这是我的困境:
我有一个DTO类用于在XML之间进行编组和解组。
问题在于:由于我们的项目处理包含复数外部标记的DTO类的数量很多,我决定创建一个委托集合,让我可以将其中一个类轻松地转换为集合,并获得方便的功能(迭代、添加等)。
在我们的项目中,我们进行了编组测试以排除注释错误等。以下是我的麻烦代码:
问题: 根据编组程序,如果我扩展此QuickCollection,则会出现下面的错误。 当使用CXF作为对Web服务请求的响应来解组对象为XML时,它会失败。具体的错误信息如下: com.sun.istack.SAXException2: unable to marshal type "java.lang.String" as an element because it is missing an @XmlRootElement annotation
在测试中使用JAXB进行编组/解组时,一切正常。 当使用相同的QuickCollection将结果从第三方编组并进行编组时,使用Spring RestOperations也可以正常工作。
混乱的想法是: 当我删除继承并将集合管理为私有成员时,所有内容都正常工作!
对我来说,这毫无意义,因为在两种情况下我都实际返回了确切的数据类型。
以下是所有相关代码。
这是继承的委托类。
public class QuickCollection<T> implements Collection<T> {
// to be set if needed after instantiation. To behave like a normal collection, we set it to something safe
protected Collection<T> delegate = Collections.emptySet();
public QuickCollection() {
}
public QuickCollection(Collection<T> delegate) {
this.delegate = delegate;
}
@Override
public int size() {
return delegate.size();
}
@Override
public boolean isEmpty() {
return delegate.isEmpty();
}
@Override
public boolean contains(Object o) {
return delegate.contains(o);
}
@Override
public Iterator<T> iterator() {
return delegate.iterator();
}
@Override
public Object[] toArray() {
return delegate.toArray();
}
@Override
public <T> T[] toArray(T[] a) {
return delegate.toArray(a);
}
@Override
public boolean add(T t) {
return delegate.add(t);
}
@Override
public boolean remove(Object o) {
return delegate.remove(o);
}
@Override
public boolean containsAll(Collection<?> c) {
return delegate.containsAll(c);
}
@Override
public boolean addAll(Collection<? extends T> c) {
return delegate.addAll(c);
}
@Override
public boolean removeAll(Collection<?> c) {
return delegate.removeAll(c);
}
@Override
public boolean retainAll(Collection<?> c) {
return delegate.retainAll(c);
}
@Override
public void clear() {
delegate.clear();
}
@Override
public String toString() {
return "" + delegate.toString();
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
QuickCollection that = (QuickCollection) o;
if (delegate != null ? !delegate.equals(that.delegate) : that.delegate != null) return false;
return true;
}
@Override
public int hashCode() {
return delegate != null ? delegate.hashCode() : 0;
}
}
这是子DTO类。
@XmlAccessorType(XmlAccessType.PROPERTY)
@XmlType(name = "BuddyCodes")
@XmlRootElement(name = "BuddyCodes")
public class BuddyCodes extends QuickCollection<String> implements Xml {
private Long accountId;
private Date expirationDate;
public BuddyCodes() {
super.delegate = new HashSet<String>();
}
public BuddyCodes(Long accountId, Set<String> codes, Date expirationDate) {
super(codes);
this.accountId = accountId;
this.expirationDate = expirationDate;
super.delegate = new HashSet<String>();
}
public BuddyCodes(Long accountId, Date expirationDate) {
this.accountId = accountId;
this.expirationDate = expirationDate;
super.delegate = new HashSet<String>();
}
@Override
public String toXml() {
String retVal;
try {
retVal = StringUtils.toXml(this);
}
catch (JAXBException e) {
retVal = e.toString();
}
return retVal;
}
public Long getAccountId() {
return accountId;
}
public void setAccountId(Long accountId) {
this.accountId = accountId;
}
public Set<String> getCodes() {
return (Set<String>) super.delegate;
}
@XmlElement(name = "code")
public void setCodes(Set<String> codes) {
super.delegate = codes;
}
public Date getExpirationDate() {
return expirationDate;
}
public void setExpirationDate(Date expirationDate) {
this.expirationDate = expirationDate;
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
BuddyCodes that = (BuddyCodes) o;
if (accountId != null ? !accountId.equals(that.accountId) : that.accountId != null) return false;
if (delegate != null ? !super.delegate.equals(that.delegate) : that.delegate != null) return false;
if (expirationDate != null ? !expirationDate.equals(that.expirationDate) : that.expirationDate != null)
return false;
return true;
}
@Override
public int hashCode() {
int result = accountId != null ? accountId.hashCode() : 0;
result = 31 * result + (expirationDate != null ? expirationDate.hashCode() : 0);
result = 31 * result + (super.delegate != null ? super.delegate.hashCode() : 0);
return result;
}
@Override
public String toString() {
return "BuddyCodes{" +
"accountId=" + accountId +
"codes=" + super.delegate +
", expirationDate=" + expirationDate +
'}';
}
}
它不起作用。我收到了错误信息。
现在,这是删除继承后的子类,它可以工作!!!
import javax.xml.bind.JAXBException;
import javax.xml.bind.annotation.*;
import java.util.Collection;
import java.util.Date;
import java.util.HashSet;
import java.util.Set;
/**
* @author christian.bongiorno
* Date: 10/3/11
* Time: 6:11 PM
*/
@XmlAccessorType(XmlAccessType.PROPERTY)
@XmlType(name = "BuddyCodes")
@XmlRootElement(name = "BuddyCodes")
public class BuddyCodes implements Xml {
private Long accountId;
private Date expirationDate;
private Set<String> delegate;
public BuddyCodes() {
delegate = new HashSet<String>();
}
public BuddyCodes(Long accountId, Set<String> codes, Date expirationDate) {
this.accountId = accountId;
this.expirationDate = expirationDate;
delegate = new HashSet<String>();
}
public BuddyCodes(Long accountId, Date expirationDate) {
this.accountId = accountId;
this.expirationDate = expirationDate;
delegate = new HashSet<String>();
}
@Override
public String toXml() {
String retVal;
try {
retVal = StringUtils.toXml(this);
}
catch (JAXBException e) {
retVal = e.toString();
}
return retVal;
}
public Long getAccountId() {
return accountId;
}
public void setAccountId(Long accountId) {
this.accountId = accountId;
}
public Set<String> getCodes() {
return delegate;
}
@XmlElement(name = "code")
public void setCodes(Set<String> codes) {
delegate = codes;
}
public Date getExpirationDate() {
return expirationDate;
}
public void setExpirationDate(Date expirationDate) {
this.expirationDate = expirationDate;
}
public boolean add(String s) {
return delegate.add(s);
}
public int size() {
return delegate.size();
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
BuddyCodes that = (BuddyCodes) o;
if (accountId != null ? !accountId.equals(that.accountId) : that.accountId != null) return false;
if (delegate != null ? !delegate.equals(that.delegate) : that.delegate != null) return false;
if (expirationDate != null ? !expirationDate.equals(that.expirationDate) : that.expirationDate != null)
return false;
return true;
}
@Override
public int hashCode() {
int result = accountId != null ? accountId.hashCode() : 0;
result = 31 * result + (expirationDate != null ? expirationDate.hashCode() : 0);
result = 31 * result + (delegate != null ? delegate.hashCode() : 0);
return result;
}
}
为什么继承很重要?
我还没有想通,但是我有另一个类似的DTO(BuddyTypes BuddyType)布局。BuddyType有两个成员:Long和String。两者都被注释为XmlElement。这个可以正常工作。
看起来问题出在我的问题案例中,构成委托的集合成员没有注释,我不知道如何注释父成员。作为一个继承类,拥有某种默认名称/注释是没有意义的。但是,我尝试了这种疯狂的方法,注释被忽略了 - 我以前见过父成员注释被忽略,所以这并不新鲜。
我不知道是否可能,但我需要注释一个父成员。
XmlElementWrapper
注解吗?如果我正确理解你的需求,那将是一种更简单的方式来添加一个复数的包装元素。 - Jörn Horstmann