反射框架Reflections

Github (opens new window)

# 一、简介

Reflections通过扫描classpath，索引元数据，并且允许在运行时查询这些元数据。

使用Reflections可以很轻松的获取以下元数据信息：

• 获取某个类型的全部子类
• 只要类型、构造器、方法，字段上带有特定注解，便能获取带有这个注解的全部信息(类型、构造器、方法，字段)
• 获取所有能匹配某个正则表达式的资源
• 获取所有带有特定签名的方法，包括参数，参数注解，返回类型
• 获取所有方法的名字
• 获取代码里所有字段、方法名、构造器的使用权

# 二、Maven依赖

<dependency>
    <groupId>org.reflections</groupId>
    <artifactId>reflections</artifactId>
    <version>0.9.11</version>
</dependency>

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# 三、使用方法

# 3.1 实例化

指定要扫描的包名

// 实例化Reflections，并指定要扫描的包名
Reflections reflections = new Reflections("my.project");
// 获取某个类的所有子类
Set<Class<? extends SomeType>> subTypes = reflections.getSubTypesOf(SomeType.class);
// 获取包含某个注解的所有类
Set<Class<?>> annotated = reflections.getTypesAnnotatedWith(SomeAnnotation.class);
  

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指定要扫描的包名并添加过滤器

ConfigurationBuilder API (opens new window)

Reflections reflections = new Reflections(
  new ConfigurationBuilder()
    .forPackage("com.my.project")
    .filterInputsBy(new FilterBuilder().includePackage("com.my.project")));

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添加扫描器

Scanners API (opens new window)

// scan package with specific scanners
Reflections reflections = new Reflections(
  new ConfigurationBuilder()
    .forPackage("com.my.project")
    .filterInputsBy(new FilterBuilder().includePackage("com.my.project").excludePackage("com.my.project.exclude"))
    .setScanners(TypesAnnotated, MethodsAnnotated, MethodsReturn));

// scan package with all standard scanners
Reflections reflections = new Reflections("com.my.project", Scanners.values());

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# 3.2 扫描子类

Set<Class<? extends Module>> modules = 
    reflections.getSubTypesOf(com.google.inject.Module.class);

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# 3.3 扫描注解

//TypeAnnotationsScanner 
Set<Class<?>> singletons = 
    reflections.getTypesAnnotatedWith(javax.inject.Singleton.class);

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# 3.4 扫描资源

//ResourcesScanner
Set<String> properties = 
    reflections.getResources(Pattern.compile(".*\\.properties"));

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# 3.5 扫描方法、构造注解

//MethodAnnotationsScanner
Set<Method> resources =
    reflections.getMethodsAnnotatedWith(javax.ws.rs.Path.class);
Set<Constructor> injectables = 
    reflections.getConstructorsAnnotatedWith(javax.inject.Inject.class);

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# 3.6 扫描字段注解

Set<Field> ids = 
    reflections.getFieldsAnnotatedWith(javax.persistence.Id.class);

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# 3.7 扫描方法参数

//MethodParameterScanner
Set<Method> someMethods =
    reflections.getMethodsMatchParams(long.class, int.class);
Set<Method> voidMethods =
    reflections.getMethodsReturn(void.class);
Set<Method> pathParamMethods =
    reflections.getMethodsWithAnyParamAnnotated(PathParam.class);

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# 3.8 扫描方法参数名

List<String> parameterNames = 
    reflections.getMethodParamNames(Method.class)

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# 3.9 扫描方法调用情况

//MemberUsageScanner
Set<Member> usages = 
    reflections.getMethodUsages(Method.class)

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