问题描述
我正在尝试实现，用于对请求的参数进行自定义验证。我需要查找将与URI匹配的资源方法，以便我可以从方法的参数中删除自定义注释。
基于我应该可以注入然后使用它来匹配方法：
public final class MyRequestFilter实现ContainerRequestFilter {
@Context private ExtendedUriInfo uriInfo;
@Override
public ContainerRequest filter（ContainerRequest containerRequest）{
System.out.println（uriInfo.getMatchedMethod（））;
return containerRequest;
}
}
但显然会返回 null ，一直到实际调用该方法为止（此时对我来说进行验证已经太晚了）。 / p>
如何在调用资源方法之前检索将与给定URI匹配的方法？ / p>
对于那些感兴趣的人，我正在尝试滚动我自己的必需参数验证，如。
我想出了如何仅使用Jersey来解决我的问题。显然没有办法将请求的URI与调用该方法之前匹配的方法相匹配，至少在Jersey 1.x中是这样。但是，我能够使用为每个单独的资源方法创建 ResourceFilter - 这些过滤器可以通过这种方式了解目标方法提前。
这是我的解决方案，包括所需查询参数的验证（使用Guava和JSR 305）：
public final class ValidationFilterFactory实现ResourceFilterFactory {
@Override
public List< ResourceFilter> create（AbstractMethod abstractMethod）{
//跟踪所需的查询参数名称
final ImmutableSet.Builder< String> requiredQueryParamsBuilder =
ImmutableSet.builder（）;
//从资源方法中获取参数列表
final ImmutableList< Parameter> params =
Invokable.from（abstractMethod.getMethod（））。getParameters（）;
for（参数param：params）{
//如果param未标记为@Nullable，
if（！param.isAnnotationPresent（Nullable.class））{
//尝试获取@QueryParam值
@Nullable final QueryParam queryParam =
param.getAnnotation（QueryParam.class）;
//如果它存在，将其值添加到集合
if（queryParam！= null）{
requiredQueryParamsBuilder.add（queryParam.value（））;
}
}
}
//返回此资源方法的新验证过滤器
return Collections。< ResourceFilter> singletonList（
新的ValidationFilter（requiredQueryParamsBuilder.build（））
）;
}
私有静态最终类ValidationFilter实现ResourceFilter {
final ImmutableSet< String> requiredQueryParams;
private ValidationFilter（ImmutableSet< String> requiredQueryParams）{
this.requiredQueryParams = requiredQueryParams;
}
@Override
public ContainerRequestFilter getRequestFilter（）{
return new ContainerRequestFilter（）{
@Override
public ContainerRequest filter（ContainerRequest）请求）{
final Collection< String> missingRequiredParams =
Sets.difference（
requiredQueryParams，
request.getQueryParameters（）。keySet（）
）;
if（！missingRequiredParams.isEmpty（））{
final String message =
缺少必需的查询参数：+
Joiner.on（ ，）。join（missingRequiredParams）;
final响应响应=响应
.status（Status.BAD_REQUEST）
.entity（message）
.build（）;
抛出新的WebApplicationException（响应）;
}
返回请求;
}
};
}
@Override
public ContainerResponseFilter getResponseFilter（）{
return null;
}
}
}
以及 ResourceFilterFactory 在Jersey注册为 web.xml 中的servlet的init参数：
< init-param>
< param-name> com.sun.jersey.spi.container.ResourceFilters< / param-name>
< param-value> my.package.name.ValidationFilterFactory< / param-value>
< / init-param>
启动时， ValidationFilterFactory.create 被调用对于泽西岛检测到的每种资源方法。
为了让我走上正轨，点击这篇文章：
I'm trying to implement a ContainerRequestFilter that does custom validation of a request's parameters. I need to look up the resource method that will be matched to the URI so that I can scrape custom annotations from the method's parameters.
Based on this answer I should be able to inject ExtendedUriInfo and then use it to match the method:
public final class MyRequestFilter implements ContainerRequestFilter {
@Context private ExtendedUriInfo uriInfo;
@Override
public ContainerRequest filter(ContainerRequest containerRequest) {
System.out.println(uriInfo.getMatchedMethod());
return containerRequest;
}
}
But getMatchedMethod apparently returns null, all the way up until the method is actually invoked (at which point it's too late for me to do validation).
How can I retrieve the Method that will be matched to a given URI, before the resource method is invoked?
For those interested, I'm trying to roll my own required parameter validation, as described in JERSEY-351.
I figured out how to solve my problem using only Jersey. There's apparently no way to match a request's URI to the method that will be matched before that method is invoked, at least in Jersey 1.x. However, I was able to use a ResourceFilterFactory to create a ResourceFilter for each individual resource method - that way these filters can know about the destination method ahead of time.
Here's my solution, including the validation for required query params (uses Guava and JSR 305):
public final class ValidationFilterFactory implements ResourceFilterFactory {
@Override
public List<ResourceFilter> create(AbstractMethod abstractMethod) {
//keep track of required query param names
final ImmutableSet.Builder<String> requiredQueryParamsBuilder =
ImmutableSet.builder();
//get the list of params from the resource method
final ImmutableList<Parameter> params =
Invokable.from(abstractMethod.getMethod()).getParameters();
for (Parameter param : params) {
//if the param isn't marked as @Nullable,
if (!param.isAnnotationPresent(Nullable.class)) {
//try getting the @QueryParam value
@Nullable final QueryParam queryParam =
param.getAnnotation(QueryParam.class);
//if it's present, add its value to the set
if (queryParam != null) {
requiredQueryParamsBuilder.add(queryParam.value());
}
}
}
//return the new validation filter for this resource method
return Collections.<ResourceFilter>singletonList(
new ValidationFilter(requiredQueryParamsBuilder.build())
);
}
private static final class ValidationFilter implements ResourceFilter {
final ImmutableSet<String> requiredQueryParams;
private ValidationFilter(ImmutableSet<String> requiredQueryParams) {
this.requiredQueryParams = requiredQueryParams;
}
@Override
public ContainerRequestFilter getRequestFilter() {
return new ContainerRequestFilter() {
@Override
public ContainerRequest filter(ContainerRequest request) {
final Collection<String> missingRequiredParams =
Sets.difference(
requiredQueryParams,
request.getQueryParameters().keySet()
);
if (!missingRequiredParams.isEmpty()) {
final String message =
"Required query params missing: " +
Joiner.on(", ").join(missingRequiredParams);
final Response response = Response
.status(Status.BAD_REQUEST)
.entity(message)
.build();
throw new WebApplicationException(response);
}
return request;
}
};
}
@Override
public ContainerResponseFilter getResponseFilter() {
return null;
}
}
}
And the ResourceFilterFactory is registered with Jersey as an init param of the servlet in web.xml:
<init-param>
<param-name>com.sun.jersey.spi.container.ResourceFilters</param-name>
<param-value>my.package.name.ValidationFilterFactory</param-value>
</init-param>
At startup, ValidationFilterFactory.create gets called for each resource method detected by Jersey.
Credit goes to this post for getting me on the right track: How can I get resource annotations in a Jersey ContainerResponseFilter
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