jgrep16.java

java编程思想第四版习题答案

// strings/JGrep16.java
// TIJ4 Chapter Strings, Exercise 16, page 546
/* Modify JGrep.java to accept a directory name or a file name as argument
* (if a directory is provided, search should include all files in the
* directory). Hint: You can generated a list of file names with:
*	File[] files = new File(".").listFiles();
*/
// {Args: = name(of dir or file) "\b[Ssct]\w+"}
import java.util.regex.*;
import net.mindview.util.*;
import java.io.*;
import java.util.*;

public class JGrep16  {
	public static void main(String[] args) throws Exception {
		if(args.length < 2) {
			System.out.println("Usage: java JGrep (file or directory) regex");
			System.exit(0);
		}
		Pattern p = Pattern.compile(args[1]);
		Matcher d = Pattern.compile("\\w+\\.{1}\\w+").matcher(args[0]);
		if(d.find()) {
			System.out.println("File: " + args[0]);
			// Iterate through the lines of the input file:
			int index = 0;
			Matcher m = p.matcher(""); // creates emtpy Matcher object
			for(String line : new TextFile(args[0])) {
				m.reset(line);
				while(m.find())
					System.out.println(index++ + ": " +
						m.group() + ": " + m.start());
			}
		}
		Matcher e = Pattern.compile("^\\.{1}$").matcher(args[0]);
		if(e.find()) {
			File[] files = new File(args[0]).listFiles();
			System.out.println("root dir of files: " + Arrays.asList(files));
			// Iterate through the lines of each file in directory:
			for(File f : files) {
				if(f.getName().matches("\\w+\\.{1}\\w+")) {
					System.out.println(f.getName() + ":");
					int index = 0;
					Matcher m = p.matcher(""); // creates emtpy Matcher object
					for(String line : new TextFile(f.getName())) {
						m.reset(line);
						while(m.find())
							System.out.println(index++ + ": " +
								m.group() + ": " + m.start());
					}
				}
				System.out.println();
			}
		}
		d.reset();
		e.reset();
		if(!(d.find() || e.find())) {
			if(new File(args[0]).listFiles() == null) {
				System.out.println("no such directory: " + args[0]);
				System.exit(0);
			}
			File[] files = new File(args[0]).listFiles();
			System.out.println(args[0] + ": subdir of files: " + Arrays.asList(files));
			// Iterate through the lines of each file in directory:
			for(File f : files) {
				int index = 0;
				Matcher m = p.matcher(""); // creates emtpy Matcher object
				for(String line : new TextFile(args[0] + "\\" + f.getName())) {
					m.reset(line);
					while(m.find())
						System.out.println(index++ + ": " +
							m.group() + ": " + m.start());
				}
				System.out.println();
			}
		}
	}
}