用Digester解析xml到bean

假设有下列xml文件:

<?xml version='1.0' encoding='utf-8'?>
<address-book>
<contact myType="individual">
<name>Zane Pasolini</name>
<address>999 W. Prince St.</address>
<city>New York</city>
<province>NY</province>
<postalcode>10013</postalcode>
<country>USA</country>
<telephone>1-212-345-6789</telephone>
</contact>
<contact myType="business">
<name>SAMOFIX d.o.o.</name>
<address>Ilica 47-2</address>
<city>Zagreb</city>
<province></province>
<postalcode>10000</postalcode>
<country from="cn">Croatia</country>
<telephone>385-1-123-4567</telephone>
</contact>
</address-book>

这是一份常用到的文件，现在我们需要将之映射到java bean,用Digester解析显得非常简单

public class AddressBookParser
{
/**
* Prints the contact information to standard output.
*
* @param contact the <code>Contact</code> to print out
*/
public void addContact(Contact contact)
{
System.out.println("TYPE: " + contact.getType());
System.out.println("NAME: " + contact.getName());
System.out.println(" ADDRESS: " + contact.getAddress());
System.out.println(" CITY: " + contact.getCity());
System.out.println(" PROVINCE: " + contact.getProvince());
System.out.println(" POSTALCODE: " + contact.getPostalcode());
System.out.println(" COUNTRY: " + contact.getCountry());
System.out.println(" COUNTRY-From: " + contact.getCountryFrom());
System.out.println(" TELEPHONE: " + contact.getTelephone());
}

/**
* Configures Digester rules and actions, parses the XML file specified
* as the first argument.
*
* @param args command line arguments
*/
public static void main(String[] args) throws IOException, SAXException
{
// instantiate Digester and disable XML validation
Digester digester = new Digester();
digester.setValidating(false);

// instantiate AddressBookParser class
digester.addObjectCreate("address-book", AddressBookParser.class );
// instantiate Contact class
digester.addObjectCreate("address-book/contact", Contact.class );

// set type property of Contact instance when 'type' attribute is found
//对有属性的值通过setProperties方法

digester.addSetProperties("address-book/contact", "myType", "type" );

// set different properties of Contact instance using specified methods
//addCallMethod与addBeanPropertySetter等价
// 参数 0代表一个参数，默认就是当前读的数据

digester.addCallMethod("address-book/contact/name", "setName", 0);
digester.addCallMethod("address-book/contact/address", "setAddress", 0);
digester.addCallMethod("address-book/contact/address", "setAddress",0);
digester.addCallMethod("address-book/contact/city", "setCity", 0);
digester.addCallMethod("address-book/contact/province", "setProvince", 0);
digester.addCallMethod("address-book/contact/postalcode", "setPostalcode", 0);
digester.addCallMethod("address-book/contact/country", "setCountry", 0);

//增加country的属性 : from
digester.addSetProperties("address-book/contact/country","from","countryFrom");
digester.addCallMethod("address-book/contact/telephone", "setTelephone", 0);

// call 'addContact' method when the next 'address-book/contact' pattern is seen
digester.addSetNext("address-book/contact", "addContact" );

// now that rules and actions are configured, start the parsing process
AddressBookParser abp = (AddressBookParser) digester.parse(new File("c://addressbook.xml"));
}

/**
* JavaBean class that holds properties of each Contact entry.
* It is important that this class be public and static, in order for
* Digester to be able to instantiate it.
*/
public static class Contact
{
private String type;
private String name;
private String address;
private String city;
private String province;
private String postalcode;
private String country;
//增加一个country的属性: from
private String countryFrom;
private String telephone;

public void setType(String newType)
{
type = newType;
}
public String getType()
{
return type;
}

public void setName(String newName)
{
name = newName;
}
public String getName()
{
return name;
}

public void setAddress(String newAddress)
{
address = newAddress;
}
public String getAddress()
{
return address;
}

public void setCity(String newCity)
{
city = newCity;
}
public String getCity()
{
return city;
}

public void setProvince(String newProvince)
{
province = newProvince;
}
public String getProvince()
{
return province;
}

public void setPostalcode(String newPostalcode)
{
postalcode = newPostalcode;
}
public String getPostalcode()
{
return postalcode;
}

public void setCountry(String newCountry)
{
country = newCountry;
}
public String getCountry()
{
return country;
}

public void setTelephone(String newTelephone)
{
telephone = newTelephone;
}
public String getTelephone()
{
return telephone;
}

public String getCountryFrom() {
return countryFrom;
}

public void setCountryFrom(String countryFrom) {
this.countryFrom = countryFrom;
}
}
}

在 AjaxChat 中的读取房间信息的方式显得更简洁
房间的xml配置文件如下:

<rooms>
<room id="1" name="General Topics" />
<room id="2" name="Programming" />
<room id="3" name="Movies" />
<room id="4" name="Music" />
<room id="5" name="Television" />
</rooms>

解析代码如下 :

public synchronized void init(InputStream isConfigFile) {

log.debug("init()");
if (isConfigFile != null) {
// Read in rooms config and create beans, hand off to DAO.
Digester digester = new Digester();
digester.setValidating(false);
digester.push(this);
digester.addObjectCreate("rooms/room",
"org.apache.struts.apps.ajaxchat.dto.RoomDTO");
//注意这里，如果xl的属性名称和bean的属性名称完全对应，则直接提供xml的位置即可
digester.addSetProperties("rooms/room");
digester.addSetNext("rooms/room", "addRoom");
try {
digester.parse(isConfigFile);
log.info("***** Rooms = " + rooms);
} catch (IOException ioe) {
ioe.printStackTrace();
} catch (SAXException se) {
se.printStackTrace();
}
}

} // End init().

如果在xml文件中增加非attribute则更改后的配置文件如下:

<rooms>
<room id="1" name="General Topics" />
<room id="2" name="Programming" />
<room id="3" name="Movies" />
<room id="4" name="Music" />
<room id="5" name="Television" />
<room>
<id>6</id>
<name>shit</name>
</room>
<room>
<id>7</id>
<name>haha</name>
</room>
</rooms>
对应的解析如下:

public synchronized void init(InputStream isConfigFile) {

log.debug("init()

");
if (isConfigFile != null) {
// Read in rooms config and create beans, hand off to DAO.
Digester digester = new Digester();
digester.setValidating(false);
digester.push(this);
digester.addObjectCreate("rooms/room",
"org.apache.struts.apps.ajaxchat.dto.RoomDTO");
digester.addSetProperties("rooms/room");
//增加addCallMethod方法
digester.addCallMethod("rooms/room/id","setId",0);
digester.addCallMethod("rooms/room/name","setName",0);
digester.addSetNext("rooms/room", "addRoom");
try {
digester.parse(isConfigFile);
log.info("***** Rooms = " + rooms);
} catch (IOException ioe) {
ioe.printStackTrace();
} catch (SAXException se) {
se.printStackTrace();
}
}

} // End init().