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本文主要研究一下 nacos client 的 ServerHttpAgent
HttpAgent
nacos-1.1.3/client/src/main/java/com/alibaba/nacos/client/config/http/HttpAgent.java
public interface HttpAgent {
/**
* start to get nacos ip list
* @return Nothing.
* @throws NacosException on get ip list error.
*/
void start() throws NacosException;
/**
* invoke http get method
* @param path http path
* @param headers http headers
* @param paramValues http paramValues http
* @param encoding http encode
* @param readTimeoutMs http timeout
* @return HttpResult http response
* @throws IOException If an input or output exception occurred
*/
HttpResult httpGet(String path, List<String> headers, List<String> paramValues, String encoding, long readTimeoutMs) throws IOException;
/**
* invoke http post method
* @param path http path
* @param headers http headers
* @param paramValues http paramValues http
* @param encoding http encode
* @param readTimeoutMs http timeout
* @return HttpResult http response
* @throws IOException If an input or output exception occurred
*/
HttpResult httpPost(String path, List<String> headers, List<String> paramValues, String encoding, long readTimeoutMs) throws IOException;
/**
* invoke http delete method
* @param path http path
* @param headers http headers
* @param paramValues http paramValues http
* @param encoding http encode
* @param readTimeoutMs http timeout
* @return HttpResult http response
* @throws IOException If an input or output exception occurred
*/
HttpResult httpDelete(String path, List<String> headers, List<String> paramValues, String encoding, long readTimeoutMs) throws IOException;
/**
* get name
* @return String
*/
String getName();
/**
* get namespace
* @return String
*/
String getNamespace();
/**
* get tenant
* @return String
*/
String getTenant();
/**
* get encode
* @return String
*/
String getEncode();}- HttpAgent 定义了 start、httpGet、httpPost、httpDelete、getName、getNamespace、getTenant、getEncode 方法
ServerHttpAgent
nacos-1.1.3/client/src/main/java/com/alibaba/nacos/client/config/http/ServerHttpAgent.java
public class ServerHttpAgent implements HttpAgent {private static final Logger LOGGER = LogUtils.logger(ServerHttpAgent.class);
/**
* @param path 相对于 web 应用根，以 / 开头
* @param headers
* @param paramValues
* @param encoding
* @param readTimeoutMs
* @return
* @throws IOException
*/
@Override
public HttpResult httpGet(String path, List<String> headers, List<String> paramValues, String encoding,
long readTimeoutMs) throws IOException {final long endTime = System.currentTimeMillis() + readTimeoutMs;
final boolean isSSL = false;
String currentServerAddr = serverListMgr.getCurrentServerAddr();
int maxRetry = this.maxRetry;
do {
try {List<String> newHeaders = getSpasHeaders(paramValues);
if (headers != null) {newHeaders.addAll(headers);
}
HttpResult result = HttpSimpleClient.httpGet(getUrl(currentServerAddr, path), newHeaders, paramValues, encoding,
readTimeoutMs, isSSL);
if (result.code == HttpURLConnection.HTTP_INTERNAL_ERROR
|| result.code == HttpURLConnection.HTTP_BAD_GATEWAY
|| result.code == HttpURLConnection.HTTP_UNAVAILABLE) {LOGGER.error("[NACOS ConnectException] currentServerAddr: {}, httpCode: {}",
serverListMgr.getCurrentServerAddr(), result.code);
} else {
// Update the currently available server addr
serverListMgr.updateCurrentServerAddr(currentServerAddr);
return result;
}
} catch (ConnectException ce) {LOGGER.error("[NACOS ConnectException httpGet] currentServerAddr:{}, err : {}", serverListMgr.getCurrentServerAddr(), ce.getMessage());
} catch (SocketTimeoutException stoe) {LOGGER.error("[NACOS SocketTimeoutException httpGet] currentServerAddr:{}，err : {}", serverListMgr.getCurrentServerAddr(), stoe.getMessage());
} catch (IOException ioe) {LOGGER.error("[NACOS IOException httpGet] currentServerAddr:" + serverListMgr.getCurrentServerAddr(), ioe);
throw ioe;
}
if (serverListMgr.getIterator().hasNext()) {currentServerAddr = serverListMgr.getIterator().next();} else {
maxRetry --;
if (maxRetry < 0) {throw new ConnectException("[NACOS HTTP-GET] The maximum number of tolerable server reconnection errors has been reached");
}
serverListMgr.refreshCurrentServerAddr();}
} while (System.currentTimeMillis() <= endTime);
LOGGER.error("no available server");
throw new ConnectException("no available server");
}
@Override
public HttpResult httpPost(String path, List<String> headers, List<String> paramValues, String encoding,
long readTimeoutMs) throws IOException {final long endTime = System.currentTimeMillis() + readTimeoutMs;
boolean isSSL = false;
String currentServerAddr = serverListMgr.getCurrentServerAddr();
int maxRetry = this.maxRetry;
do {
try {List<String> newHeaders = getSpasHeaders(paramValues);
if (headers != null) {newHeaders.addAll(headers);
}
HttpResult result = HttpSimpleClient.httpPost(getUrl(currentServerAddr, path), newHeaders, paramValues, encoding,
readTimeoutMs, isSSL);
if (result.code == HttpURLConnection.HTTP_INTERNAL_ERROR
|| result.code == HttpURLConnection.HTTP_BAD_GATEWAY
|| result.code == HttpURLConnection.HTTP_UNAVAILABLE) {LOGGER.error("[NACOS ConnectException] currentServerAddr: {}, httpCode: {}",
currentServerAddr, result.code);
} else {
// Update the currently available server addr
serverListMgr.updateCurrentServerAddr(currentServerAddr);
return result;
}
} catch (ConnectException ce) {LOGGER.error("[NACOS ConnectException httpPost] currentServerAddr: {}, err : {}", currentServerAddr, ce.getMessage());
} catch (SocketTimeoutException stoe) {LOGGER.error("[NACOS SocketTimeoutException httpPost] currentServerAddr: {}，err : {}", currentServerAddr, stoe.getMessage());
} catch (IOException ioe) {LOGGER.error("[NACOS IOException httpPost] currentServerAddr:" + currentServerAddr, ioe);
throw ioe;
}
if (serverListMgr.getIterator().hasNext()) {currentServerAddr = serverListMgr.getIterator().next();} else {
maxRetry --;
if (maxRetry < 0) {throw new ConnectException("[NACOS HTTP-POST] The maximum number of tolerable server reconnection errors has been reached");
}
serverListMgr.refreshCurrentServerAddr();}
} while (System.currentTimeMillis() <= endTime);
LOGGER.error("no available server, currentServerAddr : {}", currentServerAddr);
throw new ConnectException("no available server, currentServerAddr :" + currentServerAddr);
}
//......
}- ServerHttpAgent 实现了 HttpAgent 接口，其 httpGet、httpPost、httpDelete 方法的结构大体相同，都是以 do while 做循环，循环条件为距离开始执行时间不超过 readTimeoutMs
- 循环开始之前会通过 serverListMgr.getCurrentServerAddr() 方法获取 currentServerAddr，循环体内则通过 HttpSimpleClient 的相应方法执行请求，如果返回的 HTTP Code 为 HTTP_INTERNAL_ERROR、HTTP_BAD_GATEWAY、HTTP_UNAVAILABLE 则打印 error 日志，否则执行 serverListMgr.updateCurrentServerAddr(currentServerAddr)，然后返回
- 如果出现异常或者没有提前返回，则判断 serverListMgr.getIterator().hasNext()，如果为 true 则使用 serverListMgr.getIterator().next() 更新 currentServerAddr，为 false 则递减 maxRetry，然后执行 serverListMgr.refreshCurrentServerAddr()
小结
ServerHttpAgent 实现了 HttpAgent 接口，其 httpGet、httpPost、httpDelete 方法的结构大体相同，都是以 do while 做循环，循环条件为距离开始执行时间不超过 readTimeoutMs
doc
- ServerHttpAgent