fix typos (#1821)

dolphinscheduler-alert/src/main/java/org/apache/dolphinscheduler/alert/AlertServer.java

@@ -56,7 +56,7 @@ public class AlertServer {
         logger.info("alert server ready start ");
         while (Stopper.isRunning()){
             try {
-                Thread.sleep(Constants.ALERT_SCAN_INTERVEL);
+                Thread.sleep(Constants.ALERT_SCAN_INTERVAL);
             } catch (InterruptedException e) {
                 logger.error(e.getMessage(),e);
                 Thread.currentThread().interrupt();

dolphinscheduler-alert/src/main/java/org/apache/dolphinscheduler/alert/utils/Constants.java

@@ -133,7 +133,7 @@ public class Constants {
 
     public static final String TH_END = "</th>";
 
-    public static final int ALERT_SCAN_INTERVEL = 5000;
+    public static final int ALERT_SCAN_INTERVAL = 5000;
 
     public static final String MARKDOWN_QUOTE = ">";
 

dolphinscheduler-common/src/main/java/org/apache/dolphinscheduler/common/thread/Stopper.java

@@ -25,7 +25,7 @@ public class Stopper {
 
 	private static volatile AtomicBoolean signal = new AtomicBoolean(false);
 	
-	public static final boolean isStoped(){
+	public static final boolean isStopped(){
 		return signal.get();
 	}
 	

dolphinscheduler-common/src/test/java/org/apache/dolphinscheduler/common/threadutils/ThreadUtilsTest.java

@@ -98,7 +98,7 @@ public class ThreadUtilsTest {
     public void testStopper() {
         assertTrue(Stopper.isRunning());
         Stopper.stop();
-        assertTrue(Stopper.isStoped());
+        assertTrue(Stopper.isStopped());
     }
 
     /**

dolphinscheduler-server/src/main/java/org/apache/dolphinscheduler/server/master/MasterServer.java

@@ -173,7 +173,7 @@ public class MasterServer implements IStoppable {
 
         try {
             //execute only once
-            if(Stopper.isStoped()){
+            if(Stopper.isStopped()){
                 return;
             }
 

dolphinscheduler-server/src/main/java/org/apache/dolphinscheduler/server/worker/WorkerServer.java

@@ -201,7 +201,7 @@ public class WorkerServer implements IStoppable {
 
         try {
             //execute only once
-            if(Stopper.isStoped()){
+            if(Stopper.isStopped()){
                 return;
             }