strtsu2完成request的封装后，就创建ActionMapping
ActionMapping的创建过程也很明了。
ActionMapping mapping = prepare.findActionMapping(request, response, true);
首先，去 request中寻找是否有，如果有则返回，否则创建一个。
public ActionMapping findActionMapping(HttpServletRequest request, HttpServletResponse response, boolean forceLookup) {
ActionMapping mapping = (ActionMapping) request.getAttribute(STRUTS_ACTION_MAPPING_KEY);
if (mapping == null || forceLookup) {
try {
mapping = dispatcher.getContainer().getInstance(ActionMapper.class).getMapping(request, dispatcher.getConfigurationManager());
if (mapping != null) {
request.setAttribute(STRUTS_ACTION_MAPPING_KEY, mapping);
}
} catch (Exception ex) {
dispatcher.sendError(request, response, servletContext, HttpServletResponse.SC_INTERNAL_SERVER_ERROR, ex);
}
}
return mapping;
}
注意关键的地方是通过Dispatcher取得容器Container创建，传入的参数是request和ConfigurationManager
dispatcher.getContainer().getInstance(ActionMapper.class).getMapping(request, dispatcher.getConfigurationManager());
request不必多说，ConfigurationManager在初始化的时候也说了，是配置文件的管理类，包括了各种provider
默认的实现是DefaultActionMapper
public ActionMapping getMapping(HttpServletRequest request,
ConfigurationManager configManager) {
ActionMapping mapping = new ActionMapping();
String uri = getUri(request);
int indexOfSemicolon = uri.indexOf(";");
uri = (indexOfSemicolon > -1) ? uri.substring(0, indexOfSemicolon) : uri;
uri = dropExtension(uri, mapping);
if (uri == null) {
return null;
}
parseNameAndNamespace(uri, mapping, configManager);
handleSpecialParameters(request, mapping);
if (mapping.getName() == null) {
return null;
}
parseActionName(mapping);
return mapping;
}
在进一步了解之前，我们先看看ActionMapping。
public class ActionMapping {
private String name;
private String namespace;
private String method;
private String extension;
private Map<String, Object> params;
private Result result;
ActionMapping是一个实体类，对应的就是一个action所包含的元素，比如名称，民名空间，方法，参数，返回值以及可能的扩展。
返回ActionMapping的创建，首先是初始化了一个空的ActionMapping。
然后取得当前请求的URI
ActionMapping mapping = new ActionMapping();
String uri = getUri(request);
从request中取得uri的方法如下
protected String getUri(HttpServletRequest request) {
// handle http dispatcher includes.
String uri = (String) request
.getAttribute("javax.servlet.include.servlet_path");
if (uri != null) {
return uri;
}
uri = RequestUtils.getServletPath(request);
if (uri != null && !"".equals(uri)) {
return uri;
}
uri = request.getRequestURI();
return uri.substring(request.getContextPath().length());
}
然后从uri中去掉action请求的后缀。
比如xxx.xxx.do，则去掉.do
protected String dropExtension(String name, ActionMapping mapping) {
if (extensions == null) {
return name;
}
for (String ext : extensions) {
if ("".equals(ext)) {
// This should also handle cases such as /foo/bar-1.0/description. It is tricky to
// distinquish /foo/bar-1.0 but perhaps adding a numeric check in the future could
// work
int index = name.lastIndexOf('.');
if (index == -1 || name.indexOf('/', index) >= 0) {
return name;
}
} else {
String extension = "." + ext;
if (name.endsWith(extension)) {
name = name.substring(0, name.length() - extension.length());
mapping.setExtension(ext);
return name;
}
}
}
return null;
}然后从uri中分析action请求中的name和namespace
protected void parseNameAndNamespace(String uri, ActionMapping mapping,
ConfigurationManager configManager) {
String namespace, name;
int lastSlash = uri.lastIndexOf("/");
if (lastSlash == -1) {
namespace = "";
name = uri;
} else if (lastSlash == 0) {
// ww-1046, assume it is the root namespace, it will fallback to
// default
// namespace anyway if not found in root namespace.
namespace = "/";
name = uri.substring(lastSlash + 1);
} else if (alwaysSelectFullNamespace) {
// Simply select the namespace as everything before the last slash
namespace = uri.substring(0, lastSlash);
name = uri.substring(lastSlash + 1);
} else {
// Try to find the namespace in those defined, defaulting to ""
Configuration config = configManager.getConfiguration();
String prefix = uri.substring(0, lastSlash);
namespace = "";
boolean rootAvailable = false;
// Find the longest matching namespace, defaulting to the default
for (Object cfg : config.getPackageConfigs().values()) {
String ns = ((PackageConfig) cfg).getNamespace();
if (ns != null && prefix.startsWith(ns) && (prefix.length() == ns.length() || prefix.charAt(ns.length()) == '/')) {
if (ns.length() > namespace.length()) {
namespace = ns;
}
}
if ("/".equals(ns)) {
rootAvailable = true;
}
}
name = uri.substring(namespace.length() + 1);
// Still none found, use root namespace if found
if (rootAvailable && "".equals(namespace)) {
namespace = "/";
}
}
if (!allowSlashesInActionNames && name != null) {
int pos = name.lastIndexOf('/');
if (pos > -1 && pos < name.length() - 1) {
name = name.substring(pos + 1);
}
}
mapping.setNamespace(namespace);
mapping.setName(name);
}
分析的过程也很简单，分析完成后放入mapping中。需要注意的是在分析的过程中读取配置文件，通过Configuration完成的。
Configuration config = configManager.getConfiguration();
String prefix = uri.substring(0, lastSlash);
namespace = "";
boolean rootAvailable = false;
// Find the longest matching namespace, defaulting to the default
for (Object cfg : config.getPackageConfigs().values()) {
String ns = ((PackageConfig) cfg).getNamespace();
if (ns != null && prefix.startsWith(ns) && (prefix.length() == ns.length() || prefix.charAt(ns.length()) == '/')) {
if (ns.length() > namespace.length()) {
namespace = ns;
}
}
if ("/".equals(ns)) {
rootAvailable = true;
}
}
处理完成，然后处理特殊参数
handleSpecialParameters(request, mapping);
public void handleSpecialParameters(HttpServletRequest request,
ActionMapping mapping) {
// handle special parameter prefixes.
Set<String> uniqueParameters = new HashSet<String>();
Map parameterMap = request.getParameterMap();
for (Iterator iterator = parameterMap.keySet().iterator(); iterator
.hasNext();) {
String key = (String) iterator.next();
// Strip off the image button location info, if found
if (key.endsWith(".x") || key.endsWith(".y")) {
key = key.substring(0, key.length() - 2);
}
// Ensure a parameter doesn't get processed twice
if (!uniqueParameters.contains(key)) {
ParameterAction parameterAction = (ParameterAction) prefixTrie
.get(key);
if (parameterAction != null) {
parameterAction.execute(key, mapping);
uniqueParameters.add(key);
break;
}
}
}
}
需要注意这个类PrefixTrie，用来匹配前缀的对象
在DefaultActionMapper初始化的时候创建
public DefaultActionMapper() {
prefixTrie = new PrefixTrie() {
{
put(METHOD_PREFIX, new ParameterAction() {
public void execute(String key, ActionMapping mapping) {
if (allowDynamicMethodCalls) {
mapping.setMethod(key.substring(
METHOD_PREFIX.length()));
}
}
});
put(ACTION_PREFIX, new ParameterAction() {
public void execute(String key, ActionMapping mapping) {
String name = key.substring(ACTION_PREFIX.length());
if (allowDynamicMethodCalls) {
int bang = name.indexOf('!');
if (bang != -1) {
String method = name.substring(bang + 1);
mapping.setMethod(method);
name = name.substring(0, bang);
}
}
mapping.setName(name);
}
});
put(REDIRECT_PREFIX, new ParameterAction() {
public void execute(String key, ActionMapping mapping) {
ServletRedirectResult redirect = new ServletRedirectResult();
container.inject(redirect);
redirect.setLocation(key.substring(REDIRECT_PREFIX
.length()));
mapping.setResult(redirect);
}
});
put(REDIRECT_ACTION_PREFIX, new ParameterAction() {
public void execute(String key, ActionMapping mapping) {
String location = key.substring(REDIRECT_ACTION_PREFIX
.length());
ServletRedirectResult redirect = new ServletRedirectResult();
container.inject(redirect);
String extension = getDefaultExtension();
if (extension != null && extension.length() > 0) {
location += "." + extension;
}
redirect.setLocation(location);
mapping.setResult(redirect);
}
});
}
};
}然后在handleSpecialParameters才有了处理
ParameterAction parameterAction = (ParameterAction) prefixTrie
.get(key);
if (parameterAction != null) {
parameterAction.execute(key, mapping);
uniqueParameters.add(key);
break;
}
处理的是预先添加的，代码如下：
protected static final String METHOD_PREFIX = "method:";
protected static final String ACTION_PREFIX = "action:";
protected static final String REDIRECT_PREFIX = "redirect:";
protected static final String REDIRECT_ACTION_PREFIX = "redirectAction:";
注意这里使用的回调函数。
parameterAction.execute(key, mapping);
具体的实现则在初始化中的实现
public void execute(String key, ActionMapping mapping) {
String location = key.substring(REDIRECT_ACTION_PREFIX
.length());
ServletRedirectResult redirect = new ServletRedirectResult();
container.inject(redirect);
String extension = getDefaultExtension();
if (extension != null && extension.length() > 0) {
location += "." + extension;
}
redirect.setLocation(location);
mapping.setResult(redirect);
}
这样就给mapping设置了。
就拿这个例子来说把，创建了ServletRedirectResult
然后放入mapping中，在后续的执行中会使用，我们可以进入ServletRedirectResult 看看这个类,
有一个核心方法doExecute。
在我们调用action返回的时候会调用到这里doExecute。
这里暂时不做详细介绍，
代码如下：
protected void doExecute(String finalLocation, ActionInvocation invocation) throws Exception {
ActionContext ctx = invocation.getInvocationContext();
HttpServletRequest request = (HttpServletRequest) ctx.get(ServletActionContext.HTTP_REQUEST);
HttpServletResponse response = (HttpServletResponse) ctx.get(ServletActionContext.HTTP_RESPONSE);
if (isPathUrl(finalLocation)) {
if (!finalLocation.startsWith("/")) {
ActionMapping mapping = actionMapper.getMapping(request, Dispatcher.getInstance().getConfigurationManager());
String namespace = null;
if (mapping != null) {
namespace = mapping.getNamespace();
}
if ((namespace != null) && (namespace.length() > 0) && (!"/".equals(namespace))) {
finalLocation = namespace + "/" + finalLocation;
} else {
finalLocation = "/" + finalLocation;
}
}
// if the URL's are relative to the servlet context, append the servlet context path
if (prependServletContext && (request.getContextPath() != null) && (request.getContextPath().length() > 0)) {
finalLocation = request.getContextPath() + finalLocation;
}
ResultConfig resultConfig = invocation.getProxy().getConfig().getResults().get(invocation.getResultCode());
if (resultConfig != null) {
Map<String, String> resultConfigParams = resultConfig.getParams();
for (Map.Entry<String, String> e : resultConfigParams.entrySet()) {
if (!getProhibitedResultParams().contains(e.getKey())) {
String potentialValue = e.getValue() == null ? "" : conditionalParse(e.getValue(), invocation);
if (!suppressEmptyParameters || ((potentialValue != null) && (potentialValue.length() > 0))) {
requestParameters.put(e.getKey(), potentialValue);
}
}
}
}
StringBuilder tmpLocation = new StringBuilder(finalLocation);
urlHelper.buildParametersString(requestParameters, tmpLocation, "&");
// add the anchor
if (anchor != null) {
tmpLocation.append('#').append(anchor);
}
finalLocation = response.encodeRedirectURL(tmpLocation.toString());
}
if (LOG.isDebugEnabled()) {
LOG.debug("Redirecting to finalLocation " + finalLocation);
}
sendRedirect(response, finalLocation);
}
回到我们的 DefaultActionMapper中，完成了上面的处理，进入parseActionName
分析action的名称。
parseActionName(mapping);
具体的代码如下：
protected ActionMapping parseActionName(ActionMapping mapping) {
if (mapping.getName() == null) {
return mapping;
}
if (allowDynamicMethodCalls) {
// handle "name!method" convention.
String name = mapping.getName();
int exclamation = name.lastIndexOf("!");
if (exclamation != -1) {
mapping.setName(name.substring(0, exclamation));
mapping.setMethod(name.substring(exclamation + 1));
}
}
return mapping;
}
如果为空则之间返回，否则处理类似name!method这样的请求 action
处理完成返回.ActionMapping
actionMapping处理完成后放入request中。
if (mapping != null) {
request.setAttribute(STRUTS_ACTION_MAPPING_KEY, mapping);
}
至此，ActionMapping创建完成。
