Prepare Initial Program Structure准备初始程序结构

Here's the basic structure of the GenSig program. Place it in a file called GenSig.java.这是GenSig程序的基本结构。将其放入名为GenSig.java的文件中。

import java.io.*;
import java.security.*;

class GenSig {

    public static void main(String[] args) {

        /* Generate a DSA signature */

        if (args.length != 1) {
            System.out.println("Usage: GenSig nameOfFileToSign");
        }
        else try {

        // the rest of the code goes here

        } catch (Exception e) {
            System.err.println("Caught exception " + e.toString());
        }
    }
}

Notes:笔记：

• The methods for signing data are in the java.security package, so the program imports everything from that package. The program also imports the java.io package, which contains the methods needed to input the file data to be signed.签名数据的方法在java.security包中，因此程序从该包导入所有内容。该程序还导入javaio包，其中包含输入要签名的文件数据所需的方法。

• A single argument is expected, specifying the data file to be signed.需要一个参数，指定要签名的数据文件。

• The code written in subsequent steps will go between the try and the catch blocks.在后续步骤中编写的代码将在try和catch块之间。