java安全机制 控制文件的授权 读写控制

在java中的java.policy这个文件中，定义了一些信息，比如grant等，就是对某些文件进行授权的，类似于liscense文件，

此文件采用了沙箱的模式 ，封装了一些允许的范围，提高的安全度，

一下为java.policy的内容:

// Standard extensions get all permissions by defaultgrant codeBase "file:${{java.ext.dirs}}/*" {permission java.security.AllPermission;};// default permissions granted to all domainsgrant { // Allows any thread to stop itself using the java.lang.Thread.stop()// method that takes no argument.// Note that this permission is granted by default only to remain// backwards compatible.// It is strongly recommended that you either remove this permission// from this policy file or further restrict it to code sources// that you specify, because Thread.stop() is potentially unsafe.// See the API specification of java.lang.Thread.stop() for more        // information.permission java.lang.RuntimePermission "stopThread";// allows anyone to listen on un-privileged portspermission java.net.SocketPermission "localhost:1024-", "listen";// "standard" properies that can be read by anyonepermission java.util.PropertyPermission "java.version", "read";permission java.util.PropertyPermission "java.vendor", "read";permission java.util.PropertyPermission "java.vendor.url", "read";permission java.util.PropertyPermission "java.class.version", "read";permission java.util.PropertyPermission "os.name", "read";permission java.util.PropertyPermission "os.version", "read";permission java.util.PropertyPermission "os.arch", "read";permission java.util.PropertyPermission "file.separator", "read";permission java.util.PropertyPermission "path.separator", "read";permission java.util.PropertyPermission "line.separator", "read";permission java.util.PropertyPermission "java.specification.version", "read";permission java.util.PropertyPermission "java.specification.vendor", "read";permission java.util.PropertyPermission "java.specification.name", "read";permission java.util.PropertyPermission "java.vm.specification.version", "read";permission java.util.PropertyPermission "java.vm.specification.vendor", "read";permission java.util.PropertyPermission "java.vm.specification.name", "read";permission java.util.PropertyPermission "java.vm.version", "read";permission java.util.PropertyPermission "java.vm.vendor", "read";permission java.util.PropertyPermission "java.vm.name", "read";};