通過反射獲取泛型信息

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package com.coscon.reflectionTest;

import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.List;
import java.util.Map;

//用過反射獲取泛型信息
public class ReflectionForGenerics {
    public void test01(Map<String,User> map,List<User> users){
        System.out.println("test01");
    }
    
    public Map<Integer,User> test02(){
        System.out.println("test02");
        return null;
    }
    
    public static void main(String[] args) {
        try {
            Class clazz = Class.forName("com.coscon.reflectionTest.ReflectionForGenerics");
            //獲得指定方法參數泛型信息
            Method method = clazz.getMethod("test01", Map.class,List.class);
            //獲取泛型參數
            Type[] types = method.getGenericParameterTypes();
            for (Type type : types) {
                System.out.println("#"+type);
                if(type instanceof ParameterizedType){
                    Type[] actualTypeArguments = ((ParameterizedType) type).getActualTypeArguments();
                    for (Type type2 : actualTypeArguments) {
                        System.out.println("泛型參數類型："+type2);
                    }
                }
            }
            
            System.out.println("--------------------------------------------------------------");
            Method method2 = clazz.getMethod("test02", null);
            //獲取返回值泛型信息
            Type returnType = method2.getGenericReturnType();
            System.out.println("#"+returnType);
            if(returnType instanceof ParameterizedType){
                Type[] typeArguments = ((ParameterizedType) returnType).getActualTypeArguments();
                for (Type type : typeArguments) {
                    System.out.println("返回值泛型類型："+type);
                }
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

打印結果

#java.util.Map<java.lang.String, com.coscon.reflectionTest.User>
泛型參數類型：class java.lang.String
泛型參數類型：class com.coscon.reflectionTest.User
#java.util.List<com.coscon.reflectionTest.User>
泛型參數類型：class com.coscon.reflectionTest.User
--------------------------------------------------------------
#java.util.Map<java.lang.Integer, com.coscon.reflectionTest.User>
返回值泛型類型：class java.lang.Integer
返回值泛型類型：class com.coscon.reflectionTest.User

 

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