java解压zip文件示例

时间:2021-05-19

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:

复制代码 代码如下:
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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