java io学习（十七） CharArrayReader(字符数组输入流)

CharArrayReader 介绍

CharArrayReader 是字符数组输入流。它和ByteArrayInputStream类似，只不过ByteArrayInputStream是字节数组输入流，而CharArray是字符数组输入流。CharArrayReader 是用于读取字符数组，它继承于Reader。操作的数据是以字符为单位！

CharArrayReader 函数列表

CharArrayReader(char[] buf)
CharArrayReader(char[] buf, int offset, int length)

void      close()
void      mark(int readLimit)
boolean   markSupported()
int       read()
int       read(char[] buffer, int offset, int len)
boolean   ready()
void      reset()
long      skip(long charCount)

Reader和CharArrayReader源码分析

Reader是CharArrayReader的父类，我们先看看Reader的源码，然后再学CharArrayReader的源码。

1. Reader源码分析(基于jdk1.7.40)

package java.io;

public abstract class Reader implements Readable, Closeable {

    protected Object lock;

    protected Reader() {
        this.lock = this;
    }

    protected Reader(Object lock) {
        if (lock == null) {
            throw new NullPointerException();
        }
        this.lock = lock;
    }

    public int read(java.nio.CharBuffer target) throws IOException {
        int len = target.remaining();
        char[] cbuf = new char[len];
        int n = read(cbuf, 0, len);
        if (n > 0)
            target.put(cbuf, 0, n);
        return n;
    }

    public int read() throws IOException {
        char cb[] = new char[1];
        if (read(cb, 0, 1) == -1)
            return -1;
        else
            return cb[0];
    }

    public int read(char cbuf[]) throws IOException {
        return read(cbuf, 0, cbuf.length);
    }

    abstract public int read(char cbuf[], int off, int len) throws IOException;

    private static final int maxSkipBufferSize = 8192;

    private char skipBuffer[] = null;

    public long skip(long n) throws IOException {
        if (n < 0L)
            throw new IllegalArgumentException("skip value is negative");
        int nn = (int) Math.min(n, maxSkipBufferSize);
        synchronized (lock) {
            if ((skipBuffer == null) || (skipBuffer.length < nn))
                skipBuffer = new char[nn];
            long r = n;
            while (r > 0) {
                int nc = read(skipBuffer, 0, (int)Math.min(r, nn));
                if (nc == -1)
                    break;
                r -= nc;
            }
            return n - r;
        }
    }

    public boolean ready() throws IOException {
        return false;
    }

    public boolean markSupported() {
        return false;
    }

    public void mark(int readAheadLimit) throws IOException {
        throw new IOException("mark() not supported");
    }

    public void reset() throws IOException {
        throw new IOException("reset() not supported");
    }

     abstract public void close() throws IOException;
}

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