Thinking in java -- 文件读写实用工具

代码摘自“Thinking in java 18.7章节”

//: net/mindview/util/TextFile.java
// Static functions for reading and writing text files as
// a single string, and treating a file as an ArrayList.
package net.mindview.util;

import java.io.*;
import java.util.*;

public class TextFile extends ArrayList<String> {
    private static String gpfile = "C:\\Users\\zm\\workspace\\Thinking in java\\src\\net\\mindview\\util\\";

    // Read a file as a single string:
    public static String read(String fileName) {
        StringBuilder sb = new StringBuilder();
        try {
            BufferedReader in = new BufferedReader(new FileReader(new File(
                    fileName).getAbsoluteFile()));
            try {
                String s;
                while ((s = in.readLine()) != null) {
                    sb.append(s);
                    sb.append("\n");
                }
            } finally {
                in.close();
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        return sb.toString();
    }

    // Write a single file in one method call:
    public static void write(String fileName, String text) {
        try {
            PrintWriter out = new PrintWriter(new File(fileName)
                    .getAbsoluteFile());
            try {
                out.print(text);
            } finally {
                out.close();
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    // Read a file, split by any regular expression:
    public TextFile(String fileName, String splitter) {
        super(Arrays.asList(read(fileName).split(splitter)));
        // Regular expression split() often leaves an empty
        // String at the first position:
        if (get(0).equals(""))
            remove(0);
    }

    // Normally read by lines:
    public TextFile(String fileName) {
        this(fileName, "\n");
    }

    public void write(String fileName) {
        try {
            PrintWriter out = new PrintWriter(new File(fileName)
                    .getAbsoluteFile());
            try {
                for (String item : this)
                    out.println(item);
            } finally {
                out.close();
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    // Simple test:
    public static void main(String[] args) {
        String file = read(gpfile + "TextFile.java");
        write("d:\\test.txt", file);
        TextFile text = new TextFile("d:\\test.txt");
        text.write("d:\\test2.txt");
        // Break into unique sorted list of words:
        TreeSet<String> words = new TreeSet<String>(new TextFile(gpfile
                + "TextFile.java", "\\W+"));
        // Display the capitalized words:
        System.out.println(words.headSet("a"));
    }
}