练习 2017-08-21 文件加密和解密。 有一个问题 写出去汉字最后一个汉字会乱。

package encodedFile;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.OutputStreamWriter;

public class EncodedFileDemo {
public static void main(String[] args) {
File encodingFile = new File("D:/encodingFile.txt");
File encodedFile = new File("D:/encodedFile.txt");
File decodedFile = new File("D:/decodedFile.txt");

encodeFile(encodingFile,encodedFile);
decodeFile(encodedFile, decodedFile);
}

private static void encodeFile(File encodingFile, File encodedFile) {
char[] buffer = new char[1024];
int len = -1;

try(
InputStreamReader in = new InputStreamReader(new FileInputStream(encodingFile),"UTF-8");

OutputStreamWriter out = new OutputStreamWriter(new FileOutputStream(encodedFile),"UTF-8");
){
while((len = in.read(buffer)) != -1){
for (int i = 0; i < buffer.length; i++) {
if(Character.isLetterOrDigit(buffer[i])){
if(buffer[i] == 'z'){
buffer[i] = 'a';
}else if(buffer[i] == 'Z'){
buffer[i] = 'A';
}else if(buffer[i] == '9'){
buffer[i] = '0';
}else{
buffer[i]++;
}
}
}
System.out.println(new String(buffer,0,len));
out.write(buffer, 0, len);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}
}

public static void decodeFile(File encodedFile, File decodedFile){
char[] buffer = new char[1024];
int len = -1;

try(
InputStreamReader in = new InputStreamReader(new FileInputStream(encodedFile),"UTF-8");

OutputStreamWriter out = new OutputStreamWriter(new FileOutputStream(decodedFile),"UTF-8");
){
while((len = in.read(buffer)) != -1){
for (int i = 0; i < buffer.length; i++) {
if(Character.isLetterOrDigit(buffer[i])){
if(buffer[i] == 'a'){
buffer[i] = 'z';
}else if(buffer[i] == 'A'){
buffer[i] = 'Z';
}else if(buffer[i] == '0'){
buffer[i] = '9';
}else{
buffer[i]--;
}
}
}
System.out.println(new String(buffer,0,len));
out.write(buffer, 0, len);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e1) {
e1.printStackTrace();
}
}

}