fix: Dispatch to the given servlet when using getNamedDispatcher

aws-serverless-java-container-core/src/main/java/com/amazonaws/serverless/proxy/internal/servlet/AwsProxyRequestDispatcher.java

@@ -80,7 +80,7 @@ public void forward(ServletRequest servletRequest, ServletResponse servletRespon
         }
 
         if (isNamedDispatcher) {
-            lambdaContainerHandler.doFilter((HttpServletRequest) servletRequest, (HttpServletResponse) servletResponse, getServlet((HttpServletRequest)servletRequest));
+            lambdaContainerHandler.doFilter((HttpServletRequest) servletRequest, (HttpServletResponse) servletResponse, getServlet(dispatchTo));
             return;
         }
 
@@ -148,4 +148,9 @@ void setRequestPath(ServletRequest req, final String destinationPath) {
     private Servlet getServlet(HttpServletRequest req) {
         return ((AwsServletContext)lambdaContainerHandler.getServletContext()).getServletForPath(req.getPathInfo());
     }
+
+    private Servlet getServlet(String servletName) throws ServletException {
+        return ((AwsServletContext)lambdaContainerHandler.getServletContext()).getServlet(servletName);
+    }
+
 }

aws-serverless-java-container-core/src/main/java/com/amazonaws/serverless/proxy/internal/servlet/AwsServletContext.java

@@ -171,7 +171,7 @@ public RequestDispatcher getRequestDispatcher(String s) {
 
     @Override
     public RequestDispatcher getNamedDispatcher(String s) {
-        throw new UnsupportedOperationException();
+        return new AwsProxyRequestDispatcher(s, true, containerHandler);
     }
 
 

aws-serverless-java-container-core/src/main/java/com/amazonaws/serverless/proxy/internal/servlet/FilterChainManager.java

@@ -132,7 +132,7 @@ FilterChainHolder getFilterChain(final HttpServletRequest request, Servlet servl
             chainHolder.addFilter(new FilterHolder(new ServletExecutionFilter(servletRegistration), servletContext));
         }
 
-        putFilterChainCache(type, targetPath, chainHolder);
+        putFilterChainCache(type, targetPath, servlet, chainHolder);
         // update total filter size
         if (filtersSize != registrations.size()) {
             filtersSize = registrations.size();
@@ -151,13 +151,16 @@ FilterChainHolder getFilterChain(final HttpServletRequest request, Servlet servl
      * initialized with the cached list of {@link FilterHolder} objects
      * @param type The dispatcher type for the incoming request
      * @param targetPath The request path - this is extracted with the <code>getPath</code> method of the request object
-     * @param servlet Servlet to put at the end of the chain (optional).
+     * @param servlet The final servlet in the filter chain (if any)
      * @return A populated FilterChainHolder
      */
     private FilterChainHolder getFilterChainCache(final DispatcherType type, final String targetPath, Servlet servlet) {
         TargetCacheKey key = new TargetCacheKey();
         key.setDispatcherType(type);
         key.setTargetPath(targetPath);
+        if (servlet != null) {
+            key.setServletName(servlet.getServletConfig().getServletName());
+        }
 
         if (!filterCache.containsKey(key)) {
             return null;
@@ -174,12 +177,16 @@ private FilterChainHolder getFilterChainCache(final DispatcherType type, final S
      * method to retry this.
      * @param type DispatcherType from the incoming request
      * @param targetPath The target path in the API
-     * @param holder The FilterChainHolder object to save in the cache
+     * @param servlet The final servlet in the filter chain (if any)
+    * @param holder The FilterChainHolder object to save in the cache
      */
-    private void putFilterChainCache(final DispatcherType type, final String targetPath, final FilterChainHolder holder) {
+    private void putFilterChainCache(final DispatcherType type, final String targetPath, Servlet servlet, final FilterChainHolder holder) {
         TargetCacheKey key = new TargetCacheKey();
         key.setDispatcherType(type);
         key.setTargetPath(targetPath);
+        if (servlet != null) {
+            key.setServletName(servlet.getServletConfig().getServletName());
+        }
 
         // we couldn't compute the hash code because either the target path or dispatcher type were null
         if (key.hashCode() == -1) {
@@ -256,6 +263,7 @@ protected static class TargetCacheKey {
 
         private String targetPath;
         private DispatcherType dispatcherType;
+        private String servletName;
 
 
     //-------------------------------------------------------------
@@ -295,10 +303,15 @@ public int hashCode() {
             }
             hashString += ":" + hashDispatcher;
 
+            if (servletName != null) {
+                hashString += ":" + servletName;
+            }
+
             return hashString.hashCode();
         }
 
 
+
         @Override
         public boolean equals(Object key) {
             if (key == null) {
@@ -324,6 +337,11 @@ void setTargetPath(String targetPath) {
         void setDispatcherType(DispatcherType dispatcherType) {
             this.dispatcherType = dispatcherType;
         }
+        public void setServletName(String servletName) {
+            this.servletName = servletName;
+        }
+
+
     }
 
     @SuppressFBWarnings("URF_UNREAD_FIELD")

aws-serverless-java-container-core/src/main/java/com/amazonaws/serverless/proxy/internal/testutils/MockServlet.java

@@ -0,0 +1,23 @@
+package com.amazonaws.serverless.proxy.internal.testutils;
+
+import java.io.IOException;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+public class MockServlet extends HttpServlet {
+
+    private int serviceCalls = 0;
+
+    @Override
+    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
+        super.service(req, resp);
+        serviceCalls++;
+    }
+
+    public int getServiceCalls() {
+        return serviceCalls;
+    }
+}

aws-serverless-java-container-core/src/test/java/com/amazonaws/serverless/proxy/internal/servlet/AwsFilterChainManagerTest.java

@@ -2,6 +2,7 @@
 
 import com.amazonaws.serverless.proxy.internal.testutils.AwsProxyRequestBuilder;
 import com.amazonaws.serverless.proxy.internal.testutils.MockLambdaContext;
+import com.amazonaws.serverless.proxy.internal.testutils.MockServlet;
 import com.amazonaws.services.lambda.runtime.Context;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
@@ -17,6 +18,8 @@
 import static org.junit.jupiter.api.Assertions.*;
 
 public class AwsFilterChainManagerTest {
+    private static final String SERVLET1_NAME = "Servlet 1";
+    private static final String SERVLET2_NAME = "Servlet 2";
     private static final String REQUEST_CUSTOM_ATTRIBUTE_NAME = "X-Custom-Attribute";
     private static final String REQUEST_CUSTOM_ATTRIBUTE_VALUE = "CustomAttrValue";
 
@@ -36,6 +39,10 @@ public static void setUp() {
         reg2.addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST), true, "/second/*");
         FilterRegistration.Dynamic reg3 = servletContext.addFilter("Filter3", new MockFilter());
         reg3.addMappingForUrlPatterns(EnumSet.of(DispatcherType.REQUEST), true, "/third/fourth/*");
+        ServletRegistration.Dynamic firstServlet = servletContext.addServlet(SERVLET1_NAME, new MockServlet());
+        firstServlet.addMapping("/first/*");
+        ServletRegistration.Dynamic secondServlet = servletContext.addServlet(SERVLET2_NAME, new MockServlet());
+        secondServlet.addMapping("/second/*");
 
         chainManager = new AwsFilterChainManager((AwsServletContext) servletContext);
     }
@@ -88,6 +95,22 @@ void cacheKey_compare_differentDispatcher() {
         assertNotEquals(cacheKey, secondCacheKey);
     }
 
+    @Test
+    void cacheKey_compare_differentServlet() {
+        FilterChainManager.TargetCacheKey cacheKey = new FilterChainManager.TargetCacheKey();
+        cacheKey.setDispatcherType(DispatcherType.REQUEST);
+        cacheKey.setTargetPath("/first/path");
+        cacheKey.setServletName("Dispatcher servlet");
+
+        FilterChainManager.TargetCacheKey secondCacheKey = new FilterChainManager.TargetCacheKey();
+        secondCacheKey.setDispatcherType(DispatcherType.REQUEST);
+        secondCacheKey.setTargetPath("/first/path");
+        cacheKey.setServletName("Real servlet");
+
+        assertNotEquals(cacheKey.hashCode(), secondCacheKey.hashCode());
+        assertNotEquals(cacheKey, secondCacheKey);
+    }
+
     @Test
     void cacheKey_compare_additionalChars() {
         FilterChainManager.TargetCacheKey cacheKey = new FilterChainManager.TargetCacheKey();
@@ -154,7 +177,7 @@ void filterChain_matchMultipleTimes_expectSameMatch() {
     }
 
     @Test
-    void filerChain_executeMultipleFilters_expectRunEachTime() {
+    void filterChain_executeMultipleFilters_expectRunEachTime() {
         AwsProxyHttpServletRequest req = new AwsProxyHttpServletRequest(
                 new AwsProxyRequestBuilder("/first/second", "GET").build(), lambdaContext, null
         );
@@ -204,6 +227,34 @@ void filerChain_executeMultipleFilters_expectRunEachTime() {
         assertEquals(REQUEST_CUSTOM_ATTRIBUTE_VALUE, req2.getAttribute(REQUEST_CUSTOM_ATTRIBUTE_NAME));
     }
 
+    @Test
+    void filterChain_multipleServlets_callsCorrectServlet() throws IOException, ServletException {
+        MockServlet servlet1 = (MockServlet) servletContext.getServlet(SERVLET1_NAME);
+        ServletConfig servlet1Config = ((AwsServletRegistration) servletContext.getServletRegistration(SERVLET1_NAME)).getServletConfig();
+        servlet1.init(servlet1Config);
+
+        MockServlet servlet2 = (MockServlet) servletContext.getServlet(SERVLET2_NAME);
+        ServletConfig servlet2Config = ((AwsServletRegistration) servletContext.getServletRegistration(SERVLET2_NAME)).getServletConfig();
+        servlet2.init(servlet2Config);
+
+        AwsProxyHttpServletRequest req = new AwsProxyHttpServletRequest(
+                new AwsProxyRequestBuilder("/", "GET").build(), lambdaContext, null
+        );
+        AwsHttpServletResponse resp = new AwsHttpServletResponse(req, new CountDownLatch(1));
+
+        FilterChainHolder servlet1filterChain = chainManager.getFilterChain(req, servlet1);
+        servlet1filterChain.doFilter(req, resp);
+
+        assertEquals(1, servlet1.getServiceCalls());
+        assertEquals(0, servlet2.getServiceCalls());
+
+        FilterChainHolder servlet2filterChain = chainManager.getFilterChain(req, servlet2);
+        servlet2filterChain.doFilter(req, resp);
+
+        assertEquals(1, servlet1.getServiceCalls());
+        assertEquals(1, servlet2.getServiceCalls());
+    }
+
     @Test
     void filterChain_getFilterChain_multipleFilters() {
         AwsProxyHttpServletRequest req = new AwsProxyHttpServletRequest(

aws-serverless-java-container-core/src/test/java/com/amazonaws/serverless/proxy/internal/servlet/AwsServletContextTest.java

@@ -13,12 +13,7 @@
 import javax.servlet.http.HttpServletResponse;
 
 import java.io.File;
-import java.io.FileNotFoundException;
 import java.io.IOException;
-import java.io.PrintWriter;
-import java.io.UnsupportedEncodingException;
-import java.nio.file.Files;
-import java.nio.file.Paths;
 import java.util.concurrent.CountDownLatch;
 
 import static org.junit.jupiter.api.Assertions.*;
@@ -190,12 +185,7 @@ void unsupportedOperations_expectExceptions() {
         } catch (UnsupportedOperationException e) {
             exCount++;
         }
-        try {
-            STATIC_CTX.getNamedDispatcher("1");
-        } catch (UnsupportedOperationException e) {
-            exCount++;
-        }
-        assertEquals(2, exCount);
+        assertEquals(1, exCount);
 
         assertNull(STATIC_CTX.getServletRegistration("1"));
     }
@@ -232,6 +222,12 @@ void addServlet_callsDefaultConstructor() throws ServletException {
         assertEquals("", ((TestServlet)ctx.getServlet("srv1")).getId());
     }
 
+    @Test
+    void getNamedDispatcher_returnsDispatcher() {
+        AwsServletContext ctx = new AwsServletContext(null);
+        assertNotNull(ctx.getNamedDispatcher("/hello"));
+    }
+
     public static class TestServlet implements Servlet {
         private String id;