我很难理解泽西的注射机制. JAX-RS规范(
http://jsr311.java.net/nonav/releases/1.1/spec/spec3.html#x3-520005)规定,可以在Application子类,根资源类和提供程序中通过@Context进行注入.
我现在有一个在启动时实例化的类,并且有一个在每个请求上调用的方法.在方法内部,我需要访问当前的UriInfo对象.问题是,我的代码没有调用此方法.所以我无法直接将UriInfo传递给该方法.
我其实想做这样的事情：
public class MyClass implements ThirdPartyInterface {
// not possible because class is no Application subclass,root resource class or provider
@Context
private UriInfo uriInfo;
public void methodCallebByThirdPartyCode() {
Uri requestUri = uriInfo.getRequestUri();
// do something
}
}
我试过这个.显然没有成功：
public class MyClass implements ThirdPartyInterface {
private UriInfo uriInfo;
public MyClass(UriInfo uriInfo) {
this.uriInfo = uriInfo;
}
public void methodCallebByThirdPartyCode() {
Uri requestUri = uriInfo.getRequestUri();
// do something
}
}
@Provider
@Produces(MediaType.WILDCARD)
public class MyBodyWriter implements MessageBodyWriter<MyView> {
@Context
private UriInfo uriInfo;
private MyClass myClass;
private ThirdPartyClass thirdPartyClass;
public MyBodyWriter() {
// uriInfo is null at this time :(
myClass = new MyClass(uriInfo);
thirdPartyClass = new ThirdPartyClass();
thirdPartyClass.register(myClass);
}
public void writeTo(final MyView view,final Class<?> type,/* and so on */) throws IOException,WebApplicationException {
// execute() calls MyClass#methodCallebByThirdPartyCode()
thirdPartyClass.execute();
}
}
我能想到的唯一解决方法就是这个.我不认为它很干净：
public class MyClass implements ThirdPartyInterface {
private UriInfo uriInfo;
public void setUriInfo(final UriInfo uriInfo) {
this.uriInfo = uriInfo;
}
public void methodCallebByThirdPartyCode() {
Uri requestUri = uriInfo.getRequestUri();
// do something
}
}
@Provider
@Produces(MediaType.WILDCARD)
public class MyBodyWriter implements MessageBodyWriter<MyView> {
@Context
private UriInfo uriInfo;
private MyClass myClass;
private ThirdPartyClass thirdPartyClass;
public MyBodyWriter() {
myClass = new MyClass();
thirdPartyClass = new ThirdPartyClass();
thirdPartyClass.register(myClass);
}
public void writeTo(final MyView view,WebApplicationException {
myClass.setUriInfo(uriInfo);
// execute() calls MyClass#methodCallebByThirdPartyCode()
thirdPartyClass.execute();
myClass.setUriInfo(null);
}
}
我希望有更好的解决方案,但也许我完全走错了路.
谢谢！
迟到的回答,但是一个很好的问题…所以我们走吧：
原文链接：https://www.f2er.com/javaschema/442924.html您可以使用org.glassfish.hk2.api.Factory和javax.inject.Provider进行注射.我不知道从哪个版本可用,所以也许你必须升级你的jersery版本.对于以下样品,我使用了汗布2.12.
首先,您必须为MyClass实现并注册/绑定Factory：
MyClassFactory：
import javax.inject.Inject;
import javax.ws.rs.core.UriInfo;
import org.glassfish.hk2.api.Factory;
// ...
public class MyClassFactory implements Factory<MyClass> {
private final UriInfo uriInfo;
// we will bind MyClassFactory per lookup later,so
// the constructor will be called everytime we need the factory
// meaning,uriInfo is also per lookup
@Inject
public MyClassFactory(final UriInfo uriInfo) {
this.uriInfo = uriInfo;
}
@Override
public MyClass provide() {
return new MyClass(uriInfo)
}
@Override
public void dispose(UriInfo uriInfo) {
// ignore
}
}
通过ResourceConfig注册：
import org.glassfish.hk2.api.PerLookup;
import org.glassfish.hk2.utilities.binding.AbstractBinder;
import org.glassfish.jersey.server.ResourceConfig;
// ...
public class MyResourceConfig extends ResourceConfig {
public MyResourceConfig() {
register(new AbstractBinder() {
@Override
protected void configure() {
bindFactory(MyClassFactory.class).to(MyClass.class).in(PerLookup.class);
// ... bind additional factories here
}
});
// ...
}
}
现在,您可以将每个查询的MyClass注入提供者,资源等.
但注意：Afaig有两种方法,只有一种方法最终会被视为提供者…
import javax.inject.Inject;
import javax.ws.rs.Produces;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.Provider;
// ...
@Provider
@Produces("application/foo-bar")
public class MyBodyWriter implements MessageBodyWriter<MyView> {
// first approache - don't do it!
// will only injected once,cause MyBodyWriter is only instantiated once
@Inject
private MyClass myClass;
// second approache - works fine!
private final javax.inject.Provider<MyClass> provider;
// MyBodyWriter instantiate once
// get an inject provider here
@Inject
public MyBodyWriter(javax.inject.Provider<MyClass> myClassProvider) {
this.provider = myClassProvider;
}
@Override
public boolean isWriteable(Class<?> t,Type g,Annotation[] a,MediaType m) {
return t == MyView.class;
}
@Override
public long getSize(MyView t,Class<?> c,MediaType m) {
// deprecated by JAX-RS 2.0 and ignored by Jersey runtime
return 0;
}
@Override
public void writeTo(MyView v,Type t,MediaType m,MultivaluedMap<String,Object> s,OutputStream o) throws IOException,WebApplicationException {
// attention: its not per lookup !!!
MyClass myClassDirectInjected = myClass;
System.out.println(myClassDirectInjected); // same instance everytime
// but this is ;)
MyClass myClassFromProvider = provider.get();
System.out.println(myClassFromProvider); // it's a new instance everytime
// ...
}
}
希望这在某种程度上有所帮助.
