GWT +序列化

Question

我很难尝试序列化我的课程(实际上是3-4个小时才找到解决方案).我将一个子类添加到现有的可序列化和正常运行的类中,并获取以下错误消息:

 [ERROR] com.google.gwt.user.client.ui.DelegatingChangeListenerCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.google.gwt.user.client.ui.DelegatingClickListenerCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.google.gwt.user.client.ui.DelegatingFocusListenerCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.google.gwt.user.client.ui.DelegatingKeyboardListenerCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.google.gwt.view.client.ListDataProvider<T>.ListWrapper<> is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.client.rpc.ItemRecRpc.LogCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] com.client.rpc.ItemRecRpc.LogCollection has no available instantiable subtypes. (reached via com.client.rpc.ItemRecRpc)
                 [ERROR]    subtype com.client.rpc.ItemRecRpc.LogCollection is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] java.util.AbstractList.SubList<E> is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] java.util.Collections.UnmodifiableList<T> is not default instantiable (it must have a zero-argument constructor or no constructors at all) and has no custom serializer. (reached via com.client.rpc.ItemRecRpc)
              [ERROR] java.util.Collections.UnmodifiableRandomAccessList<T> is not default instantiable (it must have a zero-argument 

我的班级看起来像:

public class ItemRecRpc implements Serializable {

    private static final long serialVersionUID = -5828108890651522661L;
        .
        .

        private String rId;
    private LogCollection logColl;//if i comment this, no error message...

    public class LogCollection{ 

        public LogCollection(){

        }
        //public long creationTime = System.currentTimeMillis();
        //public LongVector times = new LongVector();
        //public ArrayList<Object> messages = new ArrayList<Object>();
        //public int nSkipped = 0; 
        //public int nExceptions = 0; 
        //public Exception firstException = null; 
        //public long endGcTime=0;
        public long endTime;
    }
.
.
.
}

当我评论"私有LogCollection logColl"行时,它没问题,但当我取消注释时我再次得到错误信息.我尝试使用static关键字,因为你看到我评论每个子类变量,但无法帮助...无论如何,如果我创建一个新类:

public class LogCollectionRpc implements Serializable {

    public LogCollectionRpc() {
        //
    }
    public long creationTime = System.currentTimeMillis();
    public LongVector times = new LongVector();
    public ArrayList<Object> messages = new ArrayList<Object>();
    public int nSkipped = 0; // due to reaching the limit
    public int nExceptions = 0; // due to MyAppender-s
    public Exception firstException = null; // due to MyAppender-s
    public long endGcTime = 0;
    public long endTime;

}

而不是尝试使用它作为我的功能类,它没关系...但这件事真的让我烦恼......

任何的想法？Gwt不支持子类序列化？或者我想念一些东西.感谢任何答案.

最诚挚的问候,彼得

Answer 1

这个错误:

subtype com.client.rpc.ItemRecRpc.LogCollection is not default instantiable

说它LogCollection默认不能创建和实例.这是事实.因为要创建一个实例LogCollection,首先需要有一个实例ItemRecRpc.声明LogCollection为静态类应该有所帮助.

基本上,当你想通过gwt-rpc发送一些对象时,默认情况下,所有用作此类对象中的字段的类都应该是可实例化的.(例如,没有特殊的技巧来创建它,只是新的和空的构造函数).您还可以为任何类定义自定义字段序列化程序,默认情况下可以对其进行实例化.