java-文件解码

package back;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;


public class Back {
    public static void main(String[] args) throws Exception {
        //复原格式
        FileInputStream inputStream = new FileInputStream("C:\\Users\\Administrator\\Desktop\\PathTest.txt");
        InputStreamReader input = new InputStreamReader(inputStream);
        BufferedReader buffer = new BufferedReader(input);
        String line = "";
        String str1 = "";
        String str2 = "";
        Map<Byte, String> route = new HashMap<Byte, String>();
        while ((line = buffer.readLine()) != null){
            if (line.indexOf("路径信息")>-1 ){
                str1 = line.substring(line.indexOf("[byte=")+6,line.indexOf("];"));

                str2 = line.substring(line.indexOf("[path=")+6,line.indexOf(")"));
            }
            route.put(Byte.parseByte(str1),str2);
        }


        //拆分密文
        FileInputStream inputStream2 = new FileInputStream("C:\\Users\\Administrator\\Desktop\\CodeTest2.txt");
        InputStreamReader input2 = new InputStreamReader(inputStream2);
        BufferedReader buffer2 = new BufferedReader(input2);
        String line2 = buffer2.readLine();
        int lenth = str2.length();
        int it = line2.length() / lenth;
        String[] st = new String[it];
        int j = 0;
        for (int i = 0; i < line2.length(); i+=lenth) {
            st[j++] = line2.substring(i,i+lenth);
        }

        //翻译
        byte[] st2 = new byte[it];
        for (Map.Entry<Byte, String> tmp :
                route.entrySet()) {
            String s = tmp.getValue();
            for (int i = 0; i < st.length; i++) {
                if (s.equals(st[i])){
                    st2[i] = tmp.getKey();
                }
            }
        }
        FileOutputStream fileOutputStream = new FileOutputStream("C:\\Users\\Administrator\\Desktop\\output.jpg");
        fileOutputStream.write(st2);
        fileOutputStream.flush();
        fileOutputStream.close();


    }
}