src/wallet/rpcwallet.cpp

从JSONRPCRequest当前URI(字符串)里面获得携带的wallet_name参数，赋值到wallet_name

static const std::string WALLET_ENDPOINT_BASE = "/wallet/";
bool GetWalletNameFromJSONRPCRequest(const JSONRPCRequest& request, std::string& wallet_name)
{
    if (request.URI.substr(0, WALLET_ENDPOINT_BASE.size()) == WALLET_ENDPOINT_BASE) {
        // wallet endpoint was used
        wallet_name = urlDecode(request.URI.substr(WALLET_ENDPOINT_BASE.size()));
        return true;
    }
    return false;
}