使用 Spring 引导的 REST 客户端

Question

我正在使用 spring 网站上的示例为 REST Web 服务编写客户端 https://spring.io/guides/gs/consuming-rest/

我的限制是我必须使用 JDK1.6 进行此开发。

客户端应用程序（用匿名方法调用替换了 Lambda）抛出错误，我无法找到修复方法。任何帮助将不胜感激。

错误信息是：

The method setSupportedMediaTypes(List<MediaType>) in the type AbstractHttpMessageConverter<Object> is not applicable for the arguments (List<Object>)

Application.java

package main.java.hello;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.client.RestTemplateBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.client.RestTemplate;
import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;;
//import com.fasterxml.jackson.core.*;

@SpringBootApplication
public class Application {

    private static final Logger log = LoggerFactory.getLogger(Application.class);

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

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

    @Bean
    public CommandLineRunner run(final RestTemplate restTemplate) throws Exception {
        return new CommandLineRunner() {

            @Override
            public void run(String... args) throws Exception {

                List<HttpMessageConverter<?>> messageConverters = new ArrayList<HttpMessageConverter<?>>();        

                //Add the Jackson Message converter
                MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();

                // Note: here we are making this converter to process any kind of response, 
                // not only application/*json, which is the default behaviour
                converter.setSupportedMediaTypes(Arrays.asList({MediaType.ALL}));         
                messageConverters.add(converter); 

                Quote quote = restTemplate.getForObject(
                        "http://gturnquist-quoters.cfapps.io/api/random", Quote.class);
                log.info(quote.toString());
            }
        };
    }
}

Quote.java

package main.java.hello;

import com.fasterxml.jackson.annotation.JsonIgnoreProperties;

@JsonIgnoreProperties(ignoreUnknown = true)
public class Quote {

    private String type;
    private Value value;

    public Quote() {
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public Value getValue() {
        return value;
    }

    public void setValue(Value value) {
        this.value = value;
    }

    @Override
    public String toString() {
        return "Quote{" +
                "type='" + type + '\'' +
                ", value=" + value +
                '}';
    }
}

POM.xml

<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>WebServiceClient</groupId>
  <artifactId>WebServiceClient</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <dependencies>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>4.3.17.RELEASE</version>
    </dependency>

    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
        <version>4.3.17.RELEASE</version>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot</artifactId>
        <version>1.5.13.RELEASE</version>
    </dependency>    

    <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-autoconfigure -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-autoconfigure</artifactId>
        <version>1.5.13.RELEASE</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.slf4j/slf4j-api -->
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.25</version>
    </dependency>



    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-core</artifactId>
        <version>2.9.5</version>
    </dependency>

    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-annotations</artifactId>
        <version>2.9.5</version>
    </dependency>  

    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.9.5</version>
    </dependency>   

  </dependencies>
  <build>
    <sourceDirectory>src</sourceDirectory>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.7.0</version>
        <configuration>
          <source>1.6</source>
          <target>1.6</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>

谢谢！

Answer 1

方法 run() 中的以下行肯定有问题：

converter.setSupportedMediaTypes(Arrays.asList({MediaType.ALL}));

Arrays.asList 具有以下签名：

public static <T> List<T> asList(T... a) { ... }

所以你要么像这样使用它（如果你需要传递多个参数）：

converter.setSupportedMediaTypes(Arrays.asList(new MediaType[]{MediaType.ALL}));

或

converter.setSupportedMediaTypes(Arrays.asList(MediaType.ALL));

请试试这个，看看是否有什么不同。

更新

对于 JDK 1.6，您可能需要将 Jackson 降级到 1.9.13。我发现了一些东西：

<!-- core on 1 version -->
<dependency>
    <groupId>org.codehaus.jackson</groupId>
    <artifactId>jackson-core-asl</artifactId>
    <version>1.9.13</version>
</dependency>

<!-- databind in version 1 -->
<dependency>
    <groupId>org.codehaus.jackson</groupId>
    <artifactId>jackson-mapper-asl</artifactId>
    <version>1.9.13</version>
</dependency>

但是我还没有找到 jackson-annotations 的任何内容，版本 1 没有类似的模块。也许你可以不用它试试看它是否有效。

不确定它如何与新版本的 Spring 一起使用。

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