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 default
grant codeBase "file:${{java.ext.dirs}}/*" {
	permission java.security.AllPermission;
};
// default permissions granted to all domains
grant { 
	// 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 ports
	permission java.net.SocketPermission "localhost:1024-", "listen";
	// "standard" properies that can be read by anyone
	permission 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";
};<span style="color: #ff0000;" mce_style="color: #ff0000;">
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