为这段代码增加详细注释import java.io.*; public class FileMerge { public static void main(String[] args) { if (args.length != 3) { System.out.println("Usage: java FileMerge source1 source2 target"); return; } String sourceFile1 = args[0]; String sourceFile2 = args[1]; String targetFile = args[2]; try (BufferedInputStream in1 = new BufferedInputStream(new FileInputStream(sourceFile1)); BufferedInputStream in2 = new BufferedInputStream(new FileInputStream(sourceFile2)); BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(targetFile))) { byte[] buffer = new byte[1024]; int bytesRead; while ((bytesRead = in1.read(buffer)) != -1) { out.write(buffer, 0, bytesRead); } while ((bytesRead = in2.read(buffer)) != -1) { out.write(buffer, 0, bytesRead); } System.out.println("File merge completed."); } catch (FileNotFoundException e) { System.err.println("File not found: " + e.getMessage()); } catch (IOException e) { System.err.println("IOException: " + e.getMessage()); } } }

好的，以下是对该代码进行详细注释的版本：

import java.io.*;

public class FileMerge {
    public static void main(String[] args) {
        // 判断命令行参数是否为3个，如果不是则输出用法并返回
        if (args.length != 3) {
            System.out.println("Usage: java FileMerge source1 source2 target");
            return;
        }

        // 读取命令行参数中的源文件1、源文件2和目标文件名
        String sourceFile1 = args[0];
        String sourceFile2 = args[1];
        String targetFile = args[2];

        try (
            // 创建输入流1，使用缓冲区读取文件内容
            BufferedInputStream in1 = new BufferedInputStream(new FileInputStream(sourceFile1));
            // 创建输入流2，使用缓冲区读取文件内容
            BufferedInputStream in2 = new BufferedInputStream(new FileInputStream(sourceFile2));
            // 创建输出流，使用缓冲区写入文件内容
            BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(targetFile))
        ) {
            byte[] buffer = new byte[1024]; // 缓冲区大小为1024字节
            int bytesRead; // 每次读取的字节数
            // 从输入流1读取数据，写入输出流
            while ((bytesRead = in1.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead); // 将读取到的字节数组写入输出流中
            }
            // 从输入流2读取数据，写入输出流
            while ((bytesRead = in2.read(buffer)) != -1) {
                out.write(buffer, 0, bytesRead); // 将读取到的字节数组写入输出流中
            }

            System.out.println("File merge completed.");
        } catch (FileNotFoundException e) { // 捕获文件未找到异常
            System.err.println("File not found: " + e.getMessage());
        } catch (IOException e) { // 捕获IO异常
            System.err.println("IOException: " + e.getMessage());
        }
    }
}

注释中添加了对每个方法和变量的详细说明，以及对异常的捕获和处理进行了注释。