1)使用BufferedWriter写文件。一亿条记录
1 package nioTest; 2 import java.io.BufferedWriter; 3 import java.io.FileWriter; 4 import java.io.IOException; 5 import java.util.Random; 6 7 public class nio { 8 public static void writeBigFile() throws IOException{ 9 10 @SuppressWarnings("resource") 11 BufferedWriter bufferedWriter=new BufferedWriter(new 12 FileWriter("test")); 13 //int i=0; 14 long start=System.currentTimeMillis(); 15 System.out.println("start:"); 16 for ( int i=0;i<1e8;++i) { 17 Random r1=new Random(); 18 //Random r2=new Random(); 19 bufferedWriter.write(r1.nextInt(100)+" "+r1.nextInt(50)+" "); 20 } 21 bufferedWriter.close(); 22 long end=System.currentTimeMillis(); 23 24 System.out.println("second cost:"+(end-start)/1000); 25 26 } 27 28 public static void main(String[] args) throws IOException { 29 writeBigFile(); 30 } 31 32 33 }
r1.next(100)表示生成[0,100)内的随机整数。所用时间:26s。
2)使用FileWrite写1亿条记录:
1 package nioTest; 2 import java.io.BufferedWriter; 3 import java.io.FileWriter; 4 import java.io.IOException; 5 import java.util.Random; 6 7 public class nio { 8 public static void writeBigFile() throws IOException{ 9 10 @SuppressWarnings("resource") 11 //BufferedWriter bufferedWriter=new BufferedWriter(new 12 // FileWriter("test")); 13 //int i=0; 14 FileWriter fileWriter=new FileWriter("test2"); 15 long start=System.currentTimeMillis(); 16 System.out.println("start:"); 17 for ( int i=0;i<1e8;++i) { 18 Random r1=new Random(); 19 //Random r2=new Random(); 20 //bufferedWriter.write(r1.nextInt(100)+" "+r1.nextInt(50)+" "); 21 fileWriter.write(r1.nextInt(100)+" "+r1.nextInt(50)+" "); 22 } 23 //bufferedWriter.close(); 24 fileWriter.close(); 25 long end=System.currentTimeMillis(); 26 27 System.out.println("second cost:"+(end-start)/1000); 28 29 } 30 31 public static void main(String[] args) throws IOException { 32 writeBigFile(); 33 } 34 35 36 }
所用时间为33秒,较BufferedWriter慢,BufferedWriter更适合大数据量的写入。