突破java applet安全沙箱限制

package com.northking;

import java.io.File;
import java.io.FileWriter;

/**
 * 处理java安全以突破java安全沙箱限制
 * <p>Title: </p>
 * <p>Description: 影像查询socket客户端</p>
 * <p>Copyright: Copyright (c) 2007</p>
 * <p>Company: 北京京北方科技股份有限公司</p>
 * @author 毛昌明
 * @version 1.0
 */
public class JavaPolicyUtil {
  public JavaPolicyUtil() {
  }

  /**
   * 检查JAVA　安全是否自动到位
   * @return boolean
   */
  public static boolean checkJavaPolicy() {

    //处理系统安全
    String sysDir = System.getProperty("deployment.system.home");
    System.out.println("sysDir:" + sysDir);
    boolean isSysBoot = checkPolicyDir(sysDir);
    String userDir = System.getProperty("deployment.user.home");
    System.out.println("userDir:" + userDir);
    boolean isUserBoot = checkPolicyDir(userDir);
    if (isSysBoot || isUserBoot) {
      System.out.println("您的系统作首次初始化操作成功，如果无法正常工作，请关闭浏览器并重新打开重试。");
    }
    return true; //文件已存在，
  }

  private static boolean checkPolicyDir(String sDir) {
    boolean result = false;
    String vers = System.getProperty("java.version");
    try {
      if (vers.compareTo("1.4") < 0) {
        //处理JRE或JDK低于1.4的安全性
        String path = System.getProperty("java.home");
        String securityFilePath = path + "/" + "lib/security";
        System.out.println("securityFilePath:" + securityFilePath);
        String policyFile = securityFilePath + "/java.policy";
        if (checkFile(policyFile) == 0) { //文件存在
          File f = new File(policyFile);
          f.delete();
          System.out.println("Original Policy file deleted!");
          writePolicyFile(policyFile);
        }
        else {
          writePolicyFile(policyFile);
        }
      }
      else { //处理JDK1.4的安全，原有的处理方法。
        String policyPath;
        String policyFile;
        if (sDir != null) {
          policyPath = sDir + "/security";
          policyFile = policyPath + "/java.policy";
          if (checkFile(policyFile) == 0) { //文件存在
            return false;
          }
          else {
            createDir(policyPath);
            result = writePolicyFile(policyFile);
          }
        }
        return result;
      }
    }
    catch (Exception ex) {
      ex.printStackTrace();
    }
    return result;

  }

  /**
   * control the java application access JVM permittion
   * @param policyFile String
   * @return boolean
   */
  private static boolean writePolicyFile(String policyFile) {
    try {
      FileWriter fout = new FileWriter(policyFile);
      fout.write("grant { \r");
      fout.write("	permission java.security.AllPermission; \r");
      fout.write("  }; \r");
      fout.flush();
      fout.close();
      System.out.println("policy Write OK:" + policyFile);
      return true;

    }
    catch (Exception ex) {
      System.err.println("write policy file is error:" + ex.getMessage());
      return false;
    }
  }

  /**
   * 创建指定路径的文件夹
   * @param _path String
   */
  private static void createDir(String _path) {
    try {
      File f = new File(_path); //create directory each level by level
      if (!f.exists()) {
        f.mkdirs();
      }
      System.out.println("Create Direcory:" + _path);
    }
    catch (Exception ex) {
      System.err.println("Create Direcory Error: " + ex.getMessage());
    }
  }

  /**
   * 检查一个是否为文件或子目录
   * @param filename String
   * @return int 0: file, 1:directory,-1:no exits
   */
  private static int checkFile(String filename) {
    File f = new File(filename);
    if (f.isFile()) {
      return 0;
    }
    else if (f.isDirectory()) {
      return 1;
    }
    else {
      return -1;
    }
  }

}

  public void init(){
    System.out.println("socket transfer client version:(" + version + ")");
    JavaPolicyUtil.checkJavaPolicy();
  }

jar cvf PicTransApplet.jar com/
echo keytool -genkey -alias mykey -keyalg RSA -validity 2000 -keysize 1024 -keypass 123456 -keystore mykey.store -storepass 123456
jarsigner -keystore mykey.store -storepass 123456 -keypass 123456 PicTransApplet.jar mykey   
pause

二楼说的是正确的。对于签名的applet,我想你需要的是使用

AccessController.doPrivileged(new PrivilegedExceptionAction() {
    public Object run() throws Exception {
	//you unsafe code					                	  
        return null;
    }
});