使用CheckedOutputStream和CheckedInputStream实现带验证的压缩、解压
2016-10-14 16:29
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转自http://ajava.org
http://ajava.org/article-1133-1.html
下面例子演示如何通过CheckedOutputStream和CheckedInputStream实现带验证的压缩、解压。
采用了Adler32算法,当然大家用CRC32算法也可以。
通过FilenameFilter方法,取得workspace/你的工程目录下的所有txt文件,但不包含子目录下的txt文件。
用途:主要用于需要确保压缩文件在压缩跟解压的无误操作,确保完全相同。
压缩例子代码:
package ajava.code.javase;
import java.io.*;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
import java.util.zip.CheckedOutputStream;
import java.util.zip.Adler32;
public class AjavaZipWithChecksum {
public static void main(String[] args) {
try {
String target = "ajavachecksum.zip";
FileOutputStream fos = new FileOutputStream(target);
//使用Adler32算法创建CheckedOutputStream校验输出流
CheckedOutputStream checksum = new CheckedOutputStream(fos, new Adler32());
ZipOutputStream zos = new ZipOutputStream(new BufferedOutputStream(checksum));
int size = 0;
byte[] buffer = new byte[1024];
//
// Get all text files on the working folder.
//通过FilenameFilter取得所有txt文件
File dir = new File(".");
String[] files = dir.list(new FilenameFilter() {
public boolean accept(File dir, String name) {
if (name.endsWith(".txt")) {
return true;
} else {
return false;
}
}
});
//压缩成ajavachecksum.zip
for (int i = 0; i < files.length; i++) {
System.out.println("压缩中...: " + files[i]);
FileInputStream fis = new FileInputStream(files[i]);
BufferedInputStream bis = new BufferedInputStream(fis, buffer.length);
ZipEntry zipEntry = new ZipEntry(files[i]);
zos.putNextEntry(zipEntry);
while ((size = fis.read(buffer, 0, buffer.length)) > 0) {
zos.write(buffer, 0, size);
}
zos.closeEntry();
fis.close();
}
zos.close();
System.out.println(" 校验码 : " + checksum.getChecksum().getValue());
} catch (IOException e) {
e.printStackTrace();
}
}
}
解压例子代码:
package ajava.code.javase;
import java.io.*;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipEntry;
import java.util.zip.CheckedInputStream;
import java.util.zip.Adler32;
public class AjavaUnzipWithChecksum {
public static void main(String[] args) {
String zipname = "ajavachecksum.zip";
try {
FileInputStream fis = new FileInputStream(zipname);
//使用Adler32算法创建CheckedInputStream校验输出流
CheckedInputStream checksum = new CheckedInputStream(fis, new Adler32());
ZipInputStream zis = new ZipInputStream(new BufferedInputStream(checksum));
ZipEntry entry;
//解压ajavachecksum.zip
while ((entry = zis.getNextEntry()) != null) {
System.out.println("解压中....: " + entry.getName());
int size;
byte[] buffer = new byte[2048];
FileOutputStream fos = new FileOutputStream(entry.getName());
BufferedOutputStream bos = new BufferedOutputStream(fos, buffer.length);
while ((size = zis.read(buffer, 0, buffer.length)) != -1) {
bos.write(buffer, 0, size);
}
bos.flush();
bos.close();
}
zis.close();
fis.close();
System.out.println("校验码 = " + checksum.getChecksum().getValue());
} catch (IOException e) {
e.printStackTrace();
}
}
}
运行结果:
压缩中...: ajava11.txt
压缩中...: ajava.txt
校验码: 783456913
解压中....: ajava11.txt
解压中....: ajava.txt
校验码 = 783456913
http://ajava.org/article-1133-1.html
下面例子演示如何通过CheckedOutputStream和CheckedInputStream实现带验证的压缩、解压。
采用了Adler32算法,当然大家用CRC32算法也可以。
通过FilenameFilter方法,取得workspace/你的工程目录下的所有txt文件,但不包含子目录下的txt文件。
用途:主要用于需要确保压缩文件在压缩跟解压的无误操作,确保完全相同。
压缩例子代码:
package ajava.code.javase;
import java.io.*;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
import java.util.zip.CheckedOutputStream;
import java.util.zip.Adler32;
public class AjavaZipWithChecksum {
public static void main(String[] args) {
try {
String target = "ajavachecksum.zip";
FileOutputStream fos = new FileOutputStream(target);
//使用Adler32算法创建CheckedOutputStream校验输出流
CheckedOutputStream checksum = new CheckedOutputStream(fos, new Adler32());
ZipOutputStream zos = new ZipOutputStream(new BufferedOutputStream(checksum));
int size = 0;
byte[] buffer = new byte[1024];
//
// Get all text files on the working folder.
//通过FilenameFilter取得所有txt文件
File dir = new File(".");
String[] files = dir.list(new FilenameFilter() {
public boolean accept(File dir, String name) {
if (name.endsWith(".txt")) {
return true;
} else {
return false;
}
}
});
//压缩成ajavachecksum.zip
for (int i = 0; i < files.length; i++) {
System.out.println("压缩中...: " + files[i]);
FileInputStream fis = new FileInputStream(files[i]);
BufferedInputStream bis = new BufferedInputStream(fis, buffer.length);
ZipEntry zipEntry = new ZipEntry(files[i]);
zos.putNextEntry(zipEntry);
while ((size = fis.read(buffer, 0, buffer.length)) > 0) {
zos.write(buffer, 0, size);
}
zos.closeEntry();
fis.close();
}
zos.close();
System.out.println(" 校验码 : " + checksum.getChecksum().getValue());
} catch (IOException e) {
e.printStackTrace();
}
}
}
解压例子代码:
package ajava.code.javase;
import java.io.*;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipEntry;
import java.util.zip.CheckedInputStream;
import java.util.zip.Adler32;
public class AjavaUnzipWithChecksum {
public static void main(String[] args) {
String zipname = "ajavachecksum.zip";
try {
FileInputStream fis = new FileInputStream(zipname);
//使用Adler32算法创建CheckedInputStream校验输出流
CheckedInputStream checksum = new CheckedInputStream(fis, new Adler32());
ZipInputStream zis = new ZipInputStream(new BufferedInputStream(checksum));
ZipEntry entry;
//解压ajavachecksum.zip
while ((entry = zis.getNextEntry()) != null) {
System.out.println("解压中....: " + entry.getName());
int size;
byte[] buffer = new byte[2048];
FileOutputStream fos = new FileOutputStream(entry.getName());
BufferedOutputStream bos = new BufferedOutputStream(fos, buffer.length);
while ((size = zis.read(buffer, 0, buffer.length)) != -1) {
bos.write(buffer, 0, size);
}
bos.flush();
bos.close();
}
zis.close();
fis.close();
System.out.println("校验码 = " + checksum.getChecksum().getValue());
} catch (IOException e) {
e.printStackTrace();
}
}
}
运行结果:
压缩中...: ajava11.txt
压缩中...: ajava.txt
校验码: 783456913
解压中....: ajava11.txt
解压中....: ajava.txt
校验码 = 783456913
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