java 文件按行读写

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class Demo001 {

    public static void writeFile(String strSrc, String dest) {
        FileWriter writer = null;
        FileReader reader = null;
        BufferedReader br = null;
        BufferedWriter bw = null;

        try {
            File file = new File(dest);
            if (!file.exists()) {
                file.createNewFile();
            }
            
            // 这里的true，是以追加的方式写
            writer = new FileWriter(dest, true);

            reader = new FileReader(strSrc);

            String str = null;

            br = new BufferedReader(reader);

            bw = new BufferedWriter(writer);

            while ((str = br.readLine()) != null) {
                StringBuffer sb = new StringBuffer("");

                sb.append(str + "\n");
                bw.write(sb.toString());
            }

            br.close();
            reader.close();

            bw.close();
            writer.close();

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        Demo001.writeFile("D:/hw31a.txt", "D:/hw31c.txt");
        Demo001.writeFile("D:/hw31b.txt", "D:/hw31c.txt");
    }
}