java sandbox是什么？让我们一起来了解一下吧！
java sandbox是指java程序中的沙箱。它是java安全模型的核心。沙箱是制止程序继续运行的环境。沙箱机制是把Java代码圈在虚拟机限定的运行范围，严格拒绝代码对资源系统的访问。
java沙箱是由以下基本部分组成的：
1.字节码校验器 bytecode verifier
保证java类文件遵循java语言规范，帮助程序实现内存保护。
2.存取控制器 access controller
它的作用是操控核心API对操作系统的存取权限。
3.类加载器 class loader
双亲委派机制、安全校验等，防止恶意代码干涉。
4.安全软件包 secruity package
java.secruity下的类和扩展包下的类，允许用户为自己的应用增加新的安全特性。
5.安全管理器 security manager
它是核心API和系统间的主要接口，实现权限控制，比存取控制器优先级高。
沙箱的关键内容——策略文件，查看具体步骤如下：
// 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 dynamic ports
permission java.net.SocketPermission "localhost:0", "listen";
// permission for standard RMI registry port
permission java.net.SocketPermission "localhost:1099", "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";
};以上就是小编今天的分享了，希望可以帮助到大家。