可以通过以下代码示例解决“BadRequestException: 当授权类型为无或无效时，无法更新路由。”的问题：

import com.amazonaws.services.apigatewayv2.AmazonApiGatewayV2Client;
import com.amazonaws.services.apigatewayv2.model.*;

public class Main {
    public static void main(String[] args) {
        String apiId = "your-api-id";
        String routeId = "your-route-id";
        String authorizationType = "AWS_IAM"; // 要更新的授权类型

        AmazonApiGatewayV2Client apiGatewayClient = new AmazonApiGatewayV2Client();

        // 获取现有的路由信息
        GetRouteRequest getRouteRequest = new GetRouteRequest()
                .withApiId(apiId)
                .withRouteId(routeId);
        GetRouteResult getRouteResult = apiGatewayClient.getRoute(getRouteRequest);
        Route route = getRouteResult.getRoute();

        // 更新授权类型
        UpdateRouteRequest updateRouteRequest = new UpdateRouteRequest()
                .withApiId(apiId)
                .withRouteId(routeId)
                .withAuthorizationType(authorizationType)
                .withAuthorizerId(route.getAuthorizerId()) // 保持现有的授权器
                .withModelSelectionExpression(route.getModelSelectionExpression())
                .withOperationName(route.getOperationName())
                .withRequestModels(route.getRequestModels())
                .withRouteKey(route.getRouteKey())
                .withTarget(route.getTarget());
        UpdateRouteResult updateRouteResult = apiGatewayClient.updateRoute(updateRouteRequest);

        System.out.println("路由更新成功");
    }
}

请注意替换代码中的 your-api-id 和 your-route-id 为您的实际 API ID 和路由 ID。还要确保您的 AWS 认证凭证配置正确。这段代码将使用 AWS SDK for Java v1 来更新指定路由的授权类型为 AWS_IAM。