写大文件

1）使用BufferedWriter写文件。一亿条记录

package nioTest;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Random;

public class nio {
    public static void writeBigFile() throws IOException{
        
        @SuppressWarnings("resource")
        BufferedWriter bufferedWriter=new BufferedWriter(new 
                FileWriter("test"));
        //int i=0;
        long start=System.currentTimeMillis();
        System.out.println("start:");
        for ( int i=0;i<1e8;++i) {
            Random r1=new Random();
            //Random r2=new Random();
            bufferedWriter.write(r1.nextInt(100)+"	"+r1.nextInt(50)+"
");
        }
        bufferedWriter.close();
        long end=System.currentTimeMillis();
        
        System.out.println("second cost:"+(end-start)/1000);
        
    }
    
    public static void  main(String[] args) throws IOException {
        writeBigFile();        
    }
    

}

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：

package nioTest;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Random;

public class nio {
    public static void writeBigFile() throws IOException{
        
        @SuppressWarnings("resource")
        //BufferedWriter bufferedWriter=new BufferedWriter(new 
            //    FileWriter("test"));
        //int i=0;
        FileWriter fileWriter=new FileWriter("test2");
        long start=System.currentTimeMillis();
        System.out.println("start:");
        for ( int i=0;i<1e8;++i) {
            Random r1=new Random();
            //Random r2=new Random();
            //bufferedWriter.write(r1.nextInt(100)+"	"+r1.nextInt(50)+"
");
            fileWriter.write(r1.nextInt(100)+"	"+r1.nextInt(50)+"
");
        }
        //bufferedWriter.close();
        fileWriter.close();
        long end=System.currentTimeMillis();
        
        System.out.println("second cost:"+(end-start)/1000);
        
    }
    
    public static void  main(String[] args) throws IOException {
        writeBigFile();        
    }
    

}

所用时间为33秒，较BufferedWriter慢，BufferedWriter更适合大数据量的写入。