consumes 指定处理请求的提交内容类型（media-Type），例如application/json, text/html.
所以这边的ConsumesRequestCondition就是通过content type进行url过滤的.
具体分析前,我们先准备下基础知识.
1. MediaType(org.springframework.http包下,封装n多api)
2. MediaTypeExpression接口,对MediaType和是否匹配关系(=或!=)的封装
3. AbstractMediaTypeExpression体系,也就是ConsumeMediaTypeExpression和ProduceMediaTypeExpression.
// MediaTypeExpression接口
package org.springframework.web.servlet.mvc.condition;
public interface MediaTypeExpression { MediaType getMediaType(); boolean isNegated(); }
AbstractMediaTypeExpression构造方法处理是否!后,委托MediaType处理
// AbstractMediaTypeExpression
AbstractMediaTypeExpression(String expression) {
if (expression.startsWith("!")) {
isNegated = true;
expression = expression.substring(1);
}
else {
isNegated = false;
}
this.mediaType = MediaType.parseMediaType(expression);
}看看条件匹配的match
// AbstractMediaTypeExpression
public final boolean match(HttpServletRequest request) {
try {
boolean match = matchMediaType(request);
return !isNegated ? match : !match;
}
catch (HttpMediaTypeException ex) {
return false;
}
}
protected abstract boolean matchMediaType(HttpServletRequest request) throws HttpMediaTypeException;Consume和Produce的区别终于出来了
static class ConsumeMediaTypeExpression extends AbstractMediaTypeExpression {
@Override
protected boolean matchMediaType(HttpServletRequest request) throws HttpMediaTypeNotSupportedException {
try {
MediaType contentType = StringUtils.hasLength(request.getContentType()) ?
MediaType.parseMediaType(request.getContentType()) :
MediaType.APPLICATION_OCTET_STREAM;
return getMediaType().includes(contentType);
}
catch (IllegalArgumentException ex) {
throw new HttpMediaTypeNotSupportedException(
"Can't parse Content-Type [" + request.getContentType() + "]: " + ex.getMessage());
}
}
}private final List<ProduceMediaTypeExpression> MEDIA_TYPE_ALL_LIST =
Collections.singletonList(new ProduceMediaTypeExpression("*/*")); /**
* Parses and matches a single media type expression to a request's 'Accept' header.
*/
class ProduceMediaTypeExpression extends AbstractMediaTypeExpression { @Override
protected boolean matchMediaType(HttpServletRequest request) throws HttpMediaTypeNotAcceptableException {
List<MediaType> acceptedMediaTypes = getAcceptedMediaTypes(request);
for (MediaType acceptedMediaType : acceptedMediaTypes) {
if (getMediaType().isCompatibleWith(acceptedMediaType)) {
return true;
}
}
return false;
}
}
正文
combine方法,这边不做合并,直接覆盖
// ConsumesRequestCondition
/**
* Returns the "other" instance if it has any expressions; returns "this"
* instance otherwise. Practically that means a method-level "consumes"
* overrides a type-level "consumes" condition.
*/
public ConsumesRequestCondition combine(ConsumesRequestCondition other) {
return !other.expressions.isEmpty() ? other : this;
}
getMatchingCondition的规则是存在一个即判定匹配
// ConsumesRequestCondition
/**
* Checks if any of the contained media type expressions match the given
* request 'Content-Type' header and returns an instance that is guaranteed
* to contain matching expressions only. The match is performed via
* {@link MediaType#includes(MediaType)}.
*
* @param request the current request
*
* @return the same instance if the condition contains no expressions;
* or a new condition with matching expressions only;
* or {@code null} if no expressions match.
*/
public ConsumesRequestCondition getMatchingCondition(HttpServletRequest request) {
if (isEmpty()) {
return this;
}
Set<ConsumeMediaTypeExpression> result = new LinkedHashSet<ConsumeMediaTypeExpression>(expressions);
for (Iterator<ConsumeMediaTypeExpression> iterator = result.iterator(); iterator.hasNext();) {
ConsumeMediaTypeExpression expression = iterator.next();
if (!expression.match(request)) {
iterator.remove();
}
}
return (result.isEmpty()) ? null : new ConsumesRequestCondition(result);
}
compareTo谁有匹配规则谁牛逼,都有的话比较第一个expression
// ConsumesRequestCondition
public int compareTo(ConsumesRequestCondition other, HttpServletRequest request) {
if (this.expressions.isEmpty() && other.expressions.isEmpty()) {
return 0;
}
else if (this.expressions.isEmpty()) {
return 1;
}
else if (other.expressions.isEmpty()) {
return -1;
}
else {
return this.expressions.get(0).compareTo(other.expressions.get(0));
}
}看看初始化吧
/**
* Creates a new instance with "consumes" and "header" expressions.
* "Header" expressions where the header name is not 'Content-Type' or have
* no header value defined are ignored. If 0 expressions are provided in
* total, the condition will match to every request
* @param consumes as described in {@link RequestMapping#consumes()}
* @param headers as described in {@link RequestMapping#headers()}
*/
public ConsumesRequestCondition(String[] consumes, String[] headers) {
this(parseExpressions(consumes, headers));
} private static Set<ConsumeMediaTypeExpression> parseExpressions(String[] consumes, String[] headers) {
Set<ConsumeMediaTypeExpression> result = new LinkedHashSet<ConsumeMediaTypeExpression>();
if (headers != null) {
for (String header : headers) {
HeaderExpression expr = new HeaderExpression(header);
if ("Content-Type".equalsIgnoreCase(expr.name)) {
for (MediaType mediaType : MediaType.parseMediaTypes(expr.value)) {
result.add(new ConsumeMediaTypeExpression(mediaType, expr.isNegated));
}
}
}
}
if (consumes != null) {
for (String consume : consumes) {
result.add(new ConsumeMediaTypeExpression(consume));
}
}
return result;
}