在scala中调用mechanize失败：HtmlDocument无法强制转换为scala.runtime.Nothin

Question

我有以下代码使用mechanize（可以从https://github.com/GistLabs/mechanize下载）

import com.gistlabs.mechanize._
val agent = new MechanizeAgent();
val page = agent.get("http://www.ask.com");

未能说出以下内容，我怎么能让它起作用？

scala> agent.get("http://www.ask.com")
java.lang.ClassCastException: com.gistlabs.mechanize.document.html.HtmlDocument cannot be cast to scala.runtime.Nothing$
    at .<init>(<console>:12)
    at .<clinit>(<console>)
    at .<init>(<console>:7)
    at .<clinit>(<console>)
    at $print(<console>)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)

Answer 1

问题是MechanizeAgent.get是一种通用方法（参见line 182 in MechanizeAgent.java）。所以你必须告诉Scala期望什么类型。要么是这样的：

import com.gistlabs.mechanize._
import com.gistlabs.mechanize.document._

val agent = new MechanizeAgent();
val page = agent.get[Document]("http://www.ask.com");

或者像这样：

import com.gistlabs.mechanize._
import com.gistlabs.mechanize.document._

val agent = new MechanizeAgent();
val page: Document = agent.get("http://www.ask.com");