Java client: decouple JSON handling

Author: xhh

modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/JavaClientCodegen.java

@@ -116,9 +116,10 @@ public void processOpts() {
         supportingFiles.add(new SupportingFile("ApiClient.mustache", invokerFolder, "ApiClient.java"));
         supportingFiles.add(new SupportingFile("apiException.mustache", invokerFolder, "ApiException.java"));
         supportingFiles.add(new SupportingFile("Configuration.mustache", invokerFolder, "Configuration.java"));
-        supportingFiles.add(new SupportingFile("JsonUtil.mustache", invokerFolder, "JsonUtil.java"));
-        supportingFiles.add(new SupportingFile("StringUtil.mustache", invokerFolder, "StringUtil.java"));
+        supportingFiles.add(new SupportingFile("JSON.mustache", invokerFolder, "JSON.java"));
         supportingFiles.add(new SupportingFile("Pair.mustache", invokerFolder, "Pair.java"));
+        supportingFiles.add(new SupportingFile("StringUtil.mustache", invokerFolder, "StringUtil.java"));
+        supportingFiles.add(new SupportingFile("TypeRef.mustache", invokerFolder, "TypeRef.java"));
 
         final String authFolder = (sourceFolder + File.separator + invokerPackage + ".auth").replace(".", File.separator);
         supportingFiles.add(new SupportingFile("auth/Authentication.mustache", authFolder, "Authentication.java"));

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

@@ -1,9 +1,7 @@
 package {{invokerPackage}};
 
-import com.fasterxml.jackson.core.JsonGenerator.Feature;
 import com.fasterxml.jackson.databind.*;
 import com.fasterxml.jackson.annotation.*;
-import com.fasterxml.jackson.databind.annotation.JsonSerialize;
 
 import com.sun.jersey.api.client.Client;
 import com.sun.jersey.api.client.ClientResponse;
@@ -48,6 +46,7 @@ public class ApiClient {
   private Map<String, String> defaultHeaderMap = new HashMap<String, String>();
   private boolean debugging = false;
   private String basePath = "{{basePath}}";
+  private JSON json = new JSON();
 
   private Map<String, Authentication> authentications;
 
@@ -340,50 +339,38 @@ public class ApiClient {
   }
 
   /**
-   * Deserialize the given JSON string to Java object.
-   *
-   * @param json The JSON string
-   * @param containerType The container type, one of "list", "array" or ""
-   * @param cls The type of the Java object
-   * @return The deserialized Java object
+   * Serialize the given Java object into string according the given
+   * Content-Type (only JSON is supported for now).
    */
-  public Object deserialize(String json, String containerType, Class cls) throws ApiException {
-    if(null != containerType) {
-        containerType = containerType.toLowerCase();
-    }
-    try{
-      if("list".equals(containerType) || "array".equals(containerType)) {
-        JavaType typeInfo = JsonUtil.getJsonMapper().getTypeFactory().constructCollectionType(List.class, cls);
-        List response = (List<?>) JsonUtil.getJsonMapper().readValue(json, typeInfo);
-        return response;
-      }
-      else if(String.class.equals(cls)) {
-        if(json != null && json.startsWith("\"") && json.endsWith("\"") && json.length() > 1)
-          return json.substring(1, json.length() - 2);
-        else
-          return json;
-      }
-      else {
-        return JsonUtil.getJsonMapper().readValue(json, cls);
-      }
-    }
-    catch (IOException e) {
-      throw new ApiException(500, e.getMessage(), null, json);
+  public String serialize(Object obj, String contentType) throws ApiException {
+    if (contentType.startsWith("application/json")) {
+      return json.serialize(obj);
+    } else {
+      throw new ApiException(400, "can not serialize object into Content-Type: " + contentType);
     }
   }
 
   /**
-   * Serialize the given Java object into JSON string.
+   * Deserialize response body to Java object according to the Content-Type.
    */
-  public String serialize(Object obj) throws ApiException {
-    try {
-      if (obj != null)
-        return JsonUtil.getJsonMapper().writeValueAsString(obj);
-      else
-        return null;
-    }
-    catch (Exception e) {
-      throw new ApiException(500, e.getMessage());
+  public <T> T deserialize(ClientResponse response, TypeRef returnType) throws ApiException {
+    String contentType = null;
+    List<String> contentTypes = response.getHeaders().get("Content-Type");
+    if (contentTypes != null && !contentTypes.isEmpty())
+      contentType = contentTypes.get(0);
+    if (contentType == null)
+      throw new ApiException(500, "missing Content-Type in response");
+
+    String body;
+    if (response.hasEntity())
+      body = (String) response.getEntity(String.class);
+    else
+      body = "";
+
+    if (contentType.startsWith("application/json")) {
+      return json.deserialize(body, returnType);
+    } else {
+      throw new ApiException(500, "can not deserialize Content-Type: " + contentType);
     }
   }
 
@@ -399,9 +386,10 @@ public class ApiClient {
    * @param accept The request's Accept header
    * @param contentType The request's Content-Type header
    * @param authNames The authentications to apply
+   * @param returnType The return type into which to deserialize the response
    * @return The response body in type of string
    */
-  public String invokeAPI(String path, String method, List<Pair> queryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String accept, String contentType, String[] authNames) throws ApiException {
+  public <T> T invokeAPI(String path, String method, List<Pair> queryParams, Object body, Map<String, String> headerParams, Map<String, Object> formParams, String accept, String contentType, String[] authNames, TypeRef returnType) throws ApiException {
     updateParamsForAuth(authNames, queryParams, headerParams);
 
     Client client = getClient();
@@ -465,23 +453,23 @@ public class ApiClient {
       } else if (body instanceof FormDataMultiPart) {
         response = builder.type(contentType).post(ClientResponse.class, body);
       } else {
-        response = builder.type(contentType).post(ClientResponse.class, serialize(body));
+        response = builder.type(contentType).post(ClientResponse.class, serialize(body, contentType));
       }
     } else if ("PUT".equals(method)) {
       if (encodedFormParams != null) {
         response = builder.type(contentType).put(ClientResponse.class, encodedFormParams);
       } else if(body == null) {
-        response = builder.put(ClientResponse.class, serialize(body));
+        response = builder.put(ClientResponse.class, serialize(body, contentType));
       } else {
-        response = builder.type(contentType).put(ClientResponse.class, serialize(body));
+        response = builder.type(contentType).put(ClientResponse.class, serialize(body, contentType));
       }
     } else if ("DELETE".equals(method)) {
       if (encodedFormParams != null) {
         response = builder.type(contentType).delete(ClientResponse.class, encodedFormParams);
       } else if(body == null) {
         response = builder.delete(ClientResponse.class);
       } else {
-        response = builder.type(contentType).delete(ClientResponse.class, serialize(body));
+        response = builder.type(contentType).delete(ClientResponse.class, serialize(body, contentType));
       }
     } else {
       throw new ApiException(500, "unknown method type " + method);
@@ -490,11 +478,10 @@ public class ApiClient {
     if (response.getStatusInfo() == ClientResponse.Status.NO_CONTENT) {
       return null;
     } else if (response.getStatusInfo().getFamily() == Family.SUCCESSFUL) {
-      if (response.hasEntity()) {
-        return (String) response.getEntity(String.class);
-      } else {
-        return "";
-      }
+      if (returnType == null)
+        return null;
+      else
+        return deserialize(response, returnType);
     } else {
       String message = "error";
       String respBody = null;

modules/swagger-codegen/src/main/resources/Java/JSON.mustache

@@ -0,0 +1,51 @@
+package {{invokerPackage}};
+
+import com.fasterxml.jackson.annotation.*;
+import com.fasterxml.jackson.databind.*;
+import com.fasterxml.jackson.datatype.joda.*;
+
+import java.io.IOException;
+
+public class JSON {
+  private ObjectMapper mapper;
+
+  public JSON() {
+    mapper = new ObjectMapper();
+    mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
+    mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
+    mapper.registerModule(new JodaModule());
+	}
+
+  /**
+   * Serialize the given Java object into JSON string.
+   */
+  public String serialize(Object obj) throws ApiException {
+    try {
+      if (obj != null)
+        return mapper.writeValueAsString(obj);
+      else
+        return null;
+    } catch (Exception e) {
+      throw new ApiException(400, e.getMessage());
+    }
+  }
+
+  /**
+   * Deserialize the given JSON string to Java object.
+   *
+   * @param body The JSON string
+   * @param returnType The type to deserialize inot
+   * @return The deserialized Java object
+   */
+  public <T> T deserialize(String body, TypeRef returnType) throws ApiException {
+    JavaType javaType = mapper.constructType(returnType.getType());
+    try {
+      return mapper.readValue(body, javaType);
+    } catch (IOException e) {
+      if (returnType.getType().equals(String.class))
+        return (T) body;
+      else
+        throw new ApiException(500, e.getMessage(), null, body);
+    }
+  }
+}

modules/swagger-codegen/src/main/resources/Java/JsonUtil.mustache

@@ -0,0 +1,25 @@
+package {{invokerPackage}};
+
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+
+public class TypeRef<T> {
+    private final Type type;
+
+    public TypeRef() {
+        this.type = getGenericType(getClass());
+    }
+
+    private static Type getGenericType(Class<?> klass) {
+        Type superclass = klass.getGenericSuperclass();
+        if (superclass instanceof Class) {
+            throw new RuntimeException("No type parameter provided");
+        }
+        ParameterizedType parameterized = (ParameterizedType) superclass;
+        return parameterized.getActualTypeArguments()[0];
+    }
+
+    public Type getType() {
+        return type;
+    }
+}

modules/swagger-codegen/src/main/resources/Java/TypeRef.mustache

@@ -4,6 +4,7 @@ import {{invokerPackage}}.ApiException;
 import {{invokerPackage}}.ApiClient;
 import {{invokerPackage}}.Configuration;
 import {{invokerPackage}}.Pair;
+import {{invokerPackage}}.TypeRef;
 
 import {{modelPackage}}.*;
 
@@ -83,18 +84,13 @@ public class {{classname}} {
     };
     final String contentType = apiClient.selectHeaderContentType(contentTypes);
 
-    try {
-      String[] authNames = new String[] { {{#authMethods}}"{{name}}"{{#hasMore}}, {{/hasMore}}{{/authMethods}} };
-      String response = apiClient.invokeAPI(path, "{{httpMethod}}", queryParams, postBody, headerParams, formParams, accept, contentType, authNames);
-      if(response != null){
-        return {{#returnType}}({{{returnType}}}) apiClient.deserialize(response, "{{returnContainer}}", {{returnBaseType}}.class){{/returnType}};
-      }
-      else {
-        return {{#returnType}}null{{/returnType}};
-      }
-    } catch (ApiException ex) {
-      throw ex;
-    }
+    String[] authNames = new String[] { {{#authMethods}}"{{name}}"{{#hasMore}}, {{/hasMore}}{{/authMethods}} };
+    {{#returnType}}
+    TypeRef returnType = new TypeRef<{{{returnType}}}>() {};
+    return apiClient.invokeAPI(path, "{{httpMethod}}", queryParams, postBody, headerParams, formParams, accept, contentType, authNames, returnType);
+    {{/returnType}}{{^returnType}}
+    apiClient.invokeAPI(path, "{{httpMethod}}", queryParams, postBody, headerParams, formParams, accept, contentType, authNames, null);
+    {{/returnType}}
   }
   {{/operation}}
 }