绑定spring mvc命令对象时如何自定义参数名称

Question

我有一个命令对象：

public class Job {
    private String jobType;
    private String location;
}

受spring-mvc约束：

@RequestMapping("/foo")
public Strnig doSomethingWithJob(Job job) {
   ...
}

适用于http://example.com/foo?jobType=permanent&location=Stockholm。但现在我需要让它适用于以下网址：
http://example.com/foo?jt=permanent&loc=Stockholm

显然，我不想更改我的命令对象，因为字段名称必须保持很长（因为它们在代码中使用）。我该如何定制？有没有选择做这样的事情：

public class Job {
    @RequestParam("jt")
    private String jobType;
    @RequestParam("loc")
    private String location;
}

这不起作用（@RequestParam无法应用于字段）。

我正在考虑的是一个类似于FormHttpMessageConverter的自定义消息转换器，并在目标对象上读取自定义注释

Answer 1

此解决方案更简洁但需要使用RequestMappingHandlerAdapter，Spring在启用<mvc:annotation-driven />时使用。 希望它会对某人有所帮助。 我的想法是像这样扩展ServletRequestDataBinder：

 /**
 * ServletRequestDataBinder which supports fields renaming using {@link ParamName}
 *
 * @author jkee
 */
public class ParamNameDataBinder extends ExtendedServletRequestDataBinder {

    private final Map<String, String> renameMapping;

    public ParamNameDataBinder(Object target, String objectName, Map<String, String> renameMapping) {
        super(target, objectName);
        this.renameMapping = renameMapping;
    }

    @Override
    protected void addBindValues(MutablePropertyValues mpvs, ServletRequest request) {
        super.addBindValues(mpvs, request);
        for (Map.Entry<String, String> entry : renameMapping.entrySet()) {
            String from = entry.getKey();
            String to = entry.getValue();
            if (mpvs.contains(from)) {
                mpvs.add(to, mpvs.getPropertyValue(from).getValue());
            }
        }
    }
}

适当的处理器：

/**
 * Method processor supports {@link ParamName} parameters renaming
 *
 * @author jkee
 */

public class RenamingProcessor extends ServletModelAttributeMethodProcessor {

    @Autowired
    private RequestMappingHandlerAdapter requestMappingHandlerAdapter;

    //Rename cache
    private final Map<Class<?>, Map<String, String>> replaceMap = new ConcurrentHashMap<Class<?>, Map<String, String>>();

    public RenamingProcessor(boolean annotationNotRequired) {
        super(annotationNotRequired);
    }

    @Override
    protected void bindRequestParameters(WebDataBinder binder, NativeWebRequest nativeWebRequest) {
        Object target = binder.getTarget();
        Class<?> targetClass = target.getClass();
        if (!replaceMap.containsKey(targetClass)) {
            Map<String, String> mapping = analyzeClass(targetClass);
            replaceMap.put(targetClass, mapping);
        }
        Map<String, String> mapping = replaceMap.get(targetClass);
        ParamNameDataBinder paramNameDataBinder = new ParamNameDataBinder(target, binder.getObjectName(), mapping);
        requestMappingHandlerAdapter.getWebBindingInitializer().initBinder(paramNameDataBinder, nativeWebRequest);
        super.bindRequestParameters(paramNameDataBinder, nativeWebRequest);
    }

    private static Map<String, String> analyzeClass(Class<?> targetClass) {
        Field[] fields = targetClass.getDeclaredFields();
        Map<String, String> renameMap = new HashMap<String, String>();
        for (Field field : fields) {
            ParamName paramNameAnnotation = field.getAnnotation(ParamName.class);
            if (paramNameAnnotation != null && !paramNameAnnotation.value().isEmpty()) {
                renameMap.put(paramNameAnnotation.value(), field.getName());
            }
        }
        if (renameMap.isEmpty()) return Collections.emptyMap();
        return renameMap;
    }
}

注释：

/**
 * Overrides parameter name
 * @author jkee
 */

@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface ParamName {

    /**
     * The name of the request parameter to bind to.
     */
    String value();

}

Spring config：

<mvc:annotation-driven>
    <mvc:argument-resolvers>
        <bean class="ru.yandex.metrika.util.params.RenamingProcessor">
            <constructor-arg name="annotationNotRequired" value="true"/>
        </bean>
    </mvc:argument-resolvers>
</mvc:annotation-driven> 

最后，用法（如Bozho解决方案）：

public class Job {
    @ParamName("job-type")
    private String jobType;
    @ParamName("loc")
    private String location;
}

Answer 2

这就是我的工作：

首先，参数解析器：

/**
 * This resolver handles command objects annotated with @SupportsAnnotationParameterResolution
 * that are passed as parameters to controller methods.
 * 
 * It parses @CommandPerameter annotations on command objects to
 * populate the Binder with the appropriate values (that is, the filed names
 * corresponding to the GET parameters)
 * 
 * In order to achieve this, small pieces of code are copied from spring-mvc
 * classes (indicated in-place). The alternative to the copied lines would be to
 * have a decorator around the Binder, but that would be more tedious, and still
 * some methods would need to be copied.
 * 
 * @author bozho
 * 
 */
public class AnnotationServletModelAttributeResolver extends ServletModelAttributeMethodProcessor {

    /**
     * A map caching annotation definitions of command objects (@CommandParameter-to-fieldname mappings)
     */
    private ConcurrentMap<Class<?>, Map<String, String>> definitionsCache = Maps.newConcurrentMap();

    public AnnotationServletModelAttributeResolver(boolean annotationNotRequired) {
        super(annotationNotRequired);
    }

    @Override
    public boolean supportsParameter(MethodParameter parameter) {
        if (parameter.getParameterType().isAnnotationPresent(SupportsAnnotationParameterResolution.class)) {
            return true;
        }
        return false;
    }

    @Override
    protected void bindRequestParameters(WebDataBinder binder, NativeWebRequest request) {
        ServletRequest servletRequest = request.getNativeRequest(ServletRequest.class);
        ServletRequestDataBinder servletBinder = (ServletRequestDataBinder) binder;
        bind(servletRequest, servletBinder);
    }

    @SuppressWarnings("unchecked")
    public void bind(ServletRequest request, ServletRequestDataBinder binder) {
        Map<String, ?> propertyValues = parsePropertyValues(request, binder);
        MutablePropertyValues mpvs = new MutablePropertyValues(propertyValues);
        MultipartRequest multipartRequest = WebUtils.getNativeRequest(request, MultipartRequest.class);
        if (multipartRequest != null) {
            bindMultipart(multipartRequest.getMultiFileMap(), mpvs);
        }

        // two lines copied from ExtendedServletRequestDataBinder
        String attr = HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE;
        mpvs.addPropertyValues((Map<String, String>) request.getAttribute(attr));
        binder.bind(mpvs);
    }

    private Map<String, ?> parsePropertyValues(ServletRequest request, ServletRequestDataBinder binder) {

        // similar to WebUtils.getParametersStartingWith(..) (prefixes not supported)
        Map<String, Object> params = Maps.newTreeMap();
        Assert.notNull(request, "Request must not be null");
        Enumeration<?> paramNames = request.getParameterNames();
        Map<String, String> parameterMappings = getParameterMappings(binder);
        while (paramNames != null && paramNames.hasMoreElements()) {
            String paramName = (String) paramNames.nextElement();
            String[] values = request.getParameterValues(paramName);

            String fieldName = parameterMappings.get(paramName);
            // no annotation exists, use the default - the param name=field name
            if (fieldName == null) {
                fieldName = paramName;
            }

            if (values == null || values.length == 0) {
                // Do nothing, no values found at all.
            } else if (values.length > 1) {
                params.put(fieldName, values);
            } else {
                params.put(fieldName, values[0]);
            }
        }

        return params;
    }

    /**
     * Gets a mapping between request parameter names and field names.
     * If no annotation is specified, no entry is added
     * @return
     */
    private Map<String, String> getParameterMappings(ServletRequestDataBinder binder) {
        Class<?> targetClass = binder.getTarget().getClass();
        Map<String, String> map = definitionsCache.get(targetClass);
        if (map == null) {
            Field[] fields = targetClass.getDeclaredFields();
            map = Maps.newHashMapWithExpectedSize(fields.length);
            for (Field field : fields) {
                CommandParameter annotation = field.getAnnotation(CommandParameter.class);
                if (annotation != null && !annotation.value().isEmpty()) {
                    map.put(annotation.value(), field.getName());
                }
            }
            definitionsCache.putIfAbsent(targetClass, map);
            return map;
        } else {
            return map;
        }
    }

    /**
     * Copied from WebDataBinder.
     * 
     * @param multipartFiles
     * @param mpvs
     */
    protected void bindMultipart(Map<String, List<MultipartFile>> multipartFiles, MutablePropertyValues mpvs) {
        for (Map.Entry<String, List<MultipartFile>> entry : multipartFiles.entrySet()) {
            String key = entry.getKey();
            List<MultipartFile> values = entry.getValue();
            if (values.size() == 1) {
                MultipartFile value = values.get(0);
                if (!value.isEmpty()) {
                    mpvs.add(key, value);
                }
            } else {
                mpvs.add(key, values);
            }
        }
    }
}

然后使用后处理器注册参数解析器。它应该注册为<bean>：

/**
 * Post-processor to be used if any modifications to the handler adapter need to be made
 * 
 * @author bozho
 *
 */
public class AnnotationHandlerMappingPostProcessor implements BeanPostProcessor {

    @Override
    public Object postProcessAfterInitialization(Object bean, String arg1)
            throws BeansException {
        return bean;
    }

    @Override
    public Object postProcessBeforeInitialization(Object bean, String arg1)
            throws BeansException {
        if (bean instanceof RequestMappingHandlerAdapter) {
            RequestMappingHandlerAdapter adapter = (RequestMappingHandlerAdapter) bean;
            List<HandlerMethodArgumentResolver> resolvers = adapter.getCustomArgumentResolvers();
            if (resolvers == null) {
                resolvers = Lists.newArrayList();
            }
            resolvers.add(new AnnotationServletModelAttributeResolver(false));
            adapter.setCustomArgumentResolvers(resolvers);
        }

        return bean;
    }

}

Answer 3

在Spring 3.1中，ServletRequestDataBinder为其他绑定值提供了一个钩子：

protected void addBindValues(MutablePropertyValues mpvs, ServletRequest request) {
}

ExtendedServletRequestDataBinder子类使用它将URI模板变量添加为绑定值。您可以进一步扩展它，以便可以添加特定于命令的字段别名。

您可以覆盖RequestMappingHandlerAdapter.createDataBinderFactory（..）以提供自定义WebDataBinder实例。从控制器的角度来看，它看起来像这样：

@InitBinder
public void initBinder(MyWebDataBinder binder) {
   binder.addFieldAlias("jobType", "jt");
   // ...
}

Answer 4

没有很好的内置方法，您只能选择应用的解决方法。处理

之间的区别

@RequestMapping("/foo")
public String doSomethingWithJob(Job job)

和

@RequestMapping("/foo")
public String doSomethingWithJob(String stringjob)

该作业是一个bean而stringjob不是（到目前为止并不令人意外）。真正的区别在于bean使用标准的Spring bean解析器机制解析，而字符串参数由Spring MVC解析，Spring MVC知道@RequestParam注释的概念。总而言之，标准的spring bean解析（使用PropertyValues，PropertyValue，GenericTypeAwarePropertyDescriptor等类）无法将“jt”解析为名为“jobType”的属性，或者至少我不知道它。 / p>

解决方法可以像其他人建议添加自定义PropertyEditor或过滤器一样，但我认为它只会弄乱代码。在我看来，最干净的解决方案是声明一个这样的类：

public class JobParam extends Job {
    public String getJt() {
         return super.job;
    }

    public void setJt(String jt) {
         super.job = jt;
    }

}

然后在你的控制器中使用它

@RequestMapping("/foo")
public String doSomethingWithJob(JobParam job) {
   ...
}

更新：

一个稍微简单的选择是不扩展，只需将额外的getter，setter添加到原始类

public class Job {

    private String jobType;
    private String location;

    public String getJt() {
         return jobType;
    }

    public void setJt(String jt) {
         jobType = jt;
    }

}

Answer 5

我想指出另一个方向。 但我不知道它是否有效。

我会尝试操纵绑定本身。

由WebDataBinder完成，将从HandlerMethodInvoker方法Object[] resolveHandlerArguments(Method handlerMethod, Object handler, NativeWebRequest webRequest, ExtendedModelMap implicitModel) throws Exception

调用

我在Spring 3.1中没有深入了解，但我所看到的是，Spring的这一部分已经发生了很大变化。因此可以交换WebDataBinder。在Spring 3.0中，如果不覆盖HandlerMethodInvoker，就无法进行接缝。

Answer 6

您可以使用Jackson com.fasterxml.jackson.databind.ObjectMapper将任何地图转换为具有嵌套道具的DTO / POJO类。您需要在嵌套对象上使用@JsonUnwrapped注释您的POJO。像这样：

public class Category {

private int name;
private int image;



public Category(int name, int image) {
    this.name = name;
    this.image = image;


}


public int getName() {
    return name;
}

public void setName(int name) {
    this.name = name;
}

public int getImage() {
    return image;
}

public void setImage(int image) {
    this.image = image;
}
}

而不是像这样使用它：

public class MyRequest {

    @JsonUnwrapped
    private NestedObject nested;

    public NestedObject getNested() {
        return nested;
    }
}

这就是全部。一点编码。此外，您可以为您的道具添加任何名称使用@JsonProperty。

Answer 7

尝试使用 InterceptorAdaptor 拦截请求，然后使用简单的检查机制决定是否将请求转发给控制器处理程序。同时在请求周围包裹HttpServletRequestWrapper，以便覆盖请求getParameter()。

通过这种方式，您可以将实际参数名称及其值重新记录回控制器可以看到的请求。

示例选项：

public class JobInterceptor extends HandlerInterceptorAdapter {
 private static final String requestLocations[]={"rt", "jobType"};

 private boolean isEmpty(String arg)
 {
   return (arg !=null && arg.length() > 0);
 }

 public boolean preHandle(HttpServletRequest request,
   HttpServletResponse response, Object handler) throws Exception {

   //Maybe something like this
   if(!isEmpty(request.getParameter(requestLocations[0]))|| !isEmpty(request.getParameter(requestLocations[1]))
   {
    final String value =
       !isEmpty(request.getParameter(requestLocations[0])) ? request.getParameter(requestLocations[0]) : !isEmpty(request
        .getParameter(requestLocations[1])) ? request.getParameter(requestLocations[1]) : null;

    HttpServletRequest wrapper = new HttpServletRequestWrapper(request)
    {
     public String getParameter(String name)
     {
      super.getParameterMap().put("JobType", value);
      return super.getParameter(name);
     }
    };

    //Accepted request - Handler should carry on.
    return super.preHandle(request, response, handler);
   }

   //Ignore request if above condition was false
   return false;
   }
 }

最后将HandlerInterceptorAdaptor包裹在控制器处理程序周围，如下所示。 SelectedAnnotationHandlerMapping允许您指定哪个处理程序将被截取。

<bean id="jobInterceptor" class="mypackage.JobInterceptor"/>
<bean id="publicMapper" class="org.springplugins.web.SelectedAnnotationHandlerMapping">
    <property name="urls">
        <list>
            <value>/foo</value>
        </list>
    </property>
    <property name="interceptors">
        <list>
            <ref bean="jobInterceptor"/>
        </list>
    </property>
</bean>

<强> EDITED

Answer 8

有一种简单的方法，你可以再添加一个setter方法，比如“setLoc，setJt”。

Answer 9

感谢@jkee的回答。
这是我的解决方法。
首先，一个自定义注释：

  @GetMapping(value = "/testLambdaBuilder", produces = MediaType.APPLICATION_JSON_VALUE)
  @ResponseBody
  public RestResponse<String> testEndpointLambdaBuilder() {
    return new RestResponseBuilder<String>().with($ -> $.data = "helloWorld").createRestResponse();
  }

客户DataBinder：

@Inherited
@Documented
@Target(ElementType.FIELD)
@Retention(RetentionPolicy.RUNTIME)
public @interface ParamName {

  /**
   * The name of the request parameter to bind to.
   */
  String value();

}

参数解析器：

public class ParamNameDataBinder extends ExtendedServletRequestDataBinder {

  private final Map<String, String> paramMappings;

  public ParamNameDataBinder(Object target, String objectName, Map<String, String> paramMappings) {
    super(target, objectName);
    this.paramMappings = paramMappings;
  }

  @Override
  protected void addBindValues(MutablePropertyValues mutablePropertyValues, ServletRequest request) {
    super.addBindValues(mutablePropertyValues, request);
    for (Map.Entry<String, String> entry : paramMappings.entrySet()) {
      String paramName = entry.getKey();
      String fieldName = entry.getValue();
      if (mutablePropertyValues.contains(paramName)) {
        mutablePropertyValues.add(fieldName, mutablePropertyValues.getPropertyValue(paramName).getValue());
      }
    }
  }

}

最后，一个用于将ParamNameProcessor添加到第一个参数解析器的bean配置：

public class ParamNameProcessor extends ServletModelAttributeMethodProcessor {

  @Autowired
  private RequestMappingHandlerAdapter requestMappingHandlerAdapter;

  private static final Map<Class<?>, Map<String, String>> PARAM_MAPPINGS_CACHE = new ConcurrentHashMap<>(256);

  public ParamNameProcessor() {
    super(false);
  }

  @Override
  public boolean supportsParameter(MethodParameter parameter) {
    return parameter.hasParameterAnnotation(RequestParam.class)
        && !BeanUtils.isSimpleProperty(parameter.getParameterType())
        && Arrays.stream(parameter.getParameterType().getDeclaredFields())
        .anyMatch(field -> field.getAnnotation(ParamName.class) != null);
  }

  @Override
  protected void bindRequestParameters(WebDataBinder binder, NativeWebRequest nativeWebRequest) {
    Object target = binder.getTarget();
    Map<String, String> paramMappings = this.getParamMappings(target.getClass());
    ParamNameDataBinder paramNameDataBinder = new ParamNameDataBinder(target, binder.getObjectName(), paramMappings);
    requestMappingHandlerAdapter.getWebBindingInitializer().initBinder(paramNameDataBinder, nativeWebRequest);
    super.bindRequestParameters(paramNameDataBinder, nativeWebRequest);
  }

  /**
   * Get param mappings.
   * Cache param mappings in memory.
   *
   * @param targetClass
   * @return {@link Map<String, String>}
   */
  private Map<String, String> getParamMappings(Class<?> targetClass) {
    if (PARAM_MAPPINGS_CACHE.containsKey(targetClass)) {
      return PARAM_MAPPINGS_CACHE.get(targetClass);
    }
    Field[] fields = targetClass.getDeclaredFields();
    Map<String, String> paramMappings = new HashMap<>(32);
    for (Field field : fields) {
      ParamName paramName = field.getAnnotation(ParamName.class);
      if (paramName != null && !paramName.value().isEmpty()) {
        paramMappings.put(paramName.value(), field.getName());
      }
    }
    PARAM_MAPPINGS_CACHE.put(targetClass, paramMappings);
    return paramMappings;
  }

}

Param pojo：

@Configuration
public class WebConfig {

  /**
   * Processor for annotation {@link ParamName}.
   *
   * @return ParamNameProcessor
   */
  @Bean
  protected ParamNameProcessor paramNameProcessor() {
    return new ParamNameProcessor();
  }

  /**
   * Custom {@link BeanPostProcessor} for adding {@link ParamNameProcessor} into the first of
   * {@link RequestMappingHandlerAdapter#argumentResolvers}.
   *
   * @return BeanPostProcessor
   */
  @Bean
  public BeanPostProcessor beanPostProcessor() {
    return new BeanPostProcessor() {

      @Override
      public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
        return bean;
      }

      @Override
      public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
        if (bean instanceof RequestMappingHandlerAdapter) {
          RequestMappingHandlerAdapter adapter = (RequestMappingHandlerAdapter) bean;
          List<HandlerMethodArgumentResolver> argumentResolvers = new ArrayList<>(adapter.getArgumentResolvers());
          argumentResolvers.add(0, paramNameProcessor());
          adapter.setArgumentResolvers(argumentResolvers);
        }
        return bean;
      }
    };
  }

}

控制器方法：

@Data
public class Foo {

  private Integer id;

  @ParamName("first_name")
  private String firstName;

  @ParamName("last_name")
  private String lastName;

  @ParamName("created_at")
  @DateTimeFormat(pattern = "yyyy-MM-dd")
  private Date createdAt;

}

仅此而已。

Answer 10

jkee的答案有一些改进。

为了支持继承，您还应该分析父类。

/**
 * ServletRequestDataBinder which supports fields renaming using {@link ParamName}
 *
 * @author jkee
 * @author Yauhen Parmon
 */
public class ParamRenamingProcessor extends ServletModelAttributeMethodProcessor {

    @Autowired
    private RequestMappingHandlerAdapter requestMappingHandlerAdapter;

    //Rename cache
    private final Map<Class<?>, Map<String, String>> replaceMap = new ConcurrentHashMap<>();

    public ParamRenamingProcessor(boolean annotationNotRequired) {
       super(annotationNotRequired);
    }

    @Override
    protected void bindRequestParameters(WebDataBinder binder, NativeWebRequest nativeWebRequest) {
        Object target = binder.getTarget();
        Class<?> targetClass = Objects.requireNonNull(target).getClass();
        if (!replaceMap.containsKey(targetClass)) {
            replaceMap.put(targetClass, analyzeClass(targetClass));
        }
        Map<String, String> mapping = replaceMap.get(targetClass);
        ParamNameDataBinder paramNameDataBinder = new ParamNameDataBinder(target, binder.getObjectName(), mapping);
        Objects.requireNonNull(requestMappingHandlerAdapter.getWebBindingInitializer())
                .initBinder(paramNameDataBinder);    
        super.bindRequestParameters(paramNameDataBinder, nativeWebRequest);
    }

    private Map<String, String> analyzeClass(Class<?> targetClass) {
        Map<String, String> renameMap = new HashMap<>();
        for (Field field : targetClass.getDeclaredFields()) {
            ParamName paramNameAnnotation = field.getAnnotation(ParamName.class);
            if (paramNameAnnotation != null && !paramNameAnnotation.value().isEmpty()) {
               renameMap.put(paramNameAnnotation.value(), field.getName());
            }
        }
        if (targetClass.getSuperclass() != Object.class) {
            renameMap.putAll(analyzeClass(targetClass.getSuperclass()));
        }
        return renameMap;
    }
}

此处理器将分析用@ParamName注释的超类的字段。从Spring 5.0开始不推荐使用带有两个参数的initBinder方法。 jkee回答中的所有其他内容都还可以。