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本文主要研究一下feign的RequestInterceptor
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
BasicAuthRequestInterceptor
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
BaseRequestInterceptor
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
FeignAcceptGzipEncodingInterceptor
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
FeignContentGzipEncodingInterceptor
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<String, Collection<String>> 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<String> 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<String> 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
小结
- 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
doc
- RequestInterceptor