289.10. 示例 1：从 SAP 读取数据

本例演示了从 SAP 读取 FlightCustomer 业务对象数据的路由。路由会调用 FlightCustomer BAPI 方法 BAPI_FLCUST_GETLIST 使用 SAP 同步 RFC 目标端点来检索数据。

示例路由的 Java DSL 如下：

from("direct:getFlightCustomerInfo")
    .to("bean:createFlightCustomerGetListRequest")
    .to("sap-srfc-destination:nplDest:BAPI_FLCUST_GETLIST")
    .to("bean:returnFlightCustomerInfo");

同一路由的 Spring DSL 如下：

<route>
    <from uri="direct:getFlightCustomerInfo"/>
    <to uri="bean:createFlightCustomerGetListRequest"/>
    <to uri="sap-srfc-destination:nplDest:BAPI_FLCUST_GETLIST"/>
    <to uri="bean:returnFlightCustomerInfo"/>
</route>

createFlightCustomerGetListRequest bean 负责在其交换方法中构建 SAP 请求对象，这些方法用于后续 SAP 端点 RFC 调用。以下代码片段演示了构建请求对象的操作序列：

public void create(Exchange exchange) throws Exception {

    // Get SAP Endpoint to be called from context.
    SapSynchronousRfcDestinationEndpoint endpoint =
        exchange.getContext().getEndpoint("sap-srfc-destination:nplDest:BAPI_FLCUST_GETLIST",
                                                 SapSynchronousRfcDestinationEndpoint.class);

    // Retrieve bean from message containing Flight Customer name to
    // look up.
    BookFlightRequest bookFlightRequest =
        exchange.getIn().getBody(BookFlightRequest.class);

    // Create SAP Request object from target endpoint.
    Structure request = endpoint.getRequest();

    // Add Customer Name to request if set
    if (bookFlightRequest.getCustomerName() != null &&
        bookFlightRequest.getCustomerName().length() > 0) {
            request.put("CUSTOMER_NAME",
                          bookFlightRequest.getCustomerName());
        }
    } else {
        throw new Exception("No Customer Name");
    }

    // Put request object into body of exchange message.
    exchange.getIn().setBody(request);
}

returnFlightCustomerInfo bean 负责在其从上一 SAP 端点接收的交换方法中提取 SAP 响应对象的数据。以下代码片段演示了一系列操作，从响应对象中提取数据：

public void createFlightCustomerInfo(Exchange exchange) throws Exception {

    // Retrieve SAP response object from body of exchange message.
    Structure flightCustomerGetListResponse =
        exchange.getIn().getBody(Structure.class);

    if (flightCustomerGetListResponse == null) {
        throw new Exception("No Flight Customer Get List Response");
    }

    // Check BAPI return parameter for errors
    @SuppressWarnings("unchecked")
    Table<Structure> bapiReturn =
        flightCustomerGetListResponse.get("RETURN", Table.class);
    Structure bapiReturnEntry = bapiReturn.get(0);
    if (bapiReturnEntry.get("TYPE", String.class) != "S") {
        String message = bapiReturnEntry.get("MESSAGE", String.class);
        throw new Exception("BAPI call failed: " + message);
    }

    // Get customer list table from response object.
    @SuppressWarnings("unchecked")
    Table<? extends Structure> customerList =
        flightCustomerGetListResponse.get("CUSTOMER_LIST", Table.class);

    if (customerList == null || customerList.size() == 0) {
        throw new Exception("No Customer Info.");
    }

    // Get Flight Customer data from first row of table.
    Structure customer = customerList.get(0);

    // Create bean to hold Flight Customer data.
    FlightCustomerInfo flightCustomerInfo = new FlightCustomerInfo();

    // Get customer id from Flight Customer data and add to bean.
    String customerId = customer.get("CUSTOMERID", String.class);
    if (customerId != null) {
        flightCustomerInfo.setCustomerNumber(customerId);
    }

    ...

    // Put bean into body of exchange message.
    exchange.getIn().setHeader("flightCustomerInfo", flightCustomerInfo);

}