import java.io.*;
import java.util.*;

public class Test {
  public Test() {
    try {
      readResource();
      for(int i=0;i<fileCount;i++)
      {
        System.out.println(fileName[i]);
        byte [] b=this.getData(fileName[i]);
        FileOutputStream fos=new FileOutputStream(new File("C:\\test\\"+fileName[i]));
        fos.write(b);
        fos.close();
      }
    } catch (Exception e) {
      System.out.println("hew is ex " + e);
    }
  }

  private static String[] fileName;
  private static int[] fileStart;
  private static int[] fileLength;
  private static int fileCount;
  private static String resource;


  public static void readResource() throws Exception {
    InputStream is;
     DataInputStream dis;
    is = new DataInputStream(new FileInputStream("D:/myproject/aoshifengsheng/aoshifsz_n7260/res/2.pak"));
    dis = new DataInputStream(is);
    byte[] b;
    try {
      // 文件個數 4字節
      b = new byte[4];
      dis.read(b);
      fileCount = byteToInt(b);
      fileName = new String[fileCount];
      fileStart = new int[fileCount];
      fileLength = new int[fileCount];

      for (int i = 0; i < fileCount; i++) {
        // 文件名長度 1字節
        b = new byte[1];
        dis.read(b);
        // 文件名 所占字節數等于剛剛所取出的長度值
        b = new byte[b[0]];
        dis.read(b);
        fileName[i] = byteToString(b);
        // 文件起始位置 4字節
        b = new byte[4];
        dis.read(b);
        fileStart[i] = byteToInt(b);
        // 文件長度 4字節
        b = new byte[4];
        dis.read(b);
        fileLength[i] = byteToInt(b);
      }
      dis.close();
      System.gc();
    } catch (Exception ex) {
    }
  }

  /**
   * byteToString 將字節數據轉換成字符串
   *
   * @param b byte[]
   * @return String
   */
  private static String byteToString(byte[] b) {
    String str = "";
    for (int i = 0; i < b.length; i++) {
      str += (char) b[i];
    }
    return str;
  }

  public byte[] getData(String str)throws Exception {
     DataInputStream dis = new DataInputStream(new FileInputStream("D:/myproject/aoshifengsheng/aoshifsz_n7260/res/2.pak"));
    for (int i = 0; i < fileCount; i++) {
      if (str.compareTo(fileName[i]) == 0) {
        //try {

        //} catch (FileNotFoundException ex1) {
        //}
        byte[] b = new byte[fileLength[i]];
        try {
          dis.skip(fileStart[i]);
          dis.read(b);
          dis.close();
          return b;
        } catch (IOException ex) {
          ex.printStackTrace();
        }
      }
    }
    return null;
  }

  /**
   * byteToInt 將字節數據轉換成整數值
   *
   * @param b byte[]
   * @return int
   */
  private static int byteToInt(byte[] b) {
    // 如果字節長度不能構成一個整數則返回0
    if (b.length < 4) {
      return 0;
    }
    // 返回構成的整數
    return ( (b[3] << 24) & 0xFFFFFFFF) | ( (b[2] << 16) & 0xFFFFFF) |
        ( (b[1] << 8) & 0xFFFF) | (b[0] & 0xFF);
  }

  public static void main(String args[]) {
    Test test = new Test();
  }
}