- Java 双重比较
- java - 比较器与 Apache BeanComparator
- Objective-C 完成 block 导致额外的方法调用?
- database - RESTful URI 是否应该公开数据库主键?
我正在开发一些必须序列化为以下格式的 XML 的 Java 类:
<foo value="123"/>
<!-- or this -->
<bar value="abc"/>
<!-- or this -->
<baz value="true"/>
一开始,Foo.java
看起来像这样:
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
class Foo {
@XmlAttribute
String value;
// snip constructors
// snip methods
// getValue
// equals, hashCode, toString
// static valueOf(String), static valueOf(int)
}
不需要太多想象力就可以猜出是什么Bar.java
和 Baz.java
可能看起来像。这些是(在此示例中)int
的非常简单的包装类, String
, 和 boolean
.到目前为止,一切都很顺利。写完第九轮
class WhoCares {
@XmlAttribute
Whatever value;
/* 2 constructors */
/* 6 methods found in every one of these classes */
}
我想:“嘿,我知道如何解决这个问题了——我只需要一个抽象级别!” 介绍 Wrapper<T>
:
abstract class Wrapper<T> {
@XmlAttribute
private T value;
Wrapper() {} // default ctor for JAXB
Wrapper(T value) {
this.value = value;
}
T getValue() {
return value;
}
// snip equals, hashCode, toString
}
现在,执行Foo
,我需要做的就是扩展 Wrapper
,实现我需要的工厂方法:
class Foo extends Wrapper<String> {
// snip constructors
static Foo valueOf(String value) {
return new Foo(value);
}
}
并添加 @XmlSeeAlso({... Foo.class ...})
至 Wrapper
的声明。
任何对 JAXBContext.getInstance(Wrapper.class)
的调用或 JAXBContext.getInstance(Foo.class)
由于 NullPointerException
而失败扔在 JAXB 深处的某个地方:
17:06:03,706 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/Redacted].[JAX-RS Servlet]] Servlet.service() for servlet JAX-RS Servlet threw exception: java.lang.NullPointerException
at com.sun.xml.bind.v2.runtime.reflect.TransducedAccessor.get(TransducedAccessor.java:165) [:2.2]
at com.sun.xml.bind.v2.runtime.property.AttributeProperty.<init>(AttributeProperty.java:87) [:2.2]
at com.sun.xml.bind.v2.runtime.property.PropertyFactory.create(PropertyFactory.java:104) [:2.2]
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:179) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:515) [:2.2]
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:166) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:515) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:534) [:2.2]
at com.sun.xml.bind.v2.runtime.property.SingleElementNodeProperty.<init>(SingleElementNodeProperty.java:101) [:2.2]
at sun.reflect.GeneratedConstructorAccessor49.newInstance(Unknown Source) [:1.6.0_24]
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) [:1.6.0_24]
at java.lang.reflect.Constructor.newInstance(Constructor.java:513) [:1.6.0_24]
at com.sun.xml.bind.v2.runtime.property.PropertyFactory.create(PropertyFactory.java:124) [:2.2]
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:179) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:515) [:2.2]
at com.sun.xml.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:166) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:515) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.<init>(JAXBContextImpl.java:330) [:2.2]
at com.sun.xml.bind.v2.runtime.JAXBContextImpl$JAXBContextBuilder.build(JAXBContextImpl.java:1140) [:2.2]
at com.sun.xml.bind.v2.ContextFactory.createContext(ContextFactory.java:154) [:2.2]
at com.sun.xml.bind.v2.ContextFactory.createContext(ContextFactory.java:121) [:2.2]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) [:1.6.0_24]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) [:1.6.0_24]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) [:1.6.0_24]
at java.lang.reflect.Method.invoke(Method.java:597) [:1.6.0_24]
at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:201) [:1.0.0.Final]
at javax.xml.bind.ContextFinder.find(ContextFinder.java:362) [:1.0.0.Final]
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:618) [:1.0.0.Final]
at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:565) [:1.0.0.Final]
at com.sun.jersey.core.provider.jaxb.AbstractJAXBProvider.getStoredJAXBContext(AbstractJAXBProvider.java:189) [:1.6]
at com.sun.jersey.core.provider.jaxb.AbstractJAXBProvider.getJAXBContext(AbstractJAXBProvider.java:182) [:1.6]
at com.sun.jersey.core.provider.jaxb.AbstractJAXBProvider.getMarshaller(AbstractJAXBProvider.java:160) [:1.6]
at com.sun.jersey.core.provider.jaxb.AbstractJAXBProvider.getMarshaller(AbstractJAXBProvider.java:139) [:1.6]
at com.sun.jersey.core.provider.jaxb.AbstractRootElementProvider.writeTo(AbstractRootElementProvider.java:151) [:1.6]
at com.sun.jersey.spi.container.ContainerResponse.write(ContainerResponse.java:306) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1310) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1223) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1213) [:1.6]
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:414) [:1.6]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:537) [:1.6]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:699) [:1.6]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [:1.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:324) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at com.example.mgp.filter.RetryFilter.doFilter(RetryFilter.java:109) [:]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at com.example.mgp.filter.AuthFilter.doFilter(AuthFilter.java:57) [:]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at org.jboss.weld.servlet.ConversationPropagationFilter.doFilter(ConversationPropagationFilter.java:67) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [:6.0.0.Final]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) [:6.0.0.Final]
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:181) [:6.0.0.Final]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.event(CatalinaContext.java:285) [:1.1.0.Final]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.invoke(CatalinaContext.java:261) [:1.1.0.Final]
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:88) [:6.0.0.Final]
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:100) [:6.0.0.Final]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) [:6.0.0.Final]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [:6.0.0.Final]
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158) [:6.0.0.Final]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [:6.0.0.Final]
at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.invoke(ActiveRequestResponseCacheValve.java:53) [:6.0.0.Final]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:362) [:6.0.0.Final]
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [:6.0.0.Final]
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:654) [:6.0.0.Final]
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:951) [:6.0.0.Final]
at java.lang.Thread.run(Thread.java:662) [:1.6.0_24]
我已经尝试将我的 JAXB 实现从 Metro 切换到 MOXy(我做了 check that the implementation changed )但是 MOXy 抛出了类似的 NPE:
17:46:48,481 SEVERE [com.sun.jersey.spi.container.ContainerResponse] Mapped exception to response: 500 (Internal Server Error): javax.ws.rs.WebApplicationException: javax.xml.bind.MarshalException
- with linked exception:
[Exception [EclipseLink-25003] (Eclipse Persistence Services - 2.2.0.v20110202-r8913): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: An error occurred marshalling the object
Internal Exception: java.lang.NullPointerException]
at com.sun.jersey.core.provider.jaxb.AbstractRootElementProvider.writeTo(AbstractRootElementProvider.java:159) [:1.6]
at com.sun.jersey.spi.container.ContainerResponse.write(ContainerResponse.java:306) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl._handleRequest(WebApplicationImpl.java:1310) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1223) [:1.6]
at com.sun.jersey.server.impl.application.WebApplicationImpl.handleRequest(WebApplicationImpl.java:1213) [:1.6]
at com.sun.jersey.spi.container.servlet.WebComponent.service(WebComponent.java:414) [:1.6]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:537) [:1.6]
at com.sun.jersey.spi.container.servlet.ServletContainer.service(ServletContainer.java:699) [:1.6]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) [:1.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:324) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at com.example.mgp.filter.RetryFilter.doFilter(RetryFilter.java:109) [:]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at com.example.mgp.filter.AuthFilter.doFilter(AuthFilter.java:57) [:]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at org.jboss.weld.servlet.ConversationPropagationFilter.doFilter(ConversationPropagationFilter.java:67) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:6.0.0.Final]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:6.0.0.Final]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [:6.0.0.Final]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) [:6.0.0.Final]
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:181) [:6.0.0.Final]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.event(CatalinaContext.java:285) [:1.1.0.Final]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.invoke(CatalinaContext.java:261) [:1.1.0.Final]
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:88) [:6.0.0.Final]
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:100) [:6.0.0.Final]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) [:6.0.0.Final]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [:6.0.0.Final]
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158) [:6.0.0.Final]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [:6.0.0.Final]
at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.invoke(ActiveRequestResponseCacheValve.java:53) [:6.0.0.Final]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:362) [:6.0.0.Final]
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:877) [:6.0.0.Final]
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:654) [:6.0.0.Final]
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:951) [:6.0.0.Final]
at java.lang.Thread.run(Thread.java:662) [:1.6.0_24]
Caused by: javax.xml.bind.MarshalException
- with linked exception:
[Exception [EclipseLink-25003] (Eclipse Persistence Services - 2.2.0.v20110202-r8913): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: An error occurred marshalling the object
Internal Exception: java.lang.NullPointerException]
at org.eclipse.persistence.jaxb.JAXBMarshaller.marshal(JAXBMarshaller.java:314) [:2.2.0.v20110202-r8913]
at com.sun.jersey.core.provider.jaxb.AbstractRootElementProvider.writeTo(AbstractRootElementProvider.java:179) [:1.6]
at com.sun.jersey.core.provider.jaxb.AbstractRootElementProvider.writeTo(AbstractRootElementProvider.java:157) [:1.6]
... 36 more
Caused by: Exception [EclipseLink-25003] (Eclipse Persistence Services - 2.2.0.v20110202-r8913): org.eclipse.persistence.exceptions.XMLMarshalException
Exception Description: An error occurred marshalling the object
Internal Exception: java.lang.NullPointerException
at org.eclipse.persistence.exceptions.XMLMarshalException.marshalException(XMLMarshalException.java:78) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.oxm.XMLMarshaller.marshal(XMLMarshaller.java:516) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.jaxb.JAXBMarshaller.marshal(JAXBMarshaller.java:312) [:2.2.0.v20110202-r8913]
... 38 more
Caused by: java.lang.NullPointerException
at org.eclipse.persistence.oxm.record.OutputStreamRecord.outputStreamWrite(OutputStreamRecord.java:511) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.oxm.record.OutputStreamRecord.openStartElement(OutputStreamRecord.java:159) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XPathNode.startElement(XPathNode.java:330) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshalSingleValue(XMLCompositeObjectMappingNodeValue.java:185) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshal(XMLCompositeObjectMappingNodeValue.java:116) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.NodeValue.marshal(NodeValue.java:104) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.record.ObjectMarshalContext.marshal(ObjectMarshalContext.java:60) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XPathNode.marshal(XPathNode.java:322) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.marshalAttributes(TreeObjectBuilder.java:338) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XPathNode.startElement(XPathNode.java:344) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshalSingleValue(XMLCompositeObjectMappingNodeValue.java:167) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLCompositeObjectMappingNodeValue.marshal(XMLCompositeObjectMappingNodeValue.java:116) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.NodeValue.marshal(NodeValue.java:104) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.record.ObjectMarshalContext.marshal(ObjectMarshalContext.java:60) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XPathNode.marshal(XPathNode.java:322) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:325) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLAnyObjectMappingNodeValue.marshalSingleValue(XMLAnyObjectMappingNodeValue.java:154) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XMLAnyObjectMappingNodeValue.marshal(XMLAnyObjectMappingNodeValue.java:70) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.NodeValue.marshal(NodeValue.java:104) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.record.ObjectMarshalContext.marshal(ObjectMarshalContext.java:60) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.XPathNode.marshal(XPathNode.java:322) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.internal.oxm.TreeObjectBuilder.buildRow(TreeObjectBuilder.java:325) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.oxm.XMLMarshaller.marshal(XMLMarshaller.java:932) [:2.2.0.v20110202-r8913]
at org.eclipse.persistence.oxm.XMLMarshaller.marshal(XMLMarshaller.java:486) [:2.2.0.v20110202-r8913]
... 39 more
有什么方法可以生成所需的 XML,同时最小化样板文件并保持 DRY ?
最佳答案
您看到的问题是由于 Metro(引用实现)和 EclipseLink MOXy 中的错误造成的JAXB 实现。相关的 MOXy 错误是:
关于您的用例需要注意的一件事是,由于类型删除,JAXB 实现会将值属性视为对象类型。这意味着编码操作将为您工作,但解编码操作将以字符串形式返回值。这就是为什么如果用 @XmlElement 注释值字段,那么 xsi:type 信息将被包含以保留类型信息:
MOXy 解决方法
您可以利用以下 XmlAdapter 解决 MOXy 错误:
import javax.xml.bind.annotation.adapters.XmlAdapter;
public class ObjectAdapter extends XmlAdapter<Object, Object> {
@Override
public Object unmarshal(Object v) throws Exception {
return v;
}
@Override
public Object marshal(Object v) throws Exception {
return v;
}
}
XML 适配器在您的属性上注册如下:
import javax.xml.bind.annotation.XmlAccessType;
import javax.xml.bind.annotation.XmlAccessorType;
import javax.xml.bind.annotation.XmlAttribute;
import javax.xml.bind.annotation.XmlSeeAlso;
import javax.xml.bind.annotation.XmlTransient;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
@XmlTransient
@XmlAccessorType(XmlAccessType.FIELD)
@XmlSeeAlso(Foo.class)
abstract class Wrapper<T> {
@XmlAttribute
@XmlJavaTypeAdapter(ObjectAdapter.class)
private T value;
Wrapper() {} // default ctor for JAXB
public Wrapper(T t) {
value = t;
}
}
关于java - 使用 JAXB 保持 DRY,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/5862677/
我的应用程序包含两部分:网络部分和 GUI。它的工作方式有点像浏览器 - 用户从服务器请求一些信息,服务器发回一些代表某些 View 的数据,然后 GUI 显示它。 现在我已经将网络部分实现为一项服务
给定表达式字符串exp,编写程序检查exp中“{”、“}”、“(”、“)”、“[”、“]的对和顺序是否正确。 package main import ( "fmt" stack "gi
我想要一个简单的脚本在后台保持运行。目前看起来像这样: import keyboard while True: keyboard.wait('q') keyboard.send('ct
我维护着许多 RedHat Enterprise Linux(7 台和 8 台)服务器(>100 台),其中包含不同的应用程序。为了保持理智,我当然会使用 Ansible 等工具,更重要的是,公共(p
我有一个 winforms 应用程序,它在网络服务请求期间被锁定 我已经尝试使用 doEvents 来保持应用程序解锁,但它仍然不够响应, 我怎样才能绕过这个锁定,让应用程序始终响应? 最佳答案 最好
我正在努力在我的项目中获得并保持领先的 0。以下是当前相关的代码: Dim jobNum As String jobNum = Left(r1.Cells(1, 1), 6) r2.Cells(1
我正在尝试在我的 Canvas 中定位元素相对于我的背景。 窗口被重新调整大小,保持纵横比。 背景随着窗口大小而拉伸(stretch)。 问题是一旦重新调整窗口大小,元素位置就会不正确。如果窗口的大小
一直在玩弄 Hibernate 和 PostgreSQL,试图让它按预期工作。 但是由于某种原因,当我尝试将具有@OneToMany 关系的对象与集合中的多个项目保持一致时,除了第一个项目之外,所有项
我想将某些东西提交到 github 存储库,但我(显然)没有任何权利这样做。我对那个 repo 做了一个分支,提交了我的更改并提交了一个 pull-request。 现在,问题是过了一段时间其他人已经
这是一个初学者问题,我仍在考虑“在 OOP 中”,所以如果我错过了手册中的答案或者答案很明显,我深表歉意。 假设我们有一个抽象类型, abstract type My_Abstract_type en
我们正在开展的一些项目在 jQuery 1.4.2 或更早版本中有着深厚的根基,介于缺乏最新版本的性能优势(或语法糖)、使用现已弃用的方法的耻辱以及部署一个积极维护的库的 3 年以上旧版本,升级现在迫
我看到在FMDB 2.0中,作者为线程添加了FMDatabaseQueue。例子是: // First, make your queue. FMDatabaseQueue *queue = [FMDa
我在 NSScrollView 中有一个 NSTableView。 NSTableView 的内容是通过绑定(bind)到 NSArrayController 来提供的,而 NSArrayContro
我在 TreeView 上有一个节点,我手动填充该节点并希望保持排序。通过用户交互,TreeViewItem 上的标题可能会更改,它们应该移动到列表中的适当位置。 我遍历一个 foreach,创建多个
我从主 NSWindow 打开一个 NSWindow。 DropHereWindowController *dropHereWindowController = [[DropHereWindowCon
我需要放置一个 form 3 按钮,当我单击该按钮时,将其显示为按下,其他按钮向上,当我单击另一个按钮时,它应该为“向下”,其他按钮应为“向上” 最佳答案 所有按钮的属性“Groupindex”必须设
我有一个使用 AnyEvent::MQTT 订阅消息队列的 perl 脚本。 目前我想要它做的就是在收到消息时打印出来。我对 perl 完全陌生,所以我正在使用它附带的演示代码,其中包括将 STDIN
如何在 .NET 应用程序中保持 TreeView 控件的滚动位置?例如,我有一个树形 View 控件,并经历了一个向其添加各种节点的过程,并将它们固定在底部。在此过程中,我可以滚动浏览 TreeVi
我维护了大量的 vbscripts,用于在我的网络上执行各种启动脚本,并且有一些我在几乎所有脚本中使用的函数。 除了复制和粘贴之外,有没有人对我如何创建可重用 vbscript 代码库有建议。我并不反
我有一些关于 Azure 自托管的问题。 假设用户 Alex 在物理机 M 上设置了 Windows 自托管代理。当 Alex 注销且计算机进入休眠状态时,代理将脱机。现在,当 Bob 登录同一台计算
我是一名优秀的程序员,十分优秀!