怎么写一个自己的安全管理器，它判断用户的密码是否正确，如果正确就可以读写文件。大侠们帮忙

Question

怎么写一个自己的安全管理器，它判断用户的密码是否正确，如果正确就可以读写文件。大侠们帮忙

Answer 1

此回复为自动发出,仅用于显示而已，并无任何其他特殊作用
楼主【lovemeone】截止到2008-07-23 00:17:34的历史汇总数据(不包括此帖)：
发帖的总数量:2                        发帖的总分数:150                      每贴平均分数:75                       
回帖的总数量:1                        得分贴总数量:0                        回帖的得分率:0%                       
结贴的总数量:2                        结贴的总分数:150                      
无满意结贴数:0                        无满意结贴分:0                        
未结的帖子数:0                        未结的总分数:0                        
结贴的百分比:100.00%               结分的百分比:100.00%                  
无满意结贴率:0.00  %               无满意结分率:0.00  %                  
敬礼!

Answer 2

import java.io.*;
public class MySecurityManager extends SecurityManager
{
    String password;
    MySecurityManager(String password)
    {
    super();
    this.password = password;
    }
    private boolean VerifyPassword()
    {
    BufferedReader in= new BufferedReader
    (new InputStreamReader(System.in));
    String inputString;
    System.out.println("Input Password?");
    try
       {
       inputString = in.readLine();
       if (inputString.equals(password))
       return true;
       else
       return false;
       }catch (IOException e)
       {
       return false;
       }
       }
       public void checkRead(String filename)
       {
       if (!VerifyPassword())
       throw new SecurityException("Dont read!");
       else
       System.out.println("checkRead(String filename)");
       }
       public void checkWrite(String filename)
       {
           if (!VerifyPassword())
           throw new SecurityException("Dont write!");
           else
           System.out.println("checkWrite(String filename)");
       }
}17.怎么实现数字签名啊？？
import java.io.*;
import java.security.*;
public class SignFile
{
    public static void main(String[] args)throws Exception
    {
        if (args.length != 1)
        {
            System.out.println("Usage: SignFile nameOfFileToSign");
            System.exit(-1);
        }
        /* Generate a key keyPair */
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA", "SUN");
        SecureRandom random = SecureRandom.getInstance("SHA1PRNG", "SUN");
        keyGen.initialize(1024, random);
        KeyPair keyPair = keyGen.generateKeyPair();
        PrivateKey priKey = keyPair.getPrivate();
        PublicKey pubKey = keyPair.getPublic();
        //print keyGen and key info
        System.out.println("keygen algo= "+keyGen.getAlgorithm());
        System.out.println("keygen provider= "+keyGen.getProvider());
        System.out.println("key algo= "+pubKey.getAlgorithm());
        System.out.println("key format= "+pubKey.getFormat());
        // Create a Signature object and initialize it
        Signature signObject = Signature.getInstance("SHA1withDSA", "SUN");
        signObject.initSign(priKey);
        /* supply data to to sign the data */
        DataInputStream in=new DataInputStream
        (new FileInputStream(args[0]));
        byte[] data = new byte[1024];
        in.read(data);
        signObject.update(data);
        in.close();
        /* sign data(create signature) */
        byte[] signature = signObject.sign();
        /* Save the signature in a file */
        FileOutputStream signatureFile = new FileOutputStream("signature.txt");
        signatureFile.write(signature);
        signatureFile.close();
        /* Save the public key in a file */
        byte[] key = pubKey.getEncoded();
        FileOutputStream pubKeyFile = new FileOutputStream("publicKey.txt");
        pubKeyFile.write(key);
        pubKeyFile.close();
   }
}