The documentation you are viewing is for Dapr v1.12 which is an older version of Dapr. For up-to-date documentation, see the latest version.

Java

前提

安装 Dapr CLI
初始化 Dapr 环境
JDK 11 或更高版本 - 已发布的 jar 与 Java 8 兼容：
安装以下 Java 构建工具之一：
- Maven 3.x
- Gradle 6.x

导入 Dapr 的 Java SDK

对于 Maven 项目，请将以下内容添加到 pom.xml 文件中：

<project>
  ...
  <dependencies>
    ...
    <!-- Dapr's core SDK with all features, except Actors. -->
    <dependency>
      <groupId>io.dapr</groupId>
      <artifactId>dapr-sdk</artifactId>
      <version>1.4.0</version>
    </dependency>
    <!-- Dapr's SDK for Actors (optional). -->
    <dependency>
      <groupId>io.dapr</groupId>
      <artifactId>dapr-sdk-actors</artifactId>
      <version>1.4.0</version>
    </dependency>
    <!-- Dapr's SDK integration with SpringBoot (optional). -->
    <dependency>
      <groupId>io.dapr</groupId>
      <artifactId>dapr-sdk-springboot</artifactId>
      <version>1.4.0</version>
    </dependency>
    ...
  </dependencies>
  ...
</project>

对于 Gradle 项目，请将以下内容添加到 build.gradle 文件中：

dependencies {
...
    // Dapr's core SDK with all features, except Actors.
    compile('io.dapr:dapr-sdk:1.4.0')
    // Dapr's SDK for Actors (optional).
    compile('io.dapr:dapr-sdk-actors:1.4.0')
    // Dapr's SDK integration with SpringBoot (optional).
    compile('io.dapr:dapr-sdk-springboot:1.4.0')
}

如果您还使用Spring Boot，则可能会遇到一个常见问题，即Dapr SDK使用的OkHttp版本与Spring Boot _材料清单_中指定的版本冲突。您可以通过在项目中指定兼容的 OkHttp 版本来解决此问题，以匹配 Dapr SDK 使用的版本：

<dependency>
  <groupId>com.squareup.okhttp3</groupId>
  <artifactId>okhttp</artifactId>
  <version>1.3.1</version>
</dependency>

构建块

Java SDK 允许您与的所有 Dapr 构建块进行交互。

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();
}

有关服务调用的完整指南，请访问操作方法：调用服务。
请访问 Java SDK 示例，获取代码示例和说明，以试用服务调用。

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();
}

有关状态操作的完整列表，请访问操作方法：获取 & 保存状态。
请访问 Java SDK 示例，获取代码示例和说明，以试用状态管理。

发布 & 订阅消息

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();
}

订阅消息

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);
      }
    });
  }

}

有关状态操作的完整列表，请访问操作方法: 发布 & 订阅。
请访问 Java SDK 示例，获取代码示例和说明，以试用发布订阅。

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();
}

有关输出绑定的完整指南，请访问操作方法：使用绑定。
请访问 Java SDK 示例，获取代码示例和说明，以试用输出绑定。

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));
}

有关密钥的完整指南，请访问操作方法：检索密钥。
请访问 Java SDK 示例，获取代码示例和说明，以试用秘密检索。

Actor

Actor 是具有单线程执行的隔离、独立的计算和状态单元。 Dapr 提供了一个基于虚拟 Actor 模式的 actor 实现，它提供了一个单线程编程模型，其中 actor 在不使用时会进行垃圾回收。通过 Dapr 的实现，您可以根据 Actor 模型编写 Dapr Actor，而 Dapr 则利用底层平台提供的可扩展性和可靠性。

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);
}

有关 Actor 的完整指南，请访问操作方法：在 Dapr 中使用 Actor 。
请访问 Java SDK 示例，获取代码示例和说明，以试用 Actor。

获取 & 订阅应用程序配置

import io.dapr.client.DaprClientBuilder;
import io.dapr.client.DaprPreviewClient;
import io.dapr.client.domain.ConfigurationItem;
import io.dapr.client.domain.GetConfigurationRequest;
import io.dapr.client.domain.SubscribeConfigurationRequest;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

try (DaprPreviewClient client = (new DaprClientBuilder()).buildPreviewClient()) {
  // Get configuration for a single key
  Mono<ConfigurationItem> item = client.getConfiguration(CONFIG_STORE_NAME, CONFIG_KEY).block();

// Get Configurations for multiple keys
  Mono<List<ConfigurationItem>> items =
          client.getConfiguration(CONFIG_STORE_NAME, CONFIG_KEY_1, CONFIG_KEY_2);

  // Susbcribe to Confifuration changes
  Flux<List<ConfigurationItem>> outFlux = client.subscribeToConfiguration(CONFIG_STORE_NAME, CONFIG_KEY_1, CONFIG_KEY_2);
  outFlux.subscribe(configItems -> configItems.forEach(...));
}

有关配置操作的完整列表，请访问操作方法：从存储管理配置。
请访问 Java SDK 示例，获取代码示例和说明，以尝试不同的配置操作。

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