Tomcat中對於每個請求的所對於的資源（Host,Context,Wrapper）有一個映射器來實現的
Mapper中映射當前請求url所對應的Wrapper(Servlet)
private final void internalMapWrapper(ContextVersion contextVersion,
CharChunk path,
MappingData mappingData)
throws Exception {
int pathOffset = path.getOffset();
int pathEnd = path.getEnd();
int servletPath = pathOffset;
boolean noServletPath = false;
int length = contextVersion.path.length();
if (length != (pathEnd - pathOffset)) {
servletPath = pathOffset + length;
} else {
noServletPath = true;
path.append('/');
pathOffset = path.getOffset();
pathEnd = path.getEnd();
servletPath = pathOffset+length;
}
path.setOffset(servletPath);
// Rule 1 -- Exact Match
Wrapper[] exactWrappers = contextVersion.exactWrappers;
internalMapExactWrapper(exactWrappers, path, mappingData);
// Rule 2 -- Prefix Match
boolean checkJspWelcomeFiles = false;
Wrapper[] wildcardWrappers = contextVersion.wildcardWrappers;
if (mappingData.wrapper == null) {
internalMapWildcardWrapper(wildcardWrappers, contextVersion.nesting,
path, mappingData);
if (mappingData.wrapper != null && mappingData.jspWildCard) {
char[] buf = path.getBuffer();
if (buf[pathEnd - 1] == '/') {
/*
* Path ending in '/' was mapped to JSP servlet based on
* wildcard match (e.g., as specified in url-pattern of a
* jsp-property-group.
* Force the context's welcome files, which are interpreted
* as JSP files (since they match the url-pattern), to be
* considered. See Bugzilla 27664.
*/
mappingData.wrapper = null;
checkJspWelcomeFiles = true;
} else {
// See Bugzilla 27704
mappingData.wrapperPath.setChars(buf, path.getStart(),
path.getLength());
mappingData.pathInfo.recycle();
}
}
}
if(mappingData.wrapper == null && noServletPath) {
// The path is empty, redirect to "/"
mappingData.redirectPath.setChars
(path.getBuffer(), pathOffset, pathEnd-pathOffset);
path.setEnd(pathEnd - 1);
return;
}
// Rule 3 -- Extension Match
Wrapper[] extensionWrappers = contextVersion.extensionWrappers;
if (mappingData.wrapper == null && !checkJspWelcomeFiles) {
internalMapExtensionWrapper(extensionWrappers, path, mappingData,
true);
}
// Rule 4 -- Welcome resources processing for servlets
if (mappingData.wrapper == null) {
boolean checkWelcomeFiles = checkJspWelcomeFiles;
if (!checkWelcomeFiles) {
char[] buf = path.getBuffer();
checkWelcomeFiles = (buf[pathEnd - 1] == '/');
}
if (checkWelcomeFiles) {
for (int i = 0; (i < contextVersion.welcomeResources.length)
&& (mappingData.wrapper == null); i++) {
path.setOffset(pathOffset);
path.setEnd(pathEnd);
path.append(contextVersion.welcomeResources[i], 0,
contextVersion.welcomeResources[i].length());
path.setOffset(servletPath);
// Rule 4a -- Welcome resources processing for exact macth
internalMapExactWrapper(exactWrappers, path, mappingData);
// Rule 4b -- Welcome resources processing for prefix match
if (mappingData.wrapper == null) {
internalMapWildcardWrapper
(wildcardWrappers, contextVersion.nesting,
path, mappingData);
}
// Rule 4c -- Welcome resources processing
// for physical folder
if (mappingData.wrapper == null
&& contextVersion.resources != null) {
Object file = null;
String pathStr = path.toString();
try {
file = contextVersion.resources.lookup(pathStr);
} catch(NamingException nex) {
// Swallow not found, since this is normal
}
if (file != null && !(file instanceof DirContext) ) {
internalMapExtensionWrapper(extensionWrappers, path,
mappingData, true);
if (mappingData.wrapper == null
&& contextVersion.defaultWrapper != null) {
mappingData.wrapper =
contextVersion.defaultWrapper.object;
mappingData.requestPath.setChars
(path.getBuffer(), path.getStart(),
path.getLength());
mappingData.wrapperPath.setChars
(path.getBuffer(), path.getStart(),
path.getLength());
mappingData.requestPath.setString(pathStr);
mappingData.wrapperPath.setString(pathStr);
}
}
}
}
path.setOffset(servletPath);
path.setEnd(pathEnd);
}
}
/* welcome file processing - take 2
* Now that we have looked for welcome files with a physical
* backing, now look for an extension mapping listed
* but may not have a physical backing to it. This is for
* the case of index.jsf, index.do, etc.
* A watered down version of rule 4
*/
if (mappingData.wrapper == null) {
boolean checkWelcomeFiles = checkJspWelcomeFiles;
if (!checkWelcomeFiles) {
char[] buf = path.getBuffer();
checkWelcomeFiles = (buf[pathEnd - 1] == '/');
}
if (checkWelcomeFiles) {
for (int i = 0; (i < contextVersion.welcomeResources.length)
&& (mappingData.wrapper == null); i++) {
path.setOffset(pathOffset);
path.setEnd(pathEnd);
path.append(contextVersion.welcomeResources[i], 0,
contextVersion.welcomeResources[i].length());
path.setOffset(servletPath);
internalMapExtensionWrapper(extensionWrappers, path,
mappingData, false);
}
path.setOffset(servletPath);
path.setEnd(pathEnd);
}
}
// Rule 7 -- Default servlet
if (mappingData.wrapper == null && !checkJspWelcomeFiles) {
if (contextVersion.defaultWrapper != null) {
mappingData.wrapper = contextVersion.defaultWrapper.object;
mappingData.requestPath.setChars
(path.getBuffer(), path.getStart(), path.getLength());
mappingData.wrapperPath.setChars
(path.getBuffer(), path.getStart(), path.getLength());
}
// Redirection to a folder
char[] buf = path.getBuffer();
if (contextVersion.resources != null && buf[pathEnd -1 ] != '/') {
Object file = null;
String pathStr = path.toString();
try {
file = contextVersion.resources.lookup(pathStr);
} catch(NamingException nex) {
// Swallow, since someone else handles the 404
}
if (file != null && file instanceof DirContext) {
// Note: this mutates the path: do not do any processing
// after this (since we set the redirectPath, there
// shouldn't be any)
path.setOffset(pathOffset);
path.append('/');
mappingData.redirectPath.setChars
(path.getBuffer(), path.getStart(), path.getLength());
} else {
mappingData.requestPath.setString(pathStr);
mappingData.wrapperPath.setString(pathStr);
}
}
}
path.setOffset(pathOffset);
path.setEnd(pathEnd);
}// 再來看下Mapper中的信息是如何添加的，是在Connector啓動時，會去啓動MapperListener，會向Mapper註冊已經啓動的組件（Host,Context,Wrapper)
protected void addWrapper(ContextVersion context, String path,
Object wrapper, boolean jspWildCard, boolean resourceOnly) {
synchronized (context) {
Wrapper newWrapper = new Wrapper();
newWrapper.object = wrapper;
newWrapper.jspWildCard = jspWildCard;
newWrapper.resourceOnly = resourceOnly;
if (path.endsWith("/*")) {
// Wildcard wrapper
newWrapper.name = path.substring(0, path.length() - 2);
Wrapper[] oldWrappers = context.wildcardWrappers;
Wrapper[] newWrappers =
new Wrapper[oldWrappers.length + 1];
if (insertMap(oldWrappers, newWrappers, newWrapper)) {
context.wildcardWrappers = newWrappers;
int slashCount = slashCount(newWrapper.name);
if (slashCount > context.nesting) {
context.nesting = slashCount;
}
}
} else if (path.startsWith("*.")) {
// Extension wrapper
newWrapper.name = path.substring(2);
Wrapper[] oldWrappers = context.extensionWrappers;
Wrapper[] newWrappers =
new Wrapper[oldWrappers.length + 1];
if (insertMap(oldWrappers, newWrappers, newWrapper)) {
context.extensionWrappers = newWrappers;
}
} else if (path.equals("/")) {
// Default wrapper
newWrapper.name = "";
context.defaultWrapper = newWrapper;
} else {
// Exact wrapper
newWrapper.name = path;
Wrapper[] oldWrappers = context.exactWrappers;
Wrapper[] newWrappers =
new Wrapper[oldWrappers.length + 1];
if (insertMap(oldWrappers, newWrappers, newWrapper)) {
context.exactWrappers = newWrappers;
}
}
}
}