From 2819b9bab4bf660a969954993d3ce5d2cb270c4c Mon Sep 17 00:00:00 2001
From: Michael Edgar <michael@xlate.io>
Date: Tue, 21 Dec 2021 07:27:24 -0500
Subject: [PATCH] Allow loading included schemas on the class-path

---
 .../schema/ClasspathURLStreamHandler.java     | 28 +++++++++++++
 .../edi/internal/schema/SchemaReaderV4.java   | 13 +++++-
 .../schema/ClasspathURLStreamHandlerTest.java | 40 +++++++++++++++++++
 .../x12/005010X222/837_REF_impls.xml          |  2 +-
 .../x12/005010X222/837_loop1000_only.xml      |  2 +-
 5 files changed, 82 insertions(+), 3 deletions(-)
 create mode 100644 src/main/java/io/xlate/edi/internal/schema/ClasspathURLStreamHandler.java
 create mode 100644 src/test/java/io/xlate/edi/internal/schema/ClasspathURLStreamHandlerTest.java

diff --git a/src/main/java/io/xlate/edi/internal/schema/ClasspathURLStreamHandler.java b/src/main/java/io/xlate/edi/internal/schema/ClasspathURLStreamHandler.java
new file mode 100644
index 00000000..bb695212
--- /dev/null
+++ b/src/main/java/io/xlate/edi/internal/schema/ClasspathURLStreamHandler.java
@@ -0,0 +1,28 @@
+package io.xlate.edi.internal.schema;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.net.URL;
+import java.net.URLConnection;
+import java.net.URLStreamHandler;
+
+class ClasspathURLStreamHandler extends URLStreamHandler {
+    /** The classloader to find resources from. */
+    private final ClassLoader classLoader;
+
+    public ClasspathURLStreamHandler(ClassLoader classLoader) {
+        this.classLoader = classLoader;
+    }
+
+    @Override
+    protected URLConnection openConnection(URL u) throws IOException {
+        final String resourcePath = u.getPath();
+        final URL resourceUrl = classLoader.getResource(resourcePath);
+
+        if (resourceUrl == null) {
+            throw new FileNotFoundException("Class-path resource not found: " + resourcePath);
+        }
+
+        return resourceUrl.openConnection();
+    }
+}
diff --git a/src/main/java/io/xlate/edi/internal/schema/SchemaReaderV4.java b/src/main/java/io/xlate/edi/internal/schema/SchemaReaderV4.java
index 5febfb48..aaf6f476 100644
--- a/src/main/java/io/xlate/edi/internal/schema/SchemaReaderV4.java
+++ b/src/main/java/io/xlate/edi/internal/schema/SchemaReaderV4.java
@@ -48,7 +48,18 @@ protected void readInclude(XMLStreamReader reader, Map<String, EDIType> types) t
                 }
             }
 
-            URL schemaLocation = context != null ? new URL(context, location) : new URL(location);
+            URL schemaLocation;
+
+            if (location.startsWith("classpath:")) {
+                ClassLoader loader = Thread.currentThread().getContextClassLoader();
+                if (location.startsWith("classpath:/")) {
+                    location = location.substring(0, "classpath:".length()) + location.substring("classpath:/".length());
+                }
+                schemaLocation = new URL(null, location, new ClasspathURLStreamHandler(loader));
+            } else {
+                schemaLocation = new URL(context, location);
+            }
+
             types.putAll(StaEDISchemaFactory.readSchemaTypes(schemaLocation, super.properties));
             reader.nextTag(); // End of include
         } catch (Exception e) {
diff --git a/src/test/java/io/xlate/edi/internal/schema/ClasspathURLStreamHandlerTest.java b/src/test/java/io/xlate/edi/internal/schema/ClasspathURLStreamHandlerTest.java
new file mode 100644
index 00000000..7d791257
--- /dev/null
+++ b/src/test/java/io/xlate/edi/internal/schema/ClasspathURLStreamHandlerTest.java
@@ -0,0 +1,40 @@
+package io.xlate.edi.internal.schema;
+
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLConnection;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class ClasspathURLStreamHandlerTest {
+
+    ClasspathURLStreamHandler cut;
+
+    @BeforeEach
+    void setup() {
+        cut = new ClasspathURLStreamHandler(getClass().getClassLoader());
+    }
+
+    @Test
+    void testResourceUrlResolvesNull() throws MalformedURLException {
+        URL target = new URL(null, "classpath:does/not/exist.txt", cut);
+        @SuppressWarnings("unused")
+        FileNotFoundException ex = assertThrows(FileNotFoundException.class, () -> {
+            target.openConnection();
+        });
+    }
+
+    @Test
+    void testResourceUrlFound() throws IOException {
+        URL target = new URL(null, "classpath:logging.properties", cut);
+        URLConnection connection = target.openConnection();
+        assertNotNull(connection);
+    }
+
+}
diff --git a/src/test/resources/x12/005010X222/837_REF_impls.xml b/src/test/resources/x12/005010X222/837_REF_impls.xml
index d27d6579..4e71e66f 100644
--- a/src/test/resources/x12/005010X222/837_REF_impls.xml
+++ b/src/test/resources/x12/005010X222/837_REF_impls.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
 <schema xmlns="http://xlate.io/EDISchema/v4">
 
-  <include schemaLocation="file:./target/test-classes/x12/005010/837.xml"/>
+  <include schemaLocation="classpath:/x12/005010/837.xml"/>
 
   <implementation>
     <sequence>
diff --git a/src/test/resources/x12/005010X222/837_loop1000_only.xml b/src/test/resources/x12/005010X222/837_loop1000_only.xml
index a1355d67..8a284553 100644
--- a/src/test/resources/x12/005010X222/837_loop1000_only.xml
+++ b/src/test/resources/x12/005010X222/837_loop1000_only.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
 <schema xmlns="http://xlate.io/EDISchema/v4">
 
-  <include schemaLocation="file:./target/test-classes/x12/005010/837.xml"/>
+  <include schemaLocation="classpath:x12/005010/837.xml"/>
 
   <implementation>
     <sequence>