Question

我正在尝试从gZip解压缩和解码（base64）字符串。我为同一类和一个测试代码编写了一个类。我正在

Exception in thread "main" java.lang.IndexOutOfBoundsException

在线

 while ((readByte = gzipIS.read(gzipByteBuffer)) != -1) byteOS.write(

基本代码：

import java.io.BufferedReader
import java.io.ByteArrayInputStream
import java.io.ByteArrayOutputStream
import java.io.IOException
import java.io.InputStreamReader
import java.io.UnsupportedEncodingException
import java.nio.charset.StandardCharsets
import java.util.zip.GZIPInputStream
import java.util.zip.GZIPOutputStream
import org.apache.commons.codec.binary.Base64
import org.apache.commons.io.IOUtils

class ZipUtilities {

    def unzipCCBRsponse(inputB64: String): String = {
    val bDecodeBase64: Array[Byte] = Base64.decodeBase64(inputB64)
    var zipInputStream: GZIPInputStream = null
    try {
        zipInputStream = new GZIPInputStream(
        new ByteArrayInputStream(bDecodeBase64, 4, bDecodeBase64.length - 4))
        val inputStreamReader: InputStreamReader =
        new InputStreamReader(zipInputStream, StandardCharsets.UTF_8)
        val bufferedReader: BufferedReader = new BufferedReader(
        inputStreamReader)
        val output: StringBuilder = new StringBuilder()
        var line: String = null
        while ((line = bufferedReader.readLine()) != null)                                        output.append(line)
        println("Output String Length: " + output.length)
        bufferedReader.close()
        output.toString
    } catch {
      case e: IOException => e.printStackTrace()
   } 
   null
}

 def decodeBase64(b64EncodedString: String): String = {
    var bDecodeBase64: Array[Byte] = null
    try {
        bDecodeBase64 =
        Base64.decodeBase64(b64EncodedString.getBytes("ISO-8859-1"))
        new String(bDecodeBase64)
      } catch {
        case e: UnsupportedEncodingException => e.printStackTrace()
   }
   null
 }

 def decodeFromGzip(input: String): String = {
    var output: String = null
    if (input != null && !input.isEmpty) {
      try {
          var readByte: Int = 0
          val gzipByteBuffer: Array[Byte] = Array.ofDim[Byte](2048)
          val gzipIS: GZIPInputStream = new GZIPInputStream(
          new ByteArrayInputStream(Base64.decodeBase64(input)))
          val byteOS: ByteArrayOutputStream = new ByteArrayOutputStream()
          while ((readByte = gzipIS.read(gzipByteBuffer)) != -1) byteOS.write(
              gzipByteBuffer,
              0,
              readByte)
              byteOS.close()
          output = new String(byteOS.toByteArray())
      } catch {
          case e: IOException => e.printStackTrace()
    }
  }
  output
 }
}

测试代码为：

object ZipTest {

  def main(args: Array[String]): Unit = {
    val b64: String =
          "H4sIAAAAAAAAAO2dW1PbOBTH3/spNHkvgXYvLVPoCFlJtNiSR5IT8sRkUxeYJQmThMJ++5Xt3LjNNsdwVprNC8N4fPz/2dblXGTly9f70TX5kU9nV5PxUeNgb79B8vFw8u1qfHHUuJ1"
    val util: ZipUtilities = new ZipUtilities()
    println(util.decodeFromGzip(b64).replaceAll("\n", ""))
  }
}

Answer 1

在Scala中，赋值（readByte = gzipIS.read(gzipByteBuffer)）返回Unit，并且由于类型Unit的值永远不会等于-1（或任何Int值），则您的while循环实际上是无限的。

编译器应该已经警告您：

警告：使用“！=”比较Unit和Int类型的值将始终为true

注意：在惯用的Scala代码中，您很少看到null或var。几乎不需要。

线程“主”中的异常java.lang.IndexOutOfBoundsException Scala gZip并解码base64代码

1 个答案: