java(IO流对象)四种文件复制方式的效率比较

客官°小女子只卖身不卖艺 2022-01-26 22:57 207阅读 0赞

## 四种文件复制方式的效率比较 ##

*  文件复制方式，字节流，一共4个方式，源文件的大小是：40.8 MB (42,885,472 字节)
 *  1.字节流读写单个字节 运行时间：210546ms
 *  2.字节流读写字节数组 运行时间：438ms
 *  3.字节流缓冲区读写单个字节 运行时间：2304ms
 *  4.字节流缓冲区读写字节数组 运行时间：137ms

public static void main(String[] args) {
            long start=System.currentTimeMillis();
            File src = new File("E:\\software\\kugou8322.exe");
            File desc = new File("d:\\oracle code\\longzhoufeng\\kugou.exe");
            copy_1(src, desc);
            long end=System.currentTimeMillis();
            System.out.println(end-start);
        }

方法4：实现文件复制

/**
         * 方法4：实现文件复制
         * 1.字节流缓冲区读写字节数组
         * 运行时间：137ms
         */
        public static void copy_4(File src, File desc) {
            try {
                BufferedInputStream bufis = new BufferedInputStream(new FileInputStream(src));
                BufferedOutputStream bufos = new BufferedOutputStream(new FileOutputStream(desc));
                int len = 0;
                byte[] bt=new byte[1024];
                while ((len = bufis.read(bt)) != -1) {
                    bufos.write(bt,0,len);
                }
                bufis.close();
                bufos.close();
            } catch (IOException ex) {
                System.out.println(ex);
                throw new RuntimeException("文件写入失败");
            }
        }

方法3：实现文件复制

/**
         * 方法3：实现文件复制
         * 1.字节流缓冲区读写单个字节
         * 运行时间：2304ms
         */
        public static void copy_3(File src, File desc) {
            try {
                BufferedInputStream bufis = new BufferedInputStream(new FileInputStream(src));
                BufferedOutputStream bufos = new BufferedOutputStream(new FileOutputStream(desc));
                int len = 0;
                while ((len = bufis.read()) != -1) {
                    bufos.write(len);
                }
                bufis.close();
                bufos.close();
            } catch (IOException ex) {
                System.out.println(ex);
                throw new RuntimeException("文件写入失败");
            }
        }

方法2：实现文件复制

/**
         * 方法2：实现文件复制
         * 1.字节流读写字节数组
         * 运行时间：438ms
         */
        public static void copy_2(File src, File desc) {
            try {
                FileInputStream fis = new FileInputStream(src);
                FileOutputStream fos = new FileOutputStream(desc);
                int len = 0;
                byte[] bt = new byte[1024];
                while ((len = fis.read(bt)) != -1) {
                    fos.write(bt,0,len);
                }
                fis.close();
                fos.close();
            } catch (IOException ex) {
                System.out.println(ex);
                throw new RuntimeException("文件写入失败");
            }
        }

方法1：实现文件复制

/**
         * 方法1：实现文件复制
         * 1.字节流读写单个字节
         * 运行时间：210546ms
         */
        public static void copy_1(File src, File desc) {
            try {
                FileInputStream fis = new FileInputStream(src);
                FileOutputStream fos = new FileOutputStream(desc);
                int len = 0;
                while ((len = fis.read()) != -1) {
                    fos.write(len);
                }
                fis.close();
                fos.close();
            } catch (IOException ex) {
                System.out.println(ex);
                throw new RuntimeException("文件写入失败");
            }
        }