通过反射获取泛型信息

Posted 2020-08-09

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 1 package com.coscon.reflectionTest;
 2 
 3 import java.lang.reflect.Method;
 4 import java.lang.reflect.ParameterizedType;
 5 import java.lang.reflect.Type;
 6 import java.util.List;
 7 import java.util.Map;
 8 
 9 //用过反射获取泛型信息
10 public class ReflectionForGenerics {
11     public void test01(Map<String,User> map,List<User> users){
12         System.out.println("test01");
13     }
14     
15     public Map<Integer,User> test02(){
16         System.out.println("test02");
17         return null;
18     }
19     
20     public static void main(String[] args) {
21         try {
22             Class clazz = Class.forName("com.coscon.reflectionTest.ReflectionForGenerics");
23             //获得指定方法参数泛型信息
24             Method method = clazz.getMethod("test01", Map.class,List.class);
25             //获取泛型参数
26             Type[] types = method.getGenericParameterTypes();
27             for (Type type : types) {
28                 System.out.println("#"+type);
29                 if(type instanceof ParameterizedType){
30                     Type[] actualTypeArguments = ((ParameterizedType) type).getActualTypeArguments();
31                     for (Type type2 : actualTypeArguments) {
32                         System.out.println("泛型参数类型："+type2);
33                     }
34                 }
35             }
36             
37             System.out.println("--------------------------------------------------------------");
38             Method method2 = clazz.getMethod("test02", null);
39             //获取返回值泛型信息
40             Type returnType = method2.getGenericReturnType();
41             System.out.println("#"+returnType);
42             if(returnType instanceof ParameterizedType){
43                 Type[] typeArguments = ((ParameterizedType) returnType).getActualTypeArguments();
44                 for (Type type : typeArguments) {
45                     System.out.println("返回值泛型类型："+type);
46                 }
47             }
48         } catch (Exception e) {
49             // TODO Auto-generated catch block
50             e.printStackTrace();
51         }
52     }
53 }

打印结果

#java.util.Map<java.lang.String, com.coscon.reflectionTest.User>
泛型参数类型：class java.lang.String
泛型参数类型：class com.coscon.reflectionTest.User
#java.util.List<com.coscon.reflectionTest.User>
泛型参数类型：class com.coscon.reflectionTest.User
--------------------------------------------------------------
#java.util.Map<java.lang.Integer, com.coscon.reflectionTest.User>
返回值泛型类型：class java.lang.Integer
返回值泛型类型：class com.coscon.reflectionTest.User

 

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