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Delphi下WebBrowser应用示例

2011-10-25 17:27 176 查看
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
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:


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);

  SetFieldValue(theForm,'name','Brian Cryer');




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;
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