泛型参数解析详解编程语言

参考了Retrofit的解析返回类型的代码

1. 获取返回类型

Method method = this.getClass().getDeclaredMethod("execute", Request.class, Integer.class); 
Type type = method.getGenericReturnType(); 

2. 获取类的泛型参数

@SuppressWarnings("unchecked") 
private  Class<T> getClassFromInterface(MqttObserver<T> observer) {
    
    try {
    
        Type[] interfaceTypes = observer.getClass().getGenericInterfaces(); 
        Type type; 
        if (interfaceTypes.length == 0) {
    
            //非接口 
            type = observer.getClass().getGenericSuperclass(); 
        } else {
    
            type = interfaceTypes[0]; 
        } 
        if (type == null) {
    
            return null; 
        } 
        if (ParameterizedType.class.isAssignableFrom(type.getClass())) {
    
            Type item = (((ParameterizedType) type).getActualTypeArguments())[0]; 
            return ((Class<T>) item); 
        } 
    } catch (Exception e) {
    
        return null; 
    } 
    return null; 
}