Fix NullPointerException when equals or hashCode are called on proxy instance

davidmc24 · davidmc24 · commit a7128264c813 · 2013-08-30T16:56:45.000-04:00
They look something like this:

java.lang.NullPointerException
	at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:88)
	at feign.$Proxy16.equals(Unknown Source)

In  my particular instance, I had a proxy created by Feign registered in a Spring application context,
and it resulted in a NullPointerException on application shutdown.
diff --git a/CHANGES.md b/CHANGES.md
@@ -1,3 +1,6 @@
+### Version 4.4.1
+* Fix NullPointerException on calling equals and hashCode.
+
 ### Version 4.4
 * Support overriding default HostnameVerifier.
 * Support GZIP content encoding for request bodies.
diff --git a/core/src/main/java/feign/ReflectiveFeign.java b/core/src/main/java/feign/ReflectiveFeign.java
@@ -85,6 +85,17 @@ static class FeignInvocationHandler implements InvocationHandler {
     }
 
     @Override public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+      if ("equals".equals(method.getName())) {
+        try {
+          Object otherHandler = args.length > 0 && args[0] != null ? Proxy.getInvocationHandler(args[0]) : null;
+          return equals(otherHandler);
+        } catch (IllegalArgumentException e) {
+          return false;
+        }
+      }
+      if ("hashCode".equals(method.getName())) {
+        return hashCode();
+      }
       return methodToHandler.get(method).invoke(args);
     }
 
@@ -93,10 +104,15 @@ static class FeignInvocationHandler implements InvocationHandler {
     }
 
     @Override public boolean equals(Object obj) {
-      if (this == obj)
+      if (obj == null) {
+        return false;
+      }
+      if (this == obj) {
         return true;
-      if (FeignInvocationHandler.class != obj.getClass())
+      }
+      if (FeignInvocationHandler.class != obj.getClass()) {
         return false;
+      }
       FeignInvocationHandler that = FeignInvocationHandler.class.cast(obj);
       return this.target.equals(that.target);
     }
diff --git a/core/src/test/java/feign/FeignTest.java b/core/src/test/java/feign/FeignTest.java
@@ -51,6 +51,7 @@
 import static dagger.Provides.Type.SET;
 import static feign.Util.UTF_8;
 import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertFalse;
 import static org.testng.Assert.assertNull;
 import static org.testng.Assert.assertTrue;
 import static org.testng.Assert.fail;
@@ -135,6 +136,10 @@ public void iterableQueryParams() throws IOException, InterruptedException {
     }
   }
 
+  interface OtherTestInterface {
+    @RequestLine("POST /") String post();
+  }
+
   @Test
   public void observableVoid() throws IOException, InterruptedException {
     final MockWebServer server = new MockWebServer();
@@ -629,4 +634,19 @@ static class DisableHostnameVerification {
       server.shutdown();
     }
   }
+
+  @Test public void equalsAndHashCodeWork() {
+    TestInterface i1 = Feign.create(TestInterface.class, "http://localhost:8080", new TestInterface.Module());
+    TestInterface i2 = Feign.create(TestInterface.class, "http://localhost:8080", new TestInterface.Module());
+    TestInterface i3 = Feign.create(TestInterface.class, "http://localhost:8888", new TestInterface.Module());
+    OtherTestInterface i4 = Feign.create(OtherTestInterface.class, "http://localhost:8080");
+
+    assertTrue(i1.equals(i1));
+    assertTrue(i1.equals(i2));
+    assertFalse(i1.equals(i3));
+    assertFalse(i1.equals(i4));
+
+    assertEquals(i1.hashCode(), i1.hashCode());
+    assertEquals(i1.hashCode(), i2.hashCode());
+  }
 }
