83 lines
2.8 KiB
Plaintext
83 lines
2.8 KiB
Plaintext
[[dynamic-command-exitcode-annotation]]
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= @ExceptionResolver
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ifndef::snippets[:snippets: ../../test/java/org/springframework/shell/docs]
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`@ShellComponent` classes can have `@ExceptionResolver` methods to handle exceptions from component
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methods. These are meant for annotated methods.
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The exception may match against a top-level exception being propagated (e.g. a direct `IOException`
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being thrown) or against a nested cause within a wrapper exception (e.g. an `IOException` wrapped
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inside an `IllegalStateException`). This can match at arbitrary cause levels.
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For matching exception types, preferably declare the target exception as a method argument, as
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the preceding example(s) shows. When multiple exception methods match, a root exception match is
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generally preferred to a cause exception match. More specifically, the `ExceptionDepthComparator`
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is used to sort exceptions based on their depth from the thrown exception type.
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Alternatively, the annotation declaration may narrow the exception types to match, as the
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following example shows:
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[source, java, indent=0]
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----
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include::{snippets}/ErrorHandlingSnippets.java[tag=exception-resolver-with-type-in-annotation]
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----
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[source, java, indent=0]
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----
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include::{snippets}/ErrorHandlingSnippets.java[tag=exception-resolver-with-type-in-method]
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----
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`@ExceptionResolver` can also return `String` which is used as an output to console. You can
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use `@ExitCode` annotation to define return code.
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[source, java, indent=0]
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----
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include::{snippets}/ErrorHandlingSnippets.java[tag=exception-resolver-with-exitcode-annotation]
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----
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`@ExceptionResolver` with `void` return type is automatically handled as handled exception.
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You can then also define `@ExitCode` and use `Terminal` if you need to write something
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into the console:
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[source, java, indent=0]
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----
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include::{snippets}/ErrorHandlingSnippets.java[tag=exception-resolver-with-void]
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----
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[[method-arguments]]
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== Method Arguments
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`@ExceptionResolver` methods support the following arguments:
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[Attributes]
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|===
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|Method argument |Description
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|Exception type
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|For access to the raised exception. This is any type of `Exception` or `Throwable`.
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|Terminal
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|For access to underlying `JLine` terminal to i.e. get its terminal writer.
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|===
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[[return-values]]
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== Return Values
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`@ExceptionResolver` methods support the following return values:
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[Attributes]
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|===
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|Return value |Description
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|String
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|Plain text to return to a shell. Exit code 1 is used in this case.
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|CommandHandlingResult
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|Plain `CommandHandlingResult` having message and exit code.
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|void
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|A method with a void return type is considered to have fully handled the exception. Usually
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you would define `Terminal` as a method argument and write response using _terminal writer_
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from it. As exception is fully handled, Exit code 0 is used in this case.
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|===
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