springMVC源码解析--HandlerMethodArgumentResolverComposite参数解析器集合（二）

上一篇博客springMVC源码分析--HandlerMethodArgumentResolver参数解析器（一）中我们已经介绍了参数解析相关的东西，并且也提到了HandlerMethodArgumentResolverComposite，其简单来说就是所有的参数解析器的链表，保存了springMVC提供的所有的参数解析器，采用职责链的模式来完成参数解析器的查找，并完成参数解析生成目标对象。

完整源码及说明如下：

public class HandlerMethodArgumentResolverComposite implements HandlerMethodArgumentResolver {

protected final Log logger = LogFactory.getLog(getClass());

//保存springMVC提供的所有的参数解析器
private final List<HandlerMethodArgumentResolver> argumentResolvers =
new LinkedList<HandlerMethodArgumentResolver>();

//用于缓存已经查找过的参数解析器
private final Map<MethodParameter, HandlerMethodArgumentResolver> argumentResolverCache =
new ConcurrentHashMap<MethodParameter, HandlerMethodArgumentResolver>(256);
//获取所有的参数解析器
public List<HandlerMethodArgumentResolver> getResolvers() {
return Collections.unmodifiableList(this.argumentResolvers);
}

//判断参数解析器是否支持参数解析
@Override
public boolean supportsParameter(MethodParameter parameter) {
return (getArgumentResolver(parameter) != null);
}

//返回参数解析器解析后的数据
@Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer,
NativeWebRequest webRequest, WebDataBinderFactory binderFactory) throws Exception {

HandlerMethodArgumentResolver resolver = getArgumentResolver(parameter);
if (resolver == null) {
throw new IllegalArgumentException("Unknown parameter type [" + parameter.getParameterType().getName() + "]");
}
return resolver.resolveArgument(parameter, mavContainer, webRequest, binderFactory);
}

//获取支持某个参数解析的参数解析器
private HandlerMethodArgumentResolver getArgumentResolver(MethodParameter parameter) {
HandlerMethodArgumentResolver result = this.argumentResolverCache.get(parameter);
if (result == null) {
for (HandlerMethodArgumentResolver methodArgumentResolver : this.argumentResolvers) {
if (logger.isTraceEnabled()) {
logger.trace("Testing if argument resolver [" + methodArgumentResolver + "] supports [" +
parameter.getGenericParameterType() + "]");
}
if (methodArgumentResolver.supportsParameter(parameter)) {
result = methodArgumentResolver;
this.argumentResolverCache.put(parameter, result);
break;
}
}
}
return result;
}

//添加参数解析器
public HandlerMethodArgumentResolverComposite addResolver(HandlerMethodArgumentResolver resolver) {
this.argumentResolvers.add(resolver);
return this;
}
//获取参数解析器集合
public HandlerMethodArgumentResolverComposite addResolvers(List<? extends HandlerMethodArgumentResolver> resolvers) {
if (resolvers != null) {
for (HandlerMethodArgumentResolver resolver : resolvers) {
this.argumentResolvers.add(resolver);
}
}
return this;
}

}