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");
     }
 }