通过反射获取泛型

通过反射获取泛型

下面是示例代码：

User类

package com.han.reflection;

public class User {
    private String id;
    private String name;
    private int age;

    public User() {
    }

    public User(String id, String name, int age) {
        this.id = id;
        this.name = name;
        this.age = age;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Override
    public String toString() {
        return "User{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

测试类

    package com.han.reflection;
    
    import java.lang.reflect.Method;
    import java.lang.reflect.ParameterizedType;
    import java.lang.reflect.Type;
    import java.util.List;
    import java.util.Map;
    
    /*
    通过反射获取泛型
     */
    public class Test01 {
        public static void test1(Map<String,User> map, List<User> list){
            System.out.println("test1");
        }
    
        public static Map<String,User> test2(){
            System.out.println("test2");
            return null;
        }
    
        public static void main(String[] args) throws NoSuchMethodException {
            Method method = Test01.class.getMethod("test1", Map.class, List.class);
            Type[] genericParameterTypes = method.getGenericParameterTypes();
            for (Type genericParameterType : genericParameterTypes) {
                System.out.println("泛型参数化类型:"+genericParameterType);
                if(genericParameterType instanceof ParameterizedType){
                    //真实的参数类型
                    Type[] actualTypeArguments = ((ParameterizedType)     genericParameterType).getActualTypeArguments();
                    for (Type actualTypeArgument : actualTypeArguments) {
                        System.out.println("真实的参数类型:"+actualTypeArgument);
                    }
                }
            }
    
            System.out.println("==========================================");
    
            method = Test01.class.getMethod("test2",null);
            Type genericReturnType = method.getGenericReturnType();
            System.out.println("泛型返回值类型："+genericReturnType);
            if(genericReturnType instanceof ParameterizedType){
                //真实的参数类型
                Type[] actualTypeArguments = ((ParameterizedType) genericReturnType).getActualTypeArguments();
                for (Type actualTypeArgument : actualTypeArguments) {
                    System.out.println("真实的参数类型:"+actualTypeArgument);
                }
            }
    
        }
    }

输出结果如下：

泛型参数化类型:java.util.Map<java.lang.String, com.han.reflection.User>

真实的参数类型:class java.lang.String

真实的参数类型:class com.han.reflection.User

泛型参数化类型:java.util.List<com.han.reflection.User>

真实的参数类型:class com.han.reflection.User

==========================================

泛型返回值类型：java.util.Map<java.lang.String, com.han.reflection.User>

真实的参数类型:class java.lang.String

真实的参数类型:class com.han.reflection.User