[英]Convert ArrayList<String> to byte[]
I want to be able to convert an ArrayList<String>
that stores the contents of a file read from a BufferedReader, then convert the contents into a byte[] to allow it to be encrypted using Java's Cipher class. 我希望能够转换一个ArrayList<String>
,该ArrayList<String>
存储从BufferedReader读取的文件的内容,然后将内容转换为byte []以允许使用Java的Cipher类进行加密。
I have tried using .getBytes()
but it's not working since I think I need to convert the ArrayList first, and I'm having trouble on figuring out how to do that. 我尝试使用.getBytes()
但是它不起作用,因为我认为我需要先转换ArrayList,并且在弄清楚如何做到这一点时遇到了麻烦。
Code: 码:
// File variable
private static String file;
// From main()
file = args[2];
private static void sendData(SecretKey desedeKey, DataOutputStream dos) throws Exception {
ArrayList<String> fileString = new ArrayList<String>();
String line;
String userFile = file + ".txt";
BufferedReader in = new BufferedReader(new FileReader(userFile));
while ((line = in.readLine()) != null) {
fileString.add(line.getBytes()); //error here
}
Cipher cipher = Cipher.getInstance("DESede/ECB/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, desedeKey);
byte[] output = cipher.doFinal(fileString.getBytes("UTF-8")); //error here
dos.writeInt(output.length);
dos.write(output);
System.out.println("Encrypted Data: " + Arrays.toString(output));
}
Many thanks, in advance! 提前谢谢了!
Why would you want to read it as string and the convert it to byte array? 为什么要将其读取为字符串并将其转换为字节数组? Since Java 7 you can do: 从Java 7开始,您可以执行以下操作:
byte[] input= Files.readAllBytes(new File(userFile.toPath());
then pass that content to the Cipher. 然后将该内容传递给密码。
byte[] output = cipher.doFinal(input);
Also you might consider using streams (InputStream and CipherOutputStream) instead of loading the whole file into the memory in case you need handle big files. 另外,如果需要处理大文件,则可以考虑使用流(InputStream和CipherOutputStream),而不是将整个文件加载到内存中。
Either concatenate strings, or create a StringBuffer
. 连接字符串,或创建一个StringBuffer
。
StringBuffer buffer = new StringBuffer();
String line;
String userFile = file + ".txt";
BufferedReader in = new BufferedReader(new FileReader(userFile));
while ((line = in.readLine()) != null) {
buffer.append(line); //error here
}
byte[] bytes = buffer.toString().getBytes();
So, the full ArrayList
is in fact a single String
? 因此,完整的ArrayList
实际上是单个String
?
One straightforward approach would be to merge all the Strings
in it into a single one and then call the .getBytes()
on it. 一种简单的方法是将其中的所有Strings
合并为一个,然后在其上调用.getBytes()
。
Why use ArrayList. 为什么要使用ArrayList。 Just use a StringBuffer and keep the complete contents of the file into a single string. 只需使用StringBuffer并将文件的完整内容保存为单个字符串即可。
Merge all the string in a single on Like 将所有字符串合并为Like
String anyName = allstring;
and Then call this 然后叫这个
anyName.getBytes();
it will help you. 它会帮助你。
You could try to take advantage of Java's serialization functionality and use an ObjectOutputStream wrapped around a ByteOutputStream: 您可以尝试利用Java的序列化功能,并使用包裹在ByteOutputStream周围的ObjectOutputStream:
try (ByteArrayOutputStream bout = new ByteArrayOutputStream(); ObjectOutputStream out = new ObjectOutputStream(bout)) {
out.writeObject(list);
out.flush();
byte[] data = bout.toByteArray();
} catch (IOException e) {
// Do something with the exception
}
The downside to this approach is that the contents of the byte array will be tied to the list implementation's serialized form, so reading it back into a List may give weird results in later Java versions. 这种方法的缺点是字节数组的内容将与列表实现的序列化形式绑定在一起,因此在以后的Java版本中将其读回List可能会产生奇怪的结果。
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