io 缓冲读写与非缓冲 读写性能对比
package com.cn.ld.exercises.file;
?
import java.io.BufferedInputStream;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
?
public class FileRWPerformance {
private static void writeFileToDiskFW() throws IOException {
Long l1 = System.currentTimeMillis() ;
String str = "aaaaaaaaaa" ;
? ?FileWriter ?fw = new FileWriter(new File("d:"+File.pathSeparator+"buferOper.txt"));
? ?for(int i = 300000 ; i>0 ; i--){
? ?fw.write(str);
? ?}
? ?Long l2 = System.currentTimeMillis() ;
? ?
? ?System.out.println(Thread.currentThread().getStackTrace()[2].getMethodName()+" total time:"+(l2-l1));
}
private static void writeFileToDiskFWandBuf() throws IOException {
Long l1 = System.currentTimeMillis() ;
String str = "aaaaaaaaaa" ;
? ?FileWriter ?fw = new FileWriter(new File("d:"+File.pathSeparator+"buferOper.txt"));
? ?BufferedWriter ?bw = ?new BufferedWriter(fw);
? ?for(int i = 300000 ; i>0 ; i--){
? ?bw.write(str);
? ?}
? ?Long l2 = System.currentTimeMillis() ;
? ?System.out.println(Thread.currentThread().getStackTrace()[2].getMethodName()+"total time:"+(l2-l1));
}
?
private static void ReadFileFromDisk() throws IOException {
Long l1 = System.currentTimeMillis() ;
File ?f = new File("d:"+File.pathSeparator+"buferOper.txt");
byte [] b = new byte[1024];
InputStream is ?= null ;
int length = 0 ;
try {
is = new FileInputStream(f);
while( (length = is.read(b)) != -1){
;//System.out.println(b.toString());
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}finally{
is.close();
}
Long l2 = System.currentTimeMillis() ;
System.out.println("ReadFileFromDisk total time:"+(l2-l1));
}
private static void ReadFileFromMemory() throws IOException {
Long l1 = System.currentTimeMillis() ;
File ?f = new File("d:"+File.pathSeparator+"buferOper.txt");
byte [] b = new byte[1024];
BufferedInputStream bs ?= null ;
int length = 0 ;
try {
bs = new BufferedInputStream(new FileInputStream(f));
while( (length = bs.read(b)) != -1){
;//System.out.println(b.toString());
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}finally{
bs.close();
}
Long l2 = System.currentTimeMillis() ;
System.out.println(Thread.currentThread().getStackTrace()[2].getMethodName()+"total time:"+(l2-l1));
}
public static void main(String[] args) {
try {
for(int i = 100; i>0 ; i--){
FileRWPerformance.writeFileToDiskFW();
? ? ? ? ? ?FileRWPerformance.writeFileToDiskFWandBuf();
? ? ? ? ? ?
? ? ? ? ? ?FileRWPerformance.ReadFileFromDisk();
? ? ? ? ? ?
? ? ? ? ? ?FileRWPerformance.ReadFileFromMemory() ;
? ? ? ? ? ?
? ? ? ? ? ?System.out.println("----------------"+i+"------------------");
}?
} catch (IOException e) {
e.printStackTrace();
}
}
}
