routes-loader(xml-io): improve how routes are loaded

core/camel-api/src/main/java/org/apache/camel/spi/Resource.java

@@ -16,8 +16,10 @@
  */
 package org.apache.camel.spi;
 
+import java.io.ByteArrayInputStream;
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
 
 /**
  * Describe a resource, such as a file or class path resource.
@@ -62,4 +64,28 @@ public InputStream getInputStream() throws IOException {
             }
         };
     }
+
+    /**
+     * Create a resource from bytes.
+     */
+    static Resource fromBytes(String location, byte[] content) {
+        return new Resource() {
+            @Override
+            public String getLocation() {
+                return location;
+            }
+
+            @Override
+            public InputStream getInputStream() throws IOException {
+                return new ByteArrayInputStream(content);
+            }
+        };
+    }
+
+    /**
+     * Create a resource from a string.
+     */
+    static Resource fromString(String location, String content) {
+        return fromBytes(location, content.getBytes(StandardCharsets.UTF_8));
+    }
 }

core/camel-xml-io/src/main/java/org/apache/camel/xml/in/BaseParser.java

@@ -206,6 +206,18 @@ protected void expectTag(String name) throws XmlPullParserException, IOException
         }
     }
 
+    protected boolean hasTag(String name) throws XmlPullParserException, IOException {
+        if (parser.nextTag() != XmlPullParser.START_TAG) {
+            throw new XmlPullParserException("Expected starting tag");
+        }
+
+        if (!Objects.equals(name, parser.getName()) || !Objects.equals(namespace, parser.getNamespace())) {
+            return false;
+        }
+
+        return true;
+    }
+
     @SuppressWarnings("unchecked")
     protected void handleOtherAttribute(Object definition, String name, String ns, String val) throws XmlPullParserException {
         // Ignore

core/camel-xml-io/src/main/java/org/apache/camel/xml/in/XmlRoutesBuilderLoader.java

@@ -22,9 +22,6 @@
 import org.apache.camel.CamelContextAware;
 import org.apache.camel.RoutesBuilder;
 import org.apache.camel.builder.RouteBuilder;
-import org.apache.camel.model.RouteTemplatesDefinition;
-import org.apache.camel.model.RoutesDefinition;
-import org.apache.camel.model.rest.RestsDefinition;
 import org.apache.camel.spi.Resource;
 import org.apache.camel.spi.RoutesBuilderLoader;
 import org.apache.camel.spi.annotations.JdkService;
@@ -57,22 +54,19 @@ public RoutesBuilder loadRoutesBuilder(Resource resource) throws Exception {
             @Override
             public void configure() throws Exception {
                 try (InputStream is = resource.getInputStream()) {
-                    RouteTemplatesDefinition templates = new ModelParser(is, NAMESPACE).parseRouteTemplatesDefinition();
-                    if (templates != null) {
-                        setRouteTemplateCollection(templates);
-                    }
+                    new ModelParser(is, NAMESPACE)
+                            .parseRouteTemplatesDefinition()
+                            .ifPresent(this::setRouteTemplateCollection);
                 }
                 try (InputStream is = resource.getInputStream()) {
-                    RestsDefinition rests = new ModelParser(is, NAMESPACE).parseRestsDefinition();
-                    if (rests != null) {
-                        setRestCollection(rests);
-                    }
+                    new ModelParser(is, NAMESPACE)
+                            .parseRestsDefinition()
+                            .ifPresent(this::setRestCollection);
                 }
                 try (InputStream is = resource.getInputStream()) {
-                    RoutesDefinition routes = new ModelParser(is, NAMESPACE).parseRoutesDefinition();
-                    if (routes != null) {
-                        setRouteCollection(routes);
-                    }
+                    new ModelParser(is, NAMESPACE)
+                            .parseRoutesDefinition()
+                            .ifPresent(this::setRouteCollection);
                 }
             }
         };

core/camel-xml-io/src/test/java/org/apache/camel/xml/in/ModelParserTest.java

@@ -51,13 +51,13 @@ public void testFiles() throws Exception {
             boolean isRest = REST_XMLS.contains(path.getFileName().toString());
             boolean isTemplate = TEMPLATE_XMLS.contains(path.getFileName().toString());
             if (isRest) {
-                RestsDefinition rests = parser.parseRestsDefinition();
+                RestsDefinition rests = parser.parseRestsDefinition().orElse(null);
                 assertNotNull(rests);
             } else if (isTemplate) {
-                RouteTemplatesDefinition templates = parser.parseRouteTemplatesDefinition();
+                RouteTemplatesDefinition templates = parser.parseRouteTemplatesDefinition().orElse(null);
                 assertNotNull(templates);
             } else {
-                RoutesDefinition routes = parser.parseRoutesDefinition();
+                RoutesDefinition routes = parser.parseRoutesDefinition().orElse(null);
                 assertNotNull(routes);
             }
         }
@@ -67,9 +67,11 @@ public void testFiles() throws Exception {
     public void testSimpleString() throws Exception {
         RoutesDefinition routes = new ModelParser(
                 new StringReader(
-                        "<routes>" + "  <route id='foo'>" + "    <from uri='my:bar'/>" + "    <to uri='mock:res'/>"
+                        "<routes>"
+                                 + "  <route id='foo'>" + "    <from uri='my:bar'/>" + "    <to uri='mock:res'/>"
                                  + "  </route>"
-                                 + "</routes>")).parseRoutesDefinition();
+                                 + "</routes>")).parseRoutesDefinition().orElse(null);
+
         assertNotNull(routes);
     }
 
@@ -86,7 +88,7 @@ public void namespaces() throws Exception {
                                  + "      </setBody>\n"
                                  + "   </route>\n"
                                  + "</routes>";
-        final RoutesDefinition routes = new ModelParser(new StringReader(routesXml)).parseRoutesDefinition();
+        final RoutesDefinition routes = new ModelParser(new StringReader(routesXml)).parseRoutesDefinition().orElse(null);
         final RouteDefinition route0 = routes.getRoutes().get(0);
         final SetBodyDefinition setBody = (SetBodyDefinition) route0.getOutputs().get(0);
         final XPathExpression xPath = (XPathExpression) setBody.getExpression();

core/camel-xml-io/src/test/java/org/apache/camel/xml/in/XmlRoutesBuilderLoaderTest.java

@@ -0,0 +1,89 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.camel.xml.in;
+
+import org.apache.camel.builder.RouteBuilder;
+import org.apache.camel.impl.DefaultCamelContext;
+import org.apache.camel.spi.Resource;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+public class XmlRoutesBuilderLoaderTest {
+    @Test
+    public void canLoadRoutes() throws Exception {
+        String content = ""
+                         + "<routes xmlns=\"http://camel.apache.org/schema/spring\">"
+                         + "   <route id=\"xpath-route\">"
+                         + "      <from uri=\"direct:test\"/>"
+                         + "      <setBody>"
+                         + "         <xpath resultType=\"java.lang.String\">"
+                         + "            /foo:orders/order[1]/country/text()"
+                         + "         </xpath>"
+                         + "      </setBody>"
+                         + "   </route>"
+                         + "</routes>";
+
+        Resource resource = Resource.fromString("in-memory.xml", content);
+        RouteBuilder builder = (RouteBuilder) new XmlRoutesBuilderLoader().loadRoutesBuilder(resource);
+        builder.setContext(new DefaultCamelContext());
+        builder.configure();
+
+        assertFalse(builder.getRouteCollection().getRoutes().isEmpty());
+    }
+
+    @Test
+    public void canLoadRests() throws Exception {
+        String content = ""
+                         + "<rests xmlns=\"http://camel.apache.org/schema/spring\">"
+                         + "  <rest id=\"bar\" path=\"/say/hello\">"
+                         + "    <get uri=\"/bar\">"
+                         + "      <to uri=\"mock:bar\"/>"
+                         + "    </get>"
+                         + "  </rest>"
+                         + "</rests>";
+
+        Resource resource = Resource.fromString("in-memory.xml", content);
+        RouteBuilder builder = (RouteBuilder) new XmlRoutesBuilderLoader().loadRoutesBuilder(resource);
+        builder.setContext(new DefaultCamelContext());
+        builder.configure();
+
+        assertFalse(builder.getRestCollection().getRests().isEmpty());
+    }
+
+    @Test
+    public void canLoadTemplates() throws Exception {
+        String content = ""
+                         + "<routeTemplates xmlns=\"http://camel.apache.org/schema/spring\">"
+                         + "  <routeTemplate id=\"myTemplate\">"
+                         + "    <templateParameter name=\"foo\"/>"
+                         + "    <templateParameter name=\"bar\"/>"
+                         + "    <route>"
+                         + "      <from uri=\"direct:{{foo}}\"/>"
+                         + "      <to uri=\"mock:{{bar}}\"/>"
+                         + "    </route>"
+                         + "  </routeTemplate>"
+                         + "</routeTemplates>";
+
+        Resource resource = Resource.fromString("in-memory.xml", content);
+        RouteBuilder builder = (RouteBuilder) new XmlRoutesBuilderLoader().loadRoutesBuilder(resource);
+        builder.setContext(new DefaultCamelContext());
+        builder.configure();
+
+        assertFalse(builder.getRouteTemplateCollection().getRouteTemplates().isEmpty());
+    }
+}

tooling/maven/camel-package-maven-plugin/src/main/java/org/apache/camel/maven/packaging/ModelXmlParserGeneratorMojo.java

@@ -38,6 +38,7 @@
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.TreeMap;
@@ -475,8 +476,12 @@ private JavaClass generateParser(List<Class<?>> model, ClassLoader classLoader)
             });
             if (clazz == routesDefinitionClass || clazz == routeTemplatesDefinitionClass || clazz == restsDefinitionClass) {
                 String element = clazz.getAnnotation(XmlRootElement.class).name();
-                parser.addMethod().setPublic().setReturnType(clazz).setName("parse" + name).addThrows(IOException.class).addThrows(XML_PULL_PARSER_EXCEPTION)
-                    .setBody("expectTag(\"" + element + "\");\nreturn doParse" + name + "();");
+                parser.addMethod().setPublic()
+                    .setReturnType(new GenericType(Optional.class, new GenericType(clazz)))
+                    .setName("parse" + name)
+                    .addThrows(IOException.class)
+                    .addThrows(XML_PULL_PARSER_EXCEPTION)
+                    .setBodyF("return hasTag(\"%s\") ? Optional.of(doParse%s()) : Optional.empty();", element, name);
             }
             if (hasDerived) {
                 if (!attributeMembers.isEmpty()) {