测试中未使用自定义ObjectMapper

Question

我使用的是Spring Framework4.1.6版本，带有Spring web services，不带Spring Boot。为了学习这个框架，我正在编写一个REST API，并进行测试，以确保从命中一个endpoint收到的JSON响应是正确的。具体地说，我正在尝试调整ObjectMapper的PropertyNamingStrategy以使用“带下划线的小写”命名策略。

我正在使用Spring的博客中详细介绍的方法创建一个新的objectmapper并将其添加到转换器列表中。具体情况如下：

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）来验证我的更改：

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"}

当我得到：

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

我已实现了一个扫描包的WebApplicationInitializer：

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));
    }
}

编辑：我做了一些更多的挖掘发现了这个。在链接中，作者在构建MockMvc之前附加setMessageConverters()，它对作者有效。同样的做法对我也起到了作用；但是，我不确定在生产中是否一切都能正常工作，因为存储库还没有被清除。当我发现我会提交一个答案。

编辑2：见答案。

Answer 1

我研究了一下为什么会这样。重申一下，让定制的ObjectMapper在测试中工作的过程（假设MockMvc是作为一个独立的创建的）如下所示：

1. 创建扩展WebMVCConfigerAdapter的WebConfig类。
2. 在webconfig类中，创建一个新的@bean，它返回一个MappingJackson2HttpMessageConverter。此MappingJackson2HttpMessageConverter应用了所需的更改（在我的示例中，它传递给它一个Jackson2ObjectMapperBuilder，其中PropertyNamingStrategy设置为CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCONER)。
3. 同样在webconfig类中，@overrideconfigureMessageConverters()并将MappingJackson2HttpMessageConverter从（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，以通知测试您的@bean。
5. 使用@autowired注入并访问（2）中定义的@bean。
6. 在mockmvc的设置中，使用.setMessageConverters()方法，并将注入的MappingJackson2HttpMessageConverter传递给它。测试现在将使用（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Tomcat7显示命名策略正在正确使用。我认为这是因为在独立设置中，除非另有规定，否则总是使用一组默认的消息转换器。这可以在StandaloneMockMVCBuilder.java（版本4.1.6,\org\SpringFramework\test\web\servlet\setup\StandaloneMockMVCBuilder.java)中的setMessageConverters()函数的注释中看到：

   /**
     * 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MockMvc在构建MockMvc的过程中没有被明确告知对消息转换器的更改，它将不会使用这些更改。