这篇文章主要讲解了“feign中RequestInterceptor的原理和作用”，文中的讲解内容简单清晰，易于学习与理解，下面请大家跟着小编的思路慢慢深入，一起来研究和学习“feign中RequestInterceptor的原理和作用”吧！
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本文主要研究一下feign的RequestInterceptor
feign-core-10.2.3-sources.jar!/feign/RequestInterceptor.java
public interface RequestInterceptor {
/**
* Called for every request. Add data using methods on the supplied {@link RequestTemplate}.
*/
void apply(RequestTemplate template);
}RequestInterceptor接口定义了apply方法，其参数为RequestTemplate；它有一个抽象类为BaseRequestInterceptor，还有几个实现类分别为BasicAuthRequestInterceptor、FeignAcceptGzipEncodingInterceptor、FeignContentGzipEncodingInterceptor
feign-core-10.2.3-sources.jar!/feign/auth/BasicAuthRequestInterceptor.java
public class BasicAuthRequestInterceptor implements RequestInterceptor {
private final String headerValue;
/**
* Creates an interceptor that authenticates all requests with the specified username and password
* encoded using ISO-8859-1.
*
* @param username the username to use for authentication
* @param password the password to use for authentication
*/
public BasicAuthRequestInterceptor(String username, String password) {
this(username, password, ISO_8859_1);
}
/**
* Creates an interceptor that authenticates all requests with the specified username and password
* encoded using the specified charset.
*
* @param username the username to use for authentication
* @param password the password to use for authentication
* @param charset the charset to use when encoding the credentials
*/
public BasicAuthRequestInterceptor(String username, String password, Charset charset) {
checkNotNull(username, "username");
checkNotNull(password, "password");
this.headerValue = "Basic " + base64Encode((username + ":" + password).getBytes(charset));
}
/*
* This uses a Sun internal method; if we ever encounter a case where this method is not
* available, the appropriate response would be to pull the necessary portions of Guava's
* BaseEncoding class into Util.
*/
private static String base64Encode(byte[] bytes) {
return Base64.encode(bytes);
}
@Override
public void apply(RequestTemplate template) {
template.header("Authorization", headerValue);
}
}BasicAuthRequestInterceptor实现了RequestInterceptor接口，其apply方法往RequestTemplate添加名为Authorization的header
spring-cloud-openfeign-core-2.2.0.M1-sources.jar!/org/springframework/cloud/openfeign/encoding/BaseRequestInterceptor.java
public abstract class BaseRequestInterceptor implements RequestInterceptor {
/**
* The encoding properties.
*/
private final FeignClientEncodingProperties properties;
/**
* Creates new instance of {@link BaseRequestInterceptor}.
* @param properties the encoding properties
*/
protected BaseRequestInterceptor(FeignClientEncodingProperties properties) {
Assert.notNull(properties, "Properties can not be null");
this.properties = properties;
}
/**
* Adds the header if it wasn't yet specified.
* @param requestTemplate the request
* @param name the header name
* @param values the header values
*/
protected void addHeader(RequestTemplate requestTemplate, String name,
String... values) {
if (!requestTemplate.headers().containsKey(name)) {
requestTemplate.header(name, values);
}
}
protected FeignClientEncodingProperties getProperties() {
return this.properties;
}
}BaseRequestInterceptor定义了addHeader方法，往requestTemplate添加非重名的header
spring-cloud-openfeign-core-2.2.0.M1-sources.jar!/org/springframework/cloud/openfeign/encoding/FeignAcceptGzipEncodingInterceptor.java
public class FeignAcceptGzipEncodingInterceptor extends BaseRequestInterceptor {
/**
* Creates new instance of {@link FeignAcceptGzipEncodingInterceptor}.
* @param properties the encoding properties
*/
protected FeignAcceptGzipEncodingInterceptor(
FeignClientEncodingProperties properties) {
super(properties);
}
/**
* {@inheritDoc}
*/
@Override
public void apply(RequestTemplate template) {
addHeader(template, HttpEncoding.ACCEPT_ENCODING_HEADER,
HttpEncoding.GZIP_ENCODING, HttpEncoding.DEFLATE_ENCODING);
}
}FeignAcceptGzipEncodingInterceptor继承了BaseRequestInterceptor，它的apply方法往RequestTemplate添加了名为Accept-Encoding，值为gzip,deflate的header
spring-cloud-openfeign-core-2.2.0.M1-sources.jar!/org/springframework/cloud/openfeign/encoding/FeignContentGzipEncodingInterceptor.java
public class FeignContentGzipEncodingInterceptor extends BaseRequestInterceptor {
/**
* Creates new instance of {@link FeignContentGzipEncodingInterceptor}.
* @param properties the encoding properties
*/
protected FeignContentGzipEncodingInterceptor(
FeignClientEncodingProperties properties) {
super(properties);
}
/**
* {@inheritDoc}
*/
@Override
public void apply(RequestTemplate template) {
if (requiresCompression(template)) {
addHeader(template, HttpEncoding.CONTENT_ENCODING_HEADER,
HttpEncoding.GZIP_ENCODING, HttpEncoding.DEFLATE_ENCODING);
}
}
/**
* Returns whether the request requires GZIP compression.
* @param template the request template
* @return true if request requires compression, false otherwise
*/
private boolean requiresCompression(RequestTemplate template) {
final Map> headers = template.headers();
return matchesMimeType(headers.get(HttpEncoding.CONTENT_TYPE))
&& contentLengthExceedThreshold(headers.get(HttpEncoding.CONTENT_LENGTH));
}
/**
* Returns whether the request content length exceed configured minimum size.
* @param contentLength the content length header value
* @return true if length is grater than minimum size, false otherwise
*/
private boolean contentLengthExceedThreshold(Collection contentLength) {
try {
if (contentLength == null || contentLength.size() != 1) {
return false;
}
final String strLen = contentLength.iterator().next();
final long length = Long.parseLong(strLen);
return length > getProperties().getMinRequestSize();
}
catch (NumberFormatException ex) {
return false;
}
}
/**
* Returns whether the content mime types matches the configures mime types.
* @param contentTypes the content types
* @return true if any specified content type matches the request content types
*/
private boolean matchesMimeType(Collection contentTypes) {
if (contentTypes == null || contentTypes.size() == 0) {
return false;
}
if (getProperties().getMimeTypes() == null
|| getProperties().getMimeTypes().length == 0) {
// no specific mime types has been set - matching everything
return true;
}
for (String mimeType : getProperties().getMimeTypes()) {
if (contentTypes.contains(mimeType)) {
return true;
}
}
return false;
}
} FeignContentGzipEncodingInterceptor继承了BaseRequestInterceptor，其apply方法先判断是否需要compression，即mimeType是否符合要求以及content大小是否超出阈值，需要compress的话则添加名为Content-Encoding，值为gzip,deflate的header
RequestInterceptor接口定义了apply方法，其参数为RequestTemplate；它有一个抽象类为BaseRequestInterceptor，还有几个实现类分别为BasicAuthRequestInterceptor、FeignAcceptGzipEncodingInterceptor、FeignContentGzipEncodingInterceptor
BasicAuthRequestInterceptor实现了RequestInterceptor接口，其apply方法往RequestTemplate添加名为Authorization的header
BaseRequestInterceptor定义了addHeader方法，往requestTemplate添加非重名的header；FeignAcceptGzipEncodingInterceptor继承了BaseRequestInterceptor，它的apply方法往RequestTemplate添加了名为Accept-Encoding，值为gzip,deflate的header；FeignContentGzipEncodingInterceptor继承了BaseRequestInterceptor，其apply方法先判断是否需要compression，即mimeType是否符合要求以及content大小是否超出阈值，需要compress的话则添加名为Content-Encoding，值为gzip,deflate的header
感谢各位的阅读，以上就是“feign中RequestInterceptor的原理和作用”的内容了，经过本文的学习后，相信大家对feign中RequestInterceptor的原理和作用这一问题有了更深刻的体会，具体使用情况还需要大家实践验证。这里是创新互联，小编将为大家推送更多相关知识点的文章，欢迎关注！
