java：24G文件写入所要时间23.9分，读取只有67秒（1G内存测试）
转载：http://www.cnblogs.com/qiaolevip/archive/2010/05/17/1737219.html(该博客有多篇关于大数据读取，合并，拆分的有效方法)
另附上readline ready的原理：http://blog.csdn.net/neusoftware_20063500/article/details/3723176
已测，确实很快
1 package arrays.file;
2
3 import java.io.BufferedReader;
4 import java.io.BufferedWriter;
5 import java.io.FileReader;
6 import java.io.FileWriter;
7 import java.io.IOException;
8
9 public class WriteFile {
10 public static void main(String[] args) {
11 String path = "d:/data.txt";
12 writerFile(path);
13 readerFile(path);
14 }
15
16 // 写入文件
17 public static void writerFile(String path) {
18 try {
19 BufferedWriter bw = new BufferedWriter(new FileWriter(path));
20
21 // int max = Integer.MAX_VALUE;
22 int max = 1000;
23 System.out.println("总写入文件行数：" + max);
24 long start = System.currentTimeMillis();
25
26 for (int i = 0; i < max; i++) {
27 bw.write((int) (Math.random() * max) + "");
28 bw.newLine();
29 }
30
31 bw.close();
32
33 long end = System.currentTimeMillis();
34 System.out.println("写入耗时：" + (end - start) + "ms = "
35 + ((double) (end - start) / 1000) + "s");
36 } catch (IOException e) {
37 e.printStackTrace();
38 }
39 }
40
41 // 读取文件
42 public static void readerFile(String path) {
43 try {
44 BufferedReader br = new BufferedReader(new FileReader(path));
45
46 long start = System.currentTimeMillis();
47
48 while (br.ready()) {
49 br.readLine();
50 }
51
52 br.close();
53
54 long end = System.currentTimeMillis();
55 System.out.println("读取耗时：" + (end - start) + "ms = "
56 + ((double) (end - start) / 1000) + "s");
57 } catch (IOException e) {
58 e.printStackTrace();
59 }
60 }
61
62 }
