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

Former-commit-id: ed635ee95de7160cde11eaabc0c1dcb0e460a620

_examples/caddy/server2/main.go

@@ -0,0 +1,68 @@
+package main
+
+import (
+	"github.com/kataras/iris/v12"
+	"github.com/kataras/iris/v12/mvc"
+)
+
+type postValue func(string) string
+
+func main() {
+	app := iris.New()
+
+	mvc.New(app.Party("/user")).Register(
+		func(ctx iris.Context) postValue {
+			return ctx.PostValue
+		}).Handle(new(UserController))
+
+	// GET http://localhost:9092/user
+	// GET http://localhost:9092/user/42
+	// POST http://localhost:9092/user
+	// PUT http://localhost:9092/user/42
+	// DELETE http://localhost:9092/user/42
+	// GET http://localhost:9092/user/followers/42
+	app.Listen(":9092")
+}
+
+// UserController is our user example controller.
+type UserController struct{}
+
+// Get handles GET /user
+func (c *UserController) Get() string {
+	return "Select all users"
+}
+
+// User is our test User model, nothing tremendous here.
+type User struct{ ID int64 }
+
+// GetBy handles GET /user/42, equal to .Get("/user/{id:int64}")
+func (c *UserController) GetBy(id int64) User {
+	// Select User by ID == $id.
+	return User{id}
+}
+
+// Post handles POST /user
+func (c *UserController) Post(post postValue) string {
+	username := post("username")
+	return "Create by user with username: " + username
+}
+
+// PutBy handles PUT /user/42
+func (c *UserController) PutBy(id int) string {
+	// Update user by ID == $id
+	return "User updated"
+}
+
+// DeleteBy handles DELETE /user/42
+func (c *UserController) DeleteBy(id int) bool {
+	// Delete user by ID == %id
+	//
+	// when boolean then true = iris.StatusOK, false = iris.StatusNotFound
+	return true
+}
+
+// GetFollowersBy handles GET /user/followers/42
+func (c *UserController) GetFollowersBy(id int) []User {
+	// Select all followers by user ID == $id
+	return []User{ /* ... */ }
+}