Ok Boom

”勿忘初心,方得始终“

spring-source-1

我们知道spring mvc是通过ContextLoaderListener来监听web容器启动并在web上下文初始化,那spring mvc的ContextLoaderListener是怎么做到的呢
我带着这个疑问来看下spring源码

ContextLoadListener-UML

ContextLoadListener继承了ContextLoader,并实现了ServletContextListener

ServletContextListener是Servlet提供的接口类,监听了Web应用的生命周期,它提供了2个方法

//在所有filters和servlet初始化前,ServletContextListeners被
public void contextInitialized(ServletContextEvent sce);

//所有servlets和filters在调用本方法前被销毁
public void contextDestroyed(ServletContextEvent sce);

我们再来看看ContextLoaderListener在初始化的时候调用了ContextLoader类中的initWebApplicationContext方法
ContextLoader类在

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540


/**
* <p>Looks for a {@link #CONTEXT_CLASS_PARAM "contextClass"} parameter
* at the {@code web.xml} context-param level to specify the context
* class type, falling back to the default of
* {@link org.springframework.web.context.support.XmlWebApplicationContext}
* if not found. With the default ContextLoader implementation, any context class
* specified needs to implement the ConfigurableWebApplicationContext interface.
*
* CONTEXT_CLASS_PARAM
* 在配置文件中找不到这个变量,那么将使用默认的类型,org.springframework.web.context.support.XmlWebApplicationContext。
* 如果使用默认的ContextLoader实现类,任何一个ContextLoader都需要实现ConfigurableWebApplicationContext接口

* <p>Processes a {@link #CONFIG_LOCATION_PARAM "contextConfigLocation"}
* context-param and passes its value to the context instance, parsing it into
* potentially multiple file paths which can be separated by any number of
* commas and spaces, e.g. "WEB-INF/applicationContext1.xml,
* WEB-INF/applicationContext2.xml". Ant-style path patterns are supported as well,
* e.g. "WEB-INF/*Context.xml,WEB-INF/spring*.xml" or "WEB-INF/&#42;&#42;/*Context.xml".
* If not explicitly specified, the context implementation is supposed to use a
* default location (with XmlWebApplicationContext: "/WEB-INF/applicationContext.xml").
*
* <p>Note: In case of multiple config locations, later bean definitions will
* override ones defined in previously loaded files, at least when using one of
* Spring's default ApplicationContext implementations. This can be leveraged
* to deliberately override certain bean definitions via an extra XML file.
* 如果配置了多个文件路径,后面的配置文件将复写前面的配置文件中的内容
*/
public class ContextLoader {

/**
* web应用上下文id
*/
public static final String CONTEXT_ID_PARAM = "contextId";

/**
* 上下文配置路径
* @see org.springframework.web.context.support.XmlWebApplicationContext#DEFAULT_CONFIG_LOCATION
*/
public static final String CONFIG_LOCATION_PARAM = "contextConfigLocation";

/**
* WebApplicationContext的实现类
* @see #determineContextClass(ServletContext)
*/
public static final String CONTEXT_CLASS_PARAM = "contextClass";

/**
* 上下文相关全局特性
* @see #customizeContext(ServletContext, ConfigurableWebApplicationContext)
*/
public static final String CONTEXT_INITIALIZER_CLASSES_PARAM = "contextInitializerClasses";

/**
* 上下文相关全局特性
* @see #customizeContext(ServletContext, ConfigurableWebApplicationContext)
*/
public static final String GLOBAL_INITIALIZER_CLASSES_PARAM = "globalInitializerClasses";

/**
* BeanFactory工厂路径
*/
public static final String LOCATOR_FACTORY_SELECTOR_PARAM = "locatorFactorySelector";

/**
* Optional servlet context parameter (i.e., "{@code parentContextKey}")
* used only when obtaining a parent context using the default implementation
* of {@link #loadParentContext(ServletContext servletContext)}.
* Specifies the 'factoryKey' used in the
* {@link BeanFactoryLocator#useBeanFactory(String factoryKey)} method call,
* obtaining the parent application context from the BeanFactoryLocator instance.
* <p>Supplying this "parentContextKey" parameter is sufficient when relying
* on the default {@code classpath*:beanRefContext.xml} selector for
* candidate factory references.
*/
public static final String LOCATOR_FACTORY_KEY_PARAM = "parentContextKey";

/**
* Any number of these characters are considered delimiters between
* multiple values in a single init-param String value.
*/
private static final String INIT_PARAM_DELIMITERS = ",; \t\n";

/**
* Name of the class path resource (relative to the ContextLoader class)
* that defines ContextLoader's default strategy names.
*/
private static final String DEFAULT_STRATEGIES_PATH = "ContextLoader.properties";


private static final Properties defaultStrategies;

static {
// Load default strategy implementations from properties file.
// This is currently strictly internal and not meant to be customized
// by application developers.
try {
ClassPathResource resource = new ClassPathResource(DEFAULT_STRATEGIES_PATH, ContextLoader.class);
defaultStrategies = PropertiesLoaderUtils.loadProperties(resource);
}
catch (IOException ex) {
throw new IllegalStateException("Could not load 'ContextLoader.properties': " + ex.getMessage());
}
}


/**
* Map from (thread context) ClassLoader to corresponding 'current' WebApplicationContext.
*/
private static final Map<ClassLoader, WebApplicationContext> currentContextPerThread =
new ConcurrentHashMap<ClassLoader, WebApplicationContext>(1);

/**
* The 'current' WebApplicationContext, if the ContextLoader class is
* deployed in the web app ClassLoader itself.
*/
private static volatile WebApplicationContext currentContext;


/**
* The root WebApplicationContext instance that this loader manages.
*/
private WebApplicationContext context;

/**
* Holds BeanFactoryReference when loading parent factory via
* ContextSingletonBeanFactoryLocator.
*/
private BeanFactoryReference parentContextRef;

/** Actual ApplicationContextInitializer instances to apply to the context */
private final List<ApplicationContextInitializer<ConfigurableApplicationContext>> contextInitializers =
new ArrayList<ApplicationContextInitializer<ConfigurableApplicationContext>>();


/**
* Create a new {@code ContextLoader} that will create a web application context
* based on the "contextClass" and "contextConfigLocation" servlet context-params.
* See class-level documentation for details on default values for each.
* <p>This constructor is typically used when declaring the {@code
* ContextLoaderListener} subclass as a {@code <listener>} within {@code web.xml}, as
* a no-arg constructor is required.
* <p>The created application context will be registered into the ServletContext under
* the attribute name {@link WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE}
* and subclasses are free to call the {@link #closeWebApplicationContext} method on
* container shutdown to close the application context.
* @see #ContextLoader(WebApplicationContext)
* @see #initWebApplicationContext(ServletContext)
* @see #closeWebApplicationContext(ServletContext)
*/
public ContextLoader() {
}

/**
* Create a new {@code ContextLoader} with the given application context. This
* constructor is useful in Servlet 3.0+ environments where instance-based
* registration of listeners is possible through the {@link ServletContext#addListener}
* API.
* <p>The context may or may not yet be {@linkplain
* ConfigurableApplicationContext#refresh() refreshed}. If it (a) is an implementation
* of {@link ConfigurableWebApplicationContext} and (b) has <strong>not</strong>
* already been refreshed (the recommended approach), then the following will occur:
* <ul>
* <li>If the given context has not already been assigned an {@linkplain
* ConfigurableApplicationContext#setId id}, one will be assigned to it</li>
* <li>{@code ServletContext} and {@code ServletConfig} objects will be delegated to
* the application context</li>
* <li>{@link #customizeContext} will be called</li>
* <li>Any {@link ApplicationContextInitializer}s specified through the
* "contextInitializerClasses" init-param will be applied.</li>
* <li>{@link ConfigurableApplicationContext#refresh refresh()} will be called</li>
* </ul>
* If the context has already been refreshed or does not implement
* {@code ConfigurableWebApplicationContext}, none of the above will occur under the
* assumption that the user has performed these actions (or not) per his or her
* specific needs.
* <p>See {@link org.springframework.web.WebApplicationInitializer} for usage examples.
* <p>In any case, the given application context will be registered into the
* ServletContext under the attribute name {@link
* WebApplicationContext#ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE} and subclasses are
* free to call the {@link #closeWebApplicationContext} method on container shutdown
* to close the application context.
* @param context the application context to manage
* @see #initWebApplicationContext(ServletContext)
* @see #closeWebApplicationContext(ServletContext)
*/
public ContextLoader(WebApplicationContext context) {
this.context = context;
}


/**
* Specify which {@link ApplicationContextInitializer} instances should be used
* to initialize the application context used by this {@code ContextLoader}.
* @since 4.2
* @see #configureAndRefreshWebApplicationContext
* @see #customizeContext
*/
@SuppressWarnings("unchecked")
public void setContextInitializers(ApplicationContextInitializer<?>... initializers) {
if (initializers != null) {
for (ApplicationContextInitializer<?> initializer : initializers) {
this.contextInitializers.add((ApplicationContextInitializer<ConfigurableApplicationContext>) initializer);
}
}
}


/**
* 初始化spring上下文
* @param servletContext current servlet context
* @return the new WebApplicationContext
* @see #ContextLoader(WebApplicationContext)
* @see #CONTEXT_CLASS_PARAM
* @see #CONFIG_LOCATION_PARAM
*/
public WebApplicationContext initWebApplicationContext(ServletContext servletContext) {
if (servletContext.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE) != null) {
throw new IllegalStateException(
"Cannot initialize context because there is already a root application context present - " +
"check whether you have multiple ContextLoader* definitions in your web.xml!");
}

Log logger = LogFactory.getLog(ContextLoader.class);
servletContext.log("Initializing Spring root WebApplicationContext");
if (logger.isInfoEnabled()) {
logger.info("Root WebApplicationContext: initialization started");
}
long startTime = System.currentTimeMillis();

try {
// 创建WebApplicationContext实现类
if (this.context == null) {
this.context = createWebApplicationContext(servletContext);
}
if (this.context instanceof ConfigurableWebApplicationContext) {
ConfigurableWebApplicationContext cwac = (ConfigurableWebApplicationContext) this.context;
//AtomicBoolean来保证原子性操作
if (!cwac.isActive()) {
// The context has not yet been refreshed -> provide services such as
// setting the parent context, setting the application context id, etc
if (cwac.getParent() == null) {
// The context instance was injected without an explicit parent ->
// determine parent for root web application context, if any.
ApplicationContext parent = loadParentContext(servletContext);
cwac.setParent(parent);
}
//ApplicationContext初始化,配置刷新上下文
configureAndRefreshWebApplicationContext(cwac, servletContext);
}
}
//WebApplicationContext放入servlet全局变量中
servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, this.context);

ClassLoader ccl = Thread.currentThread().getContextClassLoader();
if (ccl == ContextLoader.class.getClassLoader()) {
currentContext = this.context;
}
else if (ccl != null) {
currentContextPerThread.put(ccl, this.context);
}

if (logger.isDebugEnabled()) {
logger.debug("Published root WebApplicationContext as ServletContext attribute with name [" +
WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE + "]");
}
if (logger.isInfoEnabled()) {
long elapsedTime = System.currentTimeMillis() - startTime;
logger.info("Root WebApplicationContext: initialization completed in " + elapsedTime + " ms");
}

return this.context;
}
catch (RuntimeException ex) {
logger.error("Context initialization failed", ex);
servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, ex);
throw ex;
}
catch (Error err) {
logger.error("Context initialization failed", err);
servletContext.setAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, err);
throw err;
}
}

/**
* 创建WebApplicationContext Bean
* @param sc current servlet context
* @return the root WebApplicationContext
*
* @see ConfigurableWebApplicationContext
*/
protected WebApplicationContext createWebApplicationContext(ServletContext sc) {
Class<?> contextClass = determineContextClass(sc);
if (!ConfigurableWebApplicationContext.class.isAssignableFrom(contextClass)) {
throw new ApplicationContextException("Custom context class [" + contextClass.getName() +
"] is not of type [" + ConfigurableWebApplicationContext.class.getName() + "]");
}
return (ConfigurableWebApplicationContext) BeanUtils.instantiateClass(contextClass);
}

/**
* 返回WebApplicationContext的实现类
* 默认是org.springframework.web.context.support.XmlWebApplicationContext
* @param servletContext current servlet context
* @return the WebApplicationContext implementation class to use
* @see #CONTEXT_CLASS_PARAM
* @see org.springframework.web.context.support.XmlWebApplicationContext
*/
protected Class<?> determineContextClass(ServletContext servletContext) {
String contextClassName = servletContext.getInitParameter(CONTEXT_CLASS_PARAM);
if (contextClassName != null) {
try {
return ClassUtils.forName(contextClassName, ClassUtils.getDefaultClassLoader());
}
catch (ClassNotFoundException ex) {
throw new ApplicationContextException(
"Failed to load custom context class [" + contextClassName + "]", ex);
}
}
else {
contextClassName = defaultStrategies.getProperty(WebApplicationContext.class.getName());
try {
return ClassUtils.forName(contextClassName, ContextLoader.class.getClassLoader());
}
catch (ClassNotFoundException ex) {
throw new ApplicationContextException(
"Failed to load default context class [" + contextClassName + "]", ex);
}
}
}

protected void configureAndRefreshWebApplicationContext(ConfigurableWebApplicationContext wac, ServletContext sc) {
if (ObjectUtils.identityToString(wac).equals(wac.getId())) {
// The application context id is still set to its original default value
// -> assign a more useful id based on available information
String idParam = sc.getInitParameter(CONTEXT_ID_PARAM);
if (idParam != null) {
wac.setId(idParam);
}
else {
// Generate default id...
wac.setId(ConfigurableWebApplicationContext.APPLICATION_CONTEXT_ID_PREFIX +
ObjectUtils.getDisplayString(sc.getContextPath()));
}
}

wac.setServletContext(sc);
String configLocationParam = sc.getInitParameter(CONFIG_LOCATION_PARAM);
if (configLocationParam != null) {
wac.setConfigLocation(configLocationParam);
}

// The wac environment's #initPropertySources will be called in any case when the context
// is refreshed; do it eagerly here to ensure servlet property sources are in place for
// use in any post-processing or initialization that occurs below prior to #refresh
ConfigurableEnvironment env = wac.getEnvironment();
if (env instanceof ConfigurableWebEnvironment) {
((ConfigurableWebEnvironment) env).initPropertySources(sc, null);
}

customizeContext(sc, wac);
//刷新动作,加载xml,bean
wac.refresh();
}

/**
* Customize the {@link ConfigurableWebApplicationContext} created by this
* ContextLoader after config locations have been supplied to the context
* but before the context is <em>refreshed</em>.
* <p>The default implementation {@linkplain #determineContextInitializerClasses(ServletContext)
* determines} what (if any) context initializer classes have been specified through
* {@linkplain #CONTEXT_INITIALIZER_CLASSES_PARAM context init parameters} and
* {@linkplain ApplicationContextInitializer#initialize invokes each} with the
* given web application context.
* <p>Any {@code ApplicationContextInitializers} implementing
* {@link org.springframework.core.Ordered Ordered} or marked with @{@link
* org.springframework.core.annotation.Order Order} will be sorted appropriately.
* @param sc the current servlet context
* @param wac the newly created application context
* @see #CONTEXT_INITIALIZER_CLASSES_PARAM
* @see ApplicationContextInitializer#initialize(ConfigurableApplicationContext)
*/
protected void customizeContext(ServletContext sc, ConfigurableWebApplicationContext wac) {
List<Class<ApplicationContextInitializer<ConfigurableApplicationContext>>> initializerClasses =
determineContextInitializerClasses(sc);

for (Class<ApplicationContextInitializer<ConfigurableApplicationContext>> initializerClass : initializerClasses) {
Class<?> initializerContextClass =
GenericTypeResolver.resolveTypeArgument(initializerClass, ApplicationContextInitializer.class);
if (initializerContextClass != null) {
Assert.isAssignable(initializerContextClass, wac.getClass(), String.format(
"Could not add context initializer [%s] since its generic parameter [%s] " +
"is not assignable from the type of application context used by this " +
"context loader [%s]: ", initializerClass.getName(), initializerContextClass.getName(),
wac.getClass().getName()));
}
this.contextInitializers.add(BeanUtils.instantiateClass(initializerClass));
}

AnnotationAwareOrderComparator.sort(this.contextInitializers);
for (ApplicationContextInitializer<ConfigurableApplicationContext> initializer : this.contextInitializers) {
initializer.initialize(wac);
}
}

/**
* Return the {@link ApplicationContextInitializer} implementation classes to use
* if any have been specified by {@link #CONTEXT_INITIALIZER_CLASSES_PARAM}.
* @param servletContext current servlet context
* @see #CONTEXT_INITIALIZER_CLASSES_PARAM
*/
protected List<Class<ApplicationContextInitializer<ConfigurableApplicationContext>>>
determineContextInitializerClasses(ServletContext servletContext) {

List<Class<ApplicationContextInitializer<ConfigurableApplicationContext>>> classes =
new ArrayList<Class<ApplicationContextInitializer<ConfigurableApplicationContext>>>();

String globalClassNames = servletContext.getInitParameter(GLOBAL_INITIALIZER_CLASSES_PARAM);
if (globalClassNames != null) {
for (String className : StringUtils.tokenizeToStringArray(globalClassNames, INIT_PARAM_DELIMITERS)) {
classes.add(loadInitializerClass(className));
}
}

String localClassNames = servletContext.getInitParameter(CONTEXT_INITIALIZER_CLASSES_PARAM);
if (localClassNames != null) {
for (String className : StringUtils.tokenizeToStringArray(localClassNames, INIT_PARAM_DELIMITERS)) {
classes.add(loadInitializerClass(className));
}
}

return classes;
}

@SuppressWarnings("unchecked")
private Class<ApplicationContextInitializer<ConfigurableApplicationContext>> loadInitializerClass(String className) {
try {
Class<?> clazz = ClassUtils.forName(className, ClassUtils.getDefaultClassLoader());
Assert.isAssignable(ApplicationContextInitializer.class, clazz);
return (Class<ApplicationContextInitializer<ConfigurableApplicationContext>>) clazz;
}
catch (ClassNotFoundException ex) {
throw new ApplicationContextException("Failed to load context initializer class [" + className + "]", ex);
}
}

/**
* Template method with default implementation (which may be overridden by a
* subclass), to load or obtain an ApplicationContext instance which will be
* used as the parent context of the root WebApplicationContext. If the
* return value from the method is null, no parent context is set.
* <p>The main reason to load a parent context here is to allow multiple root
* web application contexts to all be children of a shared EAR context, or
* alternately to also share the same parent context that is visible to
* EJBs. For pure web applications, there is usually no need to worry about
* having a parent context to the root web application context.
* <p>The default implementation uses
* {@link org.springframework.context.access.ContextSingletonBeanFactoryLocator},
* configured via {@link #LOCATOR_FACTORY_SELECTOR_PARAM} and
* {@link #LOCATOR_FACTORY_KEY_PARAM}, to load a parent context
* which will be shared by all other users of ContextsingletonBeanFactoryLocator
* which also use the same configuration parameters.
* @param servletContext current servlet context
* @return the parent application context, or {@code null} if none
* @see org.springframework.context.access.ContextSingletonBeanFactoryLocator
*/
protected ApplicationContext loadParentContext(ServletContext servletContext) {
ApplicationContext parentContext = null;
String locatorFactorySelector = servletContext.getInitParameter(LOCATOR_FACTORY_SELECTOR_PARAM);
String parentContextKey = servletContext.getInitParameter(LOCATOR_FACTORY_KEY_PARAM);

if (parentContextKey != null) {
// locatorFactorySelector may be null, indicating the default "classpath*:beanRefContext.xml"
BeanFactoryLocator locator = ContextSingletonBeanFactoryLocator.getInstance(locatorFactorySelector);
Log logger = LogFactory.getLog(ContextLoader.class);
if (logger.isDebugEnabled()) {
logger.debug("Getting parent context definition: using parent context key of '" +
parentContextKey + "' with BeanFactoryLocator");
}
this.parentContextRef = locator.useBeanFactory(parentContextKey);
parentContext = (ApplicationContext) this.parentContextRef.getFactory();
}

return parentContext;
}

/**
* Close Spring's web application context for the given servlet context. If
* the default {@link #loadParentContext(ServletContext)} implementation,
* which uses ContextSingletonBeanFactoryLocator, has loaded any shared
* parent context, release one reference to that shared parent context.
* <p>If overriding {@link #loadParentContext(ServletContext)}, you may have
* to override this method as well.
* @param servletContext the ServletContext that the WebApplicationContext runs in
*/
public void closeWebApplicationContext(ServletContext servletContext) {
servletContext.log("Closing Spring root WebApplicationContext");
try {
if (this.context instanceof ConfigurableWebApplicationContext) {
((ConfigurableWebApplicationContext) this.context).close();
}
}
finally {
ClassLoader ccl = Thread.currentThread().getContextClassLoader();
if (ccl == ContextLoader.class.getClassLoader()) {
currentContext = null;
}
else if (ccl != null) {
currentContextPerThread.remove(ccl);
}
servletContext.removeAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
if (this.parentContextRef != null) {
this.parentContextRef.release();
}
}
}


/**
* Obtain the Spring root web application context for the current thread
* (i.e. for the current thread's context ClassLoader, which needs to be
* the web application's ClassLoader).
* @return the current root web application context, or {@code null}
* if none found
* @see org.springframework.web.context.support.SpringBeanAutowiringSupport
*/
public static WebApplicationContext getCurrentWebApplicationContext() {
ClassLoader ccl = Thread.currentThread().getContextClassLoader();
if (ccl != null) {
WebApplicationContext ccpt = currentContextPerThread.get(ccl);
if (ccpt != null) {
return ccpt;
}
}
return currentContext;
}

}