Java学习(尚硅谷)IO流学习之图片的加密和解密

package com.atguigu.exer;

import org.junit.Test;

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


public class PicTest {
    //图片的加密

    @Test
    public void test1() {
        FileInputStream fis = null;
        FileOutputStream fos = null;
        try {
            fis = new FileInputStream("CSDN封面图.jpg");
            fos = new FileOutputStream("CSDN封面图3.jpg");
            byte[] buffer = new byte[20];
            int len;
            while ((len = fis.read(buffer)) != -1) {
    //            //错误，只是修改了赋给的b，并未修改buffer内的内容
    //            for (byte b : buffer) {
    //                b = (byte) (b ^ 5);
    //            }

                //正确的
                for (int i = 0; i < len; i++) {
                    buffer[i] = (byte) (buffer[i] ^ 5);
                }


                fos.write(buffer, 0, len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (fos!=null){

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

                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }



    //图片解密

    @Test
    public void test2() {
        FileInputStream fis = null;
        FileOutputStream fos = null;
        try {
            fis = new FileInputStream("CSDN封面图3.jpg");
            fos = new FileOutputStream("CSDN封面图4.jpg");
            byte[] buffer = new byte[20];
            int len;
            while ((len = fis.read(buffer)) != -1) {
                //            //错误，只是修改了赋给的b，并未修改buffer内的内容
                //            for (byte b : buffer) {
                //                b = (byte) (b ^ 5);
                //            }

                //正确的
                for (int i = 0; i < len; i++) {
                    buffer[i] = (byte) (buffer[i] ^ 5);
                }


                fos.write(buffer, 0, len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (fos!=null){

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

                try {
                    fis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }
}