方法用Java语言从文件中读取

问题描述

我将提升一个老算法，用java语言，我希望它读取文件中的文本进行加密，所以我会让从文件中逐行读取文本行，然后将它们存储在阵列的方法。我做了这个方法，它的工作原理，但变量2号线正确地读取第一线，但一旦下一行来到它将抹去的第一行，并把第二行我能够这么做讨好??

//将codeS

 专用字节[] 2号线;公众的byte [] readFromFile（）{
    尝试（BR的BufferedReader =新的BufferedReader（新的FileReader（C：\\\\ \\\\用户\\\\只是桌面\\\\ message.txt）））
    {        串sCurrentLine;        而（（sCurrentLine = br.readLine（））！= NULL）{
            2号线= sCurrentLine.getBytes（）;
        }    }赶上（IOException异常五）{
        e.printStackTrace（）;
    }
    返回2号线;
}
 

解决方案

Reading as text is a surefire way of getting corrupted data. Read as bytes. More on this below.

With Java 7, it is as simple as:

final Path file = Paths.get("C:\\Users\\just\\Desktop\\message.txt");
final byte[] content = Files.readAllBytes(file);

---

Why corruption?

• first of all, a BufferedReader's .readLine() strips newlines; the content you will encrypt will therefore not be the same;
• second, you don't specify an encoding with which to read the file, and you don't specify an encoding to encode to bytes; and the JVM can choose to use a different default encoding and file encoding. Imagine what would happen if you read the file in windows-1252 and decoded them using UTF-8.

More generally:

• when you "read a string" from a file, what is read is not characters; those are bytes. And a CharsetDecoder will then decode this sequence of bytes into a sequence of chars (possibly with information loss);
• when you "write a string" to a file, what is written is not characters; again, those are bytes. And a CharsetEncoder will encode this sequence of chars into a sequence of bytes.

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