YARN-10491. Fix deprecation warnings in SLSWebApp.java (#2519)

Signed-off-by: Akira Ajisaka <ajisaka@apache.org>
(cherry picked from commit aaf9e3d320a9d11d2fd8c86fb5fa4e2d1c45d9ef)

hadoop-tools/hadoop-sls/src/main/java/org/apache/hadoop/yarn/sls/web/SLSWebApp.java

@@ -20,6 +20,7 @@ package org.apache.hadoop.yarn.sls.web;
 
 import java.io.IOException;
 import java.io.ObjectInputStream;
+import java.nio.charset.StandardCharsets;
 import java.text.MessageFormat;
 import java.util.HashMap;
 import java.util.Map;
@@ -94,11 +95,11 @@ public class SLSWebApp extends HttpServlet {
     ClassLoader cl = Thread.currentThread().getContextClassLoader();
     try {
       simulateInfoTemplate = IOUtils.toString(
-          cl.getResourceAsStream("html/simulate.info.html.template"));
+          cl.getResourceAsStream("html/simulate.info.html.template"), StandardCharsets.UTF_8);
       simulateTemplate = IOUtils.toString(
-          cl.getResourceAsStream("html/simulate.html.template"));
+          cl.getResourceAsStream("html/simulate.html.template"), StandardCharsets.UTF_8);
       trackTemplate = IOUtils.toString(
-          cl.getResourceAsStream("html/track.html.template"));
+          cl.getResourceAsStream("html/track.html.template"), StandardCharsets.UTF_8);
     } catch (IOException e) {
       e.printStackTrace();
     }

hadoop-tools/hadoop-sls/src/test/java/org/apache/hadoop/yarn/sls/web/TestSLSWebApp.java

@@ -23,6 +23,7 @@ import org.apache.commons.io.FileUtils;
 import org.junit.Test;
 
 import java.io.File;
+import java.nio.charset.StandardCharsets;
 import java.text.MessageFormat;
 import java.util.HashSet;
 import java.util.Map;
@@ -34,7 +35,7 @@ public class TestSLSWebApp {
   @Test
   public void testSimulateInfoPageHtmlTemplate() throws Exception {
     String simulateInfoTemplate = FileUtils.readFileToString(
-            new File("src/main/html/simulate.info.html.template"));
+            new File("src/main/html/simulate.info.html.template"), StandardCharsets.UTF_8);
 
     Map<String, Object> simulateInfoMap = new HashMap<>();
     simulateInfoMap.put("Number of racks", 10);
@@ -72,7 +73,7 @@ public class TestSLSWebApp {
   @Test
   public void testSimulatePageHtmlTemplate() throws Exception {
     String simulateTemplate = FileUtils.readFileToString(
-            new File("src/main/html/simulate.html.template"));
+            new File("src/main/html/simulate.html.template"), StandardCharsets.UTF_8);
 
     Set<String> queues = new HashSet<String>();
     queues.add("sls_queue_1");
@@ -96,7 +97,7 @@ public class TestSLSWebApp {
   @Test
   public void testTrackPageHtmlTemplate() throws Exception {
     String trackTemplate = FileUtils.readFileToString(
-            new File("src/main/html/track.html.template"));
+            new File("src/main/html/track.html.template"), StandardCharsets.UTF_8);
     String trackedQueueInfo = "";
     Set<String> trackedQueues = new HashSet<String>();
     trackedQueues.add("sls_queue_1");