java - 为什么我们不能调用 servlet 构造函数而不是 init 方法来初始化配置参数？

Question

我想知道为什么我们不调用 servlet 构造函数而不是 init 方法来初始化配置参数。

谢谢

Answer 1

This thread should clarify the differences.

引用一篇更有启发性的帖子:

The init() method is typically used to perform servlet initialization--creating or loading objects that are used by the servlet in the handling of its requests. Why not use a constructor instead? Well, in JDK 1.0 (for which servlets were originally written), constructors for dynamically loaded Java classes (such as servlets) couldn't accept arguments. So, in order to provide a new servlet any information about itself and its environment, a server had to call a servlet's init() method and pass along an object that implements the ServletConfig interface. Also, Java doesn't allow interfaces to declare constructors. This means that the javax.servlet.Servlet interface cannot declare a constructor that accepts a ServletConfig parameter. It has to declare another method, like init(). It's still possible, of course, for you to define constructors for your servlets, but in the constructor you don't have access to the ServletConfig object or the ability to throw a ServletException.