文件與流課後作業
一、編寫一個程序，指定一個文件夾，能自動計算出其總容量。
package TEST1;
import java.io.File;
import java.util.ArrayList;
public class total {
static long Size=0;
private static ArrayList<String>filelist=new ArrayList<String>();
public static void main(String[] args)
{
total s =new total();
String filePath="D:\\QQ文件";
s.getFile(filePath);
}
void getFile(String filePath)
{
File root=new File(filePath);
File[]files=root.listFiles();
for(File file:files)
{
if(file.isDirectory())
{
getFile(file.getAbsolutePath());
filelist.add(file.getAbsolutePath());
}
else
{
Size+=file.getAbsolutePath().length();
}
}
System.out.println("容量為:"+Size);
}
}
二、編寫一個文件加解密程序，通過命令行完成加解密工作。
package TEST1;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.Key;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
public class code {
Key key;
public code(String str)
{
getKey(str);
}
public void getKey(String strKey)
{
try
{
KeyGenerator _generator = KeyGenerator.getInstance("DES");
_generator.init(new SecureRandom(strKey.getBytes()));
this.key = _generator.generateKey();
_generator = null;
}
catch (Exception e)
{
throw new RuntimeException("Error: " + e);
}
}
public void encrypt(String file, String destFile) throws Exception
{
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.ENCRYPT_MODE, this.key);
InputStream is = new FileInputStream(file);
OutputStream out = new FileOutputStream(destFile);
CipherInputStream cis = new CipherInputStream(is, cipher);
byte[] buffer = new byte[1024];
int r;
while ((r = cis.read(buffer)) > 0) {
out.write(buffer, 0, r);
}
cis.close();
is.close();
out.close();
}
public void decrypt(String file, String dest) throws Exception
{
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.DECRYPT_MODE, this.key);
InputStream is = new FileInputStream(file);
OutputStream out = new FileOutputStream(dest);
CipherOutputStream cos = new CipherOutputStream(out, cipher);
byte[] buffer = new byte[1024];
int r;
while ((r = is.read(buffer)) >= 0) {
System.out.println();
cos.write(buffer, 0, r);
}
cos.close();
out.close();
is.close();
}
public static void main(String[] args){
code td = new code("aaa");
try {
td.encrypt("D:/r.txt", "D:/r加密後.txt");
} catch (Exception e) {
e.printStackTrace();
}
try {
td.decrypt("D:/r加密後.txt", "D:/r解密後.txt");
} catch (Exception e) {
e.printStackTrace();
}
}
}
三、編寫一個文件分割工具，能把一個大文件分割成多個小的文件。並且能再次把它們合並起來得到完整的文件。
package TEST3;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
public class pew {
public static void splitFileDemo(File src, int m) throws IOException {
if(src.isFile()) {
//獲取文件的總長度
long l = src.length();
//獲取文件名
String fileName = src.getName().substring(0, src.getName().indexOf("."));
//獲取文件後綴
String endName = src.getName().substring(src.getName().lastIndexOf("."));
System.out.println(endName);
InputStream in = null;
try {
in = new FileInputStream(src);
for(int i = 1; i <= m; i++) {
StringBuffer sb = new StringBuffer();
sb.append(src.getParent());
sb.append("\\");
sb.append(fileName);
sb.append("_data");
sb.append(i);
sb.append(endName);
System.out.println(sb.toString());
File file2 = new File(sb.toString());
//創建寫文件的輸出流
OutputStream out = new FileOutputStream(file2);
int len = -1;
byte[] bytes = new byte[10*1024*1024];
while((len = in.read(bytes))!=-1) {
out.write(bytes, 0, len);
if(file2.length() > (l / m)) {
break;
}
}
out.close();
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if(in != null)
in.close();
}
System.out.println("--- 文件分割完成 ---");
}
}
public static void joinFileDemo(String[] src) {
// 獲取合並文件
File newFile = new File(src[0].toString());
// 獲取文件名 後綴
String fileName = newFile.getName().substring(0, newFile.getName().indexOf("_"));
String endName = newFile.getName().substring(newFile.getName().lastIndexOf("."));
// 得到新的文件名
StringBuffer sb = new StringBuffer();
sb.append(newFile.getParent());
sb.append("\\");
sb.append(fileName);
sb.append(endName);
newFile = new File(sb.toString());
for(int i = 0; i < src.length; i++) {
File file = new File(src[i]);
try {
//讀取小文件的輸入流
InputStream in = new FileInputStream(file);
OutputStream out = new FileOutputStream(newFile, true);
int len = -1;
byte[] bytes = new byte[10*1024*1024];
while((len = in.read(bytes))!=-1) {
out.write(bytes, 0, len);
}
out.close();
in.close();
} catch (Exception e) {
e.printStackTrace();
}
}
System.out.println("文件合並完成！");
}
}
package TEST3;
import java.io.File;
public class pew1 {
public void main(String[] args) throws Exception {
//分割文件
pew.splitFileDemo(new File("TEST"), 2);
//合並文件
pew.joinFileDemo(new String[]{"TEST2", "TEST3"});
}
}
實驗結果截圖傳不上去。
文件與流課後作業