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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