最佳做法：捕获java.net.URL中的失败点

使用 Scala和Play 2.0进行JVM的新功能

我将遗留应用程序转换为Play,需要通过Authorize.net进行付款处理.通过java.net.URL源码,有许多潜在的失败点.给出我在下面写的接口,你将在哪里实现try / catch块？我需要相应地调整方法签名,可能返回一个[错误,成功]到调用客户端代码

import java.net.{URL,URLEncoder}
import java.io.{BufferedReader,DataOutputStream,InputStreamReader}
import javax.net.ssl._

trait Authnet {
  private val prodUrl = "https://secure.authorize.net/gateway/transact.dll"
  private val testUrl = "https://test.authorize.net/gateway/transact.dll"

  protected def authNetProcess(params: Map[String,String]) = {
    val(conn,urlParams) = connect(params)
    val request = new DataOutputStream( conn.getoutputStream )
    request.write(urlParams.getBytes)
    request.flush()
    request.close()
    val response = new BufferedReader(new InputStreamReader(conn.getInputStream))
    val results = response.readLine().split("\\|")
    response.close()
    results.toList
  }  

  private def connect(params: Map[String,String]) = {
    val urlParams = (config ++ params) map { case(k,v) =>
        URLEncoder.encode(k,"UTF-8") + "=" + URLEncoder.encode(v,"UTF-8")
    } mkString("&")

    lazy val url = if (isDev) new URL(testUrl) else new URL(prodUrl)
    val conn = url.openConnection
    conn.setDoOutput(true)
    conn.setUseCaches(false)
    (conn,urlParams)
  }

  private val config = Map(
    'x_login        -> "...",'x_tran_key     -> "...",...
  )
}

解决方法

坚持拇指规则：

Only catch an exception if you must handle it.

“必须处理”没有清晰的定义,但这意味着你应该抵制一个异常的冲动,因为你只能抛出一个异常.

“必须处理”主要由应用程序应该如何工作或其他依赖关系定义.

If the application requires to display an error to the user instead of aborting with an exception,then it’s a must.

在这种情况下,抓住这一点也增加了一些有意义的处理.

If an API requires to throw a different exception,then it’s a must,but the APIs deFinition is possibly not sound.

我总是质疑用另外一个异常替换异常的附加值.

将其应用于您的示例：

Would it add some value to catch an exception from connect() in authNetProcess()?

没有！没有办法在connect()中处理这个异常.所以它可以将该异常留给authNetProcess的调用者.在那里,您可以根据异常的类型提供不同的处理.