文件加密解密（字节流）

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package cn.lruihao.base; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; public class EncryptFile { public static void main(String[] args) throws IOException { byte pwd=123;//加密/解密密码 FileInputStream f=new FileInputStream("src/cn/lruihao/base/EncryptFile.java");//待加密文件 FileOutputStream fout=new FileOutputStream("encrypted.txt");//已加密文件 System.out.println("开始加密。"); int n=f.available()/5; byte[] b=new byte[n];//以一个字节数组的长度读取和复制 int count=0; while((count=f.read(b,0,n))!=-1) { //写入之前先加密/解密 for(int i=0;i<count;i++) { b[i]=(byte)(b[i]^pwd);// } fout.write(b,0,count); } System.out.println("完成加密"); f.close(); fout.close(); // f=new FileInputStream("encrypted.txt"); // fout=new FileOutputStream("unencrypted.txt"); // System.out.println("开始解密。"); // n=f.available()/5; // b=new byte[n];//以一个字节数组的长度读取和复制 // count=0; // while((count=f.read(b,0,n))!=-1) { // //写入之前先加密/解密 // for(int i=0;i<count;i++) { // b[i]=(byte)(b[i]^pwd); // } // fout.write(b,0,count); // } // System.out.println("完成解密"); // f.close(); // fout.close(); } }

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package cn.lruihao.base; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; public class FileStreamCopy { public static void main(String[] args) throws IOException { int size; FileInputStream f=new FileInputStream("src/cn/lruihao/base/FileStreamCopy.java"); FileOutputStream fout=new FileOutputStream("copy-of-file.txt"); System.out.println("总长度："+(size=f.available())); int n=size/10; System.out.print("使用单字节方法读取后："); for(int i=0;i<n;i++) { fout.write(f.read()); } System.out.println("剩余长度："+f.available()); System.out.println("读取一个字节数组后："); byte b[]=new byte[n]; f.read(b); fout.write(b); System.out.println("剩余长度："+f.available()); System.out.println("读取余下数据："); int count=0; while((count=f.read(b,0,n))!=-1) { //System.out.println(count); fout.write(b,0,count); } System.out.println("剩余长度："+f.available()); f.close(); fout.flush(); fout.close(); } }

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package cn.lruihao.base; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; public class BufferedStreamCopy { public static void main(String[] args) throws IOException { FileInputStream f=new FileInputStream("src/cn/lruihao/base/BufferedStreamCopy.java"); FileOutputStream fout=new FileOutputStream("copy-of-file.txt"); BufferedInputStream bis=new BufferedInputStream(f); BufferedOutputStream bos=new BufferedOutputStream(fout); System.out.println("开始复制。"); int n=f.available()/5; byte[] b=new byte[n]; int count=0; while((count=bis.read(b,0,n))!=-1) { bos.write(b,0,count); } System.out.println("复制完成"); bis.close(); bos.flush(); bos.close(); f.close(); fout.flush(); fout.close(); } }