Delphi下WebBrowser应用示例

待我称王封你为后i 2021-11-02 13:52 476阅读 0赞

以下是示范如何读取及提交TWebBrowser中的网页

示例内容:

*  获得网页中表单(form)的数量
 *  按编号从页面中获取表单
 *  按编号得到表单的名称
 *  按名称提取表单
 *  获取表单中所有字段的名称
 *  获取表单中指定名称的字段的值
 *  设置表单中指定名称的字段的值
 *  提交表单
 *  [其它演示][Link 1]

以下的示例假设TWebBrowser被命名为WebBrowser而且网页被已经打开.

--------------------

#### 获得网页中表单(form)的数量 ####

>     function NumberOfForms(document: IHTMLDocument2): integer;
>     var
>       forms: IHTMLElementCollection;
>     begin
>       forms := document.Forms as IHTMLElementCollection;
>       result := forms.Length;
>     end;

--------------------

#### 按编号从页面中获取表单 ####

网页中可能会有多个表单,表单的编号从零开始

>     function GetFormByNumber(document: IHTMLDocument2;
>         formNumber: integer): IHTMLFormElement;
>     var
>       forms: IHTMLElementCollection;
>     begin
>       forms := document.Forms as IHTMLElementCollection;
>       if formNumber < forms.Length then
>         result := forms.Item(formNumber,'') as IHTMLFormElement
>       else
>         result := nil;
>     end;

--------------------

#### 按编号得到表单的名称 ####

>     var
>       firstForm: IHTMLFormElement;
>       document: IHTMLDocument2;
>     begin
>       document := WebBrowser.Document as IHTMLDocument2;
>       firstForm := GetFormByNumber(document,0);
>       if Assigned(firstForm) then
>         ShowMessage('这个表单的名称是' + firstForm.Name)
>       else
>         ShowMessage(这个页面不包含任何表单');

--------------------

#### 按名称提取表单 ####

如果知道表单的名称就可以直接按名称提取表单

>     function GetFormByName(document: IHTMLDocument2;
>         const formName: string): IHTMLFormElement;
>     var
>       forms: IHTMLElementCollection;
>     begin
>       forms := document.Forms as IHTMLElementCollection;
>       result := forms.Item(formName,'') as IHTMLFormElement
>     end;

如果网页中不包含表单则返回nil

--------------------

#### 获取表单中所有字段的名称 ####

>     function GetFormFieldNames(fromForm: IHTMLFormElement): TStringList;
>     var
>       index: integer;
>       field: IHTMLElement;
>       input: IHTMLInputElement;
>       select: IHTMLSelectElement;
>       text: IHTMLTextAreaElement;
>     begin
>       result := TStringList.Create;
>       for index := 0 to fromForm.length do
>       begin
>         field := fromForm.Item(index,'') as IHTMLElement;
>         if Assigned(field) then
>         begin
>           if field.tagName = 'INPUT' then
>           begin
>             // Input field.
>             input := field as IHTMLInputElement;
>             result.Add(input.name);
>           end
>           else if field.tagName = 'SELECT' then
>           begin
>             // Select field.
>             select := field as IHTMLSelectElement;
>             result.Add(select.name);
>           end
>           else if field.tagName = 'TEXTAREA' then
>           begin
>             // TextArea field.
>             text := field as IHTMLTextAreaElement;
>             result.Add(text.name);
>           end;
>         end;
>       end;
>     end;

应用:

>     procedure TMyForm.Button1Click(Sender: TObject);
>     var
>       document: IHTMLDocument2;
>       theForm: IHTMLFormElement;
>       index: integer;
>     begin
>       document := TWebBrowser.Document as IHTMLDocument2;
>       theForm := GetFormByNumber(WebBrowser.Document as IHTMLDocument2,0);
>       fields := GetFormFieldNames(theForm);
>     
>       for index := 0 to fields.count-1 do
>         ShowMessage('Field ' + IntToStr(index) + ' called ' + fields[index]);
>     end;

--------------------

#### 获取表单中指定名称的字段的值 ####

>     function GetFieldValue(fromForm: IHTMLFormElement;
>       const fieldName: string): string;
>     var
>       field: IHTMLElement;
>       inputField: IHTMLInputElement;
>       selectField: IHTMLSelectElement;
>       textField: IHTMLTextAreaElement;
>     begin
>       field := fromForm.Item(fieldName,'') as IHTMLElement;
>       if not Assigned(field) then
>         result := ''
>       else if field.tagName = 'INPUT' then
>       begin
>         inputField := field as IHTMLInputElement;
>         if (inputField.type_ <> 'radio') and
>            (inputField.type_ <> 'checkbox')
>         then
>           result := inputField.value
>         else if inputField.checked then
>           result := 'checked'
>         else
>           result := 'unchecked';
>       end
>       else if field.tagName = 'SELECT' then
>       begin
>         selectField := field as IHTMLSelectElement;
>         result := selectField.value
>       end
>       else if field.tagName = 'TEXTAREA' then
>         begin
>         textField := field as IHTMLTextAreaElement;
>         result := textField.value;
>       end;
>     end;

应用:

> `procedure TMyForm.Button1Click(Sender: TObject); var   document: IHTMLDocument2;   theForm: IHTMLFormElement;   index: integer; begin   document := TWebBrowser.Document as IHTMLDocument2;   theForm := GetFormByNumber(WebBrowser.Document as IHTMLDocument2,0);   ShowMessage('Field "name" has value ' + GetFieldValue(theForm,'name'));`

"GetFieldValue" 函数在猎取字段值之前先判断该字段的类型,如果已知字段类型,该函数可以被简化,

举例说如果你确定字段是一个input字段,

> `function GetInputField(fromForm: IHTMLFormElement;   const inputName: string;   const instance: integer=0): HTMLInputElement; var   field: IHTMLElement; begin   field := fromForm.Item(inputName,instance) as IHTMLElement;   if Assigned(field) then   begin     if field.tagName = 'INPUT' then     begin       result := field as HTMLInputElement;       exit;     end;   end;   result := nil; end;`

--------------------

#### 设置表单中指定名称的字段的值 ####

>     procedure SetFieldValue(theForm: IHTMLFormElement;
>       const fieldName: string; const newValue: string;
>       const instance: integer=0);
>     var
>       field: IHTMLElement;
>       inputField: IHTMLInputElement;
>       selectField: IHTMLSelectElement;
>       textField: IHTMLTextAreaElement;
>     begin
>       field := theForm.Item(fieldName,instance) as IHTMLElement;
>       if Assigned(field) then
>       begin
>         if field.tagName = 'INPUT' then
>         begin
>           inputField := field as IHTMLInputElement;
>           if (inputField.type_ <> 'radio') and
>              (inputField.type_ <> 'checkbox')
>           then
>             inputField.value := newValue
>           else
>             inputField.checked := (newValue = 'checked');
>         end
>         else if field.tagName = 'SELECT' then
>         begin
>           selectField := field as IHTMLSelectElement;
>           selectField.value := newValue;
>         end
>         else if field.tagName = 'TEXTAREA' then
>         begin
>           textField := field as IHTMLTextAreaElement;
>           textField.value := newValue;
>         end;
>       end;
>     end;

应用:

--------------------

#### 提交表单 ####

最后一件事就是向服务器提交表单:

>     procedure TMyForm.Button1Click(Sender: TObject);
>     var
>       document: IHTMLDocument2;
>       theForm: IHTMLFormElement;
>       index: integer;
>     begin
>       document := TWebBrowser.Document as IHTMLDocument2;
>       theForm := GetFormByNumber(document,0);
>       SetFieldValue(theForm,'name','Brian Cryer');
>       theForm.submit;

转载于:https://www.cnblogs.com/karinthy/archive/2011/10/25/2224187.html

[Link 1]: http://cnbook.fw.hu