BAEL-3732: Move core-java-security-manager into core-java-security (#8460)

* BAEL-3732: Move core-java-security-manager into core-java-security

* BAEL-3732: Teardown the security manager to not interfere with other tests

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

@@ -0,0 +1,13 @@
+package com.baeldung.securitymanager;
+
+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/src/main/java/com/baeldung/securitymanager/Service.java

@@ -0,0 +1,18 @@
+package com.baeldung.securitymanager;
+
+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/src/test/java/com/baeldung/java/md5/JavaMD5UnitTest.java

@@ -1,4 +1,4 @@
-package org.baeldung.java.md5;
+package com.baeldung.java.md5;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

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

@@ -0,0 +1,35 @@
+package com.baeldung.securitymanager;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.net.URL;
+import java.security.AccessControlException;
+
+public class SecurityManagerUnitTest {
+
+    private static final String TESTING_SECURITY_POLICY = "file:src/test/resources/testing.policy";
+
+    @Before
+    public void setUp() {
+        System.setProperty("java.security.policy", TESTING_SECURITY_POLICY);
+        System.setSecurityManager(new SecurityManager());
+    }
+
+    @After
+    public void tearDown() {
+        System.setSecurityManager(null);
+    }
+
+    @Test(expected = AccessControlException.class)
+    public void whenSecurityManagerIsActive_thenNetworkIsNotAccessibleByDefault() throws IOException {
+        new URL("http://www.google.com").openConnection().connect();
+    }
+
+    @Test(expected = AccessControlException.class)
+    public void whenUnauthorizedClassTriesToAccessProtectedOperation_thenAnExceptionIsThrown() {
+        new Service().operation();
+    }
+}

core-java-modules/core-java-security/src/test/resources/testing.policy

@@ -0,0 +1,5 @@
+grant {
+        // This is for testing purposes only.
+        // It allows us to properly reset the security manager after the unit test completes.
+        permission java.lang.RuntimePermission "setSecurityManager";
+};