Add Watch support

Author: mbohlool

examples/src/main/java/io/kubernetes/client/examples/WatchExample.java

@@ -0,0 +1,44 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package io.kubernetes.client.examples;
+
+import com.google.gson.reflect.TypeToken;
+import io.kubernetes.client.ApiClient;
+import io.kubernetes.client.Watch;
+import io.kubernetes.client.ApiException;
+import io.kubernetes.client.Configuration;
+import io.kubernetes.client.apis.CoreV1Api;
+import io.kubernetes.client.models.V1Namespace;
+import io.kubernetes.client.util.Config;
+
+import java.io.IOException;
+
+/**
+ * A simple example of how to use Watch API to watch changes in Namespace list.
+ */
+public class WatchExample {
+    public static void main(String[] args) throws IOException, ApiException{
+        ApiClient client = Config.defaultClient();
+        Configuration.setDefaultApiClient(client);
+
+        CoreV1Api api = new CoreV1Api();
+
+        Watch<V1Namespace> watch = client.watch(
+                api.listNamespaceCall(null, null, null, null, 5, Boolean.TRUE, null, null),
+                new TypeToken<Watch.Response<V1Namespace>>(){}.getType());
+
+        for (Watch.Response<V1Namespace> item : watch) {
+            System.out.printf("%s : %s%n", item.type, item.object.getMetadata().getName());
+        }
+    }
+}

kubernetes/src/main/java/io/kubernetes/client/ApiClient.java

@@ -949,6 +949,26 @@ public File prepareDownloadFile(Response response) throws IOException {
             return File.createTempFile(prefix, suffix, new File(tempFolderPath));
     }
 
+    public <T> Watch<T> watch(Call call, Type watchType) throws ApiException {
+        try {
+            Response response = call.execute();
+            if (!response.isSuccessful()) {
+                String respBody = null;
+                if (response.body() != null) {
+                    try {
+                        respBody = response.body().string();
+                    } catch (IOException e) {
+                        throw new ApiException(response.message(), e, response.code(), response.headers().toMultimap());
+                    }
+                }
+                throw new ApiException(response.message(), response.code(), response.headers().toMultimap(), respBody);
+            }
+            return new Watch<>(this.json, response.body(), watchType);
+        } catch (IOException e) {
+            throw new ApiException(e);
+        }
+    }
+
     /**
      * {@link #execute(Call, Type)}
      *

kubernetes/src/main/java/io/kubernetes/client/Watch.java

@@ -0,0 +1,88 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package io.kubernetes.client;
+
+import com.google.gson.annotations.SerializedName;
+import com.squareup.okhttp.ResponseBody;
+
+import java.io.IOException;
+import java.lang.reflect.Type;
+import java.util.Iterator;
+
+/**
+ * Watch class implements watch mechansim of kubernetes. For every list API
+ * call with a watch parameter you should be able to pass its call to this class
+ * and watch changes to that list. For example CoreV1Api.listNamespace has watch
+ * parameter, so you can create a call using CoreV1Api.listNamespaceCall and
+ * set watch to True and watch the changes to namespaces.
+ */
+public class Watch<T> implements Iterable<Watch.Response<T>>,
+        Iterator<Watch.Response<T>> {
+
+    /**
+     * Response class holds a watch response that has a `type` that can be
+     * ADDED, MODIFIED, DELETED and ERROR. It also hold the actual target
+     * object.
+     */
+    public static class Response<T> {
+        @SerializedName("type")
+        public String type;
+
+        @SerializedName("object")
+        public T object;
+
+        Response(String type, T object) {
+            this.type = type;
+            this.object = object;
+        }
+    }
+
+    Type watchType;
+    ResponseBody response;
+    JSON json;
+
+    public Watch(JSON json, ResponseBody body, Type watchType) {
+        this.response = body;
+        this.watchType = watchType;
+        this.json = json;
+    }
+
+    public Response<T> next() {
+        try {
+            String line = response.source().readUtf8Line();
+            if (line == null) {
+                throw new RuntimeException("Null response from the server.");
+            }
+            return json.deserialize(line, watchType);
+        } catch (IOException e) {
+            throw new RuntimeException("IO Exception during next method.", e);
+        }
+    }
+
+    public boolean hasNext() {
+        try {
+            return !response.source().exhausted();
+        } catch (IOException e) {
+            throw new RuntimeException("IO Exception during hasNext method.",
+                    e);
+        }
+    }
+
+    public Iterator<Response<T>> iterator() {
+        return this;
+    }
+
+    public void remove() {
+        throw new UnsupportedOperationException("remove");
+    }
+}