="UTF-8"?> <customer age="28"> <flag>true</flag> <name>zaixian</name> <address>Haikou Haidiandao</address> </customer>
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