JavaEE6规范CDI教程第五部分

1. 在​同​一​个​注​入​点​上​使​用​多​个​@Qualifiers来​进​一​步​区​分​
你​可​以​使​用​多​个​限​定​注​解​来​进​一​步​区​分​你​的​注​入​目​标​。​ 
我​们​定​义​限​定​注​解​SuperFast和​StandardFrameRelaySwitchingFlubber来​演​示​这​个​用​法​。​那​样​的​话​我​们​就​有​第​二​个​传​输​器​StandardFrameRelaySwitchingFlubber和​SuperFast，我​们​要​注​入​的​传​输​器​不​仅​有​StandardFrameRelaySwitchingFlubber，还​有​SuperFast。​ 
首​先​我​们​来​定​义​限​定​注​解​，如​下​： 
例 1. 定​义​新​的​SuperFast限​定​注​解​
package org.cdi.advocacy;
...
@Qualifier @Retention(RUNTIME) @Target({TYPE, METHOD, FIELD, PARAMETER})
public @inte易做图ce SuperFast {
}

例 2. 定​义​另​一​个​新​的​StandardFrameRelaySwitchingFlubber限​定​注​解​
package org.cdi.advocacy;
...
@Qualifier @Retention(RUNTIME) @Target({TYPE, METHOD, FIELD, PARAMETER})
public @inte易做图ce StandardFrameRelaySwitchingFlubber {
}

OK，下​面​的​代​码​是​给​SuperFastAtmTransport同​时​使​用​@SuperFast和​@StandardFrameRelaySwitchingFlubber限​定​注​解​。​ 
例 3. SuperFastAtmTransport使​用​两​个​限​定​注​解​
package org.cdi.advocacy;
@SuperFast @StandardFrameRelaySwitchingFlubber 
public class SuperFastAtmTransport implements ATMTransport {
        public void communicateWithBank(byte[] datapacket) {
                System.out.println("communicating with bank via the Super Fast transport " );
        }
}

Ok，我​们​也​给​StandardAtmTransport加​上​StandardFrameRelaySwitchingFlubber限​定​注​解​。​ 
例 4. StandardAtmTransport使​用​一​个​限​定​注​解​
package org.cdi.advocacy;

@StandardFrameRelaySwitchingFlubber @Default
public class StandardAtmTransport implements ATMTransport {
        public void communicateWithBank(byte[] datapacket) {
                System.out.println("communicating with bank via Standard transport");
        }
}

接​下​来​，我​希​望​我​的​自​动​柜​员​机​使​用​SuperFast传​输​并​带​有​StandardFrameRelaySwitchingFlubber，我​必​须​在​注​入​点​同​时​使​用​它​们​，如​下​： 
例 5. AutomatedTellerMachineImpl更​改​为​使​用​两​个​限​定​注​解​
public class AutomatedTellerMachineImpl implements AutomatedTellerMachine {
        
        @Inject @SuperFast @StandardFrameRelaySwitchingFlubber
        private ATMTransport transport;
       ...

deposit called
                communicating with bank via the Super Fast transport
练​习​:创​建​一​个​具​有​@SuperFast, @StandardFrameRelaySwitchingFlubber 和​ @Alternative的​传​输​器​。​然​后​使​用​beans.xml激​活​SuperFast, StandardFrameRelaySwitchingFlubber, Alternative支​持​。​通​过​CDI Group邮​件​列​表​发​给​我​你​的​解​决​方​案​。​第​一​发​送​的​将​会​张​贴​在​CDI墙​壁​上​。​ 
阅​读​者​练​习​：更​改​注​入​点​限​定​，只​使​用​StandardAtmTransport。​通​过​CDI Group邮​件​列​表​发​给​我​你​的​解​决​方​案​。​第​一​发​送​的​将​会​张​贴​在​CDI墙​壁​上​。​ 

补充：软件开发 , Java ,

上一个：Java7 和C# 2.0
下一个：JavaEE6 FAQs之@Model