Joshua Yan — Sat, 20 Dec 2008 10:01:00 GMT

在学习tuscany到过�E�遇��C��个疑问（java�l��g实现是如何解析java�c�L��件中的服务的�Q�如果没有配�|�服务，默认服务应该是什么？�Q�，开始的时候一直无法想清楚�Q�通过阅读源码�l�于了解了部分解析过�E?br />
以tuscany中的Calculator��Z��说明服务的定义：

1. 如果按照例子本��n的代码和配置�Q�我们应该如何获取服务呢�Q?br />

CalculatorService实现代码

package calculator;

import org.osoa.sca.annotations.Reference;

/**
* An implementation of the Calculator service.
*/
public class CalculatorServiceImpl implements CalculatorService {

    private AddService addService;
    private SubtractService subtractService;
    private MultiplyService multiplyService;
。。。。。。。。。。。。�?br />

配置�Q?br />

<component name="CalculatorServiceComponent">
        <implementation.java class="calculator.CalculatorServiceImpl"/>
        <reference name="addService" target="AddServiceComponent" />
        <reference name="subtractService" target="SubtractServiceComponent" />
        <reference name="multiplyService" target="MultiplyServiceComponent" />
        <reference name="divideService" target="DivideServiceComponent" />
    component>

a. 例子中获取服务的�Ҏ��Q?br />

CalculatorService calculatorService =
scaDomain.getService(CalculatorService.class, "CalculatorServiceComponent");

通过上述代码我们��可以获取相应的服务了，我们不仅要问�Q��ؓ什么能够获取相应的服务呢？

�Ҏ��java�l��g实现规范说明�Q�如果组件只包含一个服务，那么我们在获取服务的时候可以省略服务的名字�?/span>

我的问题是：省略的服务名字是什么？

b. 完整获取服务的方法：

CalculatorService calculatorService1 =scaDomain.getService(CalculatorService.class, "CalculatorServiceComponent/CalculatorServiceImpl");

大家通过比较��可以知道，其实省略�?span style="color: red;">服务名字�?/span> CalculatorServiceImpl

��Z��么是�q�个名字�Q�大家可以参考源码中�?

if (services.isEmpty()) {
       // class is the interface
       addService(type, clazz);
    }

2. 自己定义一个服�?br />
自己在实��C��d��服务声明

1 @Service(CalculatorService.class)
2 public class CalculatorServiceImpl implements CalculatorService {
3
4     private AddService addService;
5     private SubtractService subtractService;
6     private MultiplyService multiplyService;
7     private DivideService divideService;
。。。。。�?br />

我们可以通过如下方式获取服务�Q?br />
a. 例子中的方式

CalculatorService calculatorService =
scaDomain.getService(CalculatorService.class, "CalculatorServiceComponent");

b. 完整方式

CalculatorService calculatorService1 =scaDomain.getService(CalculatorService.class, "CalculatorServiceComponent/CalculatorService");

我们通过如下方式��?span style="font-size: 24pt;">�Q�不能＊获取服务�?/span>

CalculatorService calculatorService1 =scaDomain.getService(CalculatorService.class, "CalculatorServiceComponent/CalculatorServiceImpl");

原因很简单，实现不会再添加默认服务（CalculatorServiceImpl�Q�了

源码摘录如下�Q?br />

1 org.apache.tuscany.sca.implementation.java.introspect.impl.HeuristicPojoProcessor
2
3
4 public <T> void visitEnd(Class<T> clazz, JavaImplementation type) throws IntrospectionException {
5         List<org.apache.tuscany.sca.assembly.Service> services = type.getServices();
6         if (services.isEmpty()) {
7             // heuristically determine the service
8             /**
9              * The following is quoted from Java Specification 1.2.1.3. Introspecting services offered by a Java implementation
10              * In the cases described below, the services offered by a Java implementation class may be determined
11              * through introspection, eliding the need to specify them using @Service. The following algorithm is used
12              * to determine how services are introspected from an implementation class:
13              *
14              * If the interfaces of the SCA services are not specified with the @Service annotation on the
15              * implementation class, it is assumed that all implemented interfaces that have been annotated
16              * as @Remotable are the service interfaces provided by the component. If none of the implemented
17              * interfaces is remotable, then by default the implementation offers a single service whose type
18              * is the implementation class.
19              */
20             Set<Class> interfaces = getAllInterfaces(clazz);
21             for (Class i : interfaces) {
22                 if (i.isAnnotationPresent(Remotable.class) || i.isAnnotationPresent(WebService.class)) {
23                     addService(type, i);
24                 }
25             }
26             if (services.isEmpty()) {
27                 // class is the interface
28                 addService(type, clazz);
29             }
30         }
31         Set<Method> methods = getAllUniquePublicProtectedMethods(clazz, false);
32         if (!type.getReferenceMembers().isEmpty() || !type.getPropertyMembers().isEmpty()) {
33             // references and properties have been explicitly defined
34             //            if (type.getServices().isEmpty()) {
35             //                calculateServiceInterface(clazz, type, methods);
36             //                if (type.getServices().isEmpty()) {
37             //                    throw new ServiceTypeNotFoundException(clazz.getName());
38             //                }
39             //            }
40             evaluateConstructor(type, clazz);
41             return;
42         }
43         calcPropRefs(methods, services, type, clazz);
44         evaluateConstructor(type, clazz);
45     }
46

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