若是使用java自带的压缩工具包来实现解压缩文件到指定文件夹的功能，因为jdk提供的zip只能按utf-8格式处理，而windows系统中文件名是以gbk方式编码的，所以如果是解压一个包含中文文件名的zip包，会报非法参数异常，所以要实现解压缩，就得对deflateroutputstream.java、inflaterinputstream.java、zipconstants.java、zipentry.java、zipinputstream.java以及zipoutputstream.java这些相关的类进行修改，过程如下：
因为从 j2se 1.4 开始，java 编译器不再支持 import 进未命包名的类、接口，所以在创建的java项目中，一定要新建一个自己定义的包，包命名的格式一般为学校域名的逆序+自己的网名，比如cn.edu.xidian.crytoll。
在包内新建deflateroutputstream类，代码如下：
deflateroutputstream.java:
package cn.edu.xdian.crytoll;
import java.io.filteroutputstream;
import java.io.ioexception;
import java.io.outputstream;
import java.util.zip.deflater;
/**
* this class implements an output stream filter for compressing data in
* the "deflate" compression format. it is also used as the basis for other
* types of compression filters, such as gzipoutputstream.
*
* @see deflater
* @version 1.36, 03/13/06
* @author david connelly
*/
public
class deflateroutputstream extends filteroutputstream {
/**
* compressor for this stream.
*/
protected deflater def;
/**
* output buffer for writing compressed data.
*/
protected byte[] buf;
/**
* indicates that the stream has been closed.
*/
private boolean closed = false;
/**
* creates a new output stream with the specified compressor and
* buffer size.
* @param out the output stream
* @param def the compressor ("deflater")
* @param size the output buffer size
* @exception illegalargumentexception if size is <= 0
*/
public deflateroutputstream(outputstream out, deflater def, int size) {
super(out);
if (out == null || def == null) {
throw new nullpointerexception();
} else if (size <= 0) {
throw new illegalargumentexception("buffer size <= 0");
}
this.def = def;
buf = new byte[size];
}
/**
* creates a new output stream with the specified compressor and
* a default buffer size.
* @param out the output stream
* @param def the compressor ("deflater")
*/
public deflateroutputstream(outputstream out, deflater def) {
this(out, def, 512);
}
boolean usesdefaultdeflater = false;
/**
* creates a new output stream with a default compressor and buffer size.
* @param out the output stream
*/
public deflateroutputstream(outputstream out) {
this(out, new deflater());
usesdefaultdeflater = true;
}
/**
* writes a byte to the compressed output stream. this method will
* block until the byte can be written.
* @param b the byte to be written
* @exception ioexception if an i/o error has occurred
*/
public void write(int b) throws ioexception {
byte[] buf = new byte[1];
buf[0] = (byte)(b & 0xff);
write(buf, 0, 1);
}
/**
* writes an array of bytes to the compressed output stream. this
* method will block until all the bytes are written.
* @param b the data to be written
* @param off the start offset of the data
* @param len the length of the data
* @exception ioexception if an i/o error has occurred
*/
public void write(byte[] b, int off, int len) throws ioexception {
if (def.finished()) {
throw new ioexception("write beyond end of stream");
}
if ((off | len | (off + len) | (b.length - (off + len))) < 0) {
throw new indexoutofboundsexception();
} else if (len == 0) {
return;
}
if (!def.finished()) {
// deflate no more than stride bytes at a time. this avoids
// excess copying in deflatebytes (see deflater.c)
int stride = buf.length;
for (int i = 0; i < len; i+= stride) {
def.setinput(b, off + i, math.min(stride, len - i));
while (!def.needsinput()) {
deflate();
}
}
}
}
/**
* finishes writing compressed data to the output stream without closing
* the underlying stream. use this method when applying multiple filters
* in succession to the same output stream.
* @exception ioexception if an i/o error has occurred
*/
public void finish() throws ioexception {
if (!def.finished()) {
def.finish();
while (!def.finished()) {
deflate();
}
}
}
/**
* writes remaining compressed data to the output stream and closes the
* underlying stream.
* @exception ioexception if an i/o error has occurred
*/
public void close() throws ioexception {
if (!closed) {
finish();
if (usesdefaultdeflater)
def.end();
out.close();
closed = true;
}
}
/**
* writes next block of compressed data to the output stream.
* @throws ioexception if an i/o error has occurred
*/
protected void deflate() throws ioexception {
int len = def.deflate(buf, 0, buf.length);
if (len > 0) {
out.write(buf, 0, len);
}
}
}
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