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Dapr Java SDK

Java SDK packages for developing Dapr applications

前提

Importing Dapr’s Java SDK

For a Maven project, add the following to your pom.xml file:

<project>
  ...
  <dependencies>
    ...
     // Dapr's core SDK with all features, except Actors. 
    <dependency>
      <groupId>io.dapr</groupId>
      <artifactId>dapr-sdk</artifacetId>
      <version>1.1.0</version>
    </dependency>
    // Dapr's SDK for Actors (optional).
    <dependency>
      <groupId>io.dapr</groupId>
      <artifactId>dapr-sdk-actors</artifactId>
      <version>1.1.0</version>>
    </dependency>
    // Dapr's SDK integration with SpringBoot (optional).
    <dependency>
      <groupId>io.dapr</groupId>
      <artifactId>dapr-sdk-springboot</artifactId>
      <version>1.1.0</version>>
    </dependency>
    ...
  </dependencies>
  ...
</project>

For a Gradle project, add the following to your build.gradle file:

dependencies {
...
    // Dapr's core SDK with all features, except Actors.
    compile('io.dapr:dapr-sdk:1.1.0'))
    // Dapr's SDK for Actors (optional).
    compile('io.dapr:dapr-sdk-actors:1.1.0')
    // Dapr's SDK integration with SpringBoot (optional).
    compile('io.dapr:dapr-sdk-springboot:1.1.0')
}

构建块

The Java SDK allows you to interface with all of the Dapr building blocks.

调用服务

import io.dapr.client.DaprClient;
import io.dapr.client.DaprClientBuilder;

try (DaprClient client = (new DaprClientBuilder()).build()) {
  // invoke a 'GET' method (HTTP) skipping serialization: \say with a Mono<byte[]> return type
  // for gRPC set HttpExtension.NONE parameters below
  response = client.invokeMethod(SERVICE_TO_INVOKE, METHOD_TO_INVOKE, "{\"name\":\"World!\"}", HttpExtension.GET, byte[].class).block();

  // invoke a 'POST' method (HTTP) skipping serialization: to \say with a Mono<byte[]> return type     
  response = client.invokeMethod(SERVICE_TO_INVOKE, METHOD_TO_INVOKE, "{\"id\":\"100\", \"FirstName\":\"Value\", \"LastName\":\"Value\"}", HttpExtension.POST, byte[].class).block();

  System.out.println(new String(response));

  // invoke a 'POST' method (HTTP) with serialization: \employees with a Mono<Employee> return type      
  Employee newEmployee = new Employee("Nigel", "Guitarist");
  Employee employeeResponse = client.invokeMethod(SERVICE_TO_INVOKE, "employees", newEmployee, HttpExtension.POST, Employee.class).block();
}

保存 & 获取 应用程序状态

import io.dapr.client.DaprClient;
import io.dapr.client.DaprClientBuilder;
import io.dapr.client.domain.State;
import reactor.core.publisher.Mono;

try (DaprClient client = (new DaprClientBuilder()).build()) {
  // Save state
  client.saveState(STATE_STORE_NAME, FIRST_KEY_NAME, myClass).block();

  // Get state
  State<MyClass> retrievedMessage = client.getState(STATE_STORE_NAME, FIRST_KEY_NAME, MyClass.class).block();

  // Delete state
  client.deleteState(STATE_STORE_NAME, FIRST_KEY_NAME).block();
}

Publish & subscribe to messages

发布消息
import io.dapr.client.DaprClient;
import io.dapr.client.DaprClientBuilder;
import io.dapr.client.domain.Metadata;
import static java.util.Collections.singletonMap;

try (DaprClient client = (new DaprClientBuilder()).build()) {
  client.publishEvent(PUBSUB_NAME, TOPIC_NAME, message, singletonMap(Metadata.TTL_IN_SECONDS, MESSAGE_TTL_IN_SECONDS)).block();
}
Subscribe to messages
import com.fasterxml.jackson.databind.ObjectMapper;
import io.dapr.Topic;
import io.dapr.client.domain.CloudEvent;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import reactor.core.publisher.Mono;

@RestController
public class SubscriberController {

  private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();

  @Topic(name = "testingtopic", pubsubName = "${myAppProperty:messagebus}")
  @PostMapping(path = "/testingtopic")
  public Mono<Void> handleMessage(@RequestBody(required = false) CloudEvent cloudEvent) {
    return Mono.fromRunnable(() -> {
      try {
        System.out.println("Subscriber got: " + cloudEvent.getData());
        System.out.println("Subscriber got: " + OBJECT_MAPPER.writeValueAsString(cloudEvent));
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    });
  }

}

与输出绑定交互

import io.dapr.client.DaprClient;
import io.dapr.client.DaprClientBuilder;

try (DaprClient client = (new DaprClientBuilder()).build()) {
  // sending a class with message; BINDING_OPERATION="create"
  client.invokeBinding(BINDING_NAME, BINDING_OPERATION, myClass).block();

  // sending a plain string
  client.invokeBinding(BINDING_NAME, BINDING_OPERATION, message).block();
}

检索密钥

import com.fasterxml.jackson.databind.ObjectMapper;
import io.dapr.client.DaprClient;
import io.dapr.client.DaprClientBuilder;
import java.util.Map;

try (DaprClient client = (new DaprClientBuilder()).build()) {
  Map<String, String> secret = client.getSecret(SECRET_STORE_NAME, secretKey).block();
  System.out.println(JSON_SERIALIZER.writeValueAsString(secret));
}

Actors

参与者是孤立的独立计算单元,具有单线程执行。 Dapr provides an actor implementation based on the Virtual Actor pattern, which provides a single-threaded programming model and where actors are garbage collected when not in use. With Dapr’s implementaiton, you write your Dapr actors according to the Actor model, and Dapr leverages the scalability and reliability that the underlying platform provides.

import io.dapr.actors.ActorMethod;
import io.dapr.actors.ActorType;
import reactor.core.publisher.Mono;

@ActorType(name = "DemoActor")
public interface DemoActor {

  void registerReminder();

  @ActorMethod(name = "echo_message")
  String say(String something);

  void clock(String message);

  @ActorMethod(returns = Integer.class)
  Mono<Integer> incrementAndGet(int delta);
}

相关链接