java安全性编程实例电子版书附源码,是网络安全编程者不可多得的好书

				import java.io.*;
				import java.security.*;
				public class MySecManager extends SecurityManager {
				  public void checkRead(String file) {
				              int p1=file.lastIndexOf(".");
				              int p2=file.length();
				              String suffix=file.substring(p1,p2);
				       checkPermission(new SuffixPermission(suffix));
				       checkPermission(new FilePermission(file,"read"));
				  }
				}