Package org.apache.tika.io

Class LookaheadInputStream

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable
    public class LookaheadInputStream
extends java.io.InputStream
    Stream wrapper that make it easy to read up to n bytes ahead from a stream that supports the mark feature. This class insulates the underlying stream from things like possible mark(), reset() and close() calls by external components that might otherwise invalidate the marked state of a stream.

    The recommended usage pattern of this class is: 

         try (InputStream lookahead = new LookaheadInputStream(stream, n)) {
         processStream(lookahead);
     }

    This usage pattern guarantees that only up to n bytes from the original stream can ever be read, and that the stream will have been marked and then reset to its original state once the above code block exits. No code in the fictional processStream() method can affect the the state of the original stream.

    Since:
    Apache Tika 0.10

    • Constructor Summary

      Constructors 
      Constructor Description
      LookaheadInputStream​(java.io.InputStream stream, int n)
      Creates a lookahead wrapper for the given input stream.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      int available()  
      void close()  
      void mark​(int readlimit)  
      boolean markSupported()  
      int read()  
      int read​(byte[] b, int off, int len)  
      void reset()  
      long skip​(long n)  

      • Methods inherited from class java.io.InputStream

        nullInputStream, read, readAllBytes, readNBytes, readNBytes, transferTo

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • LookaheadInputStream

        public LookaheadInputStream​(java.io.InputStream stream,
                            int n)
        Creates a lookahead wrapper for the given input stream. The given input stream should support the mark feature, as otherwise the state of that stream will be undefined after the lookahead wrapper has been closed. As a special case a null stream is treated as an empty stream.
        Parameters:
        stream - input stream, can be null
        n - maximum number of bytes to look ahead

    • Method Detail

      • close

        public void close()
           throws java.io.IOException
        Specified by:
        close in interface java.lang.AutoCloseable
        Specified by:
        close in interface java.io.Closeable
        Overrides:
        close in class java.io.InputStream
        Throws:
        java.io.IOException

      • read

        public int read()
         throws java.io.IOException
        Specified by:
        read in class java.io.InputStream
        Throws:
        java.io.IOException

      • read

        public int read​(byte[] b,
                int off,
                int len)
         throws java.io.IOException
        Overrides:
        read in class java.io.InputStream
        Throws:
        java.io.IOException

      • skip

        public long skip​(long n)
          throws java.io.IOException
        Overrides:
        skip in class java.io.InputStream
        Throws:
        java.io.IOException

      • available

        public int available()
        Overrides:
        available in class java.io.InputStream

      • markSupported

        public boolean markSupported()
        Overrides:
        markSupported in class java.io.InputStream

      • mark

        public void mark​(int readlimit)
        Overrides:
        mark in class java.io.InputStream

      • reset

        public void reset()
        Overrides:
        reset in class java.io.InputStream