Cuando escribas un texto destacado de Java, te recomendamos que controles los errores de forma personalizada en tu código Java. Por ejemplo, quizás desees mostrar mensajes de error y encabezados personalizados o configurar variables de flujo con información de error en el flujo del proxy en Apigee.
Veamos un ejemplo simple de texto destacado de Java que ilustra patrones de manejo de errores personalizados básicos. En el ejemplo, se muestra un mensaje de error personalizado cuando se produce una excepción. También coloca el seguimiento de pila de errores en una variable de flujo, lo que puede ser una técnica de depuración práctica.
Descarga el proyecto
Para simplificar el proceso, puedes descargar este proyecto del repositorio api-platform-samples de Apigee en GitHub.
En un editor de código o terminal de tu elección, ve al proyecto api-platform-samples/doc-samples/java-error.
El código Java de muestra
Los patrones de manejo de errores son directos. Puedes configurar variables de flujo en el contexto de flujo actual de Apigee con el método messageContext.setVariable(). Para mostrar información de error personalizada, construye una instancia ExecutionResult y llama a los métodos en ella a fin de configurar la respuesta de error y los encabezados.
packagecom.apigeesample;importcom.apigee.flow.execution.ExecutionContext;importcom.apigee.flow.execution.ExecutionResult;importcom.apigee.flow.execution.spi.Execution;importcom.apigee.flow.message.MessageContext;importcom.apigee.flow.execution.Action;importorg.apache.commons.lang.exception.ExceptionUtils;publicclassJavaErrorimplementsExecution{publicExecutionResultexecute(MessageContextmessageContext,ExecutionContextexecutionContext){try{Stringname=messageContext.getMessage().getHeader("username");if(name!=null && name.length()>0){messageContext.getMessage().setContent("Hello, "+name+"!");messageContext.getMessage().removeHeader("username");}else{thrownewRuntimeException("Please specify a name parameter!");}returnExecutionResult.SUCCESS;}catch(RuntimeExceptionex){ExecutionResultexecutionResult=newExecutionResult(false,Action.ABORT);//--Returns custom error message and headerexecutionResult.setErrorResponse(ex.getMessage());executionResult.addErrorResponseHeader("ExceptionClass",ex.getClass().getName());//--Set flow variables -- may be useful for debugging.messageContext.setVariable("JAVA_ERROR",ex.getMessage());messageContext.setVariable("JAVA_STACKTRACE",ExceptionUtils.getStackTrace(ex));returnexecutionResult;}}}
Compila tu código con Maven
El proyecto está configurado para que puedas compilar con Maven. Si quieres usar javac, también incluiremos un ejemplo.
Asegúrate de haber instalado Maven:
mvn-version
Ejecuta la siguiente secuencia de comandos java-error/buildsetup.sh. Esta secuencia de comandos instala las dependencias JAR necesarias en tu repositorio local de Maven.
cd al directorio java-error/callout.
Ejecuta Maven:
mvncleanpackage
Si lo deseas, verifica que el archivo JAR edge-custom-policy-java-error.jar se copió en java-error/apiproxy/resources/java. Esta es la ubicación requerida para los archivos JAR que deseas implementar con un proxy.
Implementa y llama al proxy
Se proporciona una secuencia de comandos de implementación en el directorio ./java-error. Pero antes de ejecutarla, debes hacer una configuración rápida.
Debido a que la llamada no incluye un parámetro de consulta “name”, el código Java muestra un error en entorno de ejecución. El proxy muestra este mensaje y encabezado:
Mensaje de error: Please specify a name parameter!
[[["Fácil de comprender","easyToUnderstand","thumb-up"],["Resolvió mi problema","solvedMyProblem","thumb-up"],["Otro","otherUp","thumb-up"]],[["Difícil de entender","hardToUnderstand","thumb-down"],["Información o código de muestra incorrectos","incorrectInformationOrSampleCode","thumb-down"],["Faltan la información o los ejemplos que necesito","missingTheInformationSamplesINeed","thumb-down"],["Problema de traducción","translationIssue","thumb-down"],["Otro","otherDown","thumb-down"]],["Última actualización: 2025-09-04 (UTC)"],[[["\u003cp\u003eThis guide provides an example of creating a Java callout in Apigee and Apigee hybrid that includes custom error handling.\u003c/p\u003e\n"],["\u003cp\u003eJava callouts can handle errors by setting flow variables using \u003ccode\u003emessageContext.setVariable()\u003c/code\u003e and returning custom error information with \u003ccode\u003eExecutionResult\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThe provided sample code demonstrates how to return custom error messages and headers, as well as place error stacktraces into flow variables for debugging.\u003c/p\u003e\n"],["\u003cp\u003eThe project can be downloaded from the Apigee api-platform-samples GitHub repository and compiled using Maven, and detailed compilation instructions are included in the sample.\u003c/p\u003e\n"],["\u003cp\u003eInstructions are provided on deploying the sample proxy to Apigee using a zip file and how to test it using the \u003ccode\u003ecurl\u003c/code\u003e command.\u003c/p\u003e\n"]]],[],null,["# How to handle JavaCallout policy errors\n\n*This page\napplies to **Apigee** and **Apigee hybrid**.*\n\n\n*View [Apigee Edge](https://docs.apigee.com/api-platform/get-started/what-apigee-edge) documentation.*\n\nWhat is a Java Callout?\n-----------------------\n\nIf you're new to JavaCallout, we recommend that you start with [How to create a Java\ncallout](/apigee/docs/api-platform/develop/how-create-java-callout).\n\nHandling errors in JavaCallout policies\n---------------------------------------\n\nWhen you write a JavaCallout policy, you may want to do custom error handling in your Java code. For\nexample, you may wish to return custom error messages and headers and/or set flow variables with\nerror information in the proxy flow on Apigee.\n\nLet's walk through a simple JavaCallout policy example that illustrates basic custom error handling\npatterns. The sample returns a custom error message when an exception occurs. It also places the\nerror stacktrace into a flow variable, which can be a handy debugging technique.\n| **Tip:** See also [this community post](https://community.apigee.com/questions/32883/how-to-continue-on-error-in-a-java-callout.html) about handling errors in Java callout code.\n\n### Download the project\n\nTo make things simple, you can download this project from the Apigee [api-platform-samples](https://github.com/apigee/api-platform-samples) repository on\nGitHub.\n\n1. Download or clone [api-platform-samples](https://github.com/apigee/api-platform-samples) to your system.\n2. In a terminal or code editor of your choice, go to the `api-platform-samples/doc-samples/java-error` project.\n\n### The sample Java code\n\nThe error handling patterns are straightforward. You can set flow variables in the current\nApigee flow context with the `messageContext.setVariable()` method. To return custom\nerror information, construct an `ExecutionResult` instance and call methods on it to\nset the error response and headers. \n\n```java\npackage com.apigeesample;\n\nimport com.apigee.flow.execution.ExecutionContext;\nimport com.apigee.flow.execution.ExecutionResult;\nimport com.apigee.flow.execution.spi.Execution;\nimport com.apigee.flow.message.MessageContext;\nimport com.apigee.flow.execution.Action;\n\nimport org.apache.commons.lang.exception.ExceptionUtils;\n\n\npublic class JavaError implements Execution {\n public ExecutionResult execute(MessageContext messageContext, ExecutionContext executionContext) {\n\n try {\n\n String name = messageContext.getMessage().getHeader(\"username\");\n\n if (name != null && name.length()\u003e0) {\n messageContext.getMessage().setContent(\"Hello, \" + name + \"!\");\n messageContext.getMessage().removeHeader(\"username\");\n\n } else {\n throw new RuntimeException(\"Please specify a name parameter!\");\n }\n\n return ExecutionResult.SUCCESS;\n\n } catch (RuntimeException ex) {\n\n ExecutionResult executionResult = new ExecutionResult(false, Action.ABORT);\n\n //--Returns custom error message and header\n executionResult.setErrorResponse(ex.getMessage());\n executionResult.addErrorResponseHeader(\"ExceptionClass\", ex.getClass().getName());\n\n //--Set flow variables -- may be useful for debugging.\n messageContext.setVariable(\"JAVA_ERROR\", ex.getMessage());\n messageContext.setVariable(\"JAVA_STACKTRACE\", ExceptionUtils.getStackTrace(ex));\n return executionResult;\n }\n }\n}\n```\n\n### Compile your code with Maven\n\nThe project is set up so that you can compile with Maven. If you want to use\n`javac`, we'll include an example as well.\n| **Note:** The POM file and configuration for the Maven compile should work, but are offered in the Git repository as an example only. You may need to make adjustments for your environment. If you make changes to the sample code, you may also need to adjust the Maven configuration.\n\n1. Be sure that you have Maven installed: \n\n ```java\n mvn -version\n ```\n2. Execute the script `java-error/buildsetup.sh`. This script installs the required JAR dependencies in your local Maven repo.\n3. cd to the `java-error/callout` directory.\n4. Execute Maven: \n\n ```java\n mvn clean package\n ```\n | **Note:** If you get a Maven error, be sure that you are in the `java-error/callout` directory.\n5. If you wish, verify that the JAR file `edge-custom-policy-java-error.jar` was copied to `java-error/apiproxy/resources/java`. This is the required location for JAR files that you wish to deploy with a proxy.\n\n### Deploy and call the proxy\n\nA deploy script is provided in the `./java-error` directory. But before you run it,\nyou need to do a quick setup.\n\n1. cd to `api-platform-samples/doc-samples/java-error`\n2. The simplest way to deploy the proxy is to bundle it in a zip file and upload the proxy bundle to an environment in your Apigee organization. See [Creating an API proxy](/apigee/docs/api-platform/develop/ui-create-proxy). Be sure to use the **Upload Proxy Bundle** option. See also [Tips and tricks for uploading API proxy in a proxy bundle](https://community.apigee.com/questions/64498/tips-and-tricks-for-uploading-api-proxy-in-proxy-b.html) in the Apigee community.\n3. When the proxy is deployed, try calling it: \n\n ```java\n curl https://$HOSTNAME/java-error\n ```\n\n Because the call does not include a \"name\" query parameter, the Java code throws a runtime\n error. The proxy returns this message and header:\n\n- Error message: `Please specify a name parameter!`\n- Header: `ExceptionClass: java.lang.RuntimeException`\n\n| **Note:** If you look at the Debug Tool in the Apigee UI, you'll see that a flow variable is set called JAVA_STACKTRACE. This is a useful technique for debugging, rather than returning a stacktrace to the client."]]
