Castor是一个java object的OR Mapping工具，可以将java objects保存于database、xml文件和LDAP数据库中（目前版本好像LDAP支持有问题）。下面简单介绍一下怎样用Castor来操纵XML文件
1. 一 最简单的XML文件的操纵
1. 1 读取XML文件
有一个xml文件如下，表示了一个人的信息
person.xml
<?xml version="1.0"?>
<person>
<name>Bob Harris</name>
<ssn>222-222-2222</ssn>
<address>123 Foo Street</address>
<work-phone>(123) 123-1234</work-phone>
<home-phone>(123) 123-1234</home-phone>
<email>bob@harris.org</email>
</person>
对应的java文件
/*
* Person.java
*
*/
/**
*
* @author yj
*/
import java.io.*;
public class Person {
private String name;
private String address;
private String ssn;
private String email;
private String homePhone;
private String workPhone;
// -- allows us to create a Person via the constructor
public Person(String name, String address, String ssn,
String email, String homePhone, String workPhone) {
this.name = name;
this.address = address;
this.ssn = ssn;
this.email = email;
this.homePhone = homePhone;
this.workPhone = workPhone;
}
// -- used by the data-binding framework
public Person() { }
// -- accessors
public String getName() { return name; }
public String getAddress() { return address; }
public String getSsn() { return ssn; }
public String getEmail() { return email; }
public String getHomePhone() { return homePhone; }
public String getWorkPhone() { return workPhone; }
// -- mutators
public void setName(String name) { this.name = name; }
public void setAddress(String address) {
this.address = address;
}
public void setSsn(String ssn) { this.ssn = ssn; }
public void setEmail(String email) { this.email = email; }
public void setHomePhone(String homePhone) {
this.homePhone = homePhone;
}
public void setWorkPhone(String workPhone) {
this.workPhone = workPhone;
}
}
这是一个读取person.xml文件的例子
/*
* ReadPerson.java
*
*/
/**
*
* @author yj
*/
import org.exolab.castor.xml.*;
import java.io.FileReader;
public class ReadPerson {
public static void main(String args[]) {
try {
Person person = (Person)
Unmarshaller.unmarshal(Person.class,
new FileReader("person.xml"));
System.out.println("Person Attributes");
System.out.println("-----------------");
System.out.println("Name: " + person.getName() );
System.out.println("Address: " + person.getAddress() );
System.out.println("SSN: " + person.getSsn() );
System.out.println("Email: " + person.getEmail() );
System.out.println("Home Phone: " +
person.getHomePhone() );
System.out.println("Work Phone: " +
person.getWorkPhone() );
} catch (Exception e) {
System.out.println( e );
}
}
}
传统上，如果需要操纵XML文件，需要用SAX或者DOM来处理，比较繁琐，有了Castor提供的marshalling and unmarshalling功能，就可以方便的在xml和java object之间方便的映射了。
2. 2 生成XML文件
下面是生成XML文件的例子：
/*
* CreatPerson.java
*
*/
/**
*
* @author yj
*/
import org.exolab.castor.xml.*;
import java.io.FileWriter;
public class CreatePerson {
public static void main(String args[]) {
try {
// -- create a person to work with
Person person = new Person("Bob Harris",
"123 Foo Street", "222-222-2222",
"bob@harris.org", "(123) 123-1234",
"(123) 123-1234");
// -- marshal the person object out as a <person>
FileWriter file = new FileWriter("bob_person.xml");
Marshaller.marshal(person, file);
file.close();
} catch (Exception e) {
System.out.println( e);
}
}
}
这是上面的CreatePerson生成的xml文件
bob_person.xml
<?xml version="1.0"?>
<person><ssn>222-222-2222</ssn><address>123 Foo Street</address><work-phone>(123) 123-1234</work-phone><home-phone>(123) 123-1234</home-phone><email>bob@harris.org</email><name>Bob Harris</name></person>
3. 3 修改现有的XML文件
修改现有的XML文件也很简单
/*
* ModifyPerson.java
*
*/
/**
*
* @author yj
*/
import org.exolab.castor.xml.*;
import java.io.FileWriter;
import java.io.FileReader;
public class ModifyPerson {
public static void main(String args[]) {
try {
// -- read in the person
Person person = (Person)
Unmarshaller.unmarshal(Person.class,
new FileReader("person.xml"));
// -- change the name
person.setName("David Beckham");
person.setEmail("David@beckham.com");
// -- marshal the changed person back to disk
FileWriter file = new FileWriter("person.xml");
Marshaller.marshal(person, file);
file.close();
} catch (Exception e) {
System.out.println( e );
}
}
}
2. 二 复杂XML文件的操纵
这个例子演示了如果操纵复杂的xml文件
文件addressbook.xml如下
<?xml version="1.0"?>
<addressbook name="Manchester United Address Book">
<person name="Roy Keane">
<address>23 Whistlestop Ave</address>
<ssn>111-222-3333</ssn>
<email>roykeane@manutd.com</email>
<home-phone>720.111.2222</home-phone>
<work-phone>111.222.3333</work-phone>
</person>
<person name="Juan Sebastian Veron">
<address>123 Foobar Lane</address>
<ssn>222-333-444</ssn>
<email>juanveron@manutd.com</email>
<home-phone>720.111.2222</home-phone>
<work-phone>111.222.3333</work-phone>
</person>
<person name ="Bob Harris">
<ssn>222-222-2222</ssn>
<address>123 Foo Street</address>
<work-phone>(123) 123-1234</work-phone>
<home-phone>(123) 123-1234</home-phone>
<email>bob@harris.org</email>
</person>
</addressbook>
可以看到，addressbook包含多条记录，每条记录是一个通讯录。为了对应复杂的xml文件，需要一个mapping.xml文件，来说明xml文件的项目和java object的对应关系
<?xml version="1.0"?>
<!DOCTYPE mapping PUBLIC "-//EXOLAB/Castor Object Mapping DTD Version 1.0//EN" "http://castor.exolab.org/mapping.dtd">
<mapping>
<description>A mapping file for our Address Book application</description>
<class name="Person">
<field name="name" type="string">
<bind-xml name="name" node="attribute" />
</field>
<field name="address" type="string" />
<field name="ssn" type="string" />
<field name="email" type="string" />
<field name="homePhone" type="string" />
<field name="workPhone" type="string" />
</class>
<class name="Addressbook">
<field name="name" type="string">
<bind-xml name="name" node="attribute" />
</field>
<field name="persons" type="Person" collection="collection" />
</class>
</mapping>
§这样,就可以一样很方便的使用Castor来操纵这个XML文件了
同样，需要一个java文件来对应addressbook
import java.util.List;
import java.util.ArrayList;
public class Addressbook {
private String addressBookName;
private List persons = new ArrayList();
public Addressbook() { }
// -- manipulate the List of Person objects
public void addPerson(Person person) {
persons.add(person);
}
public List getPersons() {
return persons;
}
// -- manipulate the name of the address book
public String getName() {
return addressBookName;
}
public void setName(String name) {
this.addressBookName = name;
}
}
察看addressbook的java 代码
import org.exolab.castor.xml.*;
import org.exolab.castor.mapping.*;
import java.io.FileReader;
import java.util.List;
import java.util.Iterator;
public class ViewAddressbook {
public static void main(String args[]) {
try {
// -- Load a mapping file
Mapping mapping = new Mapping();
mapping.loadMapping("mapping.xml");
Unmarshaller un = new Unmarshaller(Addressbook.class);
un.setMapping( mapping );
// -- Read in the Addressbook using the mapping
FileReader in = new FileReader("addressbook.xml");
Addressbook book = (Addressbook) un.unmarshal(in);
in.close();
// -- Display the addressbook
System.out.println( book.getName() );
List persons = book.getPersons();
Iterator iter = persons.iterator();
while ( iter.hasNext() ) {
Person person = (Person) iter.next();
System.out.println("\n" + person.getName() );
System.out.println("-----------------------------");
System.out.println("Address = "+ person.getAddress());
System.out.println("SSN = " + person.getSsn() );
System.out.println("Home Phone = " + person.getHomePhone() );
System.out.println("email = " + person.getEmail() );
}
} catch (Exception e) {
System.out.println( e );
}
}
}
再看另外一个例子：
缺省用法: 缺省用法指的是没有使用映射格式描述文件时的用法
import java.io.*;
import org.exolab.castor.xml.*;
public class Test{
public static void main(String[] argv) {
// build a test bean
FlightBean bean = new FlightBean();
bean.setCarrier("AR");
bean.setNumber(426);
bean.setDepartureTime("6:23a");
bean.setArrivalTime("8:42a");
try {
// write it out as XML
File file = new File("test.xml");
Writer writer = new FileWriter(file);
Marshaller.marshal(bean, writer);
// now restore the value and list what we get
Reader reader = new FileReader(file);
FlightBean read = (FlightBean)Unmarshaller.unmarshal(FlightBean.class, reader);
System.out.println("Flight "+read.getCarrier()+read.getNumber() + " departing at " +
read.getDepartureTime() +" and arriving at " + read.getArrivalTime());
} catch (IOException ex) {
ex.printStackTrace(System.err);
} catch (MarshalException ex) {
ex.printStackTrace(System.err);
} catch (ValidationException ex) {
ex.printStackTrace(System.err);
}
}
}
程序运行结果：
D:\java>count.bat (这个文件请下载我的,设置classpath）
D:\java>set CLASSPATH=d:\java\jar\xercesImpl.jar;d:\java\jar\castor-0.9.5.3-xml.
jar;;d:\jdk1.5\lib;d:\java
D:\java>javac FlightBean.java（这个文件请下载我的）
D:\java>javac Test.java
D:\java>java Test
Flight AR426 departing at 6:23a and arriving at 8:42a
缺省用法生成的XML文件test.xml如下:
<?xml version="1.0" encoding="UTF-8"?>
<flight-bean number="426">
<arrival-time>8:42a</arrival-time>
<departure-time>6:23a</departure-time>
<carrier>AR</carrier>
</flight-bean>
也就是说：
对FlightBena中具有基本类型值的属性创建元素的一个属性（本例中只有number属性通过 getNumber()方法公开为int值）。
对于每个具有对象类型值的属性创建根元素的一个子元素（本例中的所有其他属性，因为它们是字符串）。
标准用法：
import java.io.*;
import org.exolab.castor.xml.*;
import org.exolab.castor.mapping.*;
public class Test1{
public static void main(String[] argv) {
// build a test bean
FlightBean bean = new FlightBean();
bean.setCarrier("AR");
bean.setNumber(426);
bean.setDepartureTime("6:23a");
bean.setArrivalTime("8:42a");
try {
// write it out as XML
Mapping map=new Mapping();
map.loadMapping("mapping.xml");
File file = new File("test1.xml");
Writer writer = new FileWriter(file);
Marshaller marshaller =new Marshaller(writer);
marshaller.setMapping(map);
marshaller.marshal(bean);
// now restore the value and list what we get
Reader reader = new FileReader(file);
Unmarshaller unmarshaller = new Unmarshaller(map);
FlightBean read = (FlightBean)unmarshaller.unmarshal(reader);
System.out.println("Flight " + read.getCarrier() +
read.getNumber() + " departing at " +
read.getDepartureTime() +" and arriving at " + read.getArrivalTime());
} catch (IOException ex) {
ex.printStackTrace(System.err);
} catch (MarshalException ex) {
ex.printStackTrace(System.err);
} catch (ValidationException ex) {
ex.printStackTrace(System.err);
}catch (MappingException ex) {
ex.printStackTrace(System.err);
}
}
}
程序结果：D:\java>java Test1
Flight AR426 departing at 6:23a and arriving at 8:42a
D:\java>
标准用法生成的XML文件test1.xml如下:
<?xml version="1.0" encoding="UTF-8"?>
<flight carrier="AR" depart="6:23a" arrive="8:42a" number="426"/>
这一般是我们期望的，只所以生成我们所期望的格式，是因为我们使用了映射格式描述文件mapping.xml。它也是XML文件:
<!DOCTYPE databases PUBLIC
"-//EXOLAB/Castor Mapping DTD Version 1.0//EN"
"http://castor.exolab.org/mapping.dtd">
<mapping>
<description>Basic mapping example</description>
<class name="FlightBean" auto-complete="ture">
<map-to xml="flight"/>
<field name="carrier">
<bind-xml name="carrier" node="attribute"/>
</field>
<field name="departureTime">
<bind-xml name="depart" node="attribute"/>
</field>
<field name="arrivalTime">
<bind-xml name="arrive" node="attribute"/>
</field>
</class>
</mapping>
注意
(1) class标签里name应该是带有包名的JavaBean类全名
(2) map-to xml="flight"指XML文件的根节点,区分大小写
(3) auto-complete="false"或没有auto-complete属性时number属性会没有
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