如何使用 Swagger 代码生成开发一个简单的 REST 客户端？

Question

我正在学习Swagger以及如何使用Swagger代码生成REST客户端。我知道如何使用Swagger做文档，我也知道如何使用Swagger生成一个简单的REST服务器，但我不知道如何使用Swagger代码生成一个简单的REST客户端。

例如，我有一个简单的应用程序，它是一个REST服务器，我想生成REST客户端。我能用斯威格代码吗？

REST服务器的控制器：

package com.dgs.spring.springbootswagger.controller;

import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import io.swagger.annotations.ApiParam;
import io.swagger.annotations.ApiResponse;
import io.swagger.annotations.ApiResponses;

@RestController
@RequestMapping("/api/v1")
@Api(value = "Employee Management System", description = "Operations pertaining to employee in Employee Management System")
public class EmployeeController {

     @Autowired
     private EmployeeRepository employeeRepository;

        @ApiOperation(value = "View a list of available employees", response = List.class)
        @ApiResponses(value = {
            @ApiResponse(code = 200, message = "Successfully retrieved list"),
            @ApiResponse(code = 401, message = "You are not authorized to view the resource"),
            @ApiResponse(code = 403, message = "Accessing the resource you were trying to reach is forbidden"),
            @ApiResponse(code = 404, message = "The resource you were trying to reach is not found")
        })
     @GetMapping("/employees")
     public List<Employee> getAllEmployees() {
         return employeeRepository.findAll();
     }

     @ApiOperation(value = "Get an employee by Id")   
     @GetMapping("/employees/{id}")
     public ResponseEntity<Employee> getEmployeeById(
             @ApiParam(value = "Employee id from which employee object will retrieve", required = true) @PathVariable(value = "id") Long employeeId)
             throws ResourceNotFoundException {

          Employee employee = employeeRepository.findById(employeeId)
            .orElseThrow(() -> new ResourceNotFoundException("Employee not found for this id :: " + employeeId));

          return ResponseEntity.ok().body(employee);
     }

     @ApiOperation(value = "Add an employee")
     @PostMapping("/employees")
     public Employee createEmployee(
             @ApiParam(value = "Employee object store in database table", required = true) @Valid @RequestBody Employee employee) {
         return employeeRepository.save(employee);
     }

     @ApiOperation(value = "Update an employee")
     @PutMapping("/employees/{id}")
     public ResponseEntity<Employee> updateEmployee(
             @ApiParam(value = "Employee Id to update employee object", required = true) @PathVariable(value = "id") Long employeeId,
             @ApiParam(value = "Update employee object", required = true) @Valid @RequestBody Employee employeeDetails) throws ResourceNotFoundException {

          Employee employee = employeeRepository.findById(employeeId)
            .orElseThrow(() -> new ResourceNotFoundException("Employee not found for this id :: " + employeeId));

          employee.setEmail(employeeDetails.getEmail());
          employee.setLastName(employeeDetails.getLastName());
          employee.setFirstName(employeeDetails.getFirstName());
          final Employee updatedEmployee = employeeRepository.save(employee);

          return ResponseEntity.ok(updatedEmployee);
     }

     @ApiOperation(value = "Delete an employee")
     @DeleteMapping("/employees/{id}")
     public Map<String, Boolean> deleteEmployee(
             @ApiParam(value = "Employee Id from which employee object will delete from database table", required = true) @PathVariable(value = "id") Long employeeId)
       throws ResourceNotFoundException {

      Employee employee = employeeRepository.findById(employeeId)
        .orElseThrow(() -> new ResourceNotFoundException("Employee not found for this id :: " + employeeId));

      employeeRepository.delete(employee);
      Map<String, Boolean> response = new HashMap<>();
      response.put("deleted", Boolean.TRUE);

      return response;
     }
}

之后，我开发了一个简单的REST客户端:

package com.dgs.restclient.controllers;

@Controller
public class UpdateController {

    @Autowired
    private EmployeeRestClient restClient;

    @GetMapping("/showStartUpdate")
    public String showStartCheckin() {
        return "startUpdate";
    }

    @PostMapping("/startUpdate")
    public String startCheckIn(@RequestParam("employeeId") Long employeeId, ModelMap modelMap) {

        Employee employee = restClient.findEmployee(employeeId);
        modelMap.addAttribute("employee", employee);

        return "displayEmployeeDetails";
    }

    @PostMapping("/completeUpdate")
    public String completeCheckIn(@RequestParam("employeeId") Long employeeId,
            @RequestParam("employeeFirstName") String employeeFirstName,
            @RequestParam("employeeLastName") String employeeLastName,
            @RequestParam("employeeEmail") String employeeEmail) {

        EmployeeUpdateRequest employeeUpdateRequest = new EmployeeUpdateRequest();
        employeeUpdateRequest.setId(employeeId);
        employeeUpdateRequest.setFirstName(employeeFirstName);
        employeeUpdateRequest.setLastName(employeeLastName);
        employeeUpdateRequest.setEmail(employeeEmail);
        restClient.updateEmployee(employeeUpdateRequest);

        return "updateConfirmation";
    }

}

EmployeeRestClient:

package com.dgs.restclient.integration;

@Component
public class EmployeeRestClientImpl implements EmployeeRestClient {

    private static final String EMPLOYEE_REST_URL = 
            "http://localhost:8080/api/v1/employees/";

    @Override
    public Employee findEmployee(Long id) {

        RestTemplate restTemplate = new RestTemplate();
        Employee employee = restTemplate
                .getForObject(EMPLOYEE_REST_URL + id, Employee.class);

        return employee;
    }

    @Override
    public Employee updateEmployee(EmployeeUpdateRequest request) {

        RestTemplate restTemplate = new RestTemplate();
        restTemplate
                .put(EMPLOYEE_REST_URL + request.getId(), request, Employee.class); 

        Employee employee = restTemplate
                .getForObject(EMPLOYEE_REST_URL + request.getId(), Employee.class);

        return employee;
    }

}

这个REST客户端是由我开发的，我想知道我是否可以用Swagger代码进行REST客户端开发，以及如何进行？我需要在pom中添加swagger codegen maven插件吗。xml？我听说过添加这个插件和一个yml文件，Swager将创建REST客户端。任何反馈都将不胜感激！

Answer 1

假设您的应用程序的Swagerendpoint可以访问：

>

测试 Swagger 2.0 JSON API 文档

http://localhost:8080/v2/api-文档？组=员工

http://localhost:8080/v2/api-docs（如果尚未设置名为employee的组）

测试Swagger UI

http://localhost:8080/swagger-ui.html

您可以从Maven Central存储库下载swagger-codegen-cli-2.4.7.jar。

现在您已经有了Swagger Codegen JAR，您可以通过执行以下命令来生成REST客户端:

java -jar swagger-codegen-cli-2.4.7.jar generate \
  -i http://localhost:8080/v2/api-docs?group=employee \
  -l java \
  -o swagger-codegen-client

如果没有招摇分组，

java -jar swagger-codegen-cli-2.4.7.jar generate \
  -i http://localhost:8080/v2/api-docs \
  -l java \
  -o swagger-codegen-client

尽管Swagger Codecen CLI带有许多选项，但我们使用的选项对于生成客户端代码是绝对必要的。

• -i指向您的应用程序的Swagger api docs的URL。
• -l客户端的编程语言，在本例中为java
• -o生成的客户端代码的输出文件夹。

一旦您执行了前面生成代码的命令，您应该会注意到终端上的以下消息:

[main] INFO io.swagger.parser.Swagger20Parser - reading from http://localhost:8080/v2/api-docs?group=employee
[main] WARN io.swagger.codegen.ignore.CodegenIgnoreProcessor - Output directory does not exist, or is inaccessible. No file (.swagger-codegen-ignore) will be evaluated.
[main] INFO io.swagger.codegen.AbstractGenerator - writing file swagger-codegen-client/src/main/java/io/swagger/client/model/Employee.java
[main] INFO io.swagger.codegen.AbstractGenerator - writing file swagger-codegen-client/docs/Employee.md
[main] INFO io.swagger.codegen.AbstractGenerator - writing file swagger-codegen-client/src/main/java/io/swagger/client/api/EmployeeControllerApi.java
...
[main] INFO io.swagger.codegen.AbstractGenerator - writing file swagger-codegen-client/src/main/java/io/swagger/client/ApiClient.java
...

代码生成完成后，您应该注意到具有以下结构的gradle/maven项目：

__ swagger-codegen-client
  |__ README.md
  |__ build.gradle
  |__ build.sbt
  |__ docs
  |__ git_push.sh
  |__ gradle
  |__ gradle.properties
  |__ gradlew
  |__ gradlew.bat
  |__ pom.xml
  |__ settings.gradle
  |__ src
     |__ main
        |__ java
          |__ io.swagger.client.api
             |__ EmployeeControllerApi.java
     |__ test
        |__ java
          |__ io.swagger.client.api
             |__ EmployeeControllerApiTest.java

可在此处找到生成的客户端项目的示例。

客户端项目包含许多java类。然而，最重要的类是EmployeeControllerApi.java。这是一个包含用于创建REST客户端类的所有逻辑的类。

另一个重要的类是EmployeeControllerApiTest.java。它向您展示了如何使用EmployeeControllerApi.java。生成的客户端项目还提供了一个非常有用的README文件。

类包含与建立 HTTP 客户端连接相关的信息。请确保 REST 应用程序的 basePath 正确。在生成的示例中，basePath 具有 https://localhost:8080 URL，而不是 http://localhost:8080。

生成的项目适用于Java8。如果您使用的是Java12，则必须添加以下依赖项才能编译项目：

    <dependency>
        <groupId>javax.xml.bind</groupId>
        <artifactId>jaxb-api</artifactId>
        <version>2.3.0</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-core</artifactId>
        <version>2.3.0</version>
    </dependency>
    <dependency>
        <groupId>com.sun.xml.bind</groupId>
        <artifactId>jaxb-impl</artifactId>
        <version>2.3.0</version>
    </dependency>

    <dependency>
        <groupId>javax.annotation</groupId>
        <artifactId>javax.annotation-api</artifactId>
        <version>1.3.2</version>
    </dependency>

下面是通过调用 REST POST 方法方法创建员工的示例。

Employee employee = new Employee();
employee.setId(3L);
employee.setFirstName("Sam");
employee.setLastName("Fox");
employee.setEmail("[e-mail]");

EmployeeControllerApi api = new EmployeeControllerApi();
Employee response = api.createEmployeeUsingPOST(employee);
System.out.println(response);

您应该做出类似如下的响应：

class Employee {
    email: [e-mail]
    firstName: Sam
    id: 3
    lastName: Fox
}

您可以在此处找到完整的示例。

Answer 2

更新：

您的问题已在另一篇文章中回答。看一看：相关文章

...

baeldung有一个关于它的很好的教程：如何使用swagger codecen创建rest客户端

例如，执行命令：

java -jar swagger-codegen-cli.jar generate \
  -i http://mydomain/v2/swagger.json \
  --api-package com.mypackage.api \
  --model-package com.mypackage.model \
  --invoker-package com.mypackage.invoker \
  --group-id com.mygroup \
  --artifact-id spring-swagger-codegen-api-client \
  --artifact-version 0.0.1-SNAPSHOT \
  -l java \
  --library resttemplate \
  -o spring-swagger-codegen-api-client

Swagger Codegen支持以下客户端实现:

1. 球衣1杰克逊
2. 杰克森球衣2
3. 假杰克逊
4. OkHttp Gson
5. 改装2/OkHttp Gson
6. SpringRest模板杰克逊
7. 雷斯特西·杰克逊

P.S.如您所见，rest客户机是由swagger规范定义生成的，它由“-i”参数定义。

Answer 3

是的。您可以使用swagger-codegen-maven-plugin生成REST客户端。但在此之前，您需要在OpenAPI规范中用YAML或JSON描述REST API，主要是因为swagger-codegen-maven-plugin只能从本规范中编写的文件生成REST客户端。

其他答案假设您需要手动编写规范，而我的解决方案则进一步从REST控制器源代码自动生成规范。

< sup >最新的OpenAPI版本是3.0。但是基于您导入的swagger注释的包，您使用的是2.0版(或更早)。所以我的解决方案假设您使用的是OpenAPI 2.0。

生成开放API规范

首先，您可以使用 swagger-maven-plugin 从 RestController 源代码生成 OpenAPI 规范。它基本上分析了在 @RestController 类中注释的 Swagger 注释，这些注释在

<plugin>
    <groupId>com.github.kongchen</groupId>
    <artifactId>swagger-maven-plugin</artifactId>
    <version>3.1.5</version>
    <configuration>
        <apiSources>
            <apiSource>
                <springmvc>true</springmvc>
                <locations>
                    <location>com.dgs.spring.springbootswagger.controller.EmployeeController</location>
                    <location>com.dgs.spring.springbootswagger.controller.FooController</location>
                </locations>
                <schemes>
                    <scheme>http</scheme>
                </schemes>
                <host>127.0.0.1:8080</host>
                <basePath>/</basePath>
                <info>
                    <title>My API</title>
                    <version>1.1.1</version>
                </info>
                <swaggerDirectory>${basedir}/src/main/resources/</swaggerDirectory>
            </apiSource>
        </apiSources>
    </configuration>
    <executions>
        <execution>
            <goals>
                <goal>generate</goal>
            </goals>
        </execution>
    </executions>
</plugin>

执行以下maven命令开始生成:

mvn clean compile

生成Rest客户端

生成swagger.json后，您可以将其复制并粘贴到您的客户端项目中（例如 /src/main/resources/swagger.json），然后我们可以使用swagger-codegen-maven-plugin生成HTTP客户端。

默认情况下，它将生成整个maven项目，其中包括测试用例和其他文档资料。但是我想要的只是HttpClient的源代码，没有其他东西。经过几次反复试验，我确定了以下配置:

<plugin>
    <groupId>io.swagger</groupId>
    <artifactId>swagger-codegen-maven-plugin</artifactId>
    <version>2.4.7</version>
    <executions>
        <execution>
            <goals>
                <goal>generate</goal>
            </goals>
            <configuration>
                <inputSpec>${basedir}/src/main/resources/swagger.json</inputSpec>
                <language>java</language>
                <library>resttemplate</library>
                <output>${project.basedir}/target/generated-sources/</output>

                <apiPackage>com.example.demo.restclient.api</apiPackage>
                <modelPackage>com.example.demo.restclient.model</modelPackage>
                <invokerPackage>com.example.demo.restclient</invokerPackage>

                <generateApiTests>false</generateApiTests>
                <generateModelTests>false</generateModelTests>
                <generateApiDocumentation>false</generateApiDocumentation>
                <generateModelDocumentation>false</generateModelDocumentation>
                <configOptions>
                    <dateLibrary>java8</dateLibrary>
                    <sourceFolder>restclient</sourceFolder>
                </configOptions>
            </configuration>
        </execution>
    </executions>
</plugin>

生成的HTTP客户端基于RestTemplate，将生成到文件夹target/generatedsources/restclient。您可能需要配置IDE以导入生成的客户端才能使用它➡️ Java构建路径➡️ 添加生成的rest客户端的文件夹）

要开始生成客户端，只需执行 maven 命令：

mvn clean compile

要使用生成的HTTP客户端:

ApiClient apiClient = new ApiClient();

//Override the default API base path configured in Maven
apiClient.setBasePath("http://api.example.com/api");

EmployeeManagementSystemApi api = new EmployeeManagementSystemApi(apiClient);
api.getEmployeeById(1l);

注：

• 如果在使用java8时在生成过程中遇到javax/xml/bind/nannotation/XmlRootElement异常，您可能需要参考这一点