java中zip与gzip实现文件压缩，解压

GZIP对文件进行压缩解压，代码如下：

package cn.com.normal.io;

import java.io.*;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

/**
* GZIP压缩和解压
*/
public class GZIP {

/**
* gzip文件压缩
* @param inputFile
* @param targetName
*/
public void compressFile(File inputFile,String targetName) throws IOException {
System.out.println("程序开始...");
//字符输入流,以utf-8格式读入
BufferedReader in=new BufferedReader(new InputStreamReader(new FileInputStream(inputFile),"utf-8"));
//字符输出流
BufferedOutputStream out=new BufferedOutputStream(new GZIPOutputStream(new FileOutputStream(targetName)));
int n;
while ((n=in.read())!=-1){
out.write(String.valueOf((char) n).getBytes("utf-8"));
}
in.close();
out.close();
System.out.println("压缩完毕...");

}

/**
* 解压文件
* @param inputFile
* @param targetName
* @throws IOException
*/
public void decompressFile(File inputFile,String targetName) throws IOException {
BufferedReader reader=new BufferedReader(new InputStreamReader(new GZIPInputStream(new FileInputStream(inputFile)),"utf-8"));
String s;
FileOutputStream fos=new FileOutputStream(targetName);
while ((s=reader.readLine())!=null){
fos.write(s.getBytes());
}
reader.close();
fos.close();
System.out.println("解压完毕...");
}

}

ZIP对一个文件夹中的文件进行压缩和解压，代码如下：

package cn.com.normal.io;

import java.io.*;
import java.nio.charset.Charset;
import java.util.zip.GZIPInputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;

/**
* ZIP压缩方式
*/
public class ZIP {

private void _zip(String zipEntry,File file,ZipOutputStream out,BufferedOutputStream os) throws IOException {
if(file.isDirectory()){
File[] files=file.listFiles();
if(file.length()==0){
out.putNextEntry(new ZipEntry(zipEntry+File.separator));
}else{
for(File f:files){
_zip(zipEntry+File.separator+f.getName(),f,out,os);
}
}
}else{
out.putNextEntry(new ZipEntry(zipEntry));
FileInputStream in=new FileInputStream(file);
BufferedInputStream bin=new BufferedInputStream(in);
int n;
while ((n=bin.read())!=-1){
os.write(n);
}
bin.close();
in.close();
}
}

public void zip(String output,File input) throws IOException {
FileOutputStream fos=new FileOutputStream(output);
ZipOutputStream out=new ZipOutputStream(fos);
BufferedOutputStream os=new BufferedOutputStream(out);
_zip(input.getName(),input,out,os);
os.close();
out.close();
}

public void unzip(String directory,String inputFile) throws IOException {
ZipInputStream zin=new ZipInputStream(new FileInputStream(inputFile));
BufferedInputStream bin=new BufferedInputStream(zin);
ZipEntry entry=null;
File file=null;
while ((entry=zin.getNextEntry())!=null&&!entry.isDirectory()){
file=new File(directory,entry.getName());
if(!file.exists()){
(new File(file.getParent())).mkdirs();
}
FileOutputStream out=new FileOutputStream(file);
BufferedOutputStream bout=new BufferedOutputStream(out);
int n;
while ((n=bin.read())!=-1){
bout.write(n);
}
out.close();
bout.close();
}
bin.close();
zin.close();
}

}

小结：压缩文本文件一般通过字符操作压缩，压缩过程中指定编码的格式，解压过程中也通过指定解压的格式，最后获得准确解压文件，格式指定错误，将得到乱码的文件。