OSGi 声明性服务 - NullPointer 异常
我的声明式服务有问题。我有 2 个捆绑包,一个是服务器提供商,另一个是使用该服务的用户界面。
在服务器端,实现是:
public boolean checkUser(){
return true;
}
OSGi-INF 文件夹内的 XML 文件:
<component name="ZBService">
<implementation class="service.ZBService" />
<service>
<provide interface="service.IZBService" />
</service>
</component>
在客户端,实现是:
public class GreetingServiceImpl extends RemoteServiceServlet implements GreetingService{
IZBService zb;
public void setZBService(IZBService eventAdmin) {
this.zb = eventAdmin;
}
public void unsetZBService(IZBService eventAdmin){
if(this.zb == eventAdmin){
this.zb = null;}
}
public boolean greetServer(String input, String input2) throws Exception {
return zb.checkUser();
}
}
XML 文件:
<component name="ZBService">
<implementation class="main.java.com.gwt.app.server.GreetingServiceImpl" />
<service>
<provide interface="main.java.com.gwt.app.client.GreetingService"/>
</service>
<reference name="zb" interface="service.IZBService" bind="setZBService" unbind="unsetZBService" cardinality="0..n" policy="dynamic" />
</component>
另外,我在清单文件中包含了 Service-Component 标签,并且部署了 Equinox ds捆绑包处于活动状态。
客户端是一个GWT用户界面,然后我将服务引用注入到GWT的服务器端。好吧,当我在 Equinox 上部署应用程序时,它会运行,但是当我按下按钮时,我会启动一个事件来调用 ZBService。我已经调试了该应用程序,错误是 zb 属性为空。也就是说,依赖是没有注入的。然而,这些服务是在 Equinox 上公开的。如果我在 Equinox 控制台上编写服务,则会部署服务。然后,我的结论是错误是由于注入不执行造成的。
我想知道有人知道这是什么原因吗??
预先非常感谢!
美好的一天
编辑:
我做了你的建议,但它没有运行。我更改了组件名称和条件/策略。结果是一样的-->由于注入未完成而出现 NullPointerException。
我还调试了应用程序以查看是否调用了绑定和/或取消绑定方法,但它们没有。
完整的类是:
public class GreetingServiceImpl extends RemoteServiceServlet implements GreetingService{
static protected IZBService zb;
public GreetingServiceImpl(){
System.out.println("Constructor GreetingServiceImpl");
}
public IZBService getZb() {
return zb;
}
public void setZb(IZBService zb) {
GreetingServiceImpl.zb = zb;
}
public void unsetZb(IZBService zb) {
GreetingServiceImpl.zb = zb;
}
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// Cache the current thread
Thread currentThread = Thread.currentThread();
// We are going to swap the class loader
ClassLoader oldContextClassLoader = currentThread.getContextClassLoader();
currentThread.setContextClassLoader(this.getClass().getClassLoader());
super.service(req, resp);
currentThread.setContextClassLoader(oldContextClassLoader);
}
public void activate(ComponentContext context) {
System.out.println("Creating new greeter for " + context.getProperties().get("name")
+ ": " + context.getComponentInstance().toString());
}
public void activate() {
System.out.println("Activando la referencia al servicio");
}
public void deactivate(ComponentContext context) {
System.out.println("Deactivating greeter for " + context.getProperties().get("name")
+ ": " + context.getComponentInstance().toString());
}
public boolean greetServer(String input, String input2) throws Exception {
return zb.checkUser();
}
}
XML 客户端是:
<?xml version="1.0" encoding="UTF-8" ?>
<scr:component name="serviceZB" xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0">
<implementation class="main.java.com.gwt.app.server.GreetingServiceImpl" />
<!-- <service>
<provide interface="main.java.com.gwt.app.client.GreetingService"/>
</service> -->
<reference name="zb" interface="service.IZBService"
bind="setZb" unbind="unsetZb" cardinality="1..1"
policy="static" />
</scr:component>
如果部署了服务,为什么没有注入服务???
I have a problem with my Declarative Services. I have 2 bundles, one is a server provider and another the user interface that consumes the service.
On server side, the implementation is:
public boolean checkUser(){
return true;
}
And the XML file inside OSGi-INF folder:
<component name="ZBService">
<implementation class="service.ZBService" />
<service>
<provide interface="service.IZBService" />
</service>
</component>
On client side, the implementation is:
public class GreetingServiceImpl extends RemoteServiceServlet implements GreetingService{
IZBService zb;
public void setZBService(IZBService eventAdmin) {
this.zb = eventAdmin;
}
public void unsetZBService(IZBService eventAdmin){
if(this.zb == eventAdmin){
this.zb = null;}
}
public boolean greetServer(String input, String input2) throws Exception {
return zb.checkUser();
}
}
And XML file:
<component name="ZBService">
<implementation class="main.java.com.gwt.app.server.GreetingServiceImpl" />
<service>
<provide interface="main.java.com.gwt.app.client.GreetingService"/>
</service>
<reference name="zb" interface="service.IZBService" bind="setZBService" unbind="unsetZBService" cardinality="0..n" policy="dynamic" />
</component>
Also, I have included the tag Service-Component on manifest file and I have deployed the equinox ds bundle that is ACTIVE.
The client is a GWT user interface, then I inject the service reference into server side of GWT. Well, when I deploy the application on Equinox it runs, but when I push the button, I launch an event to call ZBService. I have debugged the application and the error is zb attribute is null. It is to say, the dependence is nos injected. However the services are exposed on Equinox. If I write services on Equinox console, the services are deployed. Then, my conclusion is the error is due to the injection does not perform.
I would like to know if someone knows what is the reason??
Thanks a lot in advance!!
Nice day
EDIT:
I did your suggestions but it doesn't run. I change the component names and condinality/policy. The result is the same --> NullPointerException due to the injection isn't done.
Also I have debug the application to see if the methods bind and/or unbind are called, but they aren't.
The complete class is:
public class GreetingServiceImpl extends RemoteServiceServlet implements GreetingService{
static protected IZBService zb;
public GreetingServiceImpl(){
System.out.println("Constructor GreetingServiceImpl");
}
public IZBService getZb() {
return zb;
}
public void setZb(IZBService zb) {
GreetingServiceImpl.zb = zb;
}
public void unsetZb(IZBService zb) {
GreetingServiceImpl.zb = zb;
}
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
// Cache the current thread
Thread currentThread = Thread.currentThread();
// We are going to swap the class loader
ClassLoader oldContextClassLoader = currentThread.getContextClassLoader();
currentThread.setContextClassLoader(this.getClass().getClassLoader());
super.service(req, resp);
currentThread.setContextClassLoader(oldContextClassLoader);
}
public void activate(ComponentContext context) {
System.out.println("Creating new greeter for " + context.getProperties().get("name")
+ ": " + context.getComponentInstance().toString());
}
public void activate() {
System.out.println("Activando la referencia al servicio");
}
public void deactivate(ComponentContext context) {
System.out.println("Deactivating greeter for " + context.getProperties().get("name")
+ ": " + context.getComponentInstance().toString());
}
public boolean greetServer(String input, String input2) throws Exception {
return zb.checkUser();
}
}
And the XML client is:
<?xml version="1.0" encoding="UTF-8" ?>
<scr:component name="serviceZB" xmlns:scr="http://www.osgi.org/xmlns/scr/v1.1.0">
<implementation class="main.java.com.gwt.app.server.GreetingServiceImpl" />
<!-- <service>
<provide interface="main.java.com.gwt.app.client.GreetingService"/>
</service> -->
<reference name="zb" interface="service.IZBService"
bind="setZb" unbind="unsetZb" cardinality="1..1"
policy="static" />
</scr:component>
Why isn't the service injected if the service is deployed???
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以下是您可以尝试的操作列表:
Here is a list of things you can try:
这两个组件具有相同的名称,这在讨论它们时有点尴尬。
客户端的引用为:cardinality=“0..n”policy=“dynamic”。这意味着它可以通过零到 n 个引用来激活。但您的代码无法处理此问题。似乎只需要一份参考资料。也许您应该使用cardinality =“1..1”policy =“static”。
You have both components with the same name, , which is kind of awkward when discussing them.
The reference on the client side has: cardinality="0..n" policy="dynamic". Which means it can be activated with zero to n references. Yet your code does not handle this. It seems to expect exactly one reference. Perhaps you should use cardinality="1..1" policy="static".