在物件和xml對映時候，有些型別需要我們制定格式轉換，此時就要自定義轉換器了。

下面建立一個對於Date進行轉換的一個日期轉換器。

DateConverter

package cn.framework.t1;

import java.text.DateFormat;
import java.text.ParseException;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;

import com.thoughtworks.xstream.converters.ConversionException;
import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;

public class DateConverter implements Converter{
	private Locale locale;
	public DateConverter(Locale locale){
		super();
		this.locale=locale;
	}
	
	//判斷需要轉換的型別
	@Override
	public boolean canConvert(Class clazz) {
		// TODO Auto-generated method stub
		return Date.class.isAssignableFrom(clazz);
	}

	//編寫java物件到xml的邏輯
	@Override
	public void marshal(Object value, HierarchicalStreamWriter writer,
			MarshallingContext context) {
		DateFormat formatter = DateFormat.getDateInstance(DateFormat.FULL,this.locale);
		writer.setValue(formatter.format(value));
	}

	//編寫xml到java物件的邏輯
	@Override
	public Object unmarshal(HierarchicalStreamReader reader,
			UnmarshallingContext context) {
		GregorianCalendar calendar = new GregorianCalendar();
		DateFormat formatter = DateFormat.getDateInstance(DateFormat.FULL,this.locale);
		try{
			calendar.setGregorianChange(formatter.parse(reader.getValue()));
		}catch(ParseException e){
			throw new ConversionException(e.getMessage(),e);
		}
		return calendar.getGregorianChange();
	}

}
 

接下來，把這個自定義轉換器註冊到XStream。

package cn.framework.t1;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.util.Locale;

import org.apache.log4j.Logger;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.DomDriver;

public class XStreamUtils {
	private static final Logger logger=Logger.getLogger("cn.framework.t1.XStreamUtils");
	
	private static XStream xstream;
	static{
		logger.info("init xstream ...");
		xstream=new XStream(new DomDriver());
		
		/*******對生成的xml做一些設定*******/
		//設定別名，不設定將採用完全類名
		xstream.alias("User", User.class);
		xstream.alias("UserLog", UserLog.class);
		
		//設定類成員別名
		xstream.aliasField("id", User.class, "userId");
		
		//類的屬性預設為xml的元素，現在修改為xml屬性
		xstream.aliasAttribute(UserLog.class, "logId", "lid");
		xstream.useAttributeFor(UserLog.class, "logId");
		
		//只保留集合內元素，去掉上級標籤
		xstream.addImplicitCollection(User.class, "logs");
		
		//註冊自定義轉換器
		xstream.registerConverter(new DateConverter(Locale.SIMPLIFIED_CHINESE));
	}
	
	public static void objectToXML(User user) throws FileNotFoundException{
		logger.info("do objectToXML ...");
		FileOutputStream fileOutputStream = new FileOutputStream("e:/out/xstream_user.xml");
		xstream.toXML(user, fileOutputStream);
	}
	
	public static void xmlToObject() throws FileNotFoundException{
		logger.info("do xmlToObject ...");
		FileInputStream input = new FileInputStream("e:/out/xstream_user.xml");
		User user=(User) xstream.fromXML(input);
		System.out.println(user);
	}
	
	
}
 

<User>
  <id>1</id>
  <userName>aaa</userName>
  <pwd>123456</pwd>
  <UserLog lid="1">
    <ip>127.0.0.1</ip>
  </UserLog>
  <UserLog lid="2">
    <ip>127.0.0.1</ip>
  </UserLog>
  <lastVisted>2017年12月6日 星期三</lastVisted>
</User>