Pagination initial commit kubernetes-client/java#523

Author: denis554

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

@@ -0,0 +1,40 @@
+package io.kubernetes.client.examples;
+
+import com.google.gson.reflect.TypeToken;
+import com.squareup.okhttp.Call;
+import io.kubernetes.client.ApiClient;
+import io.kubernetes.client.Configuration;
+import io.kubernetes.client.apis.CoreV1Api;
+import io.kubernetes.client.models.V1Namespace;
+import io.kubernetes.client.models.V1NamespaceList;
+import io.kubernetes.client.pager.Pager;
+import io.kubernetes.client.util.Config;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+public class PagerExample {
+  public static void main(String[] args) {
+
+    try {
+
+      ApiClient client = Config.defaultClient();
+      client.getHttpClient().setReadTimeout(60, TimeUnit.SECONDS);
+      Configuration.setDefaultApiClient(client);
+      CoreV1Api api = new CoreV1Api();
+      Call call =
+          api.listNamespaceCall(
+              null, "pretty", null, null, null, null, null, null, null, null, null);
+
+      Pager pager = new Pager(client, call, 1, new TypeToken<V1NamespaceList>() {}.getType());
+      while (pager.hasNext()) {
+        V1NamespaceList list = pager.next();
+        List<V1Namespace> items = list.getItems();
+        for (V1Namespace namespace : items) {
+          System.out.println(namespace.getMetadata().getName());
+        }
+      }
+    } catch (Exception e) {
+      e.printStackTrace();
+    }
+  }
+}

util/src/main/java/io/kubernetes/client/pager/Pager.java

@@ -0,0 +1,97 @@
+package io.kubernetes.client.pager;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import com.google.gson.reflect.TypeToken;
+import com.squareup.okhttp.Call;
+import com.squareup.okhttp.HttpUrl;
+import com.squareup.okhttp.Request;
+import com.squareup.okhttp.Response;
+import io.kubernetes.client.ApiClient;
+import io.kubernetes.client.ApiException;
+import io.kubernetes.client.models.V1ConfigMapList;
+import io.kubernetes.client.models.V1ListMeta;
+import java.io.IOException;
+import java.lang.reflect.Field;
+import java.lang.reflect.Type;
+
+public class Pager {
+  private Request originalRequest;
+  private String _continue;
+  private String resourceVersion;
+  private int limit;
+  private ApiClient client;
+  private Call call;
+  private Type listType;
+
+  public Pager(ApiClient client, Call call, int limit, Type listType) {
+    this.client = client;
+    this.call = call;
+    this.limit = limit;
+    this.listType = listType;
+  }
+
+  public Boolean hasNext() {
+    if (_continue == null && originalRequest != null) {
+      return Boolean.FALSE;
+    }
+    return Boolean.TRUE;
+  }
+
+  public <T> T next()
+      throws NoSuchFieldException, SecurityException, IllegalArgumentException,
+          IllegalAccessException, IOException, ApiException {
+
+    // first call;
+    if (_continue == null && originalRequest == null) {
+      Class cls = call.getClass();
+      Field field = cls.getDeclaredField("originalRequest");
+      field.setAccessible(true);
+      originalRequest = (Request) field.get(call);
+    } else if (_continue == null && originalRequest != null) {
+      // list was exhausted at server
+      V1ConfigMapList list =
+          client.getJSON().deserialize("{}", new TypeToken<V1ConfigMapList>() {}.getType());
+    } else {
+      // subsequent calls
+      Request nextRequest = transFormRequest();
+      call = client.getHttpClient().newCall(nextRequest);
+    }
+    return executeRequest(client, call, listType);
+  }
+
+  private Request transFormRequest() {
+    HttpUrl url =
+        originalRequest
+            .httpUrl()
+            .newBuilder()
+            .addQueryParameter("continue", _continue)
+            .setQueryParameter("limit", String.valueOf(limit))
+            // .addQueryParameter("resourceversion", resourceVersion)
+            .build();
+    Request request = new Request.Builder().headers(originalRequest.headers()).url(url).build();
+    return request;
+  }
+
+  private <T> T executeRequest(ApiClient client, Call call, Type listType)
+      throws IOException, ApiException {
+    Response response = call.execute();
+
+    String line = response.body().source().readUtf8Line();
+    // TODO: handle all responses.
+    JsonParser parser = new JsonParser();
+    JsonObject json = (JsonObject) parser.parse(line);
+    if (json.has("kind") && json.has("metadata")) {
+      String kind = json.get("kind").getAsString();
+      if (kind.contains("List")) {
+        V1ListMeta metaList =
+            client.getJSON().deserialize(json.get("metadata").toString(), V1ListMeta.class);
+        _continue = metaList.getContinue();
+        resourceVersion = metaList.getResourceVersion();
+      }
+    } else {
+      throw new RuntimeException("Subsequent call failed " + line);
+    }
+    return client.getJSON().deserialize(line, listType);
+  }
+}