练习 2017-8-14 使用缓存字节流 和 字节流 拷贝性能对比。

package buffered;


import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;


//各种拷贝方式时间比较
public class CopyTimeCompareDemo {
public static void main(String[] args) throws Exception {
File SrcFile = new File("process/srcFile.avi");
File destFile = new File("process_copy/destFile.avi");

//test1(SrcFile,destFile);
//test2(SrcFile,destFile);
//test3(SrcFile,destFile);
test4(SrcFile,destFile);


}


//使用缓冲字节流，每次拷贝1024个字节 时间：12ms
private static void test4(File srcFile, File destFile) throws Exception {
long time = System.currentTimeMillis();


BufferedInputStream in = new BufferedInputStream(new FileInputStream(srcFile));
BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(destFile));
byte[] buffer = new byte[1024];
int len = -1;
while((len =in.read(buffer)) != -1){
out.write(buffer,0,len);
}
in.close();
out.close();
System.out.println(System.currentTimeMillis() - time);
}


//使用缓冲字节流，每次拷贝1个字节 时间：116ms
private static void test3(File srcFile, File destFile) throws Exception {
long time = System.currentTimeMillis();


BufferedInputStream in = new BufferedInputStream(new FileInputStream(srcFile));
BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(destFile));
int len = -1;
while((len =in.read()) != -1){
out.write(len);
}
in.close();
out.close();
System.out.println(System.currentTimeMillis() - time);
}


//使用字节流，每次拷贝1024个字节 时间：41ms
private static void test2(File srcFile, File destFile) throws Exception {
long time = System.currentTimeMillis();
InputStream in = new FileInputStream(srcFile);
OutputStream out = new FileOutputStream(destFile);
byte[] buffer = new byte[1024];
int len = -1;
while((len =in.read(buffer)) != -1){
out.write(buffer,0,len);
}
in.close();
out.close();
System.out.println(System.currentTimeMillis() - time);
}


//使用字节流，每次拷贝一个字节 时间：25368ms
private static void test1(File srcFile, File destFile) throws Exception {
long time = System.currentTimeMillis();
InputStream in = new FileInputStream(srcFile);
OutputStream out = new FileOutputStream(destFile);
int len = -1;
while((len =in.read()) != -1){
out.write(len);
}
in.close();
out.close();
System.out.println(System.currentTimeMillis() - time);
}
}