reorganization of _examples and add some new examples such as iris+groupcache+mysql+docker

Former-commit-id: ed635ee95de7160cde11eaabc0c1dcb0e460a620

_examples/routing/subdomains/single/hosts

@@ -0,0 +1,27 @@
+# Copyright (c) 1993-2009 Microsoft Corp.
+#
+# This is a sample HOSTS file used by Microsoft TCP/IP for Windows.
+#
+# This file contains the mappings of IP addresses to host names. Each
+# entry should be kept on an individual line. The IP address should
+# be placed in the first column followed by the corresponding host name.
+# The IP address and the host name should be separated by at least one
+# space.
+#
+# Additionally, comments (such as these) may be inserted on individual
+# lines or following the machine name denoted by a '#' symbol.
+#
+# For example:
+#
+#      102.54.94.97     rhino.acme.com          # source server
+#       38.25.63.10     x.acme.com              # x client host
+
+# localhost name resolution is handled within DNS itself.
+127.0.0.1       localhost
+::1             localhost
+#-iris-For development machine, you have to configure your dns also for online, search google how to do it if you don't know
+
+127.0.0.1		mydomain.com
+127.0.0.1		admin.mydomain.com
+
+#-END iris-

_examples/routing/subdomains/single/main.go

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+// Package main register static subdomains, simple as parties, check ./hosts if you use windows
+package main
+
+import (
+	"github.com/kataras/iris/v12"
+)
+
+func main() {
+	app := iris.New()
+
+	// Subdomain method is just another Party.
+	admin := app.Subdomain("admin")
+	{
+		// admin.mydomain.com
+		admin.Get("/", func(c iris.Context) {
+			c.Writef("INDEX FROM admin.mydomain.com")
+		})
+		// admin.mydomain.com/hey
+		admin.Get("/hey", func(c iris.Context) {
+			c.Writef("HEY FROM admin.mydomain.com/hey")
+		})
+		// admin.mydomain.com/hey2
+		admin.Get("/hey2", func(c iris.Context) {
+			c.Writef("HEY SECOND FROM admin.mydomain.com/hey")
+		})
+	}
+
+	// mydomain.com
+	app.Get("/", func(c iris.Context) {
+		c.Writef("INDEX FROM no-subdomain hey")
+	})
+
+	// mydomain.com/hey
+	app.Get("/hey", func(c iris.Context) {
+		c.Writef("HEY FROM no-subdomain hey")
+	})
+
+	// http://admin.mydomain.com
+	// http://admin.mydomain.com/hey
+	// http://admin.mydomain.com/hey2
+	// http://mydomain.com
+	// http://mydomain.com/hey
+	app.Listen("mydomain.com:80") // for beginners: look ../hosts file
+}