Feign Client
feign的client是一个接口，只有一个execute方法。
public interface Client {
// 执行请求
Response execute(Request request, Options options) throws IOException;
}
Client.Default
默认的Client是通过UrlConnection来进行实现的逻辑。
class Default implements Client {
@Override
public Response execute(Request request, Options options) throws IOException {
// 获取connection
HttpURLConnection connection = convertAndSend(request, options);
// 转换数据
return convertResponse(connection, request);
}
// 构建响应数据
Response convertResponse(HttpURLConnection connection, Request request) throws IOException {
// 获取状态码
int status = connection.getResponseCode();
// 返回消息
String reason = connection.getResponseMessage();
if (status < 0) {
throw new IOException(format("Invalid status(%s) executing %s %s", status,
connection.getRequestMethod(), connection.getURL()));
}
// 响应头信息
Map<String, Collection<String>> headers = new LinkedHashMap<>();
for (Map.Entry<String, List<String>> field : connection.getHeaderFields().entrySet()) {
// response message
if (field.getKey() != null) {
headers.put(field.getKey(), field.getValue());
}
}
// 内容长度
Integer length = connection.getContentLength();
if (length == -1) {
length = null;
}
// 获取响应流
InputStream stream;
if (status >= 400) {
stream = connection.getErrorStream();
} else {
stream = connection.getInputStream();
}
return Response.builder()
.status(status)
.reason(reason)
.headers(headers)
.request(request)
.body(stream, length)
.build();
}
// 转换数据并发送
HttpURLConnection convertAndSend(Request request, Options options) throws IOException {
// 请求地址
final URL url = new URL(request.url());
// 获取连接
final HttpURLConnection connection = this.getConnection(url);
// 判断是否是https请求
if (connection instanceof HttpsURLConnection) {
HttpsURLConnection sslCon = (HttpsURLConnection) connection;
if (sslContextFactory != null) {
sslCon.setSSLSocketFactory(sslContextFactory);
}
if (hostnameVerifier != null) {
sslCon.setHostnameVerifier(hostnameVerifier);
}
}
// 通过options设置默认超时信息
connection.setConnectTimeout(options.connectTimeoutMillis());
connection.setReadTimeout(options.readTimeoutMillis());
connection.setAllowUserInteraction(false);
connection.setInstanceFollowRedirects(options.isFollowRedirects());
connection.setRequestMethod(request.httpMethod().name());
// 头信息获取判断是否为gzip或者deflate
Collection<String> contentEncodingValues = request.headers().get(CONTENT_ENCODING);
boolean gzipEncodedRequest =
contentEncodingValues != null && contentEncodingValues.contains(ENCODING_GZIP);
boolean deflateEncodedRequest =
contentEncodingValues != null && contentEncodingValues.contains(ENCODING_DEFLATE);
boolean hasAcceptHeader = false;
Integer contentLength = null;
// 循环设置头信息
for (String field : request.headers().keySet()) {
if (field.equalsIgnoreCase("Accept")) {
hasAcceptHeader = true;
}
for (String value : request.headers().get(field)) {
if (field.equals(CONTENT_LENGTH)) {
if (!gzipEncodedRequest && !deflateEncodedRequest) {
contentLength = Integer.valueOf(value);
connection.addRequestProperty(field, value);
}
} else {
connection.addRequestProperty(field, value);
}
}
}
// Some servers choke on the default accept string.
if (!hasAcceptHeader) {
connection.addRequestProperty("Accept", "*/*");
}
// 写入body
if (request.body() != null) {
if (disableRequestBuffering) {
if (contentLength != null) {
connection.setFixedLengthStreamingMode(contentLength);
} else {
connection.setChunkedStreamingMode(8196);
}
}
connection.setDoOutput(true);
OutputStream out = connection.getOutputStream();
if (gzipEncodedRequest) {
out = new GZIPOutputStream(out);
} else if (deflateEncodedRequest) {
out = new DeflaterOutputStream(out);
}
try {
out.write(request.body());
} finally {
try {
out.close();
} catch (IOException suppressed) { // NOPMD
}
}
}
return connection;
}
}
// 创建UrlConnection连接
public HttpURLConnection getConnection(final URL url) throws IOException {
return (HttpURLConnection) url.openConnection();
}
}
