JAX-RS（Jersey 2 实现）与 URL 扩展名 .xml 或 .json 的内容协商

Question

我见过一个 Java RESTFUL 网络服务，它允许在 URL 中请求 content-type 并在末尾添加扩展名，例如

.xml
.json

这是我在自己的 Web 服务中努力实现的内容协商风格。

我知道 @Produces 注释，事实上一个方法可以使用 (value = {}) 语法解析多个类型，通过添加一个 Accept header，比如 Postman， Chrome 分机。

但我不确定如何在一种方法中有效地提取信息，然后委托给另一种方法。

我假设 REGEX 可以与 @Path 和 @PathParam 一起使用，但我的尝试尚未取得成果。

谁能举个例子？

这是我迄今为止的尝试：

package com.extratechnology.caaews;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.PathParam;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

import com.extratechnology.caaews.model.Log;


@Path("et")
@Produces(MediaType.APPLICATION_JSON)
public class CAAEWS {


    @GET
    @Path("\.{format}")
    @Produces(value = {MediaType.APPLICATION_JSON, MediaType.TEXT_XML})
    public Log getLog(
            @PathParam("format") String format
    ){
        Log result = null;
        switch (format) {
        case "json":
            result = this.getJSON();
        case "xml":
            result = this.getXML();
        }
        return result;
    }

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Log getJSON() {
        return new Log("JSON!");
    }

    @GET
    @Produces(MediaType.TEXT_XML)
    public Log getXML() {
        return new Log("XML!");
    }

}

package com.extratechnology.caaews.model;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Log {
    private String log;

    public Log(String log) {
        this.log = log;
    }

    public String getLog() {
        return log;
    }

    public void setLog(String log) {
        this.log = log;
    }

}

可以使用 Spring 工具 Suite/Eclipse 设置项目，方法是使用以下方法创建 Maven 项目（类似，但比 here circa 4:50 更新）：

org.glassfish.jersey.archetypes
jersey.quickstart.webapp
2.26

然后您取消注释 pom.xml 提供的部分以启用 JSON 支持，这有效地向您的 WAR.

添加了一些 JARS

我发现我也有一些讨厌的 BCEL 错误，并且不得不将一些条目附加到 catalina.properties 文件中，在键下：

tomcat.util.scan.StandardJarScanFilter.jarsToSkip=\
....
javax.json-api-1.1.jar, javax.json.bind-api-1.0.jar, javax.json-1.1.jar, \
yasson-1.0.jar

http://localhost:18080/caaews/webapi/et

产量：

{"log":"JSON!"}

http://localhost:18080/caaews/webapi/et.xml 或

http://localhost:18080/caaews/webapi/et.json

产量：

HTTP Status 404 - Not Found

我也想知道是否有某种 HTTP 拦截器类型的方法可以解决这个问题。我的 Java 有点生疏，但它是 servlet 过滤器，还是类似于建议之前的 AOP 的东西。

感谢@user1803551 我在 switch 语句中加入了中断。

感谢@callmepills，我对代码做了一些调整。

class 级 @Path 注释现在有这个。 @Produces(value = {MediaType.APPLICATION_JSON, MediaType.TEXT_XML})

getLog @Path 注释是“.{format}”。

为了调用和委托 getLog，您必须对 URL:

使用此语法

http://localhost:18080/caaews/webapi/et

http://localhost:18080/caaews/webapi/et/.xml

http://localhost:18080/caaews/webapi/et/.json

路径中需要有一个“/”不是我想要的，所以我想我可能必须解决 servlet 过滤器而不是 @PathParam 方法..

Answer 1

您是否尝试过在 class 级别删除 @Path 注释？您的方法级注释将是：

@Path("et.{format}")

我认为您当前的实现正在创建一个匹配如下路径的子资源：

/et/{format}

Answer 2

您的 JAX-RS 代码存在几个问题：

`@Path`

中的正则表达式

@Path 注解的 value 仅在参数模板内部和 : 字符之后解析正则表达式。您正在尝试在参数模板 "\.{format}" 之外使用正则表达式，因此它不会将其解析为正则表达式。

路径解析

一个方法的路径包括 class 路径的部分，后面跟着它自己的路径部分。当您尝试调用 /et.{format} 时，您的代码建议路径 /et/.{format} 和 /et，这在任何地方都没有定义，因此是 404.

这是一个可以根据您的代码运行的示例：

@Path("et")
public class Resource {

    private static final String JSON = "json";
    private static final String XML = "xml";

    @GET
    @Path(".{format:(" + JSON + "|" + XML + ")}")
    @Produces(value = { MediaType.APPLICATION_JSON, MediaType.TEXT_XML }) // not XML?
    public String getLog(@PathParam("format") String format) {
        switch (format) {
            case JSON:
                this.getJSON();
                break;
            case XML:
                this.getXML();
        }
        return format;
    }

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public void getJSON() {
        System.out.println("in JSON");
    }

    @GET
    @Path("otherPath")
    @Produces(MediaType.APPLICATION_XML)
    public void getXML() {
        System.out.println("in XML");
    }
}

您的有效请求现在为：

http://localhost:18080/caaews/webapi/et（JSON 到 getJSON）
http://localhost:18080/caaews/webapi/et/otherPath（XML 到 getXML）
http://localhost:18080/caaews/webapi/et/.xml（XML 到 getLog）
http://localhost:18080/caaews/webapi/et/.json（JSON 到 getLog）

根据需要更改路径。 XML方法我用了"otherPath"，因为它不能和空路径JSON方法冲突。我不推荐这种约定。

备注：

在 switch 语句中使用 break。
为了减少出现错误的机会，请像我对您的自定义格式类型所做的那样，对可重用字符串等使用常量。 enum 会更好。

编辑：

请求现在有一个路径 /et/<something>.{format}。如果我们扩展路径参数的范围以包括整个段 <something>.{format} 然后以编程方式提取格式，就可以实现这一点：

@GET
@Path("{segment:[a-zA-Z0-9_]*\.(" + JSON + "|" + XML + ")}")
@Produces(value = { MediaType.APPLICATION_JSON, MediaType.TEXT_XML })
public String getLog(@PathParam("segment") String segment) {
    String format = segment.substring(segment.indexOf('.') + 1);
    switch (format) {
        case JSON:
            this.getJSON();
            break;
        case XML:
            this.getXML();
    }
    return format;
}

正则表达式 [a-zA-Z0-9_]* 表示任何字母数字或下划线一次或多次。您可以用您想要的任何限制替换该部分。请参阅 URL 规范以了解允许的字符。

Answer 3

当我用 Google 搜索 "servlet filter with jax-rs example" 时，this 位于列表的顶部。粗略扫了一下代码，我觉得这很符合我的需要。

这是我的解决方案（到目前为止...请参阅脚注警告）

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<!-- This web.xml file is not required when using Servlet 3.0 container,
     see implementation details http://jersey.java.net/nonav/documentation/latest/jax-rs.html -->
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

  <filter>
        <filter-name>accept-filter</filter-name>
        <filter-class>com.extratechnology.filters.AcceptFilter</filter-class>
        <init-param>
            <param-name>xml</param-name>
            <param-value>text/xml</param-value>
        </init-param>
        <init-param>
            <param-name>json</param-name>
            <param-value>application/json</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>accept-filter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>
    <servlet>
        <servlet-name>Jersey Web Application</servlet-name>
        <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
        <init-param>
            <param-name>jersey.config.server.provider.packages</param-name>
            <param-value>com.extratechnology.caaews</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>
    <servlet-mapping>
        <servlet-name>Jersey Web Application</servlet-name>
        <url-pattern>/webapi/*</url-pattern>
    </servlet-mapping>
</web-app>

AcceptFilter.java

package com.extratechnology.filters;
import java.io.IOException;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class AcceptFilter implements Filter  {
    private final Map<String,String> extensions = new HashMap<String,String>();

    public void init(FilterConfig config) throws ServletException {
        Enumeration<String> exts = config.getInitParameterNames();
        while (exts.hasMoreElements()) {
            String ext = exts.nextElement();
            if (ext != null && !ext.isEmpty()) {
                this.extensions.put(ext.toLowerCase(), config.getInitParameter(ext));
            }
        }
    }

    public void destroy() {}

    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest httpRequest = (HttpServletRequest)request;
        String uri = httpRequest.getRequestURI();
        String ext = this.getExtension(uri);
        String accept = this.extensions.get(ext);

        if (accept == null) {
            accept = httpRequest.getHeader("accept");
            if (accept != null && accept.indexOf("text/html") > 0) {
                // patch WebKit-style Accept headers by elevating "text/html"
                accept = "text/html,"+accept;
                request = new RequestWrapper(httpRequest, uri, accept);
            }
        } else {
            // remove extension and remap the Accept header
            uri = uri.substring(0, uri.length() - ext.length()-1);
            request = new RequestWrapper(httpRequest, uri, accept);
        }

        // add "Vary: accept" to the response headers
        HttpServletResponse httpResponse = (HttpServletResponse)response;
        httpResponse.addHeader("Vary", "accept");

        chain.doFilter(request, response);
    }

    private String getExtension(String path) {
        String result = "";
        int index = path.lastIndexOf('.');
        if (!(index < 0 || path.lastIndexOf('/') > index)) {
            result =  path.substring(index+1).toLowerCase();
        }
        return result;
    }

    private static class RequestWrapper extends HttpServletRequestWrapper {

        private final String uri;
        private final String accept;

        public RequestWrapper(HttpServletRequest request, String uri, String accept) {
            super(request);

            this.uri = uri;
            this.accept = accept;
        }

        @Override
        public String getRequestURI() {
            return this.uri;
        }
        @Override
        public Enumeration<String> getHeaders(String name) {
            Enumeration<String> result;
            if ("accept".equalsIgnoreCase(name)) {
                Vector<String> values = new Vector<String>(1);
                values.add(this.accept);
                result = values.elements();
            } else {
                result =  super.getHeaders(name);       
            }
            return result;
        }
    }
}

CAAEWS.java

package com.extratechnology.caaews;

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

import com.extratechnology.caaews.model.Log;


@Path("et")
@Produces(value = {MediaType.APPLICATION_JSON, MediaType.TEXT_XML})
public class CAAEWS {

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Log getJSON() {
        return new Log("JSON!");
    }

    @GET
    @Produces(MediaType.TEXT_XML)
    public Log getXML() {
        return new Log("XML!");
    }

}

Log.java

package com.extratechnology.caaews.model;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class Log {
    private String log;

    public Log(String log) {
        this.log = log;
    }

    public String getLog() {
        return log;
    }

    public void setLog(String log) {
        this.log = log;
    }

}

唯一让我有点好奇的是 HTTP 有两种内容类型 XML。

text/xml
application/xml

它在 web.xml 中是可配置的，但我必须调整注释。为什么是两个？

--

脚注：

写完这篇文章后，我发现我遇到了 HTTP 500 错误。当您运行 Eclipse 中的服务器时，日志似乎在某个不起眼的文件夹中：

Documents\workspace-sts-3.8.3.RELEASE\.metadata\.plugins\org.eclipse.wst.server.core\tmp1\logs

然后我将其写入日志：

0:0:0:0:0:0:0:1 - - [25/Nov/2017:16:56:00 +0000] "GET /caaews/webapi/et.xml HTTP/1.1" 500 1082

有没有人知道如何获得更合理的日志信息？或者我需要做什么来捕获更有意义的堆栈跟踪？

看来 Log class 需要一个无参数构造函数来克服这个问题。但我承认，@peeskillet 的答案远没有那么繁琐，并且使用了 Jersey 的内置功能。

我也想知道 javax.servlet.filters 在查看示例后是否不能很好地使用 JAX-RS 2.0 here...

对于这个问题的其他相关 answers/comments，我最终实现了一个异常处理程序，因此您可以获得有关泽西岛 HTTP 500 消息的更多信息..

这是帮助指向 Log.java 需要无参数构造函数的方法的代码..

错误信息

package com.extratechnology.caaews.model;

import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement
public class ErrorMessage {
    private String errorMessage;
    private String errorStackTrace;
    private String cause;
    private String causeStackTrace;
    private int    errorCode;

    public ErrorMessage() {
    }

    public ErrorMessage(
        String errorMessage, 
        String errorStackTrace, 
        String cause,
        String causeStackTrace,
        int errorCode
    ) {
        this.errorMessage = errorMessage;
        this.errorStackTrace = errorStackTrace;
        this.cause = cause;
        this.causeStackTrace = causeStackTrace;
        this.errorCode = errorCode;
    }

    public String getErrorMessage() {
        return errorMessage;
    }

    public void setErrorMessage(String errorMessage) {
        this.errorMessage = errorMessage;
    }

    public String getErrorStackTrace() {
        return errorStackTrace;
    }

    public void setErrorStackTrace(String errorStackTrace) {
        this.errorStackTrace = errorStackTrace;
    }

    public String getCause() {
        return cause;
    }

    public void setCause(String cause) {
        this.cause = cause;
    }

    public String getCauseStackTrace() {
        return causeStackTrace;
    }

    public void setCauseStackTrace(String causeStackTrace) {
        this.causeStackTrace = causeStackTrace;
    }

    public int getErrorCode() {
        return errorCode;
    }

    public void setErrorCode(int errorCode) {
        this.errorCode = errorCode;
    }

}

GenericExceptionMapper.java

package com.extratechnology.caaews.exception;

import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.Status;
import javax.ws.rs.ext.ExceptionMapper;
import javax.ws.rs.ext.Provider;

import com.extratechnology.caaews.model.ErrorMessage;

@Provider
public class GenericExceptionMapper implements ExceptionMapper<Throwable>{

    @Override
    public Response toResponse(Throwable ex) {
        System.out.println("Stack Trace:");
        ex.printStackTrace();
        System.out.println("Cause:");
        Throwable cause = ex.getCause();
        if (cause != null) {
            cause.printStackTrace();    
        }
        ErrorMessage message = new ErrorMessage(
                ex.getMessage(),
                GenericExceptionMapper.getStackTrack(ex),
                cause.getMessage(),
                GenericExceptionMapper.getStackTrack(cause),
                Status.INTERNAL_SERVER_ERROR.getStatusCode()
                );
        return Response
                .status(Status.INTERNAL_SERVER_ERROR)
                .entity(message)
                .build();
    }

    private static String getStackTrack(Throwable ex) {
        StringBuilder sb = new StringBuilder();
        String ls = System.lineSeparator();
        if (ex != null) {
            StackTraceElement[] steAll = ex.getStackTrace();
            for (StackTraceElement ste : steAll) {
                sb.append(ste.toString());
                sb.append(ls);
            }   
        }
        return sb.toString();
    }
}

system.out.println 在调试时给出控制台消息，并且在出现错误时您也会在 Web 浏览器中返回有效负载。

例如：

This XML file does not appear to have any style information associated with it. The document tree is shown below.
<errorMessage>
<cause>1 counts of IllegalAnnotationExceptions</cause>
<causeStackTrace>
com.sun.xml.internal.bind.v2.runtime.IllegalAnnotationsException$Builder.check(Unknown Source) com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.getTypeInfoSet(Unknown Source) com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.<init>(Unknown Source) com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.<init>(Unknown Source) com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl$JAXBContextBuilder.build(Unknown Source) com.sun.xml.internal.bind.v2.ContextFactory.createContext(Unknown Source) sun.reflect.GeneratedMethodAccessor20.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) java.lang.reflect.Method.invoke(Unknown Source) javax.xml.bind.ContextFinder.newInstance(Unknown Source) javax.xml.bind.ContextFinder.newInstance(Unknown Source) javax.xml.bind.ContextFinder.find(Unknown Source) javax.xml.bind.JAXBContext.newInstance(Unknown Source) javax.xml.bind.JAXBContext.newInstance(Unknown Source) org.glassfish.jersey.jaxb.internal.AbstractJaxbProvider.getStoredJaxbContext(AbstractJaxbProvider.java:312) org.glassfish.jersey.jaxb.internal.AbstractJaxbProvider.getJAXBContext(AbstractJaxbProvider.java:297) org.glassfish.jersey.jaxb.internal.AbstractJaxbProvider.getMarshaller(AbstractJaxbProvider.java:264) org.glassfish.jersey.jaxb.internal.AbstractJaxbProvider.getMarshaller(AbstractJaxbProvider.java:231) org.glassfish.jersey.jaxb.internal.AbstractRootElementJaxbProvider.writeTo(AbstractRootElementJaxbProvider.java:175) org.glassfish.jersey.message.internal.WriterInterceptorExecutor$TerminalWriterInterceptor.invokeWriteTo(WriterInterceptorExecutor.java:266) org.glassfish.jersey.message.internal.WriterInterceptorExecutor$TerminalWriterInterceptor.aroundWriteTo(WriterInterceptorExecutor.java:251) org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:163) org.glassfish.jersey.server.internal.JsonWithPaddingInterceptor.aroundWriteTo(JsonWithPaddingInterceptor.java:109) org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:163) org.glassfish.jersey.server.internal.MappableExceptionWrapperInterceptor.aroundWriteTo(MappableExceptionWrapperInterceptor.java:85) org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:163) org.glassfish.jersey.message.internal.MessageBodyFactory.writeTo(MessageBodyFactory.java:1135) org.glassfish.jersey.server.ServerRuntime$Responder.writeResponse(ServerRuntime.java:662) org.glassfish.jersey.server.ServerRuntime$Responder.processResponse(ServerRuntime.java:395) org.glassfish.jersey.server.ServerRuntime$Responder.process(ServerRuntime.java:385) org.glassfish.jersey.server.ServerRuntime.run(ServerRuntime.java:280) org.glassfish.jersey.internal.Errors.call(Errors.java:272) org.glassfish.jersey.internal.Errors.call(Errors.java:268) org.glassfish.jersey.internal.Errors.process(Errors.java:316) org.glassfish.jersey.internal.Errors.process(Errors.java:298) org.glassfish.jersey.internal.Errors.process(Errors.java:268) org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:289) org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:256) org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:703) org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:416) org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:370) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:389) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:342) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:229) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217) org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616) org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456) java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) java.lang.Thread.run(Unknown Source)
</causeStackTrace>
<errorCode>500</errorCode>
<errorMessage>HTTP 500 Internal Server Error</errorMessage>
<errorStackTrace>
org.glassfish.jersey.jaxb.internal.AbstractRootElementJaxbProvider.writeTo(AbstractRootElementJaxbProvider.java:183) org.glassfish.jersey.message.internal.WriterInterceptorExecutor$TerminalWriterInterceptor.invokeWriteTo(WriterInterceptorExecutor.java:266) org.glassfish.jersey.message.internal.WriterInterceptorExecutor$TerminalWriterInterceptor.aroundWriteTo(WriterInterceptorExecutor.java:251) org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:163) org.glassfish.jersey.server.internal.JsonWithPaddingInterceptor.aroundWriteTo(JsonWithPaddingInterceptor.java:109) org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:163) org.glassfish.jersey.server.internal.MappableExceptionWrapperInterceptor.aroundWriteTo(MappableExceptionWrapperInterceptor.java:85) org.glassfish.jersey.message.internal.WriterInterceptorExecutor.proceed(WriterInterceptorExecutor.java:163) org.glassfish.jersey.message.internal.MessageBodyFactory.writeTo(MessageBodyFactory.java:1135) org.glassfish.jersey.server.ServerRuntime$Responder.writeResponse(ServerRuntime.java:662) org.glassfish.jersey.server.ServerRuntime$Responder.processResponse(ServerRuntime.java:395) org.glassfish.jersey.server.ServerRuntime$Responder.process(ServerRuntime.java:385) org.glassfish.jersey.server.ServerRuntime.run(ServerRuntime.java:280) org.glassfish.jersey.internal.Errors.call(Errors.java:272) org.glassfish.jersey.internal.Errors.call(Errors.java:268) org.glassfish.jersey.internal.Errors.process(Errors.java:316) org.glassfish.jersey.internal.Errors.process(Errors.java:298) org.glassfish.jersey.internal.Errors.process(Errors.java:268) org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:289) org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:256) org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:703) org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:416) org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:370) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:389) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:342) org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:229) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:217) org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106) org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616) org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:673) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1456) java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) java.lang.Thread.run(Unknown Source)
</errorStackTrace>
</errorMessage>

Answer 4

即使你没有标记 jersey, your question shows you are using Jersey, so I am going to post a Jersey-specific solution. What Jersey offers is a property that you can use to set the media type mappings

ServerPropeties.MEDIA_TYPE_MAPPINGS

public static final String MEDIA_TYPE_MAPPINGS

Defines mapping of URI extensions to media types. The property is used by UriConnegFilter. See it's javadoc for more information on media type mappings.

The property value MUST be an instance of String, String[] or Map<String, MediaType>. Each String instance represents one or more uri-extension-to-media-type map entries separated by a comma (","). Each map entry is a key-value pair separated by a colon (":"). Here is an example of an acceptable String value mapping txt extension to text/plain and xml extension to application/xml:
txt : text/plain, xml : application/xml
A default value is not set.

The name of the configuration property is "jersey.config.server.mediaTypeMappings".

带有 Java 配置的示例

final Map<String, MediaType> mediaTypeMappings = new HashMap<>();
mediaTypeMappings.put("xml", MediaType.APPLICATION_XML_TYPE);
mediaTypeMappings.put("json", MediaType.APPLICATION_JSON_TYPE);

final ResourceConfig rc = new ResourceConfig()
        .packages("com.example.jersey")
        .property(ServerProperties.MEDIA_TYPE_MAPPINGS, mediaTypeMappings);

带有 web.xml 配置的示例

<servlet>
    <servlet-name>JerseyApplication</servlet-name>
    <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
    <init-param>
        <param-name>jersey.config.server.provider.packages</param-name>
        <param-value>com.example</param-value>
    </init-param>
    <init-param>
        <param-name>jersey.config.server.mediaTypeMappings</param-name>
        <param-value>xml:application/xml, json:application/json</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>

JAX-RS（Jersey 2 实现）与 URL 扩展名 .xml 或 .json 的内容协商

JAX-RS (Jersey 2 implementation) content negotiation with URL extension .xml or .json

java

rest

content-type

jax-rs

jersey-2.0

`@Path`

路径解析

例如：

`ServerPropeties.MEDIA_TYPE_MAPPINGS`

带有 Java 配置的示例

带有 web.xml 配置的示例