#64 - [client generation] Generate services file and HttpApiProvider inner class

Author: rbygrave

http-generator-client/src/main/java/io/avaje/http/generator/client/ClientProcessor.java

@@ -12,13 +12,19 @@
 import javax.lang.model.element.AnnotationValue;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.TypeElement;
+import javax.tools.FileObject;
 import java.io.IOException;
+import java.io.Writer;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 
 public class ClientProcessor extends AbstractProcessor {
 
+  private static final String METAINF_SERVICES_PROVIDER = "META-INF/services/io.avaje.http.client.HttpApiProvider";
+
+  private final Set<String> generatedClients = new LinkedHashSet<>();
+
   protected ProcessingContext ctx;
 
   @Override
@@ -49,15 +55,30 @@ public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment
     for (Element importedElement : round.getElementsAnnotatedWith(Client.Import.class)) {
       writeForImported(importedElement);
     }
+    if (round.processingOver()) {
+      writeServicesFile();
+    }
     return false;
   }
 
+  private void writeServicesFile() {
+    try {
+      final FileObject metaInfWriter = ctx.createMetaInfWriter(METAINF_SERVICES_PROVIDER);
+      final Writer writer = metaInfWriter.openWriter();
+      for (String generatedClient : generatedClients) {
+        writer.append(generatedClient).append("$Provider\n");
+      }
+      writer.close();
+    } catch (IOException e) {
+      ctx.logError(null, "Error writing services file " + e, e);
+    }
+  }
+
   private void writeForImported(Element importedElement) {
     for (AnnotationMirror annotationMirror : importedElement.getAnnotationMirrors()) {
       for (AnnotationValue value : annotationMirror.getElementValues().values()) {
         for (Object apiClassDef : (List<?>) value.getValue()) {
-          String fullName = apiClassDef.toString();
-          writeImported(fullName);
+          writeImported(apiClassDef.toString());
         }
       }
     }
@@ -66,7 +87,6 @@ private void writeForImported(Element importedElement) {
   private void writeImported(String fullName) {
     // trim .class suffix
     String apiClassName = fullName.substring(0, fullName.length() - 6);
-    //ctx.logError(null, "build import:" + apiClassName);
     TypeElement typeElement = ctx.getTypeElement(apiClassName);
     if (typeElement != null) {
       writeClient(typeElement);
@@ -78,16 +98,16 @@ private void writeClient(Element controller) {
       ControllerReader reader = new ControllerReader((TypeElement) controller, ctx);
       reader.read(false);
       try {
-        writeClientAdapter(ctx, reader);
+        generatedClients.add(writeClientAdapter(ctx, reader));
       } catch (Throwable e) {
         e.printStackTrace();
         ctx.logError(reader.getBeanType(), "Failed to write client class " + e);
       }
     }
   }
 
-  protected void writeClientAdapter(ProcessingContext ctx, ControllerReader reader) throws IOException {
-    new ClientWriter(reader, ctx).write();
+  protected String writeClientAdapter(ProcessingContext ctx, ControllerReader reader) throws IOException {
+    return new ClientWriter(reader, ctx).write();
   }
 
 }

http-generator-client/src/main/java/io/avaje/http/generator/client/ClientWriter.java

@@ -15,6 +15,8 @@
 class ClientWriter extends BaseControllerWriter {
 
   private static final String HTTP_CLIENT_CONTEXT = "io.avaje.http.client.HttpClientContext";
+  private static final String HTTP_API_PROVIDER = "io.avaje.http.client.HttpApiProvider";
+
   private static final String AT_GENERATED = "@Generated(\"avaje-http-client-generator\")";
   private static final String SUFFIX = "$HttpClient";
 
@@ -23,6 +25,7 @@ class ClientWriter extends BaseControllerWriter {
   ClientWriter(ControllerReader reader, ProcessingContext ctx) throws IOException {
     super(reader, ctx, SUFFIX);
     reader.addImportType(HTTP_CLIENT_CONTEXT);
+    reader.addImportType(HTTP_API_PROVIDER);
     readMethods();
   }
 
@@ -42,12 +45,27 @@ private void readMethods() {
     }
   }
 
-  void write() {
+  String write() {
     writePackage();
     writeImports();
     writeClassStart();
     writeMethods();
+    writeProvider();
     writeClassEnd();
+    return fullName;
+  }
+
+  private void writeProvider() {
+    writer.append("  public static class Provider implements HttpApiProvider<%s> {", shortName).eol();
+    writer.append("    @Override").eol();
+    writer.append("    public Class<%s> type() {", shortName).eol();
+    writer.append("      return %s.class;", shortName).eol();
+    writer.append("    }").eol();
+    writer.append("    @Override").eol();
+    writer.append("    public %s provide(HttpClientContext client) {", shortName).eol();
+    writer.append("      return new %s$HttpClient(client);", shortName).eol();
+    writer.append("    }").eol();
+    writer.append("  }").eol();
   }
 
   private void writeMethods() {

http-generator-core/src/main/java/io/avaje/http/generator/core/ProcessingContext.java

@@ -5,15 +5,16 @@
 import javax.annotation.processing.Filer;
 import javax.annotation.processing.Messager;
 import javax.annotation.processing.ProcessingEnvironment;
-import javax.lang.model.SourceVersion;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.type.DeclaredType;
 import javax.lang.model.type.TypeMirror;
 import javax.lang.model.util.Elements;
 import javax.lang.model.util.Types;
 import javax.tools.Diagnostic;
+import javax.tools.FileObject;
 import javax.tools.JavaFileObject;
+import javax.tools.StandardLocation;
 import java.io.IOException;
 
 public class ProcessingContext {
@@ -59,6 +60,13 @@ public JavaFileObject createWriter(String cls, Element origin) throws IOExceptio
     return filer.createSourceFile(cls, origin);
   }
 
+  /**
+   * Create a file writer for the META-INF services file.
+   */
+  public FileObject createMetaInfWriter(String target) throws IOException {
+    return filer.createResource(StandardLocation.CLASS_OUTPUT, "", target);
+  }
+
   public String getDocComment(Element param) {
     return elements.getDocComment(param);
   }