Java 文件输入作为命令行参数
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Java file input as command line argument
提问by
How do you process information in Java that was input from a file. For Example: suppose you have a file input.txt. The contents of this file is: abcdefghizzzzjklmnop azzbcdefghijklmnop
您如何处理从文件输入的 Java 信息。例如：假设您有一个文件 input.txt。这个文件的内容是：abcdefghizzzzjklmnop azzbcdefghijklmnop
My hope would be that the information would be put into the argument array of strings such that the following code would output "abcdefghizzzzjklmnop"
我希望将信息放入字符串的参数数组中，以便以下代码输出“abcdefghizzzzjklmnop”
class Test {
public static void main(String[] args) {
System.out.println(args[0]);
}
}
The command I have been using throws an array out of bound exception. This command is:
我一直在使用的命令抛出一个数组越界异常。这个命令是：
java Test < input.txt
java测试<input.txt
Non-file based arguments work fine though. ie. java Test hello,a nd java Test < input.txt hello.
非基于文件的参数虽然工作正常。IE。java 测试你好，和 java 测试 < input.txt 你好。
More information: I have tried putting the file contents all on one line to see if \n \r characters may be messing things up. That didn't seem to help.
更多信息：我尝试将文件内容全部放在一行上，以查看 \n \r 字符是否可能会搞砸。那似乎没有帮助。
Also, I can't use the bufferedreader class for this because this is for a program for school, and it has to work with my professors shell script. He went over this during class, but I didn't write it down (or I can't find it).
另外，我不能为此使用 bufferedreader 类，因为这是用于学校的程序，并且它必须与我的教授的 shell 脚本一起使用。他在课堂上翻了一遍，但我没有写下来（或者我找不到）。
Any help?
有什么帮助吗？
回答by John Millikin
You should be able to read the input data from System.in.
您应该能够从 读取输入数据System.in。
Here's some quick-and-dirty example code. javac Test.java; java Test < Test.java:
这是一些快速而肮脏的示例代码。javac Test.java; java Test < Test.java：
class Test
{
public static void main (String[] args)
{
byte[] bytes = new byte[1024];
try
{
while (System.in.available() > 0)
{
int read = System.in.read (bytes, 0, 1024);
System.out.write (bytes, 0, read);
}
} catch (Exception e)
{
e.printStackTrace ();
}
}
}
回答by John Millikin
It seems any time you post a formal question about your problem, you figure it out.
似乎每当您发布有关您的问题的正式问题时，您都会弄清楚。
Inputing a file via "< input.txt" inputs it as user input rather than as a command line argument. I realized this shortly after I explained why the bufferedreader class wouldn't work.
通过“< input.txt”输入文件作为用户输入而不是作为命令行参数输入。在我解释了为什么 bufferedreader 类不起作用后不久，我就意识到了这一点。
Turns out you have to use the buffered reader class.
原来你必须使用缓冲阅读器类。
回答by Uri
I'm not sure why you want to pass the contents of a file as command line arguments unless you're doing some weird testbed.
我不确定为什么要将文件的内容作为命令行参数传递，除非您正在做一些奇怪的测试台。
You could write a script that would read your file, generate a temporary script in which the java command is followed by your needs.
您可以编写一个脚本来读取您的文件，生成一个临时脚本，其中 java 命令后跟您的需求。
