feat(spring): support thread-safe Spring Boot WebApplicationContext i…

…nitialization and lookup

api-el/src/main/java/org/ocpsoft/rewrite/el/TypeBasedExpression.java

@@ -15,7 +15,9 @@
  */
 package org.ocpsoft.rewrite.el;
 
+import java.util.ArrayList;
 import java.util.Iterator;
+import java.util.List;
 
 import org.ocpsoft.common.services.ServiceLoader;
 import org.ocpsoft.logging.Logger;
@@ -62,43 +64,55 @@ public String getExpression()
    @SuppressWarnings("unchecked")
    private String lookupBeanName()
    {
-
       // load the available SPI implementations
       Iterator<BeanNameResolver> iterator = ServiceLoader.load(BeanNameResolver.class).iterator();
+
+      List<Exception> deferred = new ArrayList<>();
       while (iterator.hasNext()) {
          BeanNameResolver resolver = iterator.next();
 
-         // check if this implementation is able to tell the name
-         String beanName = resolver.getBeanName(clazz);
-
-         if (log.isTraceEnabled()) {
-            log.trace("Service provider [{}] returned [{}] for class [{}]", new Object[] {
-                     resolver.getClass().getSimpleName(), beanName, clazz.getName()
-            });
-         }
-
-         // the first result is accepted
-         if (beanName != null) {
-
-            // create the complete EL expression including the component
-            String el = new StringBuilder()
-                     .append(beanName).append('.').append(component)
-                     .toString();
+         try {
+            // check if this implementation is able to tell the name
+            String beanName = resolver.getBeanName(clazz);
 
             if (log.isTraceEnabled()) {
-               log.debug("Creation of EL expression for component [{}] of class [{}] successful: {}", new Object[] {
-                        component, clazz.getName(), el
+               log.trace("Service provider [{}] returned [{}] for class [{}]", new Object[] {
+                        resolver.getClass().getSimpleName(), beanName, clazz.getName()
                });
             }
 
-            return el;
+            // the first result is accepted
+            if (beanName != null) {
+
+               // create the complete EL expression including the component
+               String el = new StringBuilder()
+                        .append(beanName).append('.').append(component)
+                        .toString();
+
+               if (log.isTraceEnabled()) {
+                  log.debug("Creation of EL expression for component [{}] of class [{}] successful: {}", new Object[] {
+                           component, clazz.getName(), el
+                  });
+               }
+
+               return el;
+            }
+         }
+         catch (Exception e) {
+            log.debug("Failed to resolve bean names using [" + resolver.getClass().getName() + "]", e);
+            deferred.add(e);
          }
 
       }
 
+      if (deferred.size() > 1) {
+         for (Exception e : deferred) {
+            log.error("Failed to resolve bean names.", e);
+         }
+      }
       throw new IllegalStateException("Unable to obtain EL name for bean of type [" + clazz.getName()
                + "] from any of the SPI implementations. You should conside placing a @"
-               + ELBeanName.class.getSimpleName() + " on the class.");
+               + ELBeanName.class.getSimpleName() + " on the class.", (deferred.size() == 1 ? deferred.get(0) : null));
 
    }
 

integration-spring/src/main/java/org/ocpsoft/rewrite/spring/SpringBeanNameResolver.java

@@ -16,37 +16,41 @@
 package org.ocpsoft.rewrite.spring;
 
 import java.util.HashSet;
-import java.util.Map;
 import java.util.Set;
 
 import org.ocpsoft.logging.Logger;
 import org.ocpsoft.rewrite.el.spi.BeanNameResolver;
 import org.springframework.beans.factory.ListableBeanFactory;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.web.context.ContextLoader;
 import org.springframework.web.context.WebApplicationContext;
 
 /**
  * {@link BeanNameResolver} implementation for Spring.
  * 
  * @author Christian Kaltepoth
+ * @author <a href="mailto:lincolnbaxter@gmail.com">Lincoln Baxter, III</a>
  */
 public class SpringBeanNameResolver implements BeanNameResolver
 {
 
    private final Logger log = Logger.getLogger(SpringBeanNameResolver.class);
 
+   @Autowired
+   private WebApplicationContext applicationContext;
+
    @Override
    public String getBeanName(Class<?> clazz)
    {
-
-      // try to obtain the WebApplicationContext using ContextLoader
-      WebApplicationContext context = ContextLoader.getCurrentWebApplicationContext();
-      if (context == null) {
-         throw new IllegalStateException("Unable to get current WebApplicationContext");
+      if (applicationContext == null) {
+         applicationContext = ContextLoader.getCurrentWebApplicationContext();
+         if (applicationContext == null) {
+            throw new IllegalStateException("Unable to get current WebApplicationContext");
+         }
       }
 
       // obtain a map of bean names
-      Set<String> beanNames = resolveBeanNames(context, clazz);
+      Set<String> beanNames = resolveBeanNames(applicationContext, clazz);
 
       // no beans of that type, nothing we can do
       if (beanNames == null || beanNames.size() == 0) {
@@ -76,15 +80,14 @@ private Set<String> resolveBeanNames(ListableBeanFactory beanFactory, Class<?> c
 
       final Set<String> result = new HashSet<String>();
 
-      Map<String, ?> beanMap = beanFactory.getBeansOfType(clazz);
-      if (beanMap != null) {
-         for (String name : beanMap.keySet()) {
+      String[] names = beanFactory.getBeanNamesForType(clazz);
+      if (names != null) {
+         for (String name : names) {
             if (name != null && !name.startsWith("scopedTarget.")) {
                result.add(name);
             }
          }
       }
-
       return result;
 
    }

integration-spring/src/main/java/org/ocpsoft/rewrite/spring/SpringExpressionLanguageProvider.java

@@ -33,6 +33,7 @@
 import org.springframework.expression.spel.support.StandardEvaluationContext;
 import org.springframework.expression.spel.support.StandardTypeConverter;
 import org.springframework.expression.spel.support.StandardTypeLocator;
+import org.springframework.web.context.ContextLoader;
 import org.springframework.web.context.WebApplicationContext;
 
 /**
@@ -136,6 +137,13 @@ public EvaluationContext getEvaluationContext()
          // we need a ConfigurableBeanFactory to build the BeanExpressionContext
          ConfigurableBeanFactory beanFactory = null;
 
+         if (applicationContext == null) {
+            applicationContext = ContextLoader.getCurrentWebApplicationContext();
+            if (applicationContext == null) {
+               throw new IllegalStateException("Unable to get current WebApplicationContext");
+            }
+         }
+
          // the WebApplicationContext MAY implement ConfigurableBeanFactory
          if (applicationContext instanceof ConfigurableBeanFactory) {
             beanFactory = (ConfigurableBeanFactory) applicationContext;

integration-spring/src/main/java/org/ocpsoft/rewrite/spring/SpringServiceEnricher.java

@@ -17,11 +17,15 @@
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.stream.Collectors;
 
 import org.ocpsoft.common.spi.ServiceEnricher;
 import org.ocpsoft.logging.Logger;
+import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.context.support.SpringBeanAutowiringSupport;
 
+import jakarta.servlet.ServletContext;
+
 /**
  * {@link ServiceEnricher} implementation for Spring.
  * 
@@ -35,7 +39,13 @@ public class SpringServiceEnricher implements ServiceEnricher
    @Override
    public <T> void enrich(final T service)
    {
-      SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(service);
+      ServletContext context = SpringServletContextLoader.findCurrentServletContext();
+      if (context != null) {
+         SpringBeanAutowiringSupport.processInjectionBasedOnServletContext(service, context);
+      }
+      else {
+         SpringBeanAutowiringSupport.processInjectionBasedOnCurrentContext(service);
+      }
       if (log.isDebugEnabled())
          log.debug("Enriched instance of service [" + service.getClass().getName() + "]");
 
@@ -44,8 +54,15 @@ public <T> void enrich(final T service)
    @Override
    public <T> Collection<T> produce(final Class<T> type)
    {
-      // TODO implement
-      return new ArrayList<T>();
+      WebApplicationContext webApplicationContext = SpringServletContextLoader.findCurrentApplicationContext();
+
+      if (webApplicationContext == null) {
+         return new ArrayList<>();
+      }
+
+      return webApplicationContext.getBeanProvider(type)
+               .stream()
+               .collect(Collectors.toList());
    }
 
 }

integration-spring/src/main/java/org/ocpsoft/rewrite/spring/SpringServiceLocator.java

@@ -21,31 +21,29 @@
 import java.util.Set;
 
 import org.ocpsoft.common.spi.ServiceLocator;
-import org.springframework.web.context.ContextLoader;
 import org.springframework.web.context.WebApplicationContext;
 
 /**
  * {@link ServiceLocator} implementation for Spring.
  * 
  * @author Christian Kaltepoth
+ * @author <a href="mailto:lincolnbaxter@gmail.com">Lincoln Baxter, III</a>
  */
 public class SpringServiceLocator implements ServiceLocator
 {
-
    @Override
    @SuppressWarnings("unchecked")
    public <T> Collection<Class<T>> locate(Class<T> clazz)
    {
       Set<Class<T>> result = new LinkedHashSet<Class<T>>();
 
-      // use the Spring API to obtain the WebApplicationContext
-      WebApplicationContext context = ContextLoader.getCurrentWebApplicationContext();
+      WebApplicationContext applicationContext = SpringServletContextLoader.findCurrentApplicationContext();
 
       // may be null if Spring hasn't started yet
-      if (context != null) {
+      if (applicationContext != null) {
 
          // ask spring about SPI implementations
-         Map<String, T> beans = context.getBeansOfType(clazz);
+         Map<String, T> beans = applicationContext.getBeansOfType(clazz);
 
          // add the implementations Class objects to the result set
          for (T type : beans.values()) {

integration-spring/src/main/java/org/ocpsoft/rewrite/spring/SpringServletContextLoader.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2011 <a href="mailto:lincolnbaxter@gmail.com">Lincoln Baxter, III</a>
+ * 
+ * Licensed 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.ocpsoft.rewrite.spring;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.ocpsoft.rewrite.servlet.spi.ContextListener;
+import org.springframework.web.context.ContextLoader;
+import org.springframework.web.context.WebApplicationContext;
+import org.springframework.web.context.request.RequestAttributes;
+import org.springframework.web.context.request.RequestContextHolder;
+import org.springframework.web.context.request.ServletRequestAttributes;
+import org.springframework.web.context.support.WebApplicationContextUtils;
+
+import jakarta.servlet.ServletContext;
+import jakarta.servlet.ServletContextEvent;
+
+/**
+ * Thread-safe {@link ServletContext} loader implementation for Spring.
+ * 
+ * @author <a href="mailto:lincolnbaxter@gmail.com">Lincoln Baxter, III</a>
+ */
+public class SpringServletContextLoader implements ContextListener
+{
+    private static final Map<ClassLoader, ServletContext> contextMap = new ConcurrentHashMap<>(1);
+
+    @Override
+    public void contextInitialized(ServletContextEvent event)
+    {
+        ServletContext servletContext = event.getServletContext();
+        contextMap.put(Thread.currentThread().getContextClassLoader(), servletContext);
+        contextMap.put(servletContext.getClassLoader(), servletContext);
+    }
+
+    @Override
+    public void contextDestroyed(ServletContextEvent event)
+    {
+        ServletContext context = event.getServletContext();
+        contextMap.entrySet().removeIf(entry -> entry.getValue() == context);
+    }
+
+    public static ServletContext findCurrentServletContext()
+    {
+        RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
+
+        if (requestAttributes instanceof ServletRequestAttributes) {
+            return ((ServletRequestAttributes) requestAttributes).getRequest().getServletContext();
+        }
+
+        return contextMap.get(Thread.currentThread().getContextClassLoader());
+    }
+
+    public static WebApplicationContext findCurrentApplicationContext()
+    {
+        ServletContext currentServletContext = findCurrentServletContext();
+
+        if (currentServletContext != null) {
+            WebApplicationContext webApplicationContext = WebApplicationContextUtils
+                        .findWebApplicationContext(currentServletContext);
+            if (webApplicationContext != null) {
+                return webApplicationContext;
+            }
+        }
+
+        return ContextLoader.getCurrentWebApplicationContext();
+    }
+
+    @Override
+    public int priority()
+    {
+        return 0;
+    }
+
+}

integration-spring/src/main/resources/META-INF/services/org.ocpsoft.rewrite.servlet.spi.ContextListener

@@ -0,0 +1 @@
+org.ocpsoft.rewrite.spring.SpringServletContextLoader

integration-spring/src/main/resources/META-INF/services/org.ocpsoft.rewrite.servlet.spi.RequestListener

@@ -0,0 +1 @@
+org.ocpsoft.rewrite.spring.SpringServletContextLoader