在Spring引导中使用REST API时发生java错误

Question

我试图使用RESTAPI，它接受JSON有效负载，并在响应中返回纯文本。但我在运行时遇到以下错误

SpotifyIntegrationApplication。java

@SpringBootApplication
public class SpotifyIntegrationApplication {

    private static final Logger LOGGER = LoggerFactory.getLogger(SpotifyIntegrationApplication.class);

    public static void main(String[] args) {
        SpringApplication.run(SpotifyIntegrationApplication.class, args);
    }

    @Bean
    public RestTemplate restTemplate(RestTemplateBuilder builder) {
        return builder.build();
    }

    @Bean
    public CommandLineRunner run(RestTemplate restTemplate) {
        NewOrder newOrder = new NewOrder();
        return args -> {
            ResponseEntity<String> responseEntity = restTemplate.postForEntity("http://localhost:9999/order-sold", newOrder, String.class);
            LOGGER.info("responseEntity: " + responseEntity);
        };
    }

}

新秩序。java

public class NewOrder {
    String orderId;
}

构建。格拉德尔

buildscript {
    ext {
        springBootVersion = '1.5.10.RELEASE'
    }
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'

group = 'com.synapse.integration'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8

repositories {
    mavenCentral()
}


dependencies {
    compile('org.springframework.boot:spring-boot-starter-web')
    runtime('com.h2database:h2')
    runtime('mysql:mysql-connector-java')
    compileOnly('org.projectlombok:lombok')
    testCompile('org.springframework.boot:spring-boot-starter-test')
}

错误：

java.lang.IllegalStateException: Failed to execute CommandLineRunner
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:735) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:716) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.afterRefresh(SpringApplication.java:703) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:304) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    at com.synapse.integration.spotify.SpotifyIntegrationApplication.main(SpotifyIntegrationApplication.java:20) [classes/:na]
Caused by: org.springframework.web.client.RestClientException: Could not write request: no suitable HttpMessageConverter found for request type [com.synapse.integration.spotify.model.NewOrder]
    at org.springframework.web.client.RestTemplate$HttpEntityRequestCallback.doWithRequest(RestTemplate.java:907) ~[spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:658) ~[spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:621) ~[spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at org.springframework.web.client.RestTemplate.postForEntity(RestTemplate.java:415) ~[spring-web-4.3.14.RELEASE.jar:4.3.14.RELEASE]
    at com.synapse.integration.spotify.SpotifyIntegrationApplication.lambda$run$0(SpotifyIntegrationApplication.java:32) [classes/:na]
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:732) [spring-boot-1.5.10.RELEASE.jar:1.5.10.RELEASE]
    ... 6 common frames omitted

Answer 1

嗯，当查看Spring的文档时，答案都有点混乱： https://spring.io/guides/gs/consuming-rest/

似乎您应该能够成功地使用响应，通过带注释的对象映射到JSON对象

然而，即使这样做：

@Bean
public CommandLineRunner run(RestTemplate restTemplate) throws Exception {
    return args -> {
        Quote quote = restTemplate.getForObject(
                "http://localhost:8978/greeting", Quote.class);
        System.out.println(quote.toString());
        log.info(quote.toString());      
    };

我仍然得到上面的未能执行CommandLineRunner错误，将不得不调查它是否值得映射到HttpResponseObject。希望大家对我的评论有一些想法

Answer 2

从上面的回答中，再加上一些额外的谷歌搜索，找到了解决方案

SpotifyIntegrationApplication。java

@SpringBootApplication
public class SpotifyIntegrationApplication {

    private static final Logger LOGGER = LoggerFactory.getLogger(SpotifyIntegrationApplication.class);
    public static final String ENDPOINT = "http://localhost:9999/order-sold";

    public static void main(String[] args) {
        SpringApplication.run(SpotifyIntegrationApplication.class, args);
    }

    @Bean
    public RestTemplate restTemplate(RestTemplateBuilder builder) {
        return builder.build();
    }

    @Bean
    public CommandLineRunner run(RestTemplate restTemplate) {
        return args -> {
            NewOrder newOrder = new NewOrder();
            HttpHeaders headers = new HttpHeaders();
            headers.setContentType(MediaType.APPLICATION_JSON);
            HttpEntity<NewOrder> entity = new HttpEntity<>(newOrder, headers);
            ResponseEntity<String> responseEntity = restTemplate.exchange(ENDPOINT, POST, entity, String.class);
            LOGGER.info("responseEntity: " + responseEntity);
        };
    }

}

新秩序。java

@Data
public class NewOrder {

    private String orderId;

}

虽然这不是原始问题的一部分，但也删除了Tomcat库依赖项，因为我只是在使用API，而不是构建API

构建。格拉德尔

compile('org.springframework.boot:spring-boot-starter-web') {
    exclude module: "spring-boot-starter-tomcat"
}