如何在请求过滤器中获取表单参数

Question

我正在尝试在请求过滤器中获取请求的表单参数:

@Override
public ContainerRequest filter(final ContainerRequest request) {

    final Form formParameters = request.getFormParameters();

    //logic

    return request;
}

但是,表格似乎总是空的.该HttpRequestContext.getFormParameters()文件说:

获取请求实体的表单参数.

此方法将确保缓冲请求实体,以便应用程序可以使用它.

返回: 表单参数,如果有请求实体且内容类型为"application/x-www-form-urlencoded",否则将返回不包含参数的实例.

我的资源是注释的@Consumes("application/x-www-form-urlencoded"),虽然它在请求过滤器之后才会匹配 - 这就是为什么这不起作用？

我尝试做一些研究,但未能找到任何确凿的证据证明这是否可行.有这个为期4年的讨论,Paul Sandoz说:

如果您正在使用泽西过滤器或使用,HttpRequestContext您可以获得如下表单参数:[到Jersey 1.1.1的断开链接HttpRequestContext.getFormParameters]

我还发现了这个有关如何在请求过滤器中获取multipart/form-data表单字段的3年讨论.在其中,Paul Sandoz使用以下代码:

// Buffer
InputStream in = request.getEntityInputStream();
if (in.getClass() != ByteArrayInputStream.class) {
    // Buffer input
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    try {
        ReaderWriter.writeTo(in, baos);
    } catch (IOException ex) {
        throw new ContainerException(ex);
    }
    in = new ByteArrayInputStream(baos.toByteArray());
    request.setEntityInputStream(in);
}

// Read entity
FormDataMultiPart multiPart = request.getEntity(FormDataMultiPart.class);

我尝试用这种方法来模仿Form,但结果request.getEntityInputStream()始终是一个空流.看看其来源getFormParameters,该方法实际上已经做了同样的事情:

@Override
public Form getFormParameters() {
    if (MediaTypes.typeEquals(MediaType.APPLICATION_FORM_URLENCODED_TYPE, getMediaType())) {
        InputStream in = getEntityInputStream();
        if (in.getClass() != ByteArrayInputStream.class) {
            // Buffer input
            ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
            try {
                ReaderWriter.writeTo(in, byteArrayOutputStream);
            } catch (IOException e) {
                throw new IllegalArgumentException(e);
            }

            in = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
            setEntityInputStream(in);
        }

        ByteArrayInputStream byteArrayInputStream = (ByteArrayInputStream) in;
        Form f = getEntity(Form.class);
        byteArrayInputStream.reset();
        return f;
    } else {
        return new Form();
    }
}

在我到达它之前,我无法弄清楚实体输入流是什么.泽西岛的某些东西必须消耗它,因为形式参数后来被传递到资源方法中.我在这里做错了什么,或者这是不可能的(为什么)？

编辑:以下是发送请求的示例:

POST /test/post-stuff HTTP/1.1
Host: local.my.application.com:8443
Cache-Control: no-cache
Content-Type: application/x-www-form-urlencoded

form_param_1=foo&form_param_2=bar

这是(有点多余的)请求记录:

INFO: 1 * Server in-bound request
1 > POST https://local.my.application.com:8443/test/post-stuff
1 > host: local.my.application.com:8443
1 > connection: keep-alive
1 > content-length: 33
1 > cache-control: no-cache
1 > origin: chrome-extension://fdmmgilgnpjigdojojpjoooidkmcomcm
1 > user-agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/28.0.1500.95 Safari/537.36
1 > content-type: application/x-www-form-urlencoded
1 > accept: */*
1 > accept-encoding: gzip,deflate,sdch
1 > accept-language: en-US,en;q=0.8
1 > cookie: [omitted]
1 > 

以下是该请求的响应标头,包括Jersey Trace:

Content-Type ?application/json;charset=UTF-8
Date ?Fri, 09 Aug 2013 18:00:17 GMT
Location ?https://local.my.application.com:8443/test/post-stuff/
Server ?Apache-Coyote/1.1
Transfer-Encoding ?chunked
X-Jersey-Trace-000 ?accept root resource classes: "/post-stuff"
X-Jersey-Trace-001 ?match path "/post-stuff" -> "/post\-stuff(/.*)?", [...], "(/.*)?"
X-Jersey-Trace-002 ?accept right hand path java.util.regex.Matcher[pattern=/post\-stuff(/.*)? region=0,11 lastmatch=/post-stuff]: "/post-stuff" -> "/post-stuff" : ""
X-Jersey-Trace-003 ?accept resource: "post-stuff" -> @Path("/post-stuff") com.application.my.jersey.resource.TestResource@7612e9d2
X-Jersey-Trace-004 ?match path "" -> ""
X-Jersey-Trace-005 ?accept resource methods: "post-stuff", POST -> com.application.my.jersey.resource.TestResource@7612e9d2
X-Jersey-Trace-006 ?matched resource method: public javax.ws.rs.core.Response com.application.my.jersey.resource.TestResource.execute(java.lang.String,java.lang.String)
X-Jersey-Trace-007 ?matched message body reader: class com.sun.jersey.api.representation.Form, "application/x-www-form-urlencoded" -> com.sun.jersey.core.impl.provider.entity.FormProvider@b98df1f
X-Jersey-Trace-008 ?matched message body writer: java.lang.String@f62, "application/json" -> com.sun.jersey.core.impl.provider.entity.StringProvider@1c5ddffa

这是(不起眼的)servlet配置:

<servlet>
    <servlet-name>jersey</servlet-name>
    <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
    <init-param>
        <param-name>com.sun.jersey.config.property.packages</param-name>
        <param-value>com.application.my.jersey</param-value>
    </init-param>
    <init-param>
        <param-name>com.sun.jersey.spi.container.ResourceFilters</param-name>
        <param-value>com.application.my.jersey.MyFilterFactory</param-value>
    </init-param>
    <init-param>
        <param-name>com.sun.jersey.config.feature.Trace</param-name>
        <param-value>true</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>

这是示例资源:

@Path("/post-stuff")
@Produces(MediaType.APPLICATION_JSON)
public final class TestResource {

    @POST
    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
    public Response execute(
            @FormParam("form_param_1") final String formParam1,
            @FormParam("form_param_2") final String formParam2
    ) {
        return Response.created(URI.create("/")).entity("{}").build();
    }
}

我正在使用Jersey 1.17.

---

对于那些感兴趣的人,我正在尝试推出我自己的必需参数验证,如JERSEY-351中所述.我的解决方案在这里工作了查询,饼干,和头PARAMS -形式PARAMS都瞒着我.

Answer 1

这是一个棘手的问题。我删除了其他 Jersey 过滤器以消除它们的问题，但错过了隐藏在底部的普通 servlet 过滤器web.xml：

<filter>
    <filter-name>myFilter</filter-name>
    <filter-class>com.application.my.MyFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>myFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

删除此过滤器解决了问题 - 表单参数显示在 Jersey 过滤器中。但为什么？我进行了更深入的研究，将问题缩小到以下内容中的一条语句MyFilter：

request.getParameter("some_param")

我试图通过删除MyFilter并在 Jersey 过滤器中进行相同的调用（通过注入HttpServletRequest）来进一步简化问题 - 但表单参数仍然显示。该问题似乎在调用传递到 的实例getParameter时特别发生。那么这实际上是 Tomcat 的错误吗？org.apache.catalina.connector.RequestFacadejavax.servlet.Filter.doFilter

的文档ServletRequest.getParameter说：

如果参数数据是在请求正文中发送的，例如 HTTP POST 请求中发生的情况，则直接通过getInputStream()或读取正文getReader()可能会干扰此方法的执行。

那么也许反过来也是如此——调用getParameter可能会被允许干扰实体输入流？我不清楚该方法的契约是否允许这种行为，也不清楚它是否表明 Tomcat、Jersey 中存在错误，或者两者都没有。

不管怎样，实际上并不需要那个旧过滤器，所以我的问题已经解决，但只需将其删除即可。

这是问题的完整再现（Tomcat 7.0）：

web.xml:

request.getParameter("some_param")

TestServletFilter.java:

package com.application.my;

import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

public final class TestServletFilter implements Filter {

    @Override
    public void init(FilterConfig config) { }

    @Override
    public void doFilter(
            final ServletRequest request,
            final ServletResponse response,
            final FilterChain chain
    ) throws IOException, ServletException {
        System.out.println("calling getParameter on " + request.getClass().getName());
        request.getParameter("blah");
        chain.doFilter(request, response);
    }

    @Override
    public void destroy() { }
}

TestFilterFactory.java:

package com.application.my;

import java.util.Collections;
import java.util.List;

import com.sun.jersey.api.model.AbstractMethod;
import com.sun.jersey.spi.container.ContainerRequest;
import com.sun.jersey.spi.container.ContainerRequestFilter;
import com.sun.jersey.spi.container.ContainerResponseFilter;
import com.sun.jersey.spi.container.ResourceFilter;
import com.sun.jersey.spi.container.ResourceFilterFactory;

public final class TestFilterFactory implements ResourceFilterFactory {

    @Override
    public List<ResourceFilter> create(final AbstractMethod method) {
        return Collections.<ResourceFilter>singletonList(new ResourceFilter() {
            @Override
            public ContainerRequestFilter getRequestFilter() {
                return new ContainerRequestFilter() {
                    @Override
                    public ContainerRequest filter(final ContainerRequest request) {

                        System.out.println("form: " + request.getFormParameters());

                        return request;
                    }
                };
            }
            @Override
            public ContainerResponseFilter getResponseFilter() {
                return null;
            }
        });
    }
}

TestResource.java:

package com.application.my;

import java.net.URI;

import javax.ws.rs.Consumes;
import javax.ws.rs.FormParam;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;


@Path("/post-stuff")
@Produces(MediaType.APPLICATION_JSON)
public final class TestResource {

    @POST
    @Consumes(MediaType.APPLICATION_FORM_URLENCODED)
    public Response execute(
            @FormParam("form_param_1") final String formParam1,
            @FormParam("form_param_2") final String formParam2
    ) {
        System.out.println("form param_1: " + formParam1);
        System.out.println("form param_2: " + formParam2);

        return Response.created(URI.create("/")).entity("{}").build();
    }
}