Java 单例类的场注入
我有接口:Java 单例类的场注入,java,singleton,guice,Java,Singleton,Guice,我有接口: public interface DataStorage { boolean setData(String dataName); boolean unsetData(String dataName); Map getData(); } 以及他的实施: public class DataStorageImpl implements DataStorage { private Map dataMap = new HashMap<>();
public interface DataStorage {
boolean setData(String dataName);
boolean unsetData(String dataName);
Map getData();
}
以及他的实施:
public class DataStorageImpl implements DataStorage {
private Map dataMap = new HashMap<>();
public synchronized boolean setData(String dataName) {
dataMap.put(dataName, true);
return true;
}
public synchronized boolean unsetData(String dataName) {
dataMap.put(dataName, false);
return true;
}
public synchronized Map getData() {
return dataMap;
}
}
public class DataStorageModule extends AbstractModule {
@Override
protected void configure() {
bind(DataStorage.class).annotatedWith(Names.named("DataStorage")).to(DataStorageImpl.class).in(Singleton.class);
}
}
我正在尝试将数据存储注入我的Netty请求处理程序。请求处理程序代码:
public class DataMethodsHandler {
@Inject @Named("DataStorage")
private DataStorage dataStorage;
public String version() {
return "0.0.1";
}
public Map list_data() {
return dataStorage.getData();
}
public boolean set_data(String dataName) {
return dataStorage.setData(dataName);
}
public boolean unset_data(String dataName) {
return dataStorage.unsetData(dataName);
}
}
以及负责将请求处理程序绑定到Netty的代码:
PropertyHandlerMapping phm = new CustomPropertyHandlerMapping();
phm.setVoidMethodEnabled(true);
try {
phm.addHandler("", dataMethodsHandler.class);
} catch (XmlRpcException e) {
e.printStackTrace();
}
调用XMLRPC方法时,set_数据请求失败,因为DataMethodsHandler中的dataStorage字段为null。我做错了什么?我找到了解决办法。首先,我们应该用以下代码替换调用Class.newInstance的默认RequestProcessorFactory方法getRequestProcessorFactory:
public class XmlRpcServerClientRequestProcessorFactoryFactory implements RequestProcessorFactoryFactory {
@Inject
private Injector injector;
@Inject
public XmlRpcServerClientRequestProcessorFactoryFactory(Injector injector) {
this.injector = injector;
}
@Override
public RequestProcessorFactory getRequestProcessorFactory(final Class pClass)
throws XmlRpcException {
return new RequestProcessorFactory() {
@SuppressWarnings("unchecked")
@Override
public Object getRequestProcessor(XmlRpcRequest pRequest)
throws XmlRpcException {
return injector.getInstance(pClass);
}
};
}
}
为GUI创建模块:
public class NettyXmlRpcModule extends AbstractModule {
@Override
protected void configure() {
bind(NettyXmlRpcModule.class);
bind(XmlRpcServerClientRequestProcessorFactoryFactory.class).in(Singleton.class);
bind(Integer.TYPE).annotatedWith(Names.named("xmlrpc.port")).toInstance(3133);
}
@Provides
@Singleton
Log providesLog(){
return LogFactory.getLog(NettyXmlRpcWebServer.class);
}
@Provides
InetAddress providesInetAddress() throws UnknownHostException {
return InetAddress.getLocalHost();
}
}
然后为处理程序设置新工厂:
PropertyHandlerMapping phm = new CustomPropertyHandlerMapping();
phm.setRequestProcessorFactoryFactory(xmlRpcServerClientRequestProcessorFactoryFactory);
phm.setVoidMethodEnabled(true);
try {
phm.addHandler("", methodsHandler);
} catch (XmlRpcException e) {
e.printStackTrace();
}
xmlRpcServer.setHandlerMapping(phm);
现在,处理程序将捕获所有请求,所有带注释的字段都将被注入。看起来您的PropertyHandlerMapping没有使用GUI来实例化DataMethodsHandler@TavianBarnes非常感谢。我刚开始学Guice。如果你不复杂,你能提供一个链接或告诉我在谷歌搜索的关键字吗?一些建议:你应该使用字段注入或构造函数注入,而不是两者都使用。当你需要注射注射器时,后退一步,重新考虑你的设计。通常,让一个注入器创建整个实例树就足够了,例如在主方法或servlet过滤器中。最后一点:什么是工厂?使用guice/DI将使大多数工厂过时,因为您在模块中配置实例的创建,使用提供者或带有辅助注入的通用工厂…@JanGalinski感谢您的建议。FactoryFactory是Apache的XMLRpc库中的一个奇怪接口。我不能完全改变这个库的行为,但是使用重写的方法效果很好。