java语言SDK中ZipInputStream

1. /*
    * @(#)ZipInputStream.java 1.45 09/11/10
    *
    * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
    */
2. package java.util.zip;
3. import java.io.InputStream;
   import java.io.IOException;
   import java.io.EOFException;
   import java.io.UnsupportedEncodingException;
   import java.io.PushbackInputStream;
   import sun.security.action.GetPropertyAction;
   import java.util.jar.JarInputStream;
4. 
   /**
    * This class implements an input stream filter for reading files in the
    * ZIP file format. Includes support for both compressed and uncompressed
    * entries.
    *
    * @author David Connelly
    * @version 1.45, 11/10/09
    */
   public
   class ZipInputStream extends InflaterInputStream implements ZipConstants {
       private ZipEntry entry;
       private int flag;
       private CRC32 crc = new CRC32();
       private long remaining;
       private byte[] tmpbuf = new byte[512];
5.     private static final int STORED = ZipEntry.STORED;
       private static final int DEFLATED = ZipEntry.DEFLATED;
6.     private boolean closed = false;
       // this flag is set to true after EOF has reached for
       // one entry
       private boolean entryEOF = false;
       // Used to decide what encoding to use while reading zip entries
       private static final String fileEncoding = java.security.AccessController
           .doPrivileged(new GetPropertyAction("sun.zip.encoding"));
7. 
       /**
        * Check to make sure that this stream has not been closed
        */
       private void ensureOpen() throws IOException {
    if (closed) {
        throw new IOException("Stream closed");
           }
       }
8.     /**
        * Creates a new ZIP input stream.
        * @param in the actual input stream
        */
       public ZipInputStream(InputStream in) {
    super(new PushbackInputStream(in, 512), new Inflater(true), 512);
           usesDefaultInflater = true;
           if(in == null) {
               throw new NullPointerException("in is null");
           }
       }
9.     /**
        * Reads the next ZIP file entry and positions the stream at the
        * beginning of the entry data.
        * @return the next ZIP file entry, or null if there are no more entries
        * @exception ZipException if a ZIP file error has occurred
        * @exception IOException if an I/O error has occurred
        */
       public ZipEntry getNextEntry() throws IOException {
           ensureOpen();
    if (entry != null) {
        closeEntry();
    }
    crc.reset();
    inf.reset();
    if ((entry = readLOC()) == null) {
        return null;
    }
    if (entry.method == STORED) {
        remaining = entry.size;
    }
           entryEOF = false;
    return entry;
       }
10.     /**
         * Closes the current ZIP entry and positions the stream for reading the
         * next entry.
         * @exception ZipException if a ZIP file error has occurred
         * @exception IOException if an I/O error has occurred
         */
        public void closeEntry() throws IOException {
            ensureOpen();
     while (read(tmpbuf, 0, tmpbuf.length) != -1) ;
            entryEOF = true;
        }
11.     /**
         * Returns 0 after EOF has reached for the current entry data,
         * otherwise always return 1.
         * <p>
         * Programs should not count on this method to return the actual number
         * of bytes that could be read without blocking.
         *
         * @return     1 before EOF and 0 after EOF has reached for current entry.
         * @exception  IOException  if an I/O error occurs.
         *
         */
        public int available() throws IOException {
            ensureOpen();
            if (entryEOF) {
                return 0;
            } else {
                return 1;
            }
        }
12.     /**
         * Reads from the current ZIP entry into an array of bytes.
         * If <code>len</code> is not zero, the method
         * blocks until some input is available; otherwise, no
         * bytes are read and <code>0</code> is returned.
         * @param b the buffer into which the data is read
         * @param off the start offset in the destination array <code>b</code>
         * @param len the maximum number of bytes read
         * @return the actual number of bytes read, or -1 if the end of the
         *         entry is reached
         * @exception  NullPointerException If <code>b</code> is <code>null</code>.
         * @exception  IndexOutOfBoundsException If <code>off</code> is negative,
         * <code>len</code> is negative, or <code>len</code> is greater than
         * <code>b.length - off</code>
         * @exception ZipException if a ZIP file error has occurred
         * @exception IOException if an I/O error has occurred
         */
        public int read(byte[] b, int off, int len) throws IOException {
            ensureOpen();
            if (off < 0 || len < 0 || off > b.length - len) {
         throw new IndexOutOfBoundsException();
     } else if (len == 0) {
         return 0;
     }
13.  if (entry == null) {
         return -1;
     }
     switch (entry.method) {
     case DEFLATED:
         len = super.read(b, off, len);
         if (len == -1) {
      readEnd(entry);
                    entryEOF = true;
      entry = null;
         } else {
      crc.update(b, off, len);
         }
         return len;
     case STORED:
         if (remaining <= 0) {
                    entryEOF = true;
      entry = null;
      return -1;
         }
         if (len > remaining) {
      len = (int)remaining;
         }
         len = in.read(b, off, len);
         if (len == -1) {
      throw new ZipException("unexpected EOF");
         }
         crc.update(b, off, len);
         remaining -= len;
         if (remaining == 0 && entry.crc != crc.getValue()) {
      throw new ZipException(
          "invalid entry CRC (expected 0x" + Long.toHexString(entry.crc) +
          " but got 0x" + Long.toHexString(crc.getValue()) + ")");
         }
         return len;
     default:
         throw new ZipException("invalid compression method");
     }
        }
14.     /**
         * Skips specified number of bytes in the current ZIP entry.
         * @param n the number of bytes to skip
         * @return the actual number of bytes skipped
         * @exception ZipException if a ZIP file error has occurred
         * @exception IOException if an I/O error has occurred
         * @exception IllegalArgumentException if n < 0
         */
        public long skip(long n) throws IOException {
            if (n < 0) {
                throw new IllegalArgumentException("negative skip length");
            }
            ensureOpen();
     int max = (int)Math.min(n, Integer.MAX_VALUE);
     int total = 0;
     while (total < max) {
         int len = max - total;
         if (len > tmpbuf.length) {
      len = tmpbuf.length;
         }
         len = read(tmpbuf, 0, len);
         if (len == -1) {
                    entryEOF = true;
      break;
         }
         total += len;
     }
     return total;
        }
15.     /**
         * Closes this input stream and releases any system resources associated
         * with the stream.
         * @exception IOException if an I/O error has occurred
         */
        public void close() throws IOException {
            if (!closed) {
         super.close();
                closed = true;
            }
        }
16.     private byte[] b = new byte[256];
17.     /*
         * Reads local file (LOC) header for next entry.
         */
        private ZipEntry readLOC() throws IOException {
     try {
         readFully(tmpbuf, 0, LOCHDR);
     } catch (EOFException e) {
         return null;
     }
     if (get32(tmpbuf, 0) != LOCSIG) {
         return null;
     }
     // get the entry name and create the ZipEntry first
     int len = get16(tmpbuf, LOCNAM);
            int blen = b.length;
            if (len > blen) {
                do
                    blen = blen * 2;
                while (len > blen);
                b = new byte[blen];
            }
     readFully(b, 0, len);
     String name = getFileName(b, len);
18.         ZipEntry e = createZipEntry(name);
     // now get the remaining fields for the entry
     flag = get16(tmpbuf, LOCFLG);
     if ((flag & 1) == 1) {
         throw new ZipException("encrypted ZIP entry not supported");
     }
     e.method = get16(tmpbuf, LOCHOW);
     e.time = get32(tmpbuf, LOCTIM);
     if ((flag & 8) == 8) {
         /* "Data Descriptor" present */
         if (e.method != DEFLATED) {
      throw new ZipException(
       "only DEFLATED entries can have EXT descriptor");
         }
     } else {
         e.crc = get32(tmpbuf, LOCCRC);
         e.csize = get32(tmpbuf, LOCSIZ);
         e.size = get32(tmpbuf, LOCLEN);
     }
     len = get16(tmpbuf, LOCEXT);
     if (len > 0) {
         byte[] bb = new byte[len];
         readFully(bb, 0, len);
         e.setExtra(bb);
     }
     return e;
        }
19.     /*
         * Fetches a UTF8-encoded String from the specified byte array.
         */
        private static String getUTF8String(byte[] b, int off, int len) {
     // First, count the number of characters in the sequence
     int count = 0;
     int max = off + len;
     int i = off;
     while (i < max) {
         int c = b[i++] & 0xff;
         switch (c >> 4) {
         case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
      // 0xxxxxxx
      count++;
      break;
         case 12: case 13:
      // 110xxxxx 10xxxxxx
      if ((int)(b[i++] & 0xc0) != 0x80) {
          throw new IllegalArgumentException();
      }
      count++;
      break;
         case 14:
      // 1110xxxx 10xxxxxx 10xxxxxx
      if (((int)(b[i++] & 0xc0) != 0x80) ||
          ((int)(b[i++] & 0xc0) != 0x80)) {
          throw new IllegalArgumentException();
      }
      count++;
      break;
         default:
      // 10xxxxxx, 1111xxxx
      throw new IllegalArgumentException();
         }
     }
     if (i != max) {
         throw new IllegalArgumentException();
     }
     // Now decode the characters...
     char[] cs = new char[count];
     i = 0;
     while (off < max) {
         int c = b[off++] & 0xff;
         switch (c >> 4) {
         case 0: case 1: case 2: case 3: case 4: case 5: case 6: case 7:
      // 0xxxxxxx
      cs[i++] = (char)c;
      break;
         case 12: case 13:
      // 110xxxxx 10xxxxxx
      cs[i++] = (char)(((c & 0x1f) << 6) | (b[off++] & 0x3f));
      break;
         case 14:
      // 1110xxxx 10xxxxxx 10xxxxxx
      int t = (b[off++] & 0x3f) << 6;
      cs[i++] = (char)(((c & 0x0f) << 12) | t | (b[off++] & 0x3f));
      break;
         default:
      // 10xxxxxx, 1111xxxx
      throw new IllegalArgumentException();
         }
     }
     return new String(cs, 0, count);
        }
20.     /**
         * Creates a new <code>ZipEntry</code> object for the specified
         * entry name.
         *
         * @param name the ZIP file entry name
         * @return the ZipEntry just created
         */
        protected ZipEntry createZipEntry(String name) {
     return new ZipEntry(name);
        }
21.     /*
         * Reads end of deflated entry as well as EXT descriptor if present.
         */
        private void readEnd(ZipEntry e) throws IOException {
     int n = inf.getRemaining();
     if (n > 0) {
         ((PushbackInputStream)in).unread(buf, len - n, n);
     }
     if ((flag & 8) == 8) {
         /* "Data Descriptor" present */
         readFully(tmpbuf, 0, EXTHDR);
         long sig = get32(tmpbuf, 0);
                if (sig != EXTSIG) { // no EXTSIG present
                    e.crc = sig;
                    e.csize = get32(tmpbuf, EXTSIZ - EXTCRC);
                    e.size = get32(tmpbuf, EXTLEN - EXTCRC);
                    ((PushbackInputStream)in).unread(
                                               tmpbuf, EXTHDR - EXTCRC - 1, EXTCRC);
                } else {
                    e.crc = get32(tmpbuf, EXTCRC);
                    e.csize = get32(tmpbuf, EXTSIZ);
                    e.size = get32(tmpbuf, EXTLEN);
                }
     }
     if (e.size != inf.getBytesWritten()) {
         throw new ZipException(
      "invalid entry size (expected " + e.size +
      " but got " + inf.getBytesWritten() + " bytes)");
     }
     if (e.csize != inf.getBytesRead()) {
         throw new ZipException(
      "invalid entry compressed size (expected " + e.csize +
      " but got " + inf.getBytesRead() + " bytes)");
     }
     if (e.crc != crc.getValue()) {
         throw new ZipException(
      "invalid entry CRC (expected 0x" + Long.toHexString(e.crc) +
      " but got 0x" + Long.toHexString(crc.getValue()) + ")");
     }
        }
22.     /*
         * Reads bytes, blocking until all bytes are read.
         */
        private void readFully(byte[] b, int off, int len) throws IOException {
     while (len > 0) {
         int n = in.read(b, off, len);
         if (n == -1) {
      throw new EOFException();
         }
         off += n;
         len -= n;
     }
        }
23.     /*
         * Fetches unsigned 16-bit value from byte array at specified offset.
         * The bytes are assumed to be in Intel (little-endian) byte order.
         */
        private static final int get16(byte b[], int off) {
     return (b[off] & 0xff) | ((b[off+1] & 0xff) << 8);
        }
24.     /*
         * Fetches unsigned 32-bit value from byte array at specified offset.
         * The bytes are assumed to be in Intel (little-endian) byte order.
         */
        private static final long get32(byte b[], int off) {
     return get16(b, off) | ((long)get16(b, off+2) << 16);
        }
25.     private String getFileName(byte[] b, int len) throws IOException {
     String name;
     try {
         if (fileEncoding == null || fileEncoding.equals("") || this instanceof JarInputStream) {
      name = getUTF8String(b, 0, len);
         } else {
      if (fileEncoding.equalsIgnoreCase("default")) {
             // use platforms's default encoding
          name = new String(b, 0, len);
      } else {
          try {
           name = new String(b, 0, len, fileEncoding);
            } catch (UnsupportedEncodingException UEE) {
       throw new ZipException("Unable to encode entry " +
           "name (sun.zip.encoding is " + fileEncoding + ")");
          }
      }
         }
     } catch (IllegalArgumentException e) {
         // Alt encoding that can be used  if
         // the initial decoding attempt fails.
         String altEncoding = java.security.AccessController
        .doPrivileged(new GetPropertyAction("sun.zip.altEncoding"));
         if (altEncoding == null || altEncoding.equals("") ||
                 this instanceof JarInputStream) {
                 throw e;
                }
         if (altEncoding.equalsIgnoreCase("default")) {
      // use platform's default encoding
      name = new String(b, 0, len);
         } else {
      try {
          // use the specified encoding
          name = new String(b, 0, len, altEncoding);
      } catch (UnsupportedEncodingException UEE) {
          throw new ZipException("Unable to encode entry " +
       "name (sun.zip.altEncoding is " + altEncoding + ")");
      }
         }
      
     }
     return name;
        }
    }

JAVA语言SDK中的这个类中的 private static String getUTF8String(byte[] b, int off, int len) 方法里边有抛出异常这个方法自己怎么不处理或往上抛了呢？这是不是个Bug？