Trường thứ hai của tư tưởng yêu cầu được mô hình với các mô hình chỉ huy và trực tiếp thực hiện. Điều này phù hợpcó mô hình xử lý yêu cầu, ví dụ. Nếu đây là tách tràNhư đã đề cập trong Chương 11, bạn thường sẽ yêu cầu những phương pháp này được thực hiện trước và sau khi xem hình thức hiển thịLiệt kê 12-21 | CHAPTER 11 INTRODUCTION TO SPRING WEB FLOW 319 So with knowledge of these basic building blocks in place the challenge of implementing a flow definition becomes 1. defining the states of the flow 2. defining the possible transitions between states and the event-driven criteria for those state transitions. Your First Flow In this section you will implement the example Purchase Product use case using Spring Web Flow. Chapter 12 will cover many of the decisions that the author has made and reevaluate some of those decisions regarding how this example works within Spring MVC. This section will not cover Spring MVC itself as that is sufficiently covered elsewhere in this book. For now let s assume you have a working Spring MVC project that can be built and deployed onto a servlet container. Installing Spring Web Flow- Instructions for downloading and installing Spring Web Flow can be found at http confluence spring display WEBFLOW Home. Proposed Flow Directory Structure From our experience it is best to partition your Spring Web Flow configuration information into file fragments that are responsible for their own concerns. Figure 11-5 is an example of a prudent directory structure for managing Spring Web Flow configuration artifacts. Bean Factory for first web flow Figure 11-5. Suggested directory layout 320 CHAPTER 11 INTRODUCTION TO SPRING WEB FLOW The Purchase Product Flow Definition A flow definition can be engineered in a number of ways. Many users use XML to define their flows as XML is a human readable and highly toolable format. However you may also define flows in Java by extending AbstractFlowBuilder or with your own custom format by implementing a custom FlowBuilder. For the Purchase Product example web flow you will use XML. Recall the graphical depiction of the flow definition in Figure 11-4. Implementing the First Step View States The first step of this flow is to enter the purchase information which .
