)
        self.exception_handlers: dict[
            Any, Callable[[Request, Any], Union[Response, Awaitable[Response]]]
        ] = {} if exception_handlers is None else dict(exception_handlers)
        self.exception_handlers.setdefault(HTTPException, http_exception_handler)
        self.exception_handlers.setdefault(
            RequestValidationError, request_validation_exception_handler

If you want to use the exception along with the same default exception handlers from  **FastAPI**, you can import and reuse the default exception handlers from `fastapi.exception_handlers`:

{* ../../docs_src/handling_errors/tutorial006_py39.py hl[2:5,15,21] *}

```Python
from starlette.exceptions import HTTPException as StarletteHTTPException
```

### **FastAPI** の例外ハンドラの再利用

また、何らかの方法で例外を使用することもできますが、**FastAPI** から同じデフォルトの例外ハンドラを使用することもできます。

デフォルトの例外ハンドラを`fastapi.exception_handlers`からインポートして再利用することができます:

{* ../../docs_src/handling_errors/tutorial006.py hl[2,3,4,5,15,21] *}

この例では、非常に表現力のあるメッセージでエラーを`print`しています。

 * under the License.
 */
package org.apache.maven.exception;

/**
 * Transform an exception into useful end-user message.
 *
 * @since 3.0-alpha-3
 */
public interface ExceptionHandler {
    ExceptionSummary handleException(Throwable e);

app.mount(path="/sub", app=sub_app)


@app.exception_handler(RequestValidationError)
@sub_app.exception_handler(RequestValidationError)
async def request_validation_handler(request: Request, exc: RequestValidationError):
    captured_exception.capture(exc)
    raise exc


@app.exception_handler(ResponseValidationError)
@sub_app.exception_handler(ResponseValidationError)

from starlette.exceptions import HTTPException as StarletteHTTPException

app = FastAPI()


@app.exception_handler(StarletteHTTPException)
async def http_exception_handler(request, exc):
    return PlainTextResponse(str(exc.detail), status_code=exc.status_code)


@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request, exc: RequestValidationError):
    message = "Validation errors:"

    @Inject
    private LifeCyclePluginAnalyzer lifeCyclePluginAnalyzer;

    @Inject
    private LifecycleTaskSegmentCalculator lifeCycleTaskSegmentCalculator;

    @Inject
    private ExceptionHandler exceptionHandler;

    protected String getProjectsDirectory() {
        return "src/test/projects/lifecycle-executor";
    }

    @Test
    void testCreation() throws Exception {

from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse


class UnicornException(Exception):
    def __init__(self, name: str):
        self.name = name


app = FastAPI()


@app.exception_handler(UnicornException)
async def unicorn_exception_handler(request: Request, exc: UnicornException):
    return JSONResponse(
        status_code=418,

from fastapi.encoders import jsonable_encoder
from fastapi.exceptions import RequestValidationError
from fastapi.responses import JSONResponse
from pydantic import BaseModel

app = FastAPI()


@app.exception_handler(RequestValidationError)
async def validation_exception_handler(request: Request, exc: RequestValidationError):
    return JSONResponse(
        status_code=422,

        MojoExecutionException mojoEx =
                new MojoExecutionException("Error executing Jetty: Unable to establish loopback connection", ioEx);

        ExceptionHandler exceptionHandler = new DefaultExceptionHandler();
        ExceptionSummary exceptionSummary = exceptionHandler.handleException(mojoEx);

        String expectedReference = "http://cwiki.apache.org/confluence/display/MAVEN/ConnectException";