测试中未使用的自定义ObjectMapper

Question

我正在使用带有Spring Web服务且没有Spring Boot的Spring Framework版本4.1.6。要学习该框架，我正在编写REST
API并进行测试以确保从命中端点收到的JSON响应正确。具体来说，我想调整ObjectMapper的PropertyNamingStrategy‘用下划线小写’命名策略使用。

我正在使用Spring博客上详细介绍的方法创建一个新方法ObjectMapper，并将其添加到转换器列表中。如下所示：

package com.myproject.config;

import com.fasterxml.jackson.databind.PropertyNamingStrategy;
import org.springframework.context.annotation.*;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import java.util.List;

@Configuration
@EnableWebMvc
public class WebConfig extends WebMvcConfigurerAdapter {

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        Jackson2ObjectMapperBuilder builder = jacksonBuilder();
        converters.add(new MappingJackson2HttpMessageConverter(builder.build()));
    }

    public Jackson2ObjectMapperBuilder jacksonBuilder() {
        Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
        builder.propertyNamingStrategy(PropertyNamingStrategy.CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES);

        return builder;
    }
}

然后，运行以下测试（使用JUnit，MockMvc和Mockito）以验证我的更改：

package com.myproject.controller;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.springframework.http.MediaType;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.web.AnnotationConfigWebContextLoader;
import org.springframework.test.context.web.WebAppConfiguration;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.MvcResult;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;

import static org.mockito.Mockito.when;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

// Along with other application imports...

@RunWith(SpringJUnit4ClassRunner.class)
@WebAppConfiguration
@ContextConfiguration(classes = {WebConfig.class}, loader = AnnotationConfigWebContextLoader.class)
public class MyControllerTest {

    @Mock
    private MyManager myManager;

    @InjectMocks
    private MyController myController;

    private MockMvc mockMvc;

    @Before
    public void setup() {
        MockitoAnnotations.initMocks(this);
        this.mockMvc = MockMvcBuilders.standaloneSetup(this.myController).build();
    }


    @Test
    public void testMyControllerWithNameParam() throws Exception {
        MyEntity expected = new MyEntity();
        String name = "expected";
        String title = "expected title";

        // Set up MyEntity with data.
        expected.setId(1); // Random ID.
        expected.setEntityName(name);
        expected.setEntityTitle(title)

        // When the MyManager instance is asked for the MyEntity with name parameter,
        // return expected.
        when(this.myManager.read(name)).thenReturn(expected);

        // Assert the proper results.
        MvcResult result = mockMvc.perform(
                get("/v1/endpoint")
                    .param("name", name))
                .andExpect(status().isOk())
                .andExpect((content().contentType("application/json;charset=UTF-8")))
                .andExpect(jsonPath("$.entity_name", is(name))))
                .andExpect(jsonPath("$.entity_title", is(title)))
                .andReturn();

        System.out.println(result.getResponse().getContentAsString());
    }
}

但是，这将返回以下响应：

{"id": 1, "entityName": "expected", "entityTitle": "expected title"}

什么时候应该得到：

{"id": 1, "entity_name": "expected", "entity_title": "expected title"}

我有一个实现的WebApplicationInitializer，它会扫描该软件包：

package com.myproject.config;

import org.springframework.web.WebApplicationInitializer;
import org.springframework.web.context.ContextLoaderListener;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletRegistration;

public class WebAppInitializer implements WebApplicationInitializer {

    public void onStartup(ServletContext servletContext) throws ServletException {
        AnnotationConfigWebApplicationContext ctx = new AnnotationConfigWebApplicationContext();
        ctx.scan("com.myproject.config");
        ctx.setServletContext(servletContext);

        ServletRegistration.Dynamic servlet = servletContext.addServlet("dispatcher", new DispatcherServlet(ctx));
        servlet.setLoadOnStartup(1);
        servlet.addMapping("/");

        servletContext.addListener(new ContextLoaderListener(ctx));
    }
}

使用IntelliJ中的调试器，我可以看到已创建并添加了构建器，但是ObjectMapper实际上并没有使用生成器。我一定想念一些东西，但是我设法找到的所有例子似乎都没有提到那是什么！我尝试消除@EnableWebMvc并实现WebMvcConfigurationSupport，MappingJackson2HttpMessageConverter作为Bean使用，并设置ObjectMapper为Bean无效。

任何帮助将不胜感激！请让我知道是否需要其他文件。

谢谢！

编辑：
正在做更多的挖掘，发现了这一点。在该链接中，作者setMessageConverters()在构建MockMvc之前附加了它，并且对作者有效。这样做同样对我有用。但是，由于存储库尚未清除，因此我不确定是否所有功能都可以在生产中使用。当我发现时，我将提交答案。

编辑2： 请参阅答案。

Answer 1

我调查了一下为什么这样做会如此。重申一下，让我的自定义ObjectMapper在我的测试中工作的过程（假定MockMvc是作为独立的创建的）如下：

1. 创建一个WebConfig扩展类WebMvcConfigurerAdapter。
2. 在WebConfig该类中，创建一个@Bean返回的新值MappingJackson2HttpMessageConverter。这MappingJackson2HttpMessageConverter已应用了所需的更改（在我的情况下，将其传递给Jackson2ObjectMapperBuilder，且PropertyNamingStrategy设置为CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES。）
3. 同样在WebConfig该类中，@Override configureMessageConverters()并将MappingJackson2HttpMessageConverterfrom（2）添加到消息转换器列表中。
4. 在测试文件中，添加@ContextConfiguration(classes = { WebConfig.class })注释以通知您的测试@Bean。
5. 使用@Autowired注入和访问的@Bean（2）中所定义。
6. 在的设置中MockMvc，使用.setMessageConverters()方法并将其传递给注入MappingJackson2HttpMessageConverter。现在，测试将使用（2）中设置的配置。

测试文件：

package com.myproject.controller;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.springframework.http.MediaType;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.web.AnnotationConfigWebContextLoader;
import org.springframework.test.context.web.WebAppConfiguration;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.MvcResult;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;

import static org.mockito.Mockito.when;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

// Along with other application imports...

@RunWith(SpringJUnit4ClassRunner.class)
@WebAppConfiguration
@ContextConfiguration(classes = {WebConfig.class})
public class MyControllerTest {

    /**
     * Note that the converter needs to be autowired into the test in order for
     * MockMvc to recognize it in the setup() method.
     */
    @Autowired
    private MappingJackson2HttpMessageConverter jackson2HttpMessageConverter;

    @Mock
    private MyManager myManager;

    @InjectMocks
    private MyController myController;

    private MockMvc mockMvc;

    @Before
    public void setup() {
        MockitoAnnotations.initMocks(this);
        this.mockMvc = MockMvcBuilders
            .standaloneSetup(this.myController)
            .setMessageConverters(this.jackson2HttpMessageConverter) // Important!
            .build();
    }


    @Test
    public void testMyControllerWithNameParam() throws Exception {
        MyEntity expected = new MyEntity();
        String name = "expected";
        String title = "expected title";

        // Set up MyEntity with data.
        expected.setId(1); // Random ID.
        expected.setEntityName(name);
        expected.setEntityTitle(title)

        // When the MyManager instance is asked for the MyEntity with name parameter,
        // return expected.
        when(this.myManager.read(name)).thenReturn(expected);

        // Assert the proper results.
        MvcResult result = mockMvc.perform(
                get("/v1/endpoint")
                    .param("name", name))
                .andExpect(status().isOk())
                .andExpect((content().contentType("application/json;charset=UTF-8")))
                .andExpect(jsonPath("$.entity_name", is(name))))
                .andExpect(jsonPath("$.entity_title", is(title)))
                .andReturn();

        System.out.println(result.getResponse().getContentAsString());
    }
}

和配置文件：

package com.myproject.config;
import com.fasterxml.jackson.databind.PropertyNamingStrategy;
import org.springframework.context.annotation.*;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter;

import java.util.List;

@Configuration
@EnableWebMvc
public class WebConfig extends WebMvcConfigurerAdapter {

    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        converters.add(jackson2HttpMessageConverter());
    }

    @Bean
    public MappingJackson2HttpMessageConverter jackson2HttpMessageConverter() {
        MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
        Jackson2ObjectMapperBuilder builder = this.jacksonBuilder();
        converter.setObjectMapper(builder.build());

        return converter;
    }

    public Jackson2ObjectMapperBuilder jacksonBuilder() {
        Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder(); 
        builder.propertyNamingStrategy(PropertyNamingStrategy.CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES);

        return builder;
    }
}

将我生成的WAR文件部署到XAMPP中的Tomcat
7表示正确使用了命名策略。我认为这样做是可行的，因为在独立安装中，除非另有说明，否则始终使用默认的消息转换器集。可以setMessageConverters()在StandAloneMockMvcBuilder.java（版本4.1.6，\org\springframework\test\web\servlet\setup\StandaloneMockMvcBuilder.java）中的函数注释中看到：

   /**
     * Set the message converters to use in argument resolvers and in return value
     * handlers, which support reading and/or writing to the body of the request
     * and response. If no message converters are added to the list, a default
     * list of converters is added instead.
     */
    public StandaloneMockMvcBuilder setMessageConverters(HttpMessageConverter<?>...messageConverters) {
        this.messageConverters = Arrays.asList(messageConverters);
        return this;
    }

因此，如果在构建MockMvc的过程中未明确告知MockMvc有关消息转换器的更改，它将不会使用这些更改。