Filter (seach and replace) array of bytes in an InputStream-白红宇

Filter (seach and replace) array of bytes in an InputStream

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发布时间：2019-06-12

本文共 2234 字，大约阅读时间需要 7 分钟。

import java.io.*;import java.util.*;class ReplacingInputStream extends FilterInputStream {    LinkedList
     
       inQueue = new LinkedList
      
       ();    LinkedList
       
         outQueue = new LinkedList
        
         ();    final byte[] search, replacement;    protected ReplacingInputStream(InputStream in, byte[] search,                                                   byte[] replacement) {        super(in);        this.search = search;        this.replacement = replacement;    }    private boolean isMatchFound() {        Iterator
         
           inIter = inQueue.iterator();        for (int i = 0; i < search.length; i++)            if (!inIter.hasNext() || search[i] != inIter.next())                return false;        return true;    }    private void readAhead() throws IOException {        // Work up some look-ahead.        while (inQueue.size() < search.length) {            int next = super.read();            inQueue.offer(next);            if (next == -1)                break;        }    }    @Override    public int read() throws IOException {        // Next byte already determined.        if (outQueue.isEmpty()) {            readAhead();            if (isMatchFound()) {                for (int i = 0; i < search.length; i++)                    inQueue.remove();                for (byte b : replacement)                    outQueue.offer((int) b);            } else                outQueue.add(inQueue.remove());        }        return outQueue.remove();    }    // TODO: Override the other read methods.}class Test {    public static void main(String[] args) throws Exception {        byte[] bytes = "hello xyz world.".getBytes("UTF-8");        ByteArrayInputStream bis = new ByteArrayInputStream(bytes);        byte[] search = "xyz".getBytes("UTF-8");        byte[] replacement = "abc".getBytes("UTF-8");        InputStream ris = new ReplacingInputStream(bis, search, replacement);        ByteArrayOutputStream bos = new ByteArrayOutputStream();        int b;        while (-1 != (b = ris.read()))            bos.write(b);        System.out.println(new String(bos.toByteArray()));    }}