写一个Python2.7的arcgis工具箱脚本：删除数据除Object ID，Shape 和 Shape_Length/Shape_Area 字段外的所有字段

下面是一个Python 2.7的ArcGIS工具箱脚本，它会删除除Object ID、Shape和Shape_Length/Shape_Area字段外的所有字段：

import arcpy

class Toolbox(object):
    def __init__(self):
        self.label = "Delete Extra Fields"
        self.alias = "Delete Extra Fields"

        # List of tool classes associated with this toolbox
        self.tools = [DeleteExtraFields]

class DeleteExtraFields(object):
    def __init__(self):
        self.label = "Delete Extra Fields"
        self.description = "Deletes all fields except for Object ID, Shape, and Shape_Length/Shape_Area."
        self.canRunInBackground = False

    def getParameterInfo(self):
        params = []

        # Input feature class parameter
        input_fc = arcpy.Parameter(
            name="input_fc",
            displayName="Input Feature Class",
            datatype="GPFeatureLayer",
            parameterType="Required",
            direction="Input")

        params.append(input_fc)

        return params

    def execute(self, parameters, messages):
        # Get the input feature class
        input_fc = parameters[0].valueAsText

        # Get a list of all the fields in the input feature class
        field_names = [field.name for field in arcpy.ListFields(input_fc)]

        # Loop through the fields and delete any fields that are not Object ID, Shape, or Shape_Length/Shape_Area
        for field_name in field_names:
            if not (field_name == "OBJECTID" or field_name == "SHAPE" or field_name == "SHAPE_Length" or field_name == "SHAPE_Area"):
                arcpy.DeleteField_management(input_fc, field_name)

        messages.addMessage("Extra fields deleted.")

        return

要使用此工具箱脚本，请按照以下步骤操作：

1. 在ArcGIS中创建一个新的工具箱。
2. 右键单击工具箱，并选择“添加脚本”。
3. 输入上面的代码，并保存脚本。
4. 在工具箱中，右键单击脚本，并选择“属性”。
5. 在“参数”选项卡上，添加一个“GPFeatureLayer”类型的参数，命名为“input_fc”。
6. 保存属性并关闭窗口。
7. 现在您可以在工具箱中使用此脚本。只需选择要处理的要素类，然后运行脚本即可删除所有除Object ID、Shape和Shape_Length/Shape_Area字段外的其他字段。