• 从本文你可以学会使用SpringBoot结合Swagger开放API，同时使用SpringCloud Feign组件来调用API。
• 本文如题分为两部分SpringBoot结合Swagger开放API，SpringCloud Feign调用API。
• 项目源码：iponkan-openapi

SpringBoot结合Swagger开放API

1. 项目模块构建(Maven多模块项目搭建)
2. 引入的依赖

<dependency>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
     <groupId>io.swagger</groupId>
     <artifactId>swagger-annotations</artifactId>
</dependency>

3. 定义数据传输层对象

@ApiModel(description = "订单")
public class OrderDto {
    /**
     * 单据uuid
     */
    private String id;
    /**
     * 单号
     */
    private String number;
    /**
     * 来源
     */
    private String source;

    @ApiModelProperty("订单uuid")
    @NotNull
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    @ApiModelProperty("单号")
    @NotNull
    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }

    @ApiModelProperty("订单来源")
    public String getSource() {
        return source;
    }

    public void setSource(String source) {
        this.source = source;
    }
}

4. 定义开放接口

@Api("订单服务")
@RequestMapping(value = "order", produces = "application/json;charset=utf-8")
public interface OrderService {
    String DEFAULT_CONTEXT_ID = "iponkan-openapi.orderService";

    @ApiOperation("保存订单，支持重复调用")
    @PostMapping("post")
    @ResponseBody
    String post(@Valid @RequestBody OrderDto order) throws Exception;


    @ApiOperation("获取订单，根据订单号")
    @GetMapping("get")
    @ResponseBody
    OrderDto get(@RequestParam String number) throws Exception;
}

5. 实现开放接口

@RestController(OrderService.DEFAULT_CONTEXT_ID)
public class OrderServiceImpl implements OrderService {

    @Autowired
    private OrderProcessor processor;

    public String post(@Valid OrderDto order) throws Exception {
        return processor.process(order);
    }

    @Override
    public OrderDto get(String number) throws Exception {
        OrderDto dto = new OrderDto();
        dto.setId(UUID.randomUUID().toString());
        dto.setNumber("20200902000001");
        dto.setSource("IPONKAN");
        return dto;
    }
}

6. 增加Swagger的配置

• 引入依赖

<dependency>
     <groupId>io.springfox</groupId>
     <artifactId>springfox-swagger2</artifactId>
</dependency>
<dependency>
     <groupId>io.springfox</groupId>
     <artifactId>springfox-swagger-ui</artifactId>
</dependency>

• 增加一个配置类

@Configuration
@ComponentScan("cn.iponkan.openapi")
public class SwaggerConfig {
    @Bean
    public Docket swaggerSpringMvcPlugin() {
        return new Docket(DocumentationType.SWAGGER_2) //
                .apiInfo(swaggerDemoApiInfo()) //
                .select() //
                .build();
    }

    private ApiInfo swaggerDemoApiInfo() {
        // 构建联系实体，在UI界面会显示
        Contact contact = new Contact("", "", "");
        return new ApiInfoBuilder().contact(contact)
                // 文档标题
                .title("OpenApi RESTful API文档")
                // 文档描述
                .description("OpenApi RESTful API文档")
                // 文档版本
                .version("1.0.0") //
                .build();
    }
}

• 启动类上加上注解

@EnableSwagger2

7. 启动项目后查看结果
   

SpringCloud Feign调用API

1. 引入Spring Cloud Feign依赖

 <dependency>
     <groupId>org.springframework.cloud</groupId>
     <artifactId>spring-cloud-starter-openfeign</artifactId>
</dependency>

2. 定义调用接口的客户端

@FeignClient
public interface OpenApiClient {

    @RequestLine("GET get?number={number}")
    Order get(URI baseUri, @Param("number") String number);
}

3. 配置调用接口的客户端

@Configuration
@Import({
        FeignClientsConfiguration.class, HttpMessageConvertersAutoConfiguration.class})
public class ProviderConfig {

    @Bean
    public OpenApiClient openApiClient(Decoder decoder, Encoder encoder) {
        return Feign.builder() //
                .encoder(encoder) //
                .decoder(decoder) //
                .logLevel(Logger.Level.FULL) //
                .target(Target.EmptyTarget.create(OpenApiClient.class));
    }
}

4. 使用客户端调用接口

@RestController
@RequestMapping("feign/order")
public class OrderController {

    @Autowired
    private OpenApiClient openApiClient;

    @RequestMapping("get")
    public Order get() throws Exception {
        return openApiClient.get(new URI("http://localhost:9999/openapi-web/service/order"), "123");
    }

}

5. 调用结果，数据成功返回
   

总结

• SpringCloud Feign:是HTTP请求调用的一个轻量级框架。可以使用Java接口注解方式调用HTTP请求。
• 留下一个疑问？Feign的实现原理。