基本上我需要从用户指定的文件中读取文本，然后通过将其转换为ASCII值来加密它。 （我知道它的弱加密就是这个任务）。加密工作正常，用户想要创建的用于存储加密值的文件正在运行，但我不知道为什么它不读取文件中的文本并加密它。因此，存储加密文本的文件为空。
我认为代码中的问题介于两者之间 FileWriter writer = null;
和
e.printStackTrace（）; }
代码中的......但我不知道它在哪里。当它工作时，它应该读取文件的内容，＆＃34; fileUse＆＃34;，将内容存储为字符串，然后使用关键字加密它。然后应该将加密的值存储在新创建的文件中，用户指定了哪个是fileWriteto
import java.util.*;
import java.io.*;
import java.io.FileReader;
import java.io.File;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileWriter;
public class finalfinal4
{
public static void main(String [] args) {// Method Created to handle exceptions when entering encrypt, decrypt, bye etc
System.out.println(""); // Nice Formatting
System.out.println("This is a programme that replicates the mechanics of keyword based encryption/decryption machine and encrypts or decrypts a message accordingly"); // Message Informing User what This Programme Does
System.out.println("");
start(); // Allows the Whole Process to Move on by going to the next and final method
}
public static void start() {
Scanner input = new Scanner (System.in); // takes in User Input
System.out.println();
System.out.println("Please type in 'encrypt' if you want to encrypt a message"); // Tells the user what to do
System.out.println();
System.out.println("'decrypt' if you want to 'decrypt' a message");
System.out.println();
System.out.println("'bye' if you want to exit the programme");
System.out.println();
String firstchoice = input.nextLine().toLowerCase(); // turns all of what the user entered into lower case
System.out.println();
//int line = ' ';
switch(firstchoice) // case statement
{ case "encrypt":
//System.out.println(" Please enter the string you wish to encrypt"); // what it does if case encrypt is activate
break;
case "decrypt":
//System.out.println("Please enter the string you wish to decrypt");
break;
case "bye":
System.out.println(" Thank you for using this programme ");
System.exit(0);
default: // the default set of actions that will occur if none of the other cases have been met
System.out.println("");
System.out.println("You did not type in the required messages please try again");
System.out.println("");
start();
}
FileWriter writer = null;
String rm ="";
try {
System.out.println("Enter the file you want to use");
String fileUse = input.nextLine();
System.out.println("Enter the file you want to write to");
String fileWriteto = input.nextLine();
System.out.println();
//PrintWriter writer = new PrintWriter(fileWriteTo + ".txt");
File file = new File(fileWriteto + ".txt");
file.createNewFile();
FileReader read = new FileReader(fileUse + ".txt");
BufferedReader bufreader = new BufferedReader(read);
writer = new FileWriter(fileWriteto + ".txt");
/*FileReader freader = new FileReader(fileUse + ".txt");
BufferedReader breader = new BufferedReader(freader);*/
String line;
while ((line = bufreader.readLine()) != null) {
rm = line;
}
//read.close();
//br.close();
}catch (IOException e) {
//found on stack overflow http://stackoverflow.com/questions/19871955/java-io-filenotfoundexception-the-system-cannot-find-the-file-specified
//found whole example on http://www.codejava.net/java-se/file-io/how-to-read-and-write-text-file-in-java
e.printStackTrace();
}
System.out.println("");
System.out.println("Enter the message that you wish to " + firstchoice); // Efficient way of prompting the user
System.out.println("");
boolean keywordcheck = false;
boolean keywordcheck2 = false;// sets a boolean up for use
String keyword = "";
String keyword2 = "";// declares variables outside the for loop so that they can be used outside the for loop
int keySize = keyword.length();
int keySize2 = keyword.length();// creates a variable that is the length of the keyword
while(keywordcheck == false)
{
int kc = 0;
System.out.println(" Please Enter Your Keyword. The Keyword should only contain text"); //prompt
System.out.println();
keyword = input.nextLine(); //scanner to take in the keyword
System.out.println();
for (int numcheck = 0; numcheck < keyword.length(); numcheck++)
{
if (Character.isLetter(keyword.charAt(numcheck))) // the function of the following if loop is to prevent the keyword from being anything other than letters or characters
{
kc = kc + 1; //if the character in the keyword is a letter, add 1
}
else if (Character.isDigit(keyword.charAt(numcheck)))
{
kc = kc + 1; // the sam but for numbers
}
else
{
// if neither a letter or a number, do nothing
}
}
if (kc == keyword.length()) //if all the characters in the keyword were numbers or letter than kc will equal the length of the keyword and the code wil get out of the for loop
{
keywordcheck = true;
}
else
{
System.out.println("You typed in numbers, special characters or entered a space in your keyword Please only enter text without spaces");
System.out.println();
// if the haven't entered only numbers and letters than it will force them to re-enter the keyword
}
}
while(keywordcheck2 == false)
{
int kc2 = 0;
System.out.println(" Please Enter Your Keyword. The Keyword should only contain text"); //prompt
System.out.println();
keyword2 = input.nextLine(); //scanner to take in the keyword
System.out.println();
for (int numcheck2 = 0; numcheck2 < keyword2.length(); numcheck2++)
{
if (Character.isLetter(keyword2.charAt(numcheck2))) // the function of the following if loop is to prevent the keyword from being anything other than letters or characters
{
kc2 = kc2 + 1; //if the character in the keyword is a letter, add 1
}
else if (Character.isDigit(keyword2.charAt(numcheck2)))
{
kc2 = kc2 + 1; // the same but for numbers
}
else
{
// if neither a letter or a number, do nothing
}
}
if (kc2 == keyword2.length()) //if all the characters in the keyword were numbers or letter than kc will equal the length of the keyword and the code wil get out of the for loop
{
keywordcheck2 = true;
}
else
{
System.out.println("You typed in numbers, special characters or entered a space in your keyword Please only enter text without spaces");
System.out.println();
// if the haven't entered only numbers and letters than it will force them to re-enter the keyword
}
}
String out1 = "";
char space = ' ';
//int encryption = 0;
for (int counter5 = 0, j = 0; counter5 < rm.length(); counter5++, j++)
{
keyword = keyword + keyword.charAt(counter5); // loops it over the keyword
}
for (int counter6 = 0, j = 0; counter6 < rm.length(); counter6++, j++)
{
keyword2 = keyword2 + keyword2.charAt(counter6); // loops it over the keyword
}
if (firstchoice.equals("encrypt"))
{
System.out.print("");
System.out.println("Encrypted - ");
}
else
{
System.out.print(" Decrypted - ");
}
int ascimessage = ' ';
int encrypted = ' ';
for (int t = 0, y = 0, z = 0; t < rm.length(); t++, y++, z++) {
ascimessage = rm.charAt(t);
int ascikeyword = keyword.charAt(y);
int ascikeyword2 = keyword2.charAt(z);
if (Character.isUpperCase(ascikeyword)) //char values are interchangeable with ascii values
{
ascikeyword = ascikeyword - 64;
}
else if (Character.isLowerCase(ascikeyword))
{
ascikeyword = ascikeyword - 96;
}
else if(Character.isDigit(ascikeyword))
{
ascikeyword = ascikeyword - 48;
}
else
{
}
if (Character.isUpperCase(ascikeyword2)) //char values are interchangeable with ascii values
{
ascikeyword2 = ascikeyword2 - 64;
}
else if (Character.isLowerCase(ascikeyword2))
{
ascikeyword2 = ascikeyword2 - 96;
}
else if(Character.isDigit(ascikeyword2))
{
ascikeyword2 = ascikeyword2 - 48;
}
else
{
}
//file writer file reader
if (firstchoice.equals("encrypt")){
encrypted = ascimessage + ascikeyword + ascikeyword2;
}
else {encrypted = ascimessage - ascikeyword - ascikeyword2;
}
if (encrypted >= 122)
{
encrypted = encrypted - 90;
}
if (encrypted <= 32)
{
encrypted = encrypted + 90;
}
System.out.print((char)encrypted);
try {
writer.write(encrypted);//for write up wasn';t working so i did
}catch(IOException e){
e.printStackTrace();
}
//out1 = out1 + ((char)encrypted);
}
System.out.println("");
System.out.println("");
start();
}
}