BAEL-1529 Intro to the Java SecurityManager (#7697)

core-java-modules/core-java-security-manager/src/main/java/com/baeldung/security/manager/CustomPermission.java

@@ -0,0 +1,13 @@
+package com.baeldung.security.manager;
+
+import java.security.BasicPermission;
+
+public class CustomPermission extends BasicPermission {
+    public CustomPermission(String name) {
+        super(name);
+    }
+
+    public CustomPermission(String name, String actions) {
+        super(name, actions);
+    }
+}

core-java-modules/core-java-security-manager/src/main/java/com/baeldung/security/manager/Service.java

@@ -0,0 +1,18 @@
+package com.baeldung.security.manager;
+
+public class Service {
+
+    public static final String OPERATION = "my-operation";
+
+    public void operation() {
+        SecurityManager securityManager = System.getSecurityManager();
+        if (securityManager != null) {
+            securityManager.checkPermission(new CustomPermission(OPERATION));
+        }
+        System.out.println("Operation is executed");
+    }
+
+    public static void main(String[] args) {
+        new Service().operation();
+    }
+}

core-java-modules/core-java-security-manager/src/test/java/com/baeldung/security/manager/SecurityManagerUnitTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.security.manager;
+
+import org.junit.Test;
+
+import java.net.URL;
+import java.security.AccessControlException;
+import java.util.concurrent.Callable;
+
+public class SecurityManagerUnitTest {
+
+    @Test(expected = AccessControlException.class)
+    public void whenSecurityManagerIsActive_thenNetworkIsNotAccessibleByDefault() throws Exception {
+        doTest(() -> {
+            new URL("http://www.google.com").openConnection().connect();
+            return null;
+        });
+    }
+
+    @Test(expected = AccessControlException.class)
+    public void whenUnauthorizedClassTriesToAccessProtectedOperation_thenAnExceptionIsThrown() throws Exception {
+        doTest(() -> {
+            new Service().operation();
+            return null;
+        });
+    }
+
+    private void doTest(Callable<Void> action) throws Exception {
+        System.setSecurityManager(new SecurityManager());
+        try {
+            action.call();
+        } finally {
+            System.setSecurityManager(null);
+        }
+    }
+}