Insert hyphenation point in BibTeX using PDFLaTeX and hyperref

If you load package hyperref or package url LaTeX is able to find proper breaking points for an unmissleading hyphenation. As a result of this it often happen, that you get big white spaces in an justified text. It is not a good idea to insert in an url an additional - sign to mark a hyphenation. The reader does not know whether the - belongs to the url or is only a hyphenation sign. Urls are best hyphenated after a /, .etc.

I suggest to use package ragged2e and to use the command \raggedright to get a left justified bibliography. All the bibliographys I did this way looked very well!

Edit: I updated the MWE with a peace of code copied from this question and got the linebreak in the url in that way you want. But keep in mind: with this solution LaTeX decides were to break the url, not you with a special character.

Try this MWE:

\RequirePackage{filecontents}
\begin{filecontents*}{\jobname.bib}
@misc{reference,
    title = {{Some dummy title in bib.}},
    howpublished = {\url{http://docs.oracle.com/javase/1.5.0/docs/relnotes/features.html\#concurrency}},
    note = {Last access: 12.03.2013},
}
\end{filecontents*}

\documentclass[10pt,a4paper]{article}

\PassOptionsToPackage{hyphens}{url}
\usepackage{hyperref}

%https://tex.stackexchange.com/questions/3033/forcing-linebreaks-in-url?rq=1
\makeatletter
\g@addto@macro{\UrlBreaks}{\UrlOrds}
\g@addto@macro{\UrlNoBreaks}{\do\.} % do not break after dot '.'
\makeatother

\usepackage[%
  newcommands     % \RaggedRight=\raggedright etc. 
 ,newparameters   % use default settings of ragged2e
]{ragged2e}
\usepackage[margin=2.5cm]{geometry}

\begin{document}

This is text with \cite{reference}.

\bibliographystyle{unsrt}
{\raggedright  % group to end left justification after bib
\bibliography{\jobname}
}              % ends group for left justified bibliography

\end{document}

The solution in this answer already shows how to fine tune the line breaking of URL's by specifying \UrlBreaks, \UrlBigBreaks, and \UrlNoBreaks.

To get a carriage return symbol at breaking points, we specify the breaking points as \UrlSpecials, that include the symbol when a line break occurs there.

\usepackage{dingbat}  % for \carriagereturn symbol
\newcommand{\urllb}{\discretionary{\carriagereturn}{}{}}
\renewcommand{\UrlBreaks}{}    % no standard breaking points
\renewcommand{\UrlBigBreaks}{}
\renewcommand{\UrlSpecials}{\do\.{\mathchar`\.\urllb}%
                            \do\/{\mathchar`\/\urllb}%
                            \do\@{\mathchar`\@\urllb}%
                            \do\\{\mathchar`\\\urllb}%
                            \do\-{\mathchar`\-\urllb}%
                            \do\#{\mathchar`\#\urllb}}% and so on

To specify breaking points by hand we use a symbol that hopefully won't occur in any URL like a star *, and make it a break URL's like the above symbols, but vanishing from the string:

\renewcommand{\UrlSpecials}{\do\*{\urllb}}

In order to have correct links with this solution the star needs to be filtered out from the link, too. We use the gorgeous solution of Qrrbrbirlbel:

\makeatletter
\def\strip@star#1*#2\@strip@star{%
    \expandafter\def\expandafter\strip@star@result\expandafter{\strip@star@result#1}%
    \if\relax\detokenize{#2}\relax\else
        \def\strip@star@temp{#2}%
        \expandafter\expandafter\expandafter\strip@star\expandafter\strip@star@temp
        \expandafter\@strip@star
    \fi
}
\patchcmd{\hyper@linkurl}{\Hy@pstringdef\Hy@pstringURI{#2}}{%
    \def\strip@star@result{}%
    \expandafter\strip@star#2*\@strip@star
    \Hy@pstringdef\Hy@pstringURI{\strip@star@result}%
}{}{}
\makeatother

Of course, both solutions can be mixed, i.e., we can specify the normal breaking points as \UrlSpecials, as well as the star for additional hand made breaking points.

Complete code:

\RequirePackage{filecontents}
\begin{filecontents*}{\jobname.bib}
@misc{reference,
    title = {{Some dummy title in bib.}},
    howpublished = {\url{http://docs.*oracle.com/*javase/*1.5.0/*docs/*rel*notes/*fea*tures.html#*concur*rency}},
    note = {Last access: 12.03.2013},
}
\end{filecontents*}
\documentclass[10pt,a4paper]{article}

\PassOptionsToPackage{hyphens}{url}
\usepackage{hyperref}
\usepackage[margin=2.5cm]{geometry}

\usepackage{etoolbox}
\usepackage{dingbat}  % for \carriagereturn symbol
\newcommand{\urllb}{\discretionary{\carriagereturn}{}{}}
%% original breaking points of url package
% \def\UrlBreaks{\do\.\do\@\do\\\do\/\do\!\do\_\do\|\do\;\do\>\do\]%
%  \do\)\do\,\do\?\do\'\do+\do\=\do\#}%
% \def\UrlBigBreaks{\do\:\do@url@hyp}%

\makeatletter
\g@addto@macro{\UrlNoBreaks}{\do\.} % do not break after dot '.'
\makeatother

\renewcommand{\UrlBreaks}{}    % no standard breaking points
\renewcommand{\UrlBigBreaks}{}
\renewcommand{\UrlSpecials}{\do\_{\mathchar`\_\urllb}%
                            \do\/{\mathchar`\/\urllb}%
                            \do\@{\mathchar`\@\urllb}%
                            \do\\{\mathchar`\\\urllb}%
                            \do\-{\mathchar`\-\urllb}%
                            \do\#{\mathchar`\#\urllb}}% and so on
% \renewcommand{\UrlSpecials}{\do\*{\urllb}}

%% solution of Qrrbrbirlbel, see https://tex.stackexchange.com/q/103870/21591
\makeatletter
\def\strip@star#1*#2\@strip@star{%
    \expandafter\def\expandafter\strip@star@result\expandafter{\strip@star@result#1}%
    \if\relax\detokenize{#2}\relax\else
        \def\strip@star@temp{#2}%
        \expandafter\expandafter\expandafter\strip@star\expandafter\strip@star@temp
        \expandafter\@strip@star
    \fi
}
\patchcmd{\hyper@linkurl}{\Hy@pstringdef\Hy@pstringURI{#2}}{%
    \def\strip@star@result{}%
    \expandafter\strip@star#2*\@strip@star
    \Hy@pstringdef\Hy@pstringURI{\strip@star@result}%
}{}{}
\makeatother

\parindent0pt
\begin{document}
This is text with \cite{reference}.

Automatic breaking with carriage return symbol:

Text text text text text text text
\url{http://docs.oracle.com/javase/1.5.0/docs/relnotes/features.html#concurrency}

Text text text text text text text text
\url{http://docs.oracle.com/javase/1.5.0/docs/relnotes/features.html#concurrency}

Text text text text text text text text text
\url{http://docs.oracle.com/javase/1.5.0/docs/relnotes/features.html#concurrency}

Text text text text text text text text text text
\url{http://docs.oracle.com/javase/1.5.0/docs/relnotes/features.html#concurrency}

Text text text text text text text text text text text
\url{http://docs.oracle.com/javase/1.5.0/docs/relnotes/features.html#concurrency}

Text text text text text text text text text text text text
\url{http://docs.oracle.com/javase/1.5.0/docs/relnotes/features.html#concurrency}

\bigskip

\renewcommand{\UrlSpecials}{\do\*{\urllb}}
Hand tuned URL breaking:

Text text text text text text text text
\url{http://docs.*oracle.com/*javase/*1.5.0/*docs/*rel*notes/*fea*tures.html#concur*rency}

Text text text text text text text text text
\url{http://docs.*oracle.com/*javase/*1.5.0/*docs/*rel*notes/*fea*tures.html#concur*rency}

Text text text text text text text text text text
\url{http://docs.*oracle.com/*javase/*1.5.0/*docs/*rel*notes/*fea*tures.html#concur*rency}

Text text text text text text text text text text text
\url{http://docs.*oracle.com/*javase/*1.5.0/*docs/*rel*notes/*fea*tures.html#concur*rency}

Text text text text text text text text text text text text
\url{http://docs.*oracle.com/*javase/*1.5.0/*docs/*rel*notes/*fea*tures.html#concur*rency}

\bibliographystyle{unsrt}
\bibliography{faramir2}
\end{document}

yields

All hail to Qrrbrbirlbel for the hard part.