IO之工具类

工具类

    package com.yishan.io2;

    import java.io.*;

    /**
    * 1.封装拷贝
    * 2.封装释放资源
    * @author : yishan
    * @date : 2020-09-06 15:35
    */
    public class FileUtils {

        public static void main(String[] args) {
            //文件到文件
            try {
                InputStream is = new FileInputStream("yishan.txt");
                OutputStream os = new FileOutputStream("yishan-c.txt");
                copy(is,os);
            } catch (IOException e) {
                e.printStackTrace();
            }

            //文件到字节数组
            byte[] datas = null;
            try {
                InputStream is = new FileInputStream("111copy.png");
                ByteArrayOutputStream os = new ByteArrayOutputStream();
                copy(is,os);
                datas = os.toByteArray();
                System.out.println(datas.length);
            } catch (IOException e) {
                e.printStackTrace();
            }

            //字节数组到文件
            try {
                InputStream is = new ByteArrayInputStream(datas);
                OutputStream os = new FileOutputStream("111copy-c.png");
                copy(is,os);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        /**
        * 对接输入输出流
        * @param is
        * @param os
        */
        public static void copy(InputStream is,OutputStream os){
            try {
                //3.操作（写出）
                byte[] flush = new byte[3];//缓冲容器
                int len = -1;
                while ((len=is.read(flush))!=-1){
                    os.write(flush,0,len);
                }
                os.flush();
            }catch (FileNotFoundException e){
                e.printStackTrace();
            }catch (IOException e){
                e.printStackTrace();
            }finally {
                //4.释放资源 先打开的后关闭
                close(is,os);
            }

        }

        /**
        * 释放资源
        * @param is
        * @param os
        */
        public static void close(InputStream is,OutputStream os){
            try {
                if (null!=os){
                    os.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }

            try {
                if (null != is){
                    is.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        /**
        * 释放资源
        * @param ios
        */
        public static void close(Closeable...ios){
            for (Closeable io:ios){
                try {
                    if (null != io){
                        io.close();
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

try…with…resource 释放资源

    public static void copy2(String srcPath,String destPath){
            //1.创建源
            File src = new File(srcPath);//源头
            File dest = new File(destPath);//目的地
            //2.选择流
            try(InputStream is = new FileInputStream(src);
                OutputStream os = new FileOutputStream(dest);) {
                //3.操作（写出）
                byte[] flush = new byte[3];//缓冲容器
                int len = -1;
                while ((len=is.read(flush))!=-1){
                    os.write(flush,0,len);
                }
                os.flush();
            }catch (FileNotFoundException e){
                e.printStackTrace();
            }catch (IOException e){
                e.printStackTrace();
            }
        }

赏

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