——每天的寥寥幾筆,堅持下去,將會是一份份沉甸甸的積累
上一篇文章講到了servlet容器的wrapper,這篇繼續上一篇來講講第二種容器context。
之前講過context的層次在wrapper之上,可以包含多個wrapper,一個wrapper完成對一個serlvet的處理,多個wrapper的時候,我們就要面臨選擇,確定到底由哪個wrapper來處理,也就是涉及到了映射查找對應的wrapper。
1.先來看看一個simpleContext
<span style="font-size:12px;">public class SimpleContext implements Context, Pipeline {
public SimpleContext() {
pipeline.setBasic(new SimpleContextValve());//依舊是設置基礎閥,同上一篇文章的介紹
}
protected HashMap children = new HashMap();//添加子wrapper
protected Loader loader = null;
protected SimplePipeline pipeline = new SimplePipeline(this);//同上一篇文章
protected HashMap servletMappings = new HashMap();//URL下的servlet與相應wrapper的鍵值對映射******
//映射器。爲了支持不同的協議。注意是協議。比如http,https兩個協議,如果請求相同的servlet,處理的wrapper是不一樣的
protected Mapper amapper = null;//默認映射器
protected HashMap mappers = new HashMap();//所有可用的映射器,第一個添加到容器中的映射器爲默認映射器
private Container parent = null;</span>
2.那又是如何映射查找對應的wrapper。流程如下:
(1)起點定在基礎閥(因爲基礎閥負責創建出serlvet實例,調用service方法)。
<span style="font-size:12px;"> wrapper = (Wrapper) context.map(request, true);</span>
(2)調用Context的map方法,判斷傳入的request對象的協議是否符合要求,不符合返回null,符合則調用SimpleContextMapper的map方法
<span style="font-size:12px;"> public Container map(Request request, boolean update) {
Mapper mapper = findMapper(request.getRequest().getProtocol());
if (mapper == null)
return (null);
return (mapper.map(request, update));
}</span>
(3)調用SimpleContextMapper的map方法。通過協議的測試後,就直接開始解析requestURL中請求的serlvet名,根據serlvet名映射找到具體wrapper名
<span style="font-size:12px;">public Container map(Request request, boolean update) {
// Identify the context-relative URI to be mapped
String contextPath =
((HttpServletRequest) request.getRequest()).getContextPath();
String requestURI = ((HttpRequest) request).getDecodedRequestURI();
String relativeURI = requestURI.substring(contextPath.length());
// Apply the standard request URI mapping rules from the specification
Wrapper wrapper = null;
String servletPath = relativeURI;
String pathInfo = null;
String name = context.findServletMapping(relativeURI);//根據serlvet名映射查找serlvetMappings那張hashmap,找到具體wrapper名
if (name != null)
wrapper = (Wrapper) context.findChild(name);//根據上面找到的wrapper名,確定Context的child Wrappper.
return (wrapper);
}</span>
(4)拿到了wrapper,後面的操作同前一篇的操作,可參考tomcat源碼分析學習筆記(三)
(5)最後貼上測試的啓動類,那就更明晰了。
public final class Bootstrap2 {
public static void main(String[] args) {
HttpConnector connector = new HttpConnector();
Wrapper wrapper1 = new SimpleWrapper();
wrapper1.setName("Primitive");//給wrapper取名
wrapper1.setServletClass("PrimitiveServlet");
Wrapper wrapper2 = new SimpleWrapper();
wrapper2.setName("Modern");
wrapper2.setServletClass("ModernServlet");
Context context = new SimpleContext();
context.addChild(wrapper1);
context.addChild(wrapper2);
Valve valve1 = new HeaderLoggerValve();
Valve valve2 = new ClientIPLoggerValve();
((Pipeline) context).addValve(valve1);
((Pipeline) context).addValve(valve2);
Mapper mapper = new SimpleContextMapper();
mapper.setProtocol("http");
context.addMapper(mapper);
Loader loader = new SimpleLoader();
context.setLoader(loader);
// context.addServletMapping(pattern, name);
context.addServletMapping("/Primitive", "Primitive");//添加requestUrl的解析結果和wrapper的映射關係
context.addServletMapping("/Modern", "Modern");
connector.setContainer(context);
try {
connector.initialize();
connector.start();
// make the application wait until we press a key.
System.in.read();
}
catch (Exception e) {
e.printStackTrace();
}
}
}
就寫到這吧,有什麼問題歡迎提出。學生黨天天熬夜,也是蠻拼的了。一起加油。