Se non hai mai utilizzato JavaCallout, ti consigliamo di iniziare dalla sezione Come creare un callout Java.
Gestione degli errori nelle norme JavaCallout
Quando scrivi una norma JavaCallout, potresti voler gestire gli gestione degli errori personalizzati nel codice Java. Ad esempio, potresti voler restituire intestazioni e messaggi di errore personalizzati e/o impostare variabili di flusso con
informazioni sugli errori nel flusso proxy su Apigee.
Vediamo un semplice esempio di criterio JavaCallout che illustra i pattern di base per la gestione degli errori personalizzata. L'esempio restituisce un messaggio di errore personalizzato quando si verifica un'eccezione. Inoltre, inserisce
la traccia dello stack di errori in una variabile di flusso, che può essere una tecnica di debug utile.
Scaricare il progetto
Per semplificare le operazioni, puoi scaricare questo progetto dal repository api-platform-samples di Apigee su
GitHub.
In un terminale o in un editor di codice a tua scelta, vai al progetto
api-platform-samples/doc-samples/java-error.
Il codice Java di esempio
I pattern di gestione degli errori sono semplici. Puoi impostare le variabili di flusso nel contesto di flusso Apigee corrente con il metodo messageContext.setVariable(). Per restituire informazioni
sull'errore personalizzate, crea un'istanza ExecutionResult e chiama i metodi per
impostare la risposta e le intestazioni di errore.
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 il codice con Maven
Il progetto è configurato in modo da poter essere compilato con Maven. Se vuoi utilizzare
javac, includeremo anche un esempio.
Assicurati di aver installato Maven:
mvn-version
Esegui lo script java-error/buildsetup.sh. Questo script installa le dipendenze JAR richieste nel tuo repository Maven locale.
Vai alla directory java-error/callout.
Esegui Maven:
mvncleanpackage
Se vuoi, verifica che il file JAR edge-custom-policy-java-error.jar sia stato
copiato in java-error/apiproxy/resources/java. Questa è la posizione richiesta per
i file JAR che vuoi eseguire il deployment con un proxy.
Esegui il deployment e chiama il proxy
Nella directory ./java-error viene fornito uno script di deployment. Ma prima di eseguirlo,
devi eseguire una rapida configurazione.
cd a api-platform-samples/doc-samples/java-error
Il modo più semplice per eseguire il deployment del proxy è raggrupparlo in un file ZIP e caricare il bundle di proxy in un ambiente dell'organizzazione Apigee. Consulta Creazione di un proxy API.
Assicurati di utilizzare l'opzione Carica pacchetto proxy. Vedi anche
Suggerimenti per caricare il proxy API in un bundle proxy nella community Apigee.
Una volta eseguito il deployment del proxy, prova a chiamarlo:
curlhttps://$HOSTNAME/java-error
Poiché la chiamata non include un parametro di query "name", il codice Java genera un errore di runtime. Il proxy restituisce questo messaggio e questa intestazione:
Messaggio di errore: Please specify a name parameter!
[[["Facile da capire","easyToUnderstand","thumb-up"],["Il problema è stato risolto","solvedMyProblem","thumb-up"],["Altra","otherUp","thumb-up"]],[["Difficile da capire","hardToUnderstand","thumb-down"],["Informazioni o codice di esempio errati","incorrectInformationOrSampleCode","thumb-down"],["Mancano le informazioni o gli esempi di cui ho bisogno","missingTheInformationSamplesINeed","thumb-down"],["Problema di traduzione","translationIssue","thumb-down"],["Altra","otherDown","thumb-down"]],["Ultimo aggiornamento 2025-09-05 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."]]
