解决方法
我试图覆盖SecurityManager checkExit(int status)方法 – 如果System.exit(status)被任意调用,那么这个方法是有效的 – 但是,当应用程序退出“正常”(没有活动线程)时,它不会设置状态,或者一个错误会杀死虚拟机.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.security.Permission;
public class ExitChecker {
public ExitChecker() {
System.setSecurityManager(new ExitMonitorSecurityManager());
Runtime.getRuntime().addShutdownHook(new Thread(new MyShutdownHook()));
BufferedReader input = new BufferedReader(new InputStreamReader(System.in));
String line = "";
while (!line.equalsIgnoreCase("Q")) {
try {
System.out.println("Press a number to exit with that status.");
System.out.println("Press 'R' to generate a RuntimeException.");
System.out.println("Press 'O' to generate an OutOfMemoryError.");
System.out.println("Press 'Q' to exit normally.");
line = input.readLine().trim();
processInput(line);
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
}
}
private void processInput(String line) {
if (line.equalsIgnoreCase("Q")) {
// continue,will exit loop and exit normally
} else if (line.equalsIgnoreCase("R")) {
throwRuntimeException();
} else if (line.equals("O")) {
throwError();
} else {
// try to parse to number
try {
int status = Integer.parseInt(line);
callExit(status);
} catch(NumberFormatException x) {
// not a number.. repeat question...
System.out.println("\nUnrecognized input...\n\n");
}
}
}
public void callExit(int status) {
System.exit(status);
}
public void throwError() {
throw new OutOfMemoryError("OutOfMemoryError");
}
public void throwRuntimeException() {
throw new RuntimeException("Runtime Exception");
}
public static void main(String[] args) {
new ExitChecker();
}
private static class ExitMonitorSecurityManager extends SecurityManager {
@Override
public void checkPermission(Permission perm) {
//System.out.println(perm.getName());
//System.out.println(perm.getActions());
}
@Override
public void checkPermission(Permission perm,Object context) {
//System.out.println(perm.getName());
//System.out.println(perm.getActions());
}
@Override
public void checkExit(int status) {
System.out.println("Setting exit value via security manager...");
MyShutdownHook.EXIT_STATUS = status;
}
}
private static class MyShutdownHook implements Runnable {
public static Integer EXIT_STATUS;
public void run() {
System.out.println("In MyShutdownHook - exit status is " + EXIT_STATUS);
}
}
}
