Confluent Cloud Spring Boot Kafka生产者代码类型不兼容问题求助

问题详情 #

运行Confluent Cloud提供的Spring Boot Kafka示例代码时，出现类型不兼容错误：

类型不兼容，找到'java.util.concurrent.CompletableFuture<org.springframework.kafka.support.SendResult<java.lang.String,java.lang.String>>'，需要'org.springframework.util.concurrent.ListenableFuture<org.springframework.kafka.support.SendResult<java.lang.String,java.lang.String>>'

原Producer代码 #

package com.ohds.kafka1;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Service;
import org.springframework.util.concurrent.ListenableFuture;
import org.springframework.util.concurrent.ListenableFutureCallback;
import org.springframework.kafka.support.SendResult;

@Service
public class Producer {

    private static final Logger logger = LoggerFactory.getLogger(Producer.class);
    private static final String TOPIC = "bets";

    @Autowired
    private KafkaTemplate<String, String> kafkaTemplate;

    public void sendMessage(String key, String value) {
        ListenableFuture<SendResult<String, String>> future = kafkaTemplate.send(TOPIC, key, value);
        future.addCallback(new ListenableFutureCallback<SendResult<String, String>>() {
            @Override
            public void onSuccess(SendResult<String, String> result) {
                logger.info(String.format("\n\n Produced event to topic %s: key = %-10s value = %s \n\n", TOPIC, key, value));
            }

            @Override
            public void onFailure(Throwable ex) {
                ex.printStackTrace();
            }
        });
    }
}

尝试将ListenableFuture改为CompletableFuture匹配返回值后，调用addCallback方法时再次报错。

项目pom.xml配置 #

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.ohds</groupId>
    <artifactId>kafka1</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>kafka1</name>
    <description>kafka test project 1</description>
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.kafka</groupId>
            <artifactId>spring-kafka</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-docker-compose</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.kafka</groupId>
            <artifactId>spring-kafka-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

解决方案 #

原因 #

Spring Boot 3.x 对应的 spring-kafka 版本默认将KafkaTemplate.send()的返回值改为CompletableFuture，而示例代码基于旧版本的ListenableFuture编写，两者API不兼容。

方案1：改用CompletableFuture原生回调 #

直接使用CompletableFuture的whenComplete方法替代ListenableFutureCallback，修改后的代码如下：

package com.ohds.kafka1;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Service;
import org.springframework.kafka.support.SendResult;
import java.util.concurrent.CompletableFuture;

@Service
public class Producer {

    private static final Logger logger = LoggerFactory.getLogger(Producer.class);
    private static final String TOPIC = "bets";

    @Autowired
    private KafkaTemplate<String, String> kafkaTemplate;

    public void sendMessage(String key, String value) {
        CompletableFuture<SendResult<String, String>> future = kafkaTemplate.send(TOPIC, key, value);
        future.whenComplete((result, ex) -> {
            if (ex == null) {
                logger.info(String.format("\n\n Produced event to topic %s: key = %-10s value = %s \n\n", TOPIC, key, value));
            } else {
                ex.printStackTrace();
            }
        });
    }
}

方案2：启用ListenableFuture兼容模式 #

在项目配置文件（application.properties或application.yml）中添加以下配置，让KafkaTemplate返回ListenableFuture，原代码无需修改即可正常运行：

spring.kafka.producer.use-listener-future=true

内容的提问来源于stack exchange，提问作者John Little