61.2. 容器请求过滤器
概述
本节介绍如何实施和注册容器请求 过滤器,该过滤器 用于截获 server (容器)端的传入请求消息。容器请求过滤器通常用于处理服务器端的标头,并可用于任何类型的通用请求处理(即处理独立于特定资源方法的处理)。
此外,容器请求过滤器是特殊情况的一部分,因为它可以在两个不同的扩展点上安装: PreMatchContainerRequest
(资源匹配步骤前)和 ContainerRequest
(资源匹配步骤之后)。
ContainerRequestFilter 接口
javax.ws.rs.container.ContainerRequestFilter
接口定义如下:
// Java ... package javax.ws.rs.container; import java.io.IOException; public interface ContainerRequestFilter { public void filter(ContainerRequestContext requestContext) throws IOException; }
// Java
...
package javax.ws.rs.container;
import java.io.IOException;
public interface ContainerRequestFilter {
public void filter(ContainerRequestContext requestContext) throws IOException;
}
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通过实现 ContainerRequestFilter
接口,您可以在服务器端为以下扩展点创建一个过滤器:
-
PreMatchContainerRequest
-
ContainerRequest
ContainerRequestContext 接口
ContainerRequestFilter
的过滤器
方法接收类型为 javax.ws.rs.container.ContainerRequestContext
的单个参数,它可用于访问传入的请求消息及其关联的元数据。ContainerRequestContext
接口定义如下:
// Java ... package javax.ws.rs.container; import java.io.InputStream; import java.net.URI; import java.util.Collection; import java.util.Date; import java.util.List; import java.util.Locale; import java.util.Map; import javax.ws.rs.core.Cookie; import javax.ws.rs.core.MediaType; import javax.ws.rs.core.MultivaluedMap; import javax.ws.rs.core.Request; import javax.ws.rs.core.Response; import javax.ws.rs.core.SecurityContext; import javax.ws.rs.core.UriInfo; public interface ContainerRequestContext { public Object getProperty(String name); public Collection getPropertyNames(); public void setProperty(String name, Object object); public void removeProperty(String name); public UriInfo getUriInfo(); public void setRequestUri(URI requestUri); public void setRequestUri(URI baseUri, URI requestUri); public Request getRequest(); public String getMethod(); public void setMethod(String method); public MultivaluedMap getHeaders(); public String getHeaderString(String name); public Date getDate(); public Locale getLanguage(); public int getLength(); public MediaType getMediaType(); public List getAcceptableMediaTypes(); public List getAcceptableLanguages(); public Map getCookies(); public boolean hasEntity(); public InputStream getEntityStream(); public void setEntityStream(InputStream input); public SecurityContext getSecurityContext(); public void setSecurityContext(SecurityContext context); public void abortWith(Response response); }
// Java
...
package javax.ws.rs.container;
import java.io.InputStream;
import java.net.URI;
import java.util.Collection;
import java.util.Date;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import javax.ws.rs.core.Cookie;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.SecurityContext;
import javax.ws.rs.core.UriInfo;
public interface ContainerRequestContext {
public Object getProperty(String name);
public Collection getPropertyNames();
public void setProperty(String name, Object object);
public void removeProperty(String name);
public UriInfo getUriInfo();
public void setRequestUri(URI requestUri);
public void setRequestUri(URI baseUri, URI requestUri);
public Request getRequest();
public String getMethod();
public void setMethod(String method);
public MultivaluedMap getHeaders();
public String getHeaderString(String name);
public Date getDate();
public Locale getLanguage();
public int getLength();
public MediaType getMediaType();
public List getAcceptableMediaTypes();
public List getAcceptableLanguages();
public Map getCookies();
public boolean hasEntity();
public InputStream getEntityStream();
public void setEntityStream(InputStream input);
public SecurityContext getSecurityContext();
public void setSecurityContext(SecurityContext context);
public void abortWith(Response response);
}
Copy to clipboardCopiedPreMatchContainerRequest 过滤器的实现示例
要为 PreMatchContainerRequest
扩展点(即,在资源匹配之前执行过滤器的位置)实现容器请求过滤器,请定义一个实施 ContainerRequestFilter
接口的类,确保为类添加 @PreMatching
注解(选择 PreMatchContainerRequest
扩展点)。
例如,以下代码显示了在 PreMatchContainerRequest
扩展点中安装的简单容器请求过滤器示例,其优先级为 20:
// Java package org.jboss.fuse.example; import javax.ws.rs.container.ContainerRequestContext; import javax.ws.rs.container.ContainerRequestFilter; import javax.ws.rs.container.PreMatching; import javax.annotation.Priority; import javax.ws.rs.ext.Provider; @PreMatching @Priority(value = 20) @Provider public class SamplePreMatchContainerRequestFilter implements ContainerRequestFilter { public SamplePreMatchContainerRequestFilter() { System.out.println("SamplePreMatchContainerRequestFilter starting up"); } @Override public void filter(ContainerRequestContext requestContext) { System.out.println("SamplePreMatchContainerRequestFilter.filter() invoked"); } }
// Java
package org.jboss.fuse.example;
import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerRequestFilter;
import javax.ws.rs.container.PreMatching;
import javax.annotation.Priority;
import javax.ws.rs.ext.Provider;
@PreMatching
@Priority(value = 20)
@Provider
public class SamplePreMatchContainerRequestFilter implements
ContainerRequestFilter {
public SamplePreMatchContainerRequestFilter() {
System.out.println("SamplePreMatchContainerRequestFilter starting up");
}
@Override
public void filter(ContainerRequestContext requestContext) {
System.out.println("SamplePreMatchContainerRequestFilter.filter() invoked");
}
}
Copy to clipboardCopiedContainerRequest 过滤器的实现示例
要为 ContainerRequest
扩展点实施容器请求过滤器(即,过滤器在资源匹配 后执行 的位置),请定义一个实施 ContainerRequestFilter
接口的类,而无需 @PreMatching
注解。
例如,以下代码显示了在 ContainerRequest
扩展点中安装的简单容器请求过滤器示例,其优先级为 30 :
// Java package org.jboss.fuse.example; import javax.ws.rs.container.ContainerRequestContext; import javax.ws.rs.container.ContainerRequestFilter; import javax.ws.rs.ext.Provider; import javax.annotation.Priority; @Provider @Priority(value = 30) public class SampleContainerRequestFilter implements ContainerRequestFilter { public SampleContainerRequestFilter() { System.out.println("SampleContainerRequestFilter starting up"); } @Override public void filter(ContainerRequestContext requestContext) { System.out.println("SampleContainerRequestFilter.filter() invoked"); } }
// Java
package org.jboss.fuse.example;
import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerRequestFilter;
import javax.ws.rs.ext.Provider;
import javax.annotation.Priority;
@Provider
@Priority(value = 30)
public class SampleContainerRequestFilter implements ContainerRequestFilter {
public SampleContainerRequestFilter() {
System.out.println("SampleContainerRequestFilter starting up");
}
@Override
public void filter(ContainerRequestContext requestContext) {
System.out.println("SampleContainerRequestFilter.filter() invoked");
}
}
Copy to clipboardCopied注入 ResourceInfo
在 ContainerRequest
扩展点(即发生资源匹配 后 ),可以通过注入 ResourceInfo
类来访问匹配的资源类和资源方法。例如,以下代码演示了如何注入 ResourceInfo
类作为 ContainerRequestFilter
类的字段:
// Java package org.jboss.fuse.example; import javax.ws.rs.container.ContainerRequestContext; import javax.ws.rs.container.ContainerRequestFilter; import javax.ws.rs.container.ResourceInfo; import javax.ws.rs.ext.Provider; import javax.annotation.Priority; import javax.ws.rs.core.Context; @Provider @Priority(value = 30) public class SampleContainerRequestFilter implements ContainerRequestFilter { @Context private ResourceInfo resinfo; public SampleContainerRequestFilter() { ... } @Override public void filter(ContainerRequestContext requestContext) { String resourceClass = resinfo.getResourceClass().getName(); String methodName = resinfo.getResourceMethod().getName(); System.out.println("REST invocation bound to resource class: " + resourceClass); System.out.println("REST invocation bound to resource method: " + methodName); } }
// Java
package org.jboss.fuse.example;
import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerRequestFilter;
import javax.ws.rs.container.ResourceInfo;
import javax.ws.rs.ext.Provider;
import javax.annotation.Priority;
import javax.ws.rs.core.Context;
@Provider
@Priority(value = 30)
public class SampleContainerRequestFilter implements ContainerRequestFilter {
@Context
private ResourceInfo resinfo;
public SampleContainerRequestFilter() {
...
}
@Override
public void filter(ContainerRequestContext requestContext) {
String resourceClass = resinfo.getResourceClass().getName();
String methodName = resinfo.getResourceMethod().getName();
System.out.println("REST invocation bound to resource class: " + resourceClass);
System.out.println("REST invocation bound to resource method: " + methodName);
}
}
Copy to clipboardCopied中止调用
通过创建合适的容器请求过滤器实施,可以中止服务器端调用。通常,这对在服务器端实施安全功能很有用:例如,为了实现身份验证功能或授权功能。如果传入的请求无法成功进行身份验证,您可以在容器请求过滤器内中止调用。
例如,以下预匹配功能尝试从 URI 的查询参数中提取用户名和密码,并调用验证方法来检查用户名和密码凭证。如果身份验证失败,则调用在 ContainerRequestContext
对象上的 abortWith
中止,传递要返回到客户端的错误响应。
// Java package org.jboss.fuse.example; import javax.annotation.Priority; import javax.ws.rs.container.ContainerRequestContext; import javax.ws.rs.container.ContainerRequestFilter; import javax.ws.rs.container.PreMatching; import javax.ws.rs.core.Response; import javax.ws.rs.core.Response.ResponseBuilder; import javax.ws.rs.core.Response.Status; import javax.ws.rs.ext.Provider; @PreMatching @Priority(value = 20) @Provider public class SampleAuthenticationRequestFilter implements ContainerRequestFilter { public SampleAuthenticationRequestFilter() { System.out.println("SampleAuthenticationRequestFilter starting up"); } @Override public void filter(ContainerRequestContext requestContext) { ResponseBuilder responseBuilder = null; Response response = null; String userName = requestContext.getUriInfo().getQueryParameters().getFirst("UserName"); String password = requestContext.getUriInfo().getQueryParameters().getFirst("Password"); if (authenticate(userName, password) == false) { responseBuilder = Response.serverError(); response = responseBuilder.status(Status.BAD_REQUEST).build(); requestContext.abortWith(response); } } public boolean authenticate(String userName, String password) { // Perform authentication of 'user' ... } }
// Java
package org.jboss.fuse.example;
import javax.annotation.Priority;
import javax.ws.rs.container.ContainerRequestContext;
import javax.ws.rs.container.ContainerRequestFilter;
import javax.ws.rs.container.PreMatching;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.ResponseBuilder;
import javax.ws.rs.core.Response.Status;
import javax.ws.rs.ext.Provider;
@PreMatching
@Priority(value = 20)
@Provider
public class SampleAuthenticationRequestFilter implements
ContainerRequestFilter {
public SampleAuthenticationRequestFilter() {
System.out.println("SampleAuthenticationRequestFilter starting up");
}
@Override
public void filter(ContainerRequestContext requestContext) {
ResponseBuilder responseBuilder = null;
Response response = null;
String userName = requestContext.getUriInfo().getQueryParameters().getFirst("UserName");
String password = requestContext.getUriInfo().getQueryParameters().getFirst("Password");
if (authenticate(userName, password) == false) {
responseBuilder = Response.serverError();
response = responseBuilder.status(Status.BAD_REQUEST).build();
requestContext.abortWith(response);
}
}
public boolean authenticate(String userName, String password) {
// Perform authentication of 'user'
...
}
}
Copy to clipboardCopied绑定服务器请求过滤器
要 绑定 服务器请求过滤器(即要将它安装到 Apache CXF 运行时中),请执行以下步骤:
将
@Provider
注释添加到容器请求过滤器类,如以下代码片段所示:// Java package org.jboss.fuse.example; import javax.ws.rs.container.ContainerRequestContext; import javax.ws.rs.container.ContainerRequestFilter; import javax.ws.rs.ext.Provider; import javax.annotation.Priority; @Provider @Priority(value = 30) public class SampleContainerRequestFilter implements ContainerRequestFilter { ... }
Copy to clipboardCopied// Java package org.jboss.fuse.example; import javax.ws.rs.container.ContainerRequestContext; import javax.ws.rs.container.ContainerRequestFilter; import javax.ws.rs.ext.Provider; import javax.annotation.Priority; @Provider @Priority(value = 30) public class SampleContainerRequestFilter implements ContainerRequestFilter { ... }
当容器请求过滤器实施加载到 Apache CXF 运行时中时,REST 实施会自动扫描加载的类,以搜索标有
@Provider
注释( 扫描阶段)。在 XML 中定义 JAX-RS 服务器端点(例如,请参阅 第 18.1 节 “配置 JAX-RS 服务器端点”)时,将服务器请求过滤器添加到
jaxrs:providers
元素中的供应商列表中。<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:jaxrs="http://cxf.apache.org/blueprint/jaxrs" xmlns:cxf="http://cxf.apache.org/blueprint/core" ... > ... <jaxrs:server id="customerService" address="/customers"> ... <jaxrs:providers> <ref bean="filterProvider" /> </jaxrs:providers> <bean id="filterProvider" class="org.jboss.fuse.example.SampleContainerRequestFilter"/> </jaxrs:server> </blueprint>
Copy to clipboardCopied<blueprint xmlns="http://www.osgi.org/xmlns/blueprint/v1.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:jaxrs="http://cxf.apache.org/blueprint/jaxrs" xmlns:cxf="http://cxf.apache.org/blueprint/core" ... > ... <jaxrs:server id="customerService" address="/customers"> ... <jaxrs:providers> <ref bean="filterProvider" /> </jaxrs:providers> <bean id="filterProvider" class="org.jboss.fuse.example.SampleContainerRequestFilter"/> </jaxrs:server> </blueprint>
注意此步骤是 Apache CXF 的非标准要求。根据 JAX-RS 标准,严格说,
@Provider
注释应当是绑定过滤器所需的所有内容。但是在实践中,标准方法有些不灵活,当许多库包含在大型项目中时,可能会导致禁止提供程序。