Reflections 通过扫描 classpath，索引元数据，允许在运行时查询这些元数据，也可以保存收集项目中多个模块的元数据信息。
使用 Reflections 可以查询以下元数据信息：
1）获得某个类型的所有子类型
2）获得标记了某个注解的所有类型／成员变量，支持注解参数匹配。
3）使用正则表达式获得所有匹配的资源文件
4）获得所有特定签名（包括参数，参数注解，返回值）的方法
Reflections 依赖 Google 的 Guava 库和 Javassist 库。
Maven 项目导入 - <dependency>
- <groupId>org.reflections</groupId>
- <artifactId>reflections</artifactId>
- <version>0.9.10</version>
- </dependency>
通常用法： - Reflections reflections = new Reflections("my.project");
- Set<Class<? extends SomeType>> subTypes = reflections.getSubTypesOf(SomeType.class);
- Set<Class<?>> annotated = reflections.getTypesAnnotatedWith(SomeAnnotation.class);
Reflections 初始化代码。 - //scan urls that contain 'my.package', include inputs starting with 'my.package', use the default scanners
- Reflections reflections = new Reflections("my.package");
- //or using ConfigurationBuilder
- new Reflections(new ConfigurationBuilder()
- .setUrls(ClasspathHelper.forPackage("my.project.prefix"))
- .setScanners(new SubTypesScanner(),
- new TypeAnnotationsScanner().filterResultsBy(optionalFilter), ...),
- .filterInputsBy(new FilterBuilder().includePackage("my.project.prefix"))
- ...);
以下是一些使用例子代码。 - //SubTypesScanner
- Set<Class<? extends Module>> modules =
- reflections.getSubTypesOf(com.google.inject.Module.class);
- //TypeAnnotationsScanner
- Set<Class<?>> singletons =
- reflections.getTypesAnnotatedWith(javax.inject.Singleton.class);
- //ResourcesScanner
- Set<String> properties =
- reflections.getResources(Pattern.compile(".*\.properties"));
- //MethodAnnotationsScanner
- Set<Method> resources =
- reflections.getMethodsAnnotatedWith(javax.ws.rs.Path.class);
- Set<Constructor> injectables =
- reflections.getConstructorsAnnotatedWith(javax.inject.Inject.class);
- //FieldAnnotationsScanner
- Set<Field> ids =
- reflections.getFieldsAnnotatedWith(javax.persistence.Id.class);
- //MethodParameterScanner
- Set<Method> someMethods =
- reflections.getMethodsMatchParams(long.class, int.class);
- Set<Method> voidMethods =
- reflections.getMethodsReturn(void.class);
- Set<Method> pathParamMethods =
- reflections.getMethodsWithAnyParamAnnotated(PathParam.class);
- //MethodParameterNamesScanner
- List<String> parameterNames =
- reflections.getMethodParamNames(Method.class)
- //MemberUsageScanner
- Set<Member> usages =
- reflections.getMethodUsages(Method.class)
项目主页：http://www.open-open.com/lib/view/home/1440247401583
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