写文件 faster and faster

import java.io.BufferedWriter;
import java.io.FileWriter;

public class Test {

	public static void main(String[] args) {
		int max = 100000000;
		long t1 = System.currentTimeMillis();
		test1(max);
		long t2 = System.currentTimeMillis();
		System.out.println("test1耗时："+(t2-t1));
		long t3 = System.currentTimeMillis();
		test2(max);
		long t4 = System.currentTimeMillis();
		System.out.println("test2耗时："+(t4-t3));
		long t5 = System.currentTimeMillis();
		test3(max);
		long t6 = System.currentTimeMillis();
		System.out.println("test3耗时："+(t6-t5));
		
		//两次测试结果
		//已知 max=100000000
		 
		//test1耗时：46593/52906
		//test2耗时：28563/28250
		//test3耗时：21859/22594
	}
	
	public static void test1(int max){
		BufferedWriter bw = null;
		String fileName = "d:/1.txt";
		try{
			bw = new BufferedWriter(new FileWriter(fileName, true));
			for(int i=0;i<max;i++){
				bw.write(i+"\r\n");
			}
			bw.flush();
			bw.close();
		}catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	public static void test2(int max){
		BufferedWriter bw = null;
		String fileName = "d:/2.txt";
		try{
			bw = new BufferedWriter(new FileWriter(fileName, true));
			for(int i=0;i<max;i++){
				bw.write(String.valueOf(i));
				bw.write("\r\n");//快于bw.newLine()
			}
			bw.flush();
			bw.close();
		}catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	public static void test3(int max){
		BufferedWriter bw = null;
		String fileName = "d:/3.txt";
		try{
			StringBuffer sb = new StringBuffer();
			bw = new BufferedWriter(new FileWriter(fileName, true));
			for(int i=0;i<max;i++){
				sb.append(i);
				sb.append("\r\n");
				//10000写入一次
				if(i%10000==0){
					bw.write(sb.toString());
					sb.delete(0, sb.length());
				}
			}
			bw.write(sb.toString());
			bw.flush();
			bw.close();
		}catch (Exception e) {
			e.printStackTrace();
		}
	}
}

备注：test1采用字符串连接的写入方式，一次写入一行，耗时最长；test2采用分别写入方式，耗时近1半；test3采用批量写入耗时不足一半。由此可知，test3的写入效率最高。

//两次测试结果
//已知 max=100000000
 
//test1耗时：46593/52906
//test2耗时：28563/28250
//test3耗时：21859/22594