我们正在共同开发一个GWT Web应用程序，该应用程序已经对其他模块进行了RPC调用。我们构建了一个新的RPC模块（基于现有的体系结构），它可以编译和运行，但是无法在以下行中抛出运行时异常：
this.dashboardService = GWT.create(DashboardService.class);
控制台中的最后一行是＆＃34;未捕获的异常转义＆＃34;然后是堆栈跟踪到上面的GWT.create()行，前面是控制台错误消息：
延迟绑定失败...预计后续失败[错误]
在这两行之前是红色错误的清单，其开头如下：
[INFO] [（...）] - 模块...已加载
[DEBUG] [（...）] - 重新绑定（...）。DashboardService
[DEBUG] [（...）] - 调用生成器com.google.gwt.user.rebind.rpc.ServiceInterfaceProxyGenerator
[DEBUG] [（...）] - 为远程服务界面生成客户端代理＆＃39;（...）。DashboardService＆＃39;
[INFO] [（...）] - 检查类型＆＃39; java.util.Arrays.ArrayList＆＃39;的类型参数0因为它在这种类型或其子类型中的一个（通过（...）到达时最大尺寸为1的数组公开.DashboardChannelSummary）
。 。 。 （没有堆栈跟踪或行号的更多错误）
控制台询问＆＃34;您是否忘记继承模块？＆＃34;但根据我的研究，这不是问题;问题出现在GWT延迟绑定过程中，在堆栈跟踪中不可见。我怀疑上面的粗线是问题，但我不能在没有行号的情况下对这个错误消息做头或者故事。以下是用（...）替换专有包/模块名称的代码：
的web.xml
<servlet>
<servlet-name>(...) DashboardService
</servlet-name>
<servlet-class>(...).server.DashboardServiceImpl
</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>(...) DashboardService
</servlet-name>
<url-pattern>/(...)/DashboardService</url-pattern>
</servlet-mapping>
DashboardChannelSummary.java
/**
* This class is an in memory representation of the results of a document search
*/
public class DashboardChannelSummary implements IsSerializable {
/** Only searches for documents from the past in this amount (the past week) */
private static final int DEFAULT_DASHBOARD_HISTORY_IN_DAYS = -7;
/** array of channels */
private List<Channel> channels;
/** iterator */
private Iterator<Channel> iterator;
/** */
private final static String IMAGE_PATH = "/images/channels/";
/** */
private final static String IMAGE_EXT = ".png";
/** constant for the channel header name */
public final static String BUSINESS_LABEL = "business aviation";
/** constant for the channel header name */
public final static String COMMERCIAL_LABEL = "commercial aviation";
/** constant for the channel header name */
public final static String MRO_LABEL = "mro";
/** constant for the channel header name */
public final static String DEFENSE_LABEL = "defense";
/**
*
*/
public enum CHANNEL_NAME {
BUSINESS (BUSINESS_LABEL, DocumentSummary.BA_ID),
COMMERCIAL (COMMERCIAL_LABEL, DocumentSummary.CA_ID),
MRO (MRO_LABEL, DocumentSummary.MRO_ID),
DEFENSE (DEFENSE_LABEL, DocumentSummary.DEFENSE_ID);
/** */
public String label;
/** */
public int ID;
/** */
private CHANNEL_NAME(String label, int ID) {
this.label = label.toUpperCase();
this.ID = ID;
}
};
/**
*
*/
public static List<String> channelNames() {
ArrayList<String> channels = new ArrayList<String>(CHANNEL_NAME.values().length);
for(int i=0; i<channels.size(); i++) {
channels.add(CHANNEL_NAME.values()[i].label);
}
return channels;
}
/**
*
*/
public static int[] channelIDs() {
int[] IDs = new int[CHANNEL_NAME.values().length];
for(int i=0; i<IDs.length; i++) {
IDs[i] = CHANNEL_NAME.values()[i].ID;
}
return IDs;
}
/**
*
* @return
*/
public static int channelCount() {
return CHANNEL_NAME.values().length;
}
/**
*
*/
public static Date cutoffDate() {
Date date = new Date(0);
CalendarUtil.addDaysToDate(date, DEFAULT_DASHBOARD_HISTORY_IN_DAYS);
return date;
}
/**
*
*/
public class Channel {
/** the name of this channel */
private CHANNEL_NAME name;
/** The list of documents */
private List<DocumentSummary> docs;
/** the iterator */
private Iterator<DocumentSummary> iterator;
/**
*
*/
public Channel(List<DocumentSummary> docs, CHANNEL_NAME name) {
this.docs = docs;
this.name = name;
iterator = docs.iterator();
}
/**
*
*/
public String getLabel() {
return name.label;
}
/**
*
*/
public List<DocumentSummary> getDocuments() {
return docs;
}
/**
*
*/
public boolean hasDocuments() {
return iterator.hasNext();
}
/**
*
* @return
*/
public DocumentSummary nextDocument() {
if(iterator.hasNext()) {
return iterator.next();
}
else {
return null;
}
}
/**
*
*/
public String nextImageURL() {
return GWT.getHostPageBaseURL().concat(IMAGE_PATH + String.valueOf(Random.nextInt(channels.size()) - 1) + IMAGE_EXT);
}
}
/**
* Constructor
*/
public DashboardChannelSummary() {
channels = new ArrayList<Channel>(CHANNEL_NAME.values().length);
iterator = channels.iterator();
}
/**
* Constructor
*/
public DashboardChannelSummary(List<List<DocumentSummary>> channelList) {
channels = new ArrayList<Channel>(CHANNEL_NAME.values().length);
iterator = channels.iterator();
int count = 0;
for(List<DocumentSummary> channelData : channelList)
{
channels.add(new Channel(channelData, CHANNEL_NAME.values()[count++]));
}
}
/**
* @return
*/
public List<Channel> getChannels() {
return channels;
}
/**
* @return
*/
public Channel getChannel(int channel) {
return channels.get(channel);
}
/**
* @return
*/
public Channel nextChannel() {
if(iterator.hasNext()) {
return iterator.next();
}
else {
return null;
}
}
/**
* @return
*/
public List<DocumentSummary> getDocuments(int channel) {
return this.getChannel(channel).getDocuments();
}
}
DashboardPresenter.java：
private final DashboardServiceAsync dashboardService;
以及构造函数中失败的延迟绑定：
this.dashboardService = GWT.create(DashboardService.class);
DashboardServiceAsync.java：
public interface DashboardServiceAsync {
/**
*
* @param channelIDs
* @param startDate
* @param async
*/
void getChannelSummary(int[] channelIDs, Date startDate, AsyncCallback<DashboardChannelSummary> async);
}
DashboardService.java：
@RemoteServiceRelativePath("DashboardService") public interface DashboardService extends RemoteService {
/**
*
* @param channelIDs
* @param startDate
* @return
*/
DashboardChannelSummary getChannelSummary(int[] channelIDs, Date startDate);
}
在服务器上：
DashboardServiceImpl.java：
public class DashboardServiceImpl extends RemoteServiceServlet implements DashboardService {
/**
*
* @param channelIDs
* @param startDate
* @return
*/
@Override
public DashboardChannelSummary getChannelSummary(int[] channelIDs, Date startDate) {
return new DashboardDaoImpl().getChannelSummary(channelIDs, startDate);
}
}
我们根据documentation和SO上的建议对RPC代码进行了双重和三重检查，例如确保方法签名在所有接口和实现中都是正确的。跳到任何人身上显然是错误的吗？有没有办法我们可以更详细地调试这个错误？
更新
DashboardChannelSummary.java 重新设计，以便在将数据从服务器传输到客户端时获得最大效率，现在所有属性都可以序列化：＆＃34;
/**
* This class is an in memory representation of the results of a document search.
*/
public class DashboardChannelSummary implements IsSerializable {
/** Only searches for documents from the past in this amount (the past week) */
private static final int DEFAULT_DASHBOARD_HISTORY_IN_DAYS = -7;
/** array of channels */
private ArrayList<ArrayList<DocumentSummary>> channels;
/** */
private int channel = 0;
/** */
private int image = 0;
/** */
private int index = 0;
/** */
private int last = 0;
/** */
private final static String IMAGE_PATH = "images/channels/";
/** */
private final static String IMAGE_EXT = ".jpg";
/** constant for the channel header name */
public final static String BUSINESS_LABEL = "business";
/** constant for the channel header name */
public final static String COMMERCIAL_LABEL = "commercial";
/** constant for the channel header name */
public final static String MRO_LABEL = "mro";
/** constant for the channel header name */
public final static String DEFENSE_LABEL = "defense";
/**
*
*/
public enum CHANNEL_NAME {
BUSINESS (BUSINESS_LABEL, DocumentSummary.BA_ID, "bus"),
COMMERCIAL (COMMERCIAL_LABEL, DocumentSummary.CA_ID, "_com"),
MRO (MRO_LABEL, DocumentSummary.MRO_ID, "mro"),
DEFENSE (DEFENSE_LABEL, DocumentSummary.DEFENSE_ID, "mil");
/** */
public String label;
/** */
public int ID;
/** */
public String prefix;
/** */
private CHANNEL_NAME(String label, int ID, String prefix) {
this.label = label.toUpperCase();
this.ID = ID;
this.prefix = prefix;
}
};
/**
*
*/
private String nextRandomImage() {
while(index == last) {
index = Random.nextInt(channels.size()) + 1;
}
last = index;
return String.valueOf(index);
}
/**
*
*/
public static List<String> channelNames() {
ArrayList<String> channels = new ArrayList<String>(CHANNEL_NAME.values().length);
for(int i=0; i<channels.size(); i++) {
channels.add(CHANNEL_NAME.values()[i].label);
}
return channels;
}
/**
*
*/
public static int[] channelIDs() {
int[] IDs = new int[CHANNEL_NAME.values().length];
for(int i=0; i<IDs.length; i++) {
IDs[i] = CHANNEL_NAME.values()[i].ID;
}
return IDs;
}
/**
*
* @return
*/
public static int channelCount() {
return CHANNEL_NAME.values().length;
}
/**
*
*/
public static Date cutoffDate() {
Date date = new Date();
CalendarUtil.addDaysToDate(date, DEFAULT_DASHBOARD_HISTORY_IN_DAYS);
return date;
}
/**
* Constructor
*/
public DashboardChannelSummary() {
}
/**
* Constructor
*/
public DashboardChannelSummary(ArrayList<ArrayList<DocumentSummary>> channels) {
this.channels = channels;
}
/**
*
*/
public String nextImageURL() {
if(++image > channels.get(channel - 1).size()) {
image = 0;
}
return GWT.getHostPageBaseURL() +
IMAGE_PATH +
CHANNEL_NAME.values()[channel - 1].prefix +
nextRandomImage() +
IMAGE_EXT;
}
/**
*
*/
public ArrayList<DocumentSummary> nextChannel() {
return channels.get(channel++);
}
/**
*
*/
public String toString() {
return this.getClass().toString() + " current channel : " + channel;
}
}
答案 0 :(得分：1)
罪魁祸首很可能DashboardChannelSummary。确保将getChannelSummary的返回类型更改为“安全”，例如String或Void。如果错误仍然存在，那么服务的配置就会出现问题（不过，我怀疑它会在GWT的编译阶段出现）。如果此服务有效，那么您可以非常确定它是因为DashboardChannelSummary不可序列化。
虽然类本身有一个no-args构造函数并实现IsSerializable，但并非所有字段都是可序列化的。您应该仔细查看Channel类（也许DocumentSummary，但问题中没有提供代码），Iterator字段（ArrayList返回Itr实例，似乎不是可序列化的。）
如果错误仍然存在，请尝试简化DashboardChannelSummary，直到找到正常工作的版本，然后按“向上”的方式工作，直到找到导致错误的部分。