转载,一个可以解析HTML中链接和图片URL的代码

博客给出了一个用于提取HTML标签值的函数ExtractHtmlTagValues,还包含多个辅助函数。通过循环查找HTML文本中的标签,处理标签内属性,提取指定属性值。并给出提取页面所有链接的示例,涉及HTML和ASP相关内容。

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function ExtractHtmlTagValues(const HtmlText: string; TagName, AttribName: string; var Values: TStrings): integer;

function FindFirstCharAfterSpace(const Line: string; StartPos: integer): Integer;
var i: integer;
begin
Result := -1;
for i := StartPos to Length(Line) do
begin
if (Line[i] <> ' ') then
begin
Result := i;
exit;
end;
end;
end;

function FindFirstSpaceAfterChars(const Line: string; StartPos: integer): Integer;
begin
Result := PosEx(' ', Line, StartPos);
end;

function FindFirstSpaceBeforeChars(const Line: string; StartPos: integer): Integer;
var i: integer;
begin
Result := 1;
for i := StartPos downto 1 do
begin
if (Line[i] = ' ') then
begin
Result := i;
exit;
end;
end;
end;

var InnerTag: string;
LastPos, LastInnerPos: Integer;
SPos, LPos, RPos: Integer;
AttribValue: string;
ClosingChar: char;
TempAttribName: string;
begin
Result := 0;
LastPos := 1;
while (true) do
begin
// find outer tags '<' & '>'
LPos := PosEx('<', HtmlText, LastPos);
if (LPos <= 0) then break;
RPos := PosEx('>', HtmlText, LPos+1);
if (RPos <= 0) then
LastPos := LPos + 1
else
LastPos := RPos + 1;

// get inner tag
InnerTag := Copy(HtmlText, LPos+1, RPos-LPos-1);
InnerTag := Trim(InnerTag); // remove spaces
if (Length(InnerTag) < Length(TagName)) then continue;

// check tag name
if (SameText(Copy(InnerTag, 1, Length(TagName)), TagName)) then
begin
// found tag
AttribValue := '';
LastInnerPos := Length(TagName)+1;
while (LastInnerPos < Length(InnerTag)) do
begin
// find first '=' after LastInnerPos
RPos := PosEx('=', InnerTag, LastInnerPos);
if (RPos <= 0) then break;

// this way you can check for multiple attrib names and not a specific attrib
SPos := FindFirstSpaceBeforeChars(InnerTag, RPos);
TempAttribName := Trim(Copy(InnerTag, SPos, RPos-SPos));
if (true) then
begin
// found correct tag
LPos := FindFirstCharAfterSpace(InnerTag, RPos+1);
if (LPos <= 0) then
begin
LastInnerPos := RPos + 1;
continue;
end;
LPos := FindFirstCharAfterSpace(InnerTag, LPos); // get to first char after '='
if (LPos <= 0) then continue;
if ((InnerTag[LPos] <> '"') and (InnerTag[LPos] <> '''')) then
begin
// AttribValue is not between '"' or ''' so get it
RPos := FindFirstSpaceAfterChars(InnerTag, LPos+1);
if (RPos <= 0) then
AttribValue := Copy(InnerTag, LPos, Length(InnerTag)-LPos+1)
else
AttribValue := Copy(InnerTag, LPos, RPos-LPos+1);
end
else
begin
// get url between '"' or '''
ClosingChar := InnerTag[LPos];
RPos := PosEx(ClosingChar, InnerTag, LPos+1);
if (RPos <= 0) then
AttribValue := Copy(InnerTag, LPos+1, Length(InnerTag)-LPos-1)
else
AttribValue := Copy(InnerTag, LPos+1, RPos-LPos-1)
end;

if (SameText(TempAttribName, AttribName)) and (AttribValue <> '') then
begin
Values.Add(AttribValue);
inc(Result);
end;
end;

if (RPos <= 0) then
LastInnerPos := Length(InnerTag)
else
LastInnerPos := RPos+1;
end;
end;
end;
end;





For eg. you want to extract all links in a page, just do:


var Links: TStrings;
begin
Links := TStrings.Create;
try
LinksFound := ExtractHtmlTagValues(HtmlText, 'A', 'HREF', Links);
Showmessage(Links.Text);
finally
Links.Free;
end;
end;

原始连接:
http://www.delphi3000.com/articles/article_4365.asp?SK=

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