图片加密，字符计算

一、图片加密

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("爱情与友情.jpg"); fos = new FileOutputStream("爱情与友情secret.jpg"); byte[] buffer = new byte[20]; int len; while ((len = fis.read(buffer)) != -1) { 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(); } } } } //图片的解密 @Test public void test2() { FileInputStream fis = null; FileOutputStream fos = null; try { fis = new FileInputStream("爱情与友情secret.jpg"); fos = new FileOutputStream("爱情与友情4.jpg"); byte[] buffer = new byte[20]; int len; while ((len = fis.read(buffer)) != -1) { //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(); } } } } }

二、字符计算

package com.atguigu.exer; import org.junit.Test; import java.io.*; import java.util.HashMap; import java.util.Map; import java.util.Set; /** * 练习3:获取文本上字符出现的次数,把数据写入文件 * * 思路： * 1.遍历文本每一个字符 * 2.字符出现的次数存在Map中 * * Map<Character,Integer> map = new HashMap<Character,Integer>(); * map.put('a',18); * map.put('你',2); * * 3.把map中的数据写入文件 */ public class WordCount { /* 说明：如果使用单元测试，文件相对路径为当前module 如果使用main()测试，文件相对路径为当前工程 */ @Test public void testWordCount() { FileReader fr = null; BufferedWriter bw = null; try { //1.创建Map集合 Map<Character, Integer> map = new HashMap<Character, Integer>(); //2.遍历每一个字符,每一个字符出现的次数放到map中 fr = new FileReader("dbcp.txt"); int c = 0; while ((c = fr.read()) != -1) { //int 还原 char char ch = (char) c; // 判断char是否在map中第一次出现 if (map.get(ch) == null) { map.put(ch, 1); } else { map.put(ch, map.get(ch) + 1); } } //3.把map中数据存在文件count.txt //3.1 创建Writer bw = new BufferedWriter(new FileWriter("wordcount.txt")); //3.2 遍历map,再写入数据 Set<Map.Entry<Character, Integer>> entrySet = map.entrySet(); for (Map.Entry<Character, Integer> entry : entrySet) { switch (entry.getKey()) { case ' ': bw.write("空格=" + entry.getValue()); break; case '\t'://\t表示tab 键字符 bw.write("tab键=" + entry.getValue()); break; case '\r':// bw.write("回车=" + entry.getValue()); break; case '\n':// bw.write("换行=" + entry.getValue()); break; default: bw.write(entry.getKey() + "=" + entry.getValue()); break; } bw.newLine(); } } catch (IOException e) { e.printStackTrace(); } finally { //4.关流 if (fr != null) { try { fr.close(); } catch (IOException e) { e.printStackTrace(); } } if (bw != null) { try { bw.close(); } catch (IOException e) { e.printStackTrace(); } } } } }