背景
某日使用okhttp设置代理并发送爬虫请求时，发现部分url请求没有走代理直接和目标url建立了连接，伪代码如下。初始化okhttpClient时设置了proxySelecter代理，但是调用okhttpClient.newCall请求时并没用调用proxySelecter.select函数获取代理，日志也没有打印。
public void call(String url) {
ProxySelector proxySelector = new ProxySelector() {
@Override
public List<Proxy> select(URI uri) {
log.info("run into proxy");
Proxy proxy = new Proxy(Proxy.Type.HTTP, new InetSocketAddress("127.0.0.1", 80));
return Collections.singletonList(proxy);
}
@Override
public void connectFailed(URI uri, SocketAddress sa, IOException ioe) {
return;
}
};
OkHttpClient client = new OkHttpClient.Builder().proxySelector(proxySelector).build();
okhttp3.Request request = new Request.Builder()
.url(url).build();
client.newCall(request);
}okHttp & 代理
Android | 彻底理解 OkHttp 代理与路由
为什么没走代理
okhttp选择proxy时，现将传入的url传换为uri，如果uri的host为空，okhttp选择直连url，放弃走代理
okhttp3.internal.connection.RouteSelector
private fun resetNextProxy(url: HttpUrl, proxy: Proxy?) {
fun selectProxies(): List<Proxy> {
// If the user specifies a proxy, try that and only that.
if (proxy != null) return listOf(proxy)
// If the URI lacks a host (as in "http://</"), don't call the ProxySelector.
val uri = url.toUri()
//此处，如果host解析出来为null。放弃走设置的代理
if (uri.host == null) return immutableListOf(Proxy.NO_PROXY)
// Try each of the ProxySelector choices until one connection succeeds.
val proxiesOrNull = address.proxySelector.select(uri)
if (proxiesOrNull.isNullOrEmpty()) return immutableListOf(Proxy.NO_PROXY)
return proxiesOrNull.toImmutableList()
}
eventListener.proxySelectStart(call, url)
proxies = selectProxies()
nextProxyIndex = 0
eventListener.proxySelectEnd(call, url, proxies)
}val uri = url.toUri() 函数扒到底，实际获取hostName的执行代码如下。java.net.Uri包解uri时，如果uri的host不合法，则降级设置host为null。
java.net.uri类节选代码
private int parseAuthority(int start, int n)
throws URISyntaxException
{
...
if (serverChars) {
// Might be (probably is) a server-based authority, so attempt
// to parse it as such. If the attempt fails, try to treat it
// as a registry-based authority.
try {
//此处解析hostName，不合法的话会扔出URISyntaxException异常
q = parseServer(p, n);
if (q < n)
failExpecting("end of authority", q);
authority = substring(p, n);
} catch (URISyntaxException x) {
// Undo results of failed parse
userInfo = null;
//host被赋值为空指针
host = null;
port = -1;
if (requireServerAuthority) {
// If we're insisting upon a server-based authority,
// then just re-throw the exception
throw x;
} else {
//
ex = x;
q = p;
}
}
}
...
return n;
}