dominicqi / autolink-java

Java library to extract links (URLs, email addresses) from plain text; fast, small and hopefully smart

autolink-java

Java library to extract links such as URLs and email addresses from plain text. Fast, small and tries to be smart with matching (text is hard).

Inspired by Rinku. Similar to it, regular expressions are not used. Instead, the input text is parsed in one pass with limited backtracking.

This library requires Java 7. It has no external dependencies. Maven coordinates (see here for other build systems):

<dependency>
    <groupId>org.nibor.autolink</groupId>
    <artifactId>autolink</artifactId>
    <version>0.4.0</version>
</dependency>

Usage

Extract links:

import org.nibor.autolink.*;

String input = "wow, so example: http://test.com";
LinkExtractor linkExtractor = LinkExtractor.builder().build();
Iterable<LinkSpan> links = linkExtractor.extractLinks(input);
LinkSpan link = links.iterator().next();
link.getType();        // LinkType.URL
link.getBeginIndex();  // 17
link.getEndIndex();    // 32
input.substring(link.getBeginIndex(), link.getEndIndex());  // "http://test.com"

Wrapping URLs in an tag (doesn't handle escaping, uses Java 8):

import org.nibor.autolink.*;

String input = "wow http://test.com such linked";
LinkExtractor linkExtractor = LinkExtractor.builder()
        .linkTypes(EnumSet.of(LinkType.URL)) // limit to URLs
        .build();
Iterable<LinkSpan> links = linkExtractor.extractLinks(input);
String result = Autolink.renderLinks(input, links, (link, text, sb) -> {
    sb.append("<a href=\"");
    sb.append(text, link.getBeginIndex(), link.getEndIndex());
    sb.append("\">");
    sb.append(text, link.getBeginIndex(), link.getEndIndex());
    sb.append("</a>");
});
result;  // "wow <a href=\"http://test.com\">http://test.com</a> such linked"

Features

URL extraction

Extracts URLs of the form scheme://example with any scheme. URIs such as example:test are not matched (may be added as an option in the future). If only certain schemes should be allowed, the result can be filtered.

Includes heuristics for not including trailing delimiters such as punctuation and unbalanced parentheses, see examples below.

Supports internationalized domain names (IDN). Note that they are not validated and as a result, invalid URLs may be matched.

Example input and linked result:

• http://example.com. → http://example.com.
• http://example.com, → http://example.com,
• (http://example.com) → (http://example.com)
• (... (see http://example.com)) → (... (see http://example.com))
• https://en.wikipedia.org/wiki/Link_(The_Legend_of_Zelda) → https://en.wikipedia.org/wiki/Link_(The_Legend_of_Zelda)
• http://üñîçøðé.com/ → http://üñîçøðé.com/

Also see test cases.

Email address extraction

Extracts emails such as [email protected]. Matches international email addresses, but doesn't verify the domain name (may match too much).

Examples:

• [email protected] → [email protected]
• [email protected]. → [email protected].
• [email protected], → [email protected],
• üñîçøðé@üñîçøðé.com → üñîçøðé@üñîçøðé.com

Not supported:

• Quoted local parts, e.g. "this is sparta"@example.com
• Address literals, e.g. foo@[127.0.0.1]

Note that the domain must have at least one dot (e.g. foo@com isn't matched), unless the emailDomainMustHaveDot option is disabled.

Also see test cases.

Contributing

Pull requests, issues and comments welcome ☺. For pull requests:

• Add tests for new features and bug fixes
• Follow the existing style (always use braces, 4 space indent)
• Separate unrelated changes into multiple pull requests

License

Copyright (c) 2015-2016 Robin Stocker

MIT licensed, see LICENSE file.