通过缓冲区提高读写效率

优化前：执行的io操作过多

package com.yqq.app6;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 * @Author yqq
 * @Date 2021/11/11 21:18
 * @Version 1.0
 */
public class FileStreamDemo {
    public static void main(String[] args) {
        FileInputStream fs = null;
        FileOutputStream fo = null;
        try {
            fs = new FileInputStream("E:/pic/2.png");
            fo =new FileOutputStream("E:/pic/2cop.png");
            int tem = 0;
            while ((tem = fs.read())!=-1){
                fo.write(tem);
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if(fs!=null){
                try {
                    fs.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(fo!=null){
                try {
                    fo.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

优化后：

package com.yqq.app6;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 * @Author yqq
 * @Date 2021/11/11 21:34
 * @Version 1.0
 */
public class FileStreamBuffDemo {
    public static void main(String[] args) {
        FileInputStream fs = null;
        FileOutputStream fo = null;
        try {
            fs = new FileInputStream("E:/pic/2.png");
            fo =new FileOutputStream("E:/pic/2cop.png");
            //创建一个字节缓冲区，提高读写效率
            byte[] buff = new byte[1024];
            int tem = 0;
            while ((tem = fs.read(buff))!=-1){
                fo.write(buff,0,tem);
            }
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            if(fs!=null){
                try {
                    fs.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(fo!=null){
                try {
                    fo.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

通过创建一个指定长度的字节数组作为缓冲区，以此来提高 IO 流的读写效率。该方式 适用于读取较大图片时的缓冲区定义。注意：缓冲区的长度一定是 2 的整数幂。一般情况下 1024 长度较为合适