/**
     * 利用指定字符數(shù)組創(chuàng)建CharArrayReader對象
     * 本質(zhì)是將字符數(shù)組賦值給對象的字符緩沖區(qū)
     */
    public CharArrayReader(char buf[]) {
        this.buf = buf;
        this.pos = 0;
        this.count = buf.length;
    }

   public CharArrayReader(char buf[], int offset, int length) {
        if ((offset < 0) || (offset > buf.length) || (length < 0) ||
            ((offset + length) < 0)) {
            throw new IllegalArgumentException();
        }
        this.buf = buf;
        this.pos = offset;
        this.count = Math.min(offset + length, buf.length);
        this.markedPos = offset;
    }

    /** 字符緩沖區(qū) */
    protected char buf[];
 
    /** 緩沖區(qū)當(dāng)前位置 */
    protected int pos;
 
    /** 標(biāo)記在緩沖區(qū)中的位置 */
    protected int markedPos = 0;
 
    /**
     * 緩沖區(qū)結(jié)束的索引，該索引或者之外沒有有效數(shù)據(jù)
     * 即緩沖區(qū)的長度值
     */
    protected int count;

 public int read() throws IOException {
        synchronized (lock) {
            ensureOpen();
            if (pos >= count) //當(dāng)前位置大于等于結(jié)束索引時(shí)，代表緩沖區(qū)內(nèi)容已讀取到尾部，返回-1
                return -1;
            else
                return buf[pos++];   //直接換回緩沖區(qū)字符
        }
    }

    public int read(char b[], int off, int len) throws IOException {
        synchronized (lock) {
            ensureOpen();
            if ((off < 0) || (off > b.length) || (len < 0) ||
                ((off + len) > b.length) || ((off + len) < 0)) {
                throw new IndexOutOfBoundsException();
            } else if (len == 0) {
                return 0;
            }
 
            if (pos >= count) { //字符緩沖區(qū)數(shù)據(jù)已讀取完畢
                return -1;
            }
            if (pos + len > count) { //字符緩沖區(qū)當(dāng)前位置讀取len個(gè)字節(jié)后超出界限的話，則只讀當(dāng)前位置到結(jié)束索引的字節(jié)
                len = count - pos;
            }
            if (len <= 0) {         //感覺此if多余
                return 0;
            }
            System.arraycopy(buf, pos, b, off, len); //從字符緩沖區(qū)中讀取len個(gè)字節(jié)到目標(biāo)數(shù)組中
            pos += len; //修改字符緩沖區(qū)當(dāng)前位置
            return len;
        }
    }

/**
     *關(guān)閉流并釋放資源--本質(zhì)是將緩沖區(qū)賦值為null,則該流其它方法都不能使用
     *根本就沒有調(diào)用過系統(tǒng)資源，因此關(guān)閉是無效的？但是一旦關(guān)閉在調(diào)用其他方法，就會拋異常
     */
    public void close() {
        buf = null;
    }
 
   /** 確保流不被關(guān)閉 */
    private void ensureOpen() throws IOException {
        if (buf == null)
            throw new IOException("Stream closed");
    }

CharArrayReader(char array[ ]) 
CharArrayReader(char array[ ], int start, int numChars) 

// Demonstrate CharArrayReader. 
import java.io.*; 
public class CharArrayReaderDemo { 
 public static void main(String args[]) throws IOException { 
 String tmp = "abcdefghijklmnopqrstuvwxyz"; 
 int length = tmp.length(); 
 char c[] = new char[length]; 
 tmp.getChars(0, length, c, 0); 
 CharArrayReader input1 = new CharArrayReader(c); 
 CharArrayReader input2 = new CharArrayReader(c, 0, 5); 
 int i; 
 System.out.println("input1 is:"); 
 while((i = input1.read()) != -1) { 
 System.out.print((char)i); 
 } 
 System.out.println(); 
 System.out.println("input2 is:"); 
 while((i = input2.read()) != -1) { 
 System.out.print((char)i); 
 } 
 System.out.println(); 
 } 
}