XStream将xml文件拼成字符串

import java.util.List;
import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.thoughtworks.xstream.annotations.XStreamImplicit;

@XStreamAlias("OrderHeader")
public class FirstXml {
//    <Receiver></Receiver>收件人
//    <ReceiverEmail></ReceiverEmail>电子邮箱
//    <ReceiverPhone></ReceiverPhone>手机号
//    <OrderLineItem>
//  <Sequencenum>1</Sequencenum> 兑换顺序号
//      <ProductCode>A</ProductCode>礼品ID
//      <Points>2000</Points>积分分数
//      <QuantityRequested>1</QuantityRequested>数量
//      <PointType>Point</PointType>分数类型
//    </OrderLineItem>
//    <OrderLineItem>
//  <Sequencenum>2</Sequencenum> 兑换顺序号
//      <ProductCode>B</ProductCode>礼品ID
//      <Points>3000</Points>积分分数
//      <QuantityRequested>1</QuantityRequested>数量
//      <PointType>Point</PointType>分数类型
//    </OrderLineItem>
    
    @XStreamAlias("Receiver")protected String Receiver ;//收件人
    @XStreamAlias("ReceiverEmail")protected String ReceiverEmail ;//电子邮箱
    @XStreamAlias("ReceiverPhone")protected String ReceiverPhone ;//手机号
    @XStreamImplicit(itemFieldName="OrderLineItem") protected List<TwoXml> OrderLineItem;
    
    public String getReceiver() {
        return Receiver;
    }
    public void setReceiver(String receiver) {
        Receiver = receiver;
    }
    public String getReceiverEmail() {
        return ReceiverEmail;
    }
    public void setReceiverEmail(String receiverEmail) {
        ReceiverEmail = receiverEmail;
    }
    public String getReceiverPhone() {
        return ReceiverPhone;
    }
    public void setReceiverPhone(String receiverPhone) {
        ReceiverPhone = receiverPhone;
    }
    public List<TwoXml> getOrderLineItem() {
        return OrderLineItem;
    }
    public void setOrderLineItem(List<TwoXml> orderLineItem) {
        OrderLineItem = orderLineItem;
    }
    
    
}

import com.thoughtworks.xstream.annotations.XStreamAlias;

@XStreamAlias("OrderLineItem")
public class TwoXml {
//    <OrderLineItem>
//  <Sequencenum>2</Sequencenum> 兑换顺序号
//      <ProductCode>B</ProductCode>礼品ID
//      <Points>5000</Points>积分分数
//      <QuantityRequested>1</QuantityRequested>数量
//      <PointType>Point</PointType>分数类型
//    </OrderLineItem>
    @XStreamAlias("Sequencenum")protected int Sequencenum;
    @XStreamAlias("ProductCode")protected String ProductCode ;
    @XStreamAlias("Points")protected String Points ;
    @XStreamAlias("QuantityRequested")protected int QuantityRequested ;
    @XStreamAlias("PointType")protected String PointType ;
    public int getSequencenum() {
        return Sequencenum;
    }
    public void setSequencenum(int sequencenum) {
        Sequencenum = sequencenum;
    }
    public String getProductCode() {
        return ProductCode;
    }
    public void setProductCode(String productCode) {
        ProductCode = productCode;
    }
    public String getPoints() {
        return Points;
    }
    public void setPoints(String points) {
        Points = points;
    }
    public int getQuantityRequested() {
        return QuantityRequested;
    }
    public void setQuantityRequested(int quantityRequested) {
        QuantityRequested = quantityRequested;
    }
    public String getPointType() {
        return PointType;
    }
    public void setPointType(String pointType) {
        PointType = pointType;
    }
    
    
}

import java.util.ArrayList;
import java.util.List;
import com.thoughtworks.xstream.XStream;

public class Test {
    private static XStream xstream = null;

    public static void main(String[] args) {
        xstream = new XStream();
        
        FirstXml  firstXml  = new FirstXml ();

        firstXml.setReceiver("张三");//姓名
        firstXml.setReceiverEmail("123@qq.com");//邮编
        firstXml.setReceiverPhone("13340118888");//电话号码
        
        List<TwoXml> aaa = new ArrayList<TwoXml>();
        
        TwoXml twoXml01=new TwoXml();
        twoXml01.setSequencenum(1);
        twoXml01.setProductCode("A");
        twoXml01.setPoints("2000");
        twoXml01.setQuantityRequested(1);
        twoXml01.setPointType("Point");
        aaa.add(twoXml01);
        
        TwoXml twoXml02=new TwoXml();
        twoXml02.setSequencenum(2);
        twoXml02.setProductCode("B");
        twoXml02.setPoints("3000");
        twoXml02.setQuantityRequested(1);
        twoXml02.setPointType("Point");
        aaa.add(twoXml02);

        firstXml.setOrderLineItem(aaa);
        
        xstream.processAnnotations(FirstXml.class);
        String inputXml = xstream.toXML(firstXml);
       System.out.println(inputXml);
        
        
        
    }
}