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;
}

然而，表格似乎总是空的。 HttpRequestContext.getFormParameters()文档说：

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。

我的资源使用@Consumes("application/x-www-form-urlencoded")注释，虽然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this 4-year old discussion，Paul Sandoz说：

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

我还发现this 3-year-old discussion有关如何在请求过滤器中获取multipart / form-data表单字段。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);

我尝试使用Form模仿该方法，但request.getEntityInputStream()的结果始终为空流。看看the source of 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();
    }
}

在我达到它之前，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（以及为什么）？

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）request logging：

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>

以下是示例资源：

@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，我正在尝试推出自己的必需参数验证，如JERSEY-351中所述。我的解决方案here适用于查询，cookie和标题参数 - 形式参数对我很有用。

Answer 1

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

<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>

删除此过滤器修复了问题 - 表格params出现在Jersey过滤器中。但为什么？我深入挖掘，将问题缩小到MyFilter中的单个陈述：

request.getParameter("some_param")

我尝试通过删除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出来。在调用传递到javax.servlet.Filter.doFilter的getParameter实例上调用org.apache.catalina.connector.RequestFacade时，问题似乎就会发生。这实际上是Tomcat的错误吗？

ServletRequest.getParameter的文档说：

如果参数数据是在请求正文中发送的，例如HTTP POST请求，则直接通过getInputStream()或getReader()读取正文会干扰此方法的执行。< / p>

所以也许反过来也是这样 - 调用getParameter可能会被允许干扰实体输入流？我不清楚方法的契约是否允许这种行为，以及它是否表示Tomcat，Jersey或其中的错误。

无论如何，那个旧的过滤器实际上并不需要，所以我的问题解决了，但只是删除它。

这是问题的完整复制品（Tomcat 7.0）：

web.xml：

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
    <display-name>test</display-name>
    <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</param-value>
        </init-param>
        <init-param>
            <param-name>com.sun.jersey.spi.container.ResourceFilters</param-name>
            <param-value>com.application.my.TestFilterFactory</param-value>
        </init-param>
        <init-param>
            <param-name>com.sun.jersey.config.feature.Trace</param-name>
            <param-value>false</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>jersey</servlet-name>
        <url-pattern>/*</url-pattern>
    </servlet-mapping>
    <filter>
        <filter-name>servletFilter</filter-name>
        <filter-class>com.application.my.TestServletFilter</filter-class>
    </filter>
    <filter-mapping>
        <filter-name>servletFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
</web-app>

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();
    }
}

Answer 2

确保ResourceFilterFactory为ResourceFilter方法创建TestResource#execute的实例，然后创建ContainerRequestFilter个实例：

public class MyFilterFactory implements ResourceFilterFactory {

    @Override
    public List<ResourceFilter> create(final AbstractMethod am) {
        return new ArrayList<ResourceFilter>() {{

            add(new ResourceFilter() {
                @Override
                public ContainerRequestFilter getRequestFilter() {
                    return new ContainerRequestFilter() {
                        @Override
                        public ContainerRequest filter(final ContainerRequest request) {
                            System.out.println(request.getFormParameters());
                            return request;
                        }
                    };
                }

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

从您提供的trace我不确定您的ContainerRequestFilter是否被调用。应该有一个跟踪标题包含这样的内容：

→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

我测试的全部痕迹：

HTTP/1.1 201 Created
Location: http://localhost:8080/helloworld-webapp/helloworld/
Content-Type: text/plain
X-Jersey-Trace-000: accept root resource classes: "/helloworld"
X-Jersey-Trace-001: match path "/helloworld" -> "/application\.wadl(/.*)?", "/helloworld(/.*)?"
X-Jersey-Trace-002: accept right hand path java.util.regex.Matcher[pattern=/helloworld(/.*)? region=0,11 lastmatch=/helloworld]: "/helloworld" -> "/helloworld" : ""
X-Jersey-Trace-003: accept resource: "helloworld" -> @Path("/helloworld") com.sun.jersey.samples.helloworld.resources.HelloWorldResource@7449df0f
X-Jersey-Trace-004: match path "" -> ""
X-Jersey-Trace-005: accept resource methods: "helloworld", POST -> com.sun.jersey.samples.helloworld.resources.HelloWorldResource@7449df0f
X-Jersey-Trace-006: matched resource method: public javax.ws.rs.core.Response com.sun.jersey.samples.helloworld.resources.HelloWorldResource.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@6bc1b916
X-Jersey-Trace-008: matched message body reader: class com.sun.jersey.api.representation.Form, "application/x-www-form-urlencoded" -> com.sun.jersey.core.impl.provider.entity.FormProvider@6bc1b916
X-Jersey-Trace-009: matched message body writer: java.lang.String@f62, "text/plain" -> com.sun.jersey.core.impl.provider.entity.StringProvider@4aae6c4e
Transfer-Encoding: chunked
Server: Jetty(6.1.24)

编辑1：

启用请求LoggingFilter：

<init-param>
    <param-name>com.sun.jersey.spi.container.ContainerRequestFilters</param-name>
    <param-value>com.sun.jersey.api.container.filter.LoggingFilter</param-value>
</init-param>

编辑2：

还要确保之前没有其他Servlet或Jersey过滤器已读取InputStream。在这种情况下，实体输入流可能不再可用（但您仍然可以将@FormParam注入资源方法 - 如本例所示。）

如何在请求过滤器中获取表单参数

2 个答案:

编辑1：

编辑2：