八、IO工具类（封装Copy）

package com.io;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * try ...with...resource
 *
 *
 */
public class TestIO008 {
    public static void main(String[] args) {
        //文件到文件
        try {
            InputStream is = new FileInputStream("abc.txt");
            OutputStream os = new FileOutputStream("b.txt");
            copy(is,os);
        } catch (IOException e) {
            e.printStackTrace();
        }

        //文件到字节数组
        byte[] datas = null;
        try {
            InputStream is = new FileInputStream("漂亮.jpg");
            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("p-copy.png");
            copy(is,os);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    /**
     * 对接输入输出流
     * try ...with...resource
     * @param is
     * @param os
     */
    public static void copy(InputStream is,OutputStream os) {
        try(InputStream iso=is;OutputStream oso=os) {
            //3、操作 (分段读取)
            byte[] flush = new byte[1024]; //缓冲容器
            int len = -1; //接收长度
            while((len=is.read(flush))!=-1) {
                os.write(flush,0,len); //分段写出
            }
            os.flush();
        }catch(FileNotFoundException e) {
            e.printStackTrace();
        }catch (IOException e) {
            e.printStackTrace();
        }
    }
}