带有空正文的 HTTP GET 响应，在 IE 中下载了 excel 文档答案

【问题标题】：HTTP GET responds with empty body, downloads excel document in IE带有空正文的 HTTP GET 响应，在 IE 中下载了 excel 文档
【发布时间】：2017-05-16 01:53:57
【问题描述】：

当我下载 Excel 报告时，我试图弄清楚 this 页面上发生了什么。它仅适用于 Internet Explorer，当我尝试使用 ScalaJ 在 Scala 中下载报告时，响应正文的输入流为空。有人可以帮我理解这里发生了什么吗？

明文请求：

GET /oca_ReportViewer.aspx?ReportName=District_and_Statutory_County_Court/DSC_Civil_Family_Activity_Detail_N.rpt&ddlFromMonth=9&ddlFromYear=2010&txtFromMonthField=@FromMonth&txtFromYearField=@FromYear&ddlToMonth=10&ddlToYear=2010&txtToMonthField=@ToMonth&txtToYearField=@ToYear&ddlCountyPostBack=0&txtCountyPostBackField=@CountyID&chkAggregateMonthlyReport=0&export=1625 HTTP/1.1
Accept: text/html, application/xhtml+xml, image/jxr, */*
Referer: http://card.txcourts.gov/ReportSelection.aspx
Accept-Language: en-US
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko
Accept-Encoding: gzip, deflate
Host: card.txcourts.gov
Connection: Keep-Alive
Cache-Control: no-cache
Cookie: ASP.NET_SessionId=j0tgci45qj3t1uqygrvkqz55

到目前为止的代码：

import java.io.{BufferedOutputStream, FileOutputStream, FileWriter, InputStream}
import scalaj.http._

object Downloader extends App {

    val url = "http://card.txcourts.gov/oca_ReportViewer.aspx"
    val keys: Map[String, String] = Map (
        ("ReportName", "District_and_Statutory_County_Court/DSC_Civil_Family_Activity_Detail_N.rpt"),
        ("ddlFromMonth", "9"),
        ("ddlFromYear", "2010"),
        ("txtFromMonthField", "@FromMonth"),
        ("txtFromYearField", "@FromYear"),
        ("ddlToMonth", "10"),
        ("ddlToYear", "2010"),
        ("txtToMonthField", "@ToMonth"),
        ("txtToYearField", "@ToYear"),
        ("ddlCountyPostBack", "0"),
        ("txtCountyPostBackField", "@CountyID"),
        ("chkAggregateMonthlyReport", "0"),
        ("export", "1625")
    )

    //println(keys)

    val heads: Map[String, String] = Map (
        ("Accept", "text/html, application/xhtml+xml, image/jxr, */*"),
        ("Accept-Encoding", "gzip, deflate"),
        ("Accept-Language", "en-US"),
        ("Cache-Control", "no-cache"),
        ("Connection", "Keep-Alive"),
        ("Cookie", "ASP.NET_SessionId=j0tgci45qj3t1uqygrvkqz55"),
        ("Host", "card.txcourts.gov"),
        ("Referer", "http://card.txcourts.gov/ReportSelection.aspx"),
        ("User-Agent", "Mozilla/5.0 (Windows NT 10.0; WOW64; Trident/7.0; rv:11.0) like Gecko")
    )

    def parse(status: Int, headers: Map[String, IndexedSeq[String]], inputStream: InputStream): Unit = {
        val output = new BufferedOutputStream(new FileOutputStream("test.xls"))
        val bytes = new Array[Byte](1024) //1024 bytes - Buffer size
        //println(status)
        //println(headers)
        Stream
            .continually (inputStream.read(bytes))
            .takeWhile (-1 !=)
            .foreach (read=>output.write(bytes,0,read))

        output.close()
    }

    val response: HttpResponse[Unit] = Http(url).params(keys).headers(heads).charset("US-ASCII").timeout(1000, 60000).exec[Unit](parse)
    println(response.isSuccess)
}

如果有人可以帮助我，我将不胜感激！我只需要将响应保存到 .xls 文件中。如果你有时间，我似乎也无法找到浏览器在哪里获取会话 ID，所以这也很有帮助。

编辑：

我可以看到实际上正在发送 excel 数据，请使用 wireshark 查看以下流：

谢谢！

【问题讨论】：

你使用的是什么 scala 版本？我使用 scala 2.11.11 运行了您的代码，并且在将大量字节打印到输出后（我打印了它们而不是写入文件），我在 `.continually (inputStream.read(bytes)) 中得到了 NullPointerException。
2.12.2，让我回滚试试。

标签： excel scala http get httpurlconnection

【解决方案1】：

好的，不太确定为什么我的流会变为空，但我将代码更改为在输出流遇到异常时关闭它。我知道这很愚蠢，但它有效并且文件已完全下载。如果其他人知道更好的解释，我将不胜感激！

这是新的解析函数：

def parse(status: Int, headers: Map[String, IndexedSeq[String]], inputStream: InputStream): Unit = {
    val output = new BufferedOutputStream(new FileOutputStream(filename))
    try {
      Iterator
        .continually (inputStream.read)
        .takeWhile (-1 !=)
        .foreach (output.write)
    }
    catch {
      case _: Throwable => output.close()
    }
    finally{
      output.close()
    }
  }

【讨论】：