# 事件：启动 - 关闭

**FastAPI** 支持定义在应用启动前，或应用关闭后执行的事件处理器（函数）。

事件函数既可以声明为异步函数（`async def`），也可以声明为普通函数（`def`）。

/// warning | "警告"

**FastAPI** 只执行主应用中的事件处理器，不执行[子应用 - 挂载](sub-applications.md){.internal-link target=_blank}中的事件处理器。

///

## `startup` 事件

使用 `startup` 事件声明 `app` 启动前运行的函数：

```Python hl_lines="8"
{!../../docs_src/events/tutorial001.py!}
```

本例中，`startup` 事件处理器函数为项目数据库（只是**字典**）提供了一些初始值。

package mockwebserver3

import assertk.assertThat
import assertk.assertions.isEqualTo
import java.net.InetAddress
import java.net.Socket
import okhttp3.Headers
import okhttp3.Headers.Companion.headersOf
import okhttp3.internal.EMPTY_HEADERS
import okio.Buffer
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.Timeout

@Timeout(30)
class RecordedRequestTest {
  private val headers: Headers = EMPTY_HEADERS

 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package jcifs.internal.fscc;


import jcifs.Decodable;


/**
 * @author mbechler
 *
 */
public interface FileSystemInformation extends Decodable {

    /**
     * 
     */

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package main // import "github.com/minio/minio"

import (
	"os"

	// MUST be first import.
	_ "github.com/minio/minio/internal/init"

	minio "github.com/minio/minio/cmd"
)

func main() {
	minio.Main(os.Args)

- [ ] Breaking change (fix or feature that would cause existing functionality to change)

## Checklist:
- [ ] Fixes a regression (If yes, please add `commit-id` or `PR #` here)
- [ ] Unit tests added/updated
- [ ] Internal documentation updated

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.extension.internal;

import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.codehaus.plexus.classworlds.realm.ClassRealm;

 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.maven.repository.internal;

import java.util.Collection;
import java.util.Collections;
import java.util.Date;
import java.util.LinkedHashMap;
import java.util.Map;

import org.eclipse.aether.RepositorySystemSession;

they won't be included in the OpenAPI schema (the API docs), because FastAPI doesn't have a way to know beforehand what you are going to return.

But you can document that in your code, using: [Additional Responses](additional-responses.md){.internal-link target=_blank}....

//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"strconv"

	"github.com/minio/minio/internal/bucket/lifecycle"
)

//go:generate stringer -type lcEventSrc -trimprefix lcEventSrc_ $GOFILE
type lcEventSrc uint8

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cmd

import (
	"sync"

	"github.com/dustin/go-humanize"
)

const (
	// Block size used for all internal operations version 1.

	// TLDR..
	// Not used anymore xl.meta captures the right blockSize
	// so blockSizeV2 should be used for all future purposes.
	// this value is kept here to calculate the max API