diff --git a/container/gtree/gtree_z_example_avltree_test.go b/container/gtree/gtree_z_example_avltree_test.go
index f96f52a07..f14a3361a 100644
--- a/container/gtree/gtree_z_example_avltree_test.go
+++ b/container/gtree/gtree_z_example_avltree_test.go
@@ -5,3 +5,737 @@
 // You can obtain one at https://github.com/gogf/gf.
 
 package gtree_test
+
+import (
+	"fmt"
+	"github.com/gogf/gf/v2/container/gtree"
+	"github.com/gogf/gf/v2/internal/json"
+	"github.com/gogf/gf/v2/util/gconv"
+	"github.com/gogf/gf/v2/util/gutil"
+)
+
+func ExampleAVLTree_Clone() {
+	avl := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		avl.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	tree := avl.Clone()
+
+	fmt.Println(tree.Map())
+	fmt.Println(tree.Size())
+
+	// Output:
+	// map[key0:val0 key1:val1 key2:val2 key3:val3 key4:val4 key5:val5]
+	// 6
+}
+
+func ExampleAVLTree_Set() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.Map())
+	fmt.Println(tree.Size())
+
+	// Output:
+	// map[key0:val0 key1:val1 key2:val2 key3:val3 key4:val4 key5:val5]
+	// 6
+}
+
+func ExampleAVLTree_Sets() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+
+	tree.Sets(map[interface{}]interface{}{
+		"key1": "val1",
+		"key2": "val2",
+	})
+
+	fmt.Println(tree.Map())
+	fmt.Println(tree.Size())
+
+	// Output:
+	// map[key1:val1 key2:val2]
+	// 2
+}
+
+func ExampleAVLTree_Get() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.Get("key1"))
+	fmt.Println(tree.Get("key10"))
+
+	// Output:
+	// val1
+	// <nil>
+}
+
+func ExampleAVLTree_GetOrSet() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.GetOrSet("key1", "newVal1"))
+	fmt.Println(tree.GetOrSet("key6", "val6"))
+
+	// Output:
+	// val1
+	// val6
+}
+
+func ExampleAVLTree_GetOrSetFunc() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.GetOrSetFunc("key1", func() interface{} {
+		return "newVal1"
+	}))
+	fmt.Println(tree.GetOrSetFunc("key6", func() interface{} {
+		return "val6"
+	}))
+
+	// Output:
+	// val1
+	// val6
+}
+
+func ExampleAVLTree_GetOrSetFuncLock() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.GetOrSetFuncLock("key1", func() interface{} {
+		return "newVal1"
+	}))
+	fmt.Println(tree.GetOrSetFuncLock("key6", func() interface{} {
+		return "val6"
+	}))
+
+	// Output:
+	// val1
+	// val6
+}
+
+func ExampleAVLTree_GetVar() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.GetVar("key1").String())
+
+	// Output:
+	// val1
+}
+
+func ExampleAVLTree_GetVarOrSet() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.GetVarOrSet("key1", "newVal1"))
+	fmt.Println(tree.GetVarOrSet("key6", "val6"))
+
+	// Output:
+	// val1
+	// val6
+}
+
+func ExampleAVLTree_GetVarOrSetFunc() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.GetVarOrSetFunc("key1", func() interface{} {
+		return "newVal1"
+	}))
+	fmt.Println(tree.GetVarOrSetFunc("key6", func() interface{} {
+		return "val6"
+	}))
+
+	// Output:
+	// val1
+	// val6
+}
+
+func ExampleAVLTree_GetVarOrSetFuncLock() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.GetVarOrSetFuncLock("key1", func() interface{} {
+		return "newVal1"
+	}))
+	fmt.Println(tree.GetVarOrSetFuncLock("key6", func() interface{} {
+		return "val6"
+	}))
+
+	// Output:
+	// val1
+	// val6
+}
+
+func ExampleAVLTree_SetIfNotExist() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.SetIfNotExist("key1", "newVal1"))
+	fmt.Println(tree.SetIfNotExist("key6", "val6"))
+
+	// Output:
+	// false
+	// true
+}
+
+func ExampleAVLTree_SetIfNotExistFunc() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.SetIfNotExistFunc("key1", func() interface{} {
+		return "newVal1"
+	}))
+	fmt.Println(tree.SetIfNotExistFunc("key6", func() interface{} {
+		return "val6"
+	}))
+
+	// Output:
+	// false
+	// true
+}
+
+func ExampleAVLTree_SetIfNotExistFuncLock() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.SetIfNotExistFuncLock("key1", func() interface{} {
+		return "newVal1"
+	}))
+	fmt.Println(tree.SetIfNotExistFuncLock("key6", func() interface{} {
+		return "val6"
+	}))
+
+	// Output:
+	// false
+	// true
+}
+
+func ExampleAVLTree_Contains() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.Contains("key1"))
+	fmt.Println(tree.Contains("key6"))
+
+	// Output:
+	// true
+	// false
+}
+
+func ExampleAVLTree_Remove() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.Remove("key1"))
+	fmt.Println(tree.Remove("key6"))
+	fmt.Println(tree.Map())
+
+	// Output:
+	// val1
+	// <nil>
+	// map[key0:val0 key2:val2 key3:val3 key4:val4 key5:val5]
+}
+
+func ExampleAVLTree_Removes() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	removeKeys := make([]interface{}, 2)
+	removeKeys = append(removeKeys, "key1")
+	removeKeys = append(removeKeys, "key6")
+
+	tree.Removes(removeKeys)
+
+	fmt.Println(tree.Map())
+
+	// Output:
+	// map[key0:val0 key2:val2 key3:val3 key4:val4 key5:val5]
+}
+
+func ExampleAVLTree_IsEmpty() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+
+	fmt.Println(tree.IsEmpty())
+
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.IsEmpty())
+
+	// Output:
+	// true
+	// false
+}
+
+func ExampleAVLTree_Size() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+
+	fmt.Println(tree.Size())
+
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.Size())
+
+	// Output:
+	// 0
+	// 6
+}
+
+func ExampleAVLTree_Keys() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 6; i > 0; i-- {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.Keys())
+
+	// Output:
+	// [key1 key2 key3 key4 key5 key6]
+}
+
+func ExampleAVLTree_Values() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 6; i > 0; i-- {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.Values())
+
+	// Output:
+	// [val1 val2 val3 val4 val5 val6]
+}
+
+func ExampleAVLTree_Map() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.Map())
+
+	// Output:
+	// map[key0:val0 key1:val1 key2:val2 key3:val3 key4:val4 key5:val5]
+}
+
+func ExampleAVLTree_MapStrAny() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set(1000+i, "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.MapStrAny())
+
+	// Output:
+	// map[1000:val0 1001:val1 1002:val2 1003:val3 1004:val4 1005:val5]
+}
+
+func ExampleAVLTree_Flip() {
+	tree := gtree.NewAVLTree(gutil.ComparatorInt)
+	for i := 1; i < 6; i++ {
+		tree.Set(i, i*10)
+	}
+
+	fmt.Println("Before Flip", tree.Map())
+
+	tree.Flip()
+
+	fmt.Println("After Flip", tree.Map())
+
+	// Output:
+	// Before Flip map[1:10 2:20 3:30 4:40 5:50]
+	// After Flip map[10:1 20:2 30:3 40:4 50:5]
+}
+
+func ExampleAVLTree_Clear() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set(1000+i, "val"+gconv.String(i))
+	}
+	fmt.Println(tree.Size())
+
+	tree.Clear()
+	fmt.Println(tree.Size())
+
+	// Output:
+	// 6
+	// 0
+}
+
+func ExampleAVLTree_Replace() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.Map())
+
+	data := map[interface{}]interface{}{
+		"newKey0": "newVal0",
+		"newKey1": "newVal1",
+		"newKey2": "newVal2",
+	}
+
+	tree.Replace(data)
+
+	fmt.Println(tree.Map())
+
+	// Output:
+	// map[key0:val0 key1:val1 key2:val2 key3:val3 key4:val4 key5:val5]
+	// map[newKey0:newVal0 newKey1:newVal1 newKey2:newVal2]
+}
+
+func ExampleAVLTree_Left() {
+	tree := gtree.NewAVLTree(gutil.ComparatorInt)
+	for i := 1; i < 100; i++ {
+		tree.Set(i, i)
+	}
+	fmt.Println(tree.Left().Key, tree.Left().Value)
+
+	emptyTree := gtree.NewAVLTree(gutil.ComparatorInt)
+	fmt.Println(emptyTree.Left())
+
+	// Output:
+	// 1 1
+	// <nil>
+}
+
+func ExampleAVLTree_Right() {
+	tree := gtree.NewAVLTree(gutil.ComparatorInt)
+	for i := 1; i < 100; i++ {
+		tree.Set(i, i)
+	}
+	fmt.Println(tree.Right().Key, tree.Right().Value)
+
+	emptyTree := gtree.NewAVLTree(gutil.ComparatorInt)
+	fmt.Println(emptyTree.Left())
+
+	// Output:
+	// 99 99
+	// <nil>
+}
+
+func ExampleAVLTree_Floor() {
+	tree := gtree.NewAVLTree(gutil.ComparatorInt)
+	for i := 1; i < 100; i++ {
+		if i != 50 {
+			tree.Set(i, i)
+		}
+	}
+
+	node, found := tree.Floor(95)
+	if found {
+		fmt.Println("Floor 95:", node.Key)
+	}
+
+	node, found = tree.Floor(50)
+	if found {
+		fmt.Println("Floor 50:", node.Key)
+	}
+
+	node, found = tree.Floor(100)
+	if found {
+		fmt.Println("Floor 100:", node.Key)
+	}
+
+	node, found = tree.Floor(0)
+	if found {
+		fmt.Println("Floor 0:", node.Key)
+	}
+
+	// Output:
+	// Floor 95: 95
+	// Floor 50: 49
+	// Floor 100: 99
+}
+
+func ExampleAVLTree_Ceiling() {
+	tree := gtree.NewAVLTree(gutil.ComparatorInt)
+	for i := 1; i < 100; i++ {
+		if i != 50 {
+			tree.Set(i, i)
+		}
+	}
+
+	node, found := tree.Ceiling(1)
+	if found {
+		fmt.Println("Ceiling 1:", node.Key)
+	}
+
+	node, found = tree.Ceiling(50)
+	if found {
+		fmt.Println("Ceiling 50:", node.Key)
+	}
+
+	node, found = tree.Ceiling(100)
+	if found {
+		fmt.Println("Ceiling 100:", node.Key)
+	}
+
+	node, found = tree.Ceiling(-1)
+	if found {
+		fmt.Println("Ceiling -1:", node.Key)
+	}
+
+	// Output:
+	// Ceiling 1: 1
+	// Ceiling 50: 51
+	// Ceiling -1: 1
+}
+
+func ExampleAVLTree_String() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.String())
+
+	// May Output:
+	// │       ┌── key5
+	// │   ┌── key4
+	// └── key3
+	//     │   ┌── key2
+	//     └── key1
+	//         └── key0
+}
+
+func ExampleAVLTree_Search() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	fmt.Println(tree.Search("key0"))
+	fmt.Println(tree.Search("key6"))
+
+	// Output:
+	// val0 true
+	// <nil> false
+}
+
+func ExampleAVLTree_Print() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	tree.Print()
+
+	// May Output:
+	// │       ┌── key5
+	// │   ┌── key4
+	// └── key3
+	//     │   ┌── key2
+	//     └── key1
+	//         └── key0
+}
+
+func ExampleAVLTree_Iterator() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 10; i++ {
+		tree.Set(i, 10-i)
+	}
+
+	var totalKey, totalValue int
+	tree.Iterator(func(key, value interface{}) bool {
+		totalKey += key.(int)
+		totalValue += value.(int)
+
+		return totalValue < 20
+	})
+
+	fmt.Println("totalKey:", totalKey)
+	fmt.Println("totalValue:", totalValue)
+
+	// Output:
+	// totalKey: 3
+	// totalValue: 27
+}
+
+func ExampleAVLTree_IteratorFrom() {
+	m := make(map[interface{}]interface{})
+	for i := 1; i <= 5; i++ {
+		m[i] = i * 10
+	}
+	tree := gtree.NewAVLTreeFrom(gutil.ComparatorInt, m)
+
+	tree.IteratorFrom(1, true, func(key, value interface{}) bool {
+		fmt.Println("key:", key, ", value:", value)
+		return true
+	})
+
+	// Output:
+	// key: 1 , value: 10
+	// key: 2 , value: 20
+	// key: 3 , value: 30
+	// key: 4 , value: 40
+	// key: 5 , value: 50
+}
+
+func ExampleAVLTree_IteratorAsc() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 10; i++ {
+		tree.Set(i, 10-i)
+	}
+
+	tree.IteratorAsc(func(key, value interface{}) bool {
+		fmt.Println("key:", key, ", value:", value)
+		return true
+	})
+
+	// Output:
+	// key: 0 , value: 10
+	// key: 1 , value: 9
+	// key: 2 , value: 8
+	// key: 3 , value: 7
+	// key: 4 , value: 6
+	// key: 5 , value: 5
+	// key: 6 , value: 4
+	// key: 7 , value: 3
+	// key: 8 , value: 2
+	// key: 9 , value: 1
+}
+
+func ExampleAVLTree_IteratorAscFrom_normal() {
+	m := make(map[interface{}]interface{})
+	for i := 1; i <= 5; i++ {
+		m[i] = i * 10
+	}
+	tree := gtree.NewAVLTreeFrom(gutil.ComparatorInt, m)
+
+	tree.IteratorAscFrom(1, true, func(key, value interface{}) bool {
+		fmt.Println("key:", key, ", value:", value)
+		return true
+	})
+
+	// Output:
+	// key: 1 , value: 10
+	// key: 2 , value: 20
+	// key: 3 , value: 30
+	// key: 4 , value: 40
+	// key: 5 , value: 50
+}
+
+func ExampleAVLTree_IteratorAscFrom_noExistKey() {
+	m := make(map[interface{}]interface{})
+	for i := 1; i <= 5; i++ {
+		m[i] = i * 10
+	}
+	tree := gtree.NewAVLTreeFrom(gutil.ComparatorInt, m)
+
+	tree.IteratorAscFrom(0, true, func(key, value interface{}) bool {
+		fmt.Println("key:", key, ", value:", value)
+		return true
+	})
+
+	// Output:
+}
+
+func ExampleAVLTree_IteratorAscFrom_noExistKeyAndMatchFalse() {
+	m := make(map[interface{}]interface{})
+	for i := 1; i <= 5; i++ {
+		m[i] = i * 10
+	}
+	tree := gtree.NewAVLTreeFrom(gutil.ComparatorInt, m)
+
+	tree.IteratorAscFrom(6, false, func(key, value interface{}) bool {
+		fmt.Println("key:", key, ", value:", value)
+		return true
+	})
+
+	// Output:
+}
+
+func ExampleAVLTree_IteratorDesc() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 10; i++ {
+		tree.Set(i, 10-i)
+	}
+
+	tree.IteratorDesc(func(key, value interface{}) bool {
+		fmt.Println("key:", key, ", value:", value)
+		return true
+	})
+
+	// Output:
+	// key: 9 , value: 1
+	// key: 8 , value: 2
+	// key: 7 , value: 3
+	// key: 6 , value: 4
+	// key: 5 , value: 5
+	// key: 4 , value: 6
+	// key: 3 , value: 7
+	// key: 2 , value: 8
+	// key: 1 , value: 9
+	// key: 0 , value: 10
+}
+
+func ExampleAVLTree_IteratorDescFrom() {
+	m := make(map[interface{}]interface{})
+	for i := 1; i <= 5; i++ {
+		m[i] = i * 10
+	}
+	tree := gtree.NewAVLTreeFrom(gutil.ComparatorInt, m)
+
+	tree.IteratorDescFrom(5, true, func(key, value interface{}) bool {
+		fmt.Println("key:", key, ", value:", value)
+		return true
+	})
+
+	// Output:
+	// key: 5 , value: 50
+	// key: 4 , value: 40
+	// key: 3 , value: 30
+	// key: 2 , value: 20
+	// key: 1 , value: 10
+}
+
+func ExampleAVLTree_MarshalJSON() {
+	tree := gtree.NewAVLTree(gutil.ComparatorString)
+	for i := 0; i < 6; i++ {
+		tree.Set("key"+gconv.String(i), "val"+gconv.String(i))
+	}
+
+	bytes, err := json.Marshal(tree)
+	if err == nil {
+		fmt.Println(gconv.String(bytes))
+	}
+
+	// Output:
+	// {"key0":"val0","key1":"val1","key2":"val2","key3":"val3","key4":"val4","key5":"val5"}
+}