深入浅析Java中的 FilterInputStream

package java.io;public class FilterInputStream extends InputStream {  protected volatile InputStream in;  protected FilterInputStream(InputStream in) {    this.in = in;  }  public int read() throws IOException {    return in.read();  }  public int read(byte b[]) throws IOException {    return read(b, 0, b.length);  }  public int read(byte b[], int off, int len) throws IOException {    return in.read(b, off, len);  }  public long skip(long n) throws IOException {    return in.skip(n);  }  public int available() throws IOException {    return in.available();  }  public void close() throws IOException {    in.close();  }  public synchronized void mark(int readlimit) {    in.mark(readlimit);  }  public synchronized void reset() throws IOException {    in.reset();  }  public boolean markSupported() {    return in.markSupported();  }}