added unit tests to feign client

modules/swagger-codegen/src/main/resources/Java/libraries/feign/ApiClient.mustache

@@ -46,7 +46,7 @@ public class ApiClient {
    */
   public <T extends Api> T buildClient(Class<T> clientClass) {
         return Feign.builder()
-                .encoder(new JacksonEncoder(objectMapper))
+                .encoder(new FormAwareEncoder(new JacksonEncoder(objectMapper)))
                 .decoder(new JacksonDecoder(objectMapper))
 // enable for basic auth:
 //                .requestInterceptor(new feign.auth.BasicAuthRequestInterceptor(username, password))

modules/swagger-codegen/src/main/resources/Java/libraries/feign/FormAwareEncoder.mustache

@@ -0,0 +1,159 @@
+package {{invokerPackage}};
+
+import java.io.*;
+import java.lang.reflect.Type;
+import java.net.URLEncoder;
+import java.net.URLConnection;
+import java.util.*;
+
+import java.text.DateFormat;
+import java.text.SimpleDateFormat;
+
+import feign.codec.Encoder;
+import feign.RequestTemplate;
+
+{{>generatedAnnotation}}
+public class FormAwareEncoder implements Encoder {
+  private static final String LINE_FEED = "\r\n";
+  private static final String BOUNDARY = "----------------314159265358979323846";
+
+  private final Encoder delegate;
+  private DateFormat dateFormat;
+
+  public FormAwareEncoder(Encoder delegate) {
+    this.delegate = delegate;
+    // Use RFC3339 format for date and datetime.
+    // See http://xml2rfc.ietf.org/public/rfc/html/rfc3339.html#anchor14
+    this.dateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX");
+
+    // Use UTC as the default time zone.
+    this.dateFormat.setTimeZone(TimeZone.getTimeZone("UTC"));
+  }
+
+  public void encode(Object object, Type bodyType, RequestTemplate template) {
+    if (object instanceof Map) {
+      StringBuilder formParamBuilder = new StringBuilder();
+      Map<String, Object> formParams = (Map<String, Object>) object;
+      boolean isMultiPart = isMultiPart(formParams);
+      for (Map.Entry<String, Object> param : formParams.entrySet()) {
+        String keyStr = param.getKey();
+        if (param.getValue() instanceof File) {
+            addFilePart(formParamBuilder, keyStr, (File) param.getValue());
+        } else {
+          String valueStr = parameterToString(param.getValue());
+          if (isMultiPart) {
+            addMultiPartFormField(formParamBuilder, keyStr, valueStr);
+          } else {
+            addEncodedFormField(formParamBuilder, keyStr, valueStr);
+          }
+        }
+      }
+
+      if (isMultiPart) {
+        formParamBuilder.append(LINE_FEED);
+        formParamBuilder.append("--").append(BOUNDARY).append("--").append(LINE_FEED);
+      }
+
+      String contentType = isMultiPart ? "multipart/form-data; boundary=" + BOUNDARY : "application/x-www-form-urlencoded";
+      template.header("Content-type");
+      template.header("Content-type", contentType);
+      template.header("MIME-Version", "1.0");
+      template.body(formParamBuilder.toString());
+    } else {
+      delegate.encode(object, bodyType, template);
+    }
+  }
+
+  /*
+   * Currently only supports text files
+   */
+  private void addFilePart(StringBuilder formParamBuilder, String fieldName, File uploadFile) {
+    try {
+      String fileName = uploadFile.getName();
+      formParamBuilder.append("--").append(BOUNDARY).append(LINE_FEED);
+      formParamBuilder.append(
+        "Content-Disposition: form-data; name=\"" + fieldName
+          + "\"; filename=\"" + fileName + "\"")
+        .append(LINE_FEED);
+      formParamBuilder.append(
+        "Content-Type: "
+          + URLConnection.guessContentTypeFromName(fileName))
+        .append(LINE_FEED);
+      formParamBuilder.append(LINE_FEED);
+
+      BufferedReader reader = new BufferedReader(new FileReader(uploadFile));
+      String line = "";
+      while ((line = reader.readLine()) != null) {
+        formParamBuilder.append(line).append(LINE_FEED);
+      }
+
+      formParamBuilder.append(LINE_FEED);
+    } catch (IOException e) {
+      e.printStackTrace();
+    }
+  }
+
+  private void addEncodedFormField(StringBuilder formParamBuilder, String name, String value) {
+    if (formParamBuilder.length() > 0) {
+      formParamBuilder.append("&");
+    }
+
+    try {
+      formParamBuilder.append(URLEncoder.encode(name, "utf8"))
+        .append("=")
+        .append(URLEncoder.encode(value, "utf8"));
+    } catch (UnsupportedEncodingException e) {
+      // move on to next
+    }
+  }
+
+  private void addMultiPartFormField(StringBuilder formParamBuilder, String name, String value) {
+    formParamBuilder.append("--").append(BOUNDARY).append(LINE_FEED);
+    formParamBuilder.append("Content-Disposition: form-data; name=\"" + name + "\"")
+            .append(LINE_FEED);
+    formParamBuilder.append("Content-Type: text/plain; charset=utf-8").append(
+            LINE_FEED);
+    formParamBuilder.append(LINE_FEED);
+    formParamBuilder.append(value).append(LINE_FEED);
+  }
+
+  private boolean isMultiPart(Map<String, Object> formParams) {
+    boolean isMultiPart = false;
+    for (Map.Entry<String, Object> entry : formParams.entrySet()) {
+        if (entry.getValue() instanceof File) {
+            isMultiPart = true;
+            break;
+        }
+    }
+    return isMultiPart;
+  }
+
+  /**
+   * Format the given parameter object into string.
+   */
+  public String parameterToString(Object param) {
+    if (param == null) {
+      return "";
+    } else if (param instanceof Date) {
+      return formatDate((Date) param);
+    } else if (param instanceof Collection) {
+      StringBuilder b = new StringBuilder();
+      for(Object o : (Collection)param) {
+        if(b.length() > 0) {
+          b.append(",");
+        }
+        b.append(String.valueOf(o));
+      }
+      return b.toString();
+    } else {
+      return String.valueOf(param);
+    }
+  }
+
+  /**
+   * Format the given Date object into string.
+   */
+  public String formatDate(Date date) {
+    return dateFormat.format(date);
+  }
+}

modules/swagger-codegen/src/main/resources/Java/libraries/feign/api.mustache

@@ -25,10 +25,12 @@ public interface {{classname}} extends {{invokerPackage}}.ApiClient.Api {
    */
   @RequestLine("{{httpMethod}} {{{path}}}{{#hasQueryParams}}?{{/hasQueryParams}}{{#queryParams}}{{paramName}}={{=<% %>=}}{<%paramName%>}<%={{ }}=%>{{#hasMore}}&{{/hasMore}}{{/queryParams}}")
   @Headers({
-    {{#headerParams}}"{{paramName}}: {{=<% %>=}}{<%paramName%>}<%={{ }}=%>"{{#hasMore}},
+    "Content-type: {{vendorExtensions.x-contentType}}",
+    "Accepts: {{vendorExtensions.x-accepts}}",{{#headerParams}}
+    "{{paramName}}: {{=<% %>=}}{<%paramName%>}<%={{ }}=%>"{{#hasMore}},
     {{/hasMore}}{{/headerParams}}
   })
-  {{#returnType}}{{{returnType}}} {{/returnType}}{{^returnType}}void {{/returnType}}{{nickname}} ({{#allParams}}@Param("{{paramName}}") {{{dataType}}} {{paramName}}{{#hasMore}}, {{/hasMore}}{{/allParams}}) throws ApiException;
+  {{#returnType}}{{{returnType}}} {{/returnType}}{{^returnType}}void {{/returnType}}{{nickname}}({{#allParams}}{{^vendorExtensions.x-isBody}}@Param("{{paramName}}") {{/vendorExtensions.x-isBody}}{{{dataType}}} {{paramName}}{{#hasMore}}, {{/hasMore}}{{/allParams}}) throws ApiException;
   {{/operation}}
 {{/operations}}
 }