screen widget 本质是基于freemarker 的,目前screen类型的view基本都是MacroScreenViewHandler.Java 负责处理的。
MacroScreenViewHandler.java 的render() 方法中首先通过配置文件加载了三个类库。如下:
MacroScreenViewHandler.java
- ScreenStringRenderer screenStringRenderer = new MacroScreenRenderer(UtilProperties.getPropertyValue("widget", getName() + ".name"), UtilProperties.getPropertyValue("widget", getName() + ".screenrenderer"));
- FormStringRenderer formStringRenderer = new MacroFormRenderer(UtilProperties.getPropertyValue("widget", getName() + ".formrenderer"), request, response);
- TreeStringRenderer treeStringRenderer = new MacroTreeRenderer(UtilProperties.getPropertyValue("widget", getName() + ".treerenderer"), writer);
正式render 页面前后,利用freemarker 编译了两个宏指令
MacroScreenViewHandler.java
- screenStringRenderer.renderScreenBegin(writer, screens.getContext());
- screens.render(page);
- screenStringRenderer.renderScreenEnd(writer, screens.getContext());
ScreenStringRenderer.java
- public void renderScreenBegin(Appendable writer, Map<String, Object> context) throws IOException;
- public void renderScreenEnd(Appendable writer, Map<String, Object> context) throws IOException;
宏指令定义为
<#macro renderScreenBegin>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
</#macro>
<#macro renderScreenEnd>
</#macro>
screen widget 大概处理过程:
获取screnn 第一个section ,解析处理action(预处理所需数据)condition,根据condition结果决定处理子widget是widget还是fail-widget 。子widget的处理过程和上层widget类似。如此深入。具体的没有嵌套的screen widget 可以使用上述freemarker 类库来编译成html。
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