使用JAX-RS（Jersey）的HTTP状态错误消息响应中的自定义原因短语

在最近的一些工作中，我收到了在发生错误时在HTTP状态响应中生成自定义“原因短语”的请求，该状态短语传递给我们的一个REST API消耗客户端。在这篇文章中，我将演示如何使用Jersey来实现。

1.定义检查的异常和异常映射器

正如您可能从我的文章使用Jersey的REST API中的错误处理中发现的那样，我喜欢使用Jersey的ExceptionMapper功能来处理已检查的异常。

为了演示的目的，我定义了一个CustomReasonPhraseException ：

CustomReasonPhraseException

package org.codingpedia.demo.rest.errorhandling;public class CustomReasonPhraseException extends Exception {private static final long serialVersionUID = -271582074543512905L;private final int businessCode;public CustomReasonPhraseException(int businessCode, String message) {super(message);this.businessCode = businessCode;}public int getBusinessCode() {return businessCode;}}

和CustomReasonPhraseExceptionMapper来处理映射到一个响应，如果CustomReasonPhraseException发生：

CustomReasonPhraseExceptionMapper

package org.codingpedia.demo.rest.errorhandling;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;@Provider
public class CustomReasonPhraseExceptionMapper implements ExceptionMapper<CustomReasonPhraseException> {public Response toResponse(CustomReasonPhraseException bex) {return Response.status(new CustomReasonPhraseExceptionStatusType(Status.BAD_REQUEST)).entity("Custom Reason Phrase exception occured : " + bex.getMessage()).build();}}

提醒：当应用程序引发CustomReasonPhraseException ，将调用CustomReasonPhraseExceptionMapper实例的toResponse方法。

在ExceptionMapper代码注释第12行中：

CustomReasonPhraseExceptionStatusType

return Response.status(new CustomReasonPhraseExceptionStatusType(Status.BAD_REQUEST))

在Jersey的ResponseBuilder您可以通过实现javax.ws.rs.core.Response.StatusType接口来定义自己的状态类型。

2.实现自定义StatusType

为了使它更具扩展性，我创建了AbstractStatusType类：

AbstractStatusType

package org.codingpedia.demo.rest.errorhandling;import javax.ws.rs.core.Response.Status;
import javax.ws.rs.core.Response.Status.Family;
import javax.ws.rs.core.Response.StatusType;/*** Class used to provide custom StatusTypes, especially for the the Reason Phrase that appears in the HTTP Status Response*/
public abstract class AbstractStatusType implements StatusType {public AbstractStatusType(final Family family, final int statusCode,final String reasonPhrase) {super();this.family = family;this.statusCode = statusCode;this.reasonPhrase = reasonPhrase;}protected AbstractStatusType(final Status status,final String reasonPhrase) {this(status.getFamily(), status.getStatusCode(), reasonPhrase);}@Overridepublic Family getFamily() { return family; }@Overridepublic String getReasonPhrase() { return reasonPhrase; }@Overridepublic int getStatusCode() { return statusCode; }private final Family family;private final int statusCode;private final String reasonPhrase;}

之后，我使用CustomReasonPhraseExceptionStatusType进行扩展，以在响应中提供我想要的自定义Reason Phrase （ 例如“自定义错误消息” ）：

CustomReasonPhraseExceptionStatusType扩展了AbstractStatusType

package org.codingpedia.demo.rest.errorhandling;import javax.ws.rs.core.Response.Status;/*** Implementation of StatusType for CustomReasonPhraseException.* The Reason Phrase is set in this case to "Custom error message"*/
public class CustomReasonPhraseExceptionStatusType extends AbstractStatusType{private static final String CUSTOM_EXCEPTION_REASON_PHRASE = "Custom error message";public CustomReasonPhraseExceptionStatusType(Status httpStatus) {super(httpStatus, CUSTOM_EXCEPTION_REASON_PHRASE);}}

3.在HTTP状态响应中测试自定义原因短语

请求

要求范例

GET http://localhost:8888/demo-rest-jersey-spring/mocked-custom-reason-phrase-exception HTTP/1.1
Accept-Encoding: gzip,deflate
Host: localhost:8888
Connection: Keep-Alive
User-Agent: Apache-HttpClient/4.1.1 (java 1.5)

响应

瞧！

回应范例

HTTP/1.1 400 Custom error message
Content-Type: text/plain
Content-Length: 95
Server: Jetty(9.0.7.v20131107)Custom Reason Phrase exception occured : message attached to the Custom Reason Phrase Exception

自定义“原因短语”将按预期方式出现在响应中。

提示：如果您真的想学习如何在Java中设计和实现REST API，请阅读以下教程–借助Jersey和Spring在Java中进行REST API设计和实现