经常用到正则匹配小括号内容，在此摘录下来

String content = "src: local('Open Sans Light'), local('OpenSans-Light'), url(http://fonts.gstatic.com/s/opensans/v13/DXI1ORHCpsQm3Vp6mXoaTa-j2U0lmluP9RWlSytm3ho.woff2) format('woff2')";
// 从内容上截取路径数组
Pattern pattern = Pattern.compile("(?<=\\()[^\\)]+");  
Matcher matcher = pattern.matcher(content);
while(matcher.find()){System.out.println(matcher.group());
}

输出

'Open Sans Light'
'OpenSans-Light'
http://fonts.gstatic.com/s/opensans/v13/DXI1ORHCpsQm3Vp6mXoaTa-j2U0lmluP9RWlSytm3ho.woff2
'woff2'

还有一种情况是，我们只匹配url里面的内容，比如要匹配的字符串是

String content = "local('OpenSans-Light'),url(http://fonts.gstatic.com/s/opensans/v13/DXI1ORHCpsQm3Vp6mXoaTa-j2U0lmluP9RWlSytm3ho.woff2) format('woff2');unicode-range:U+0460-052F,U+20B4,U+2DE0-2DFF,U+A640-A69F;}@font-face{font-family:'Open Sans';font-style:normal;font-weight:300;src:local('Open Sans Light'),local('OpenSans-Light'),url(http://fonts.gstatic.com/s/opensans/v13/DXI1ORHCpsQm3Vp6mXoaTZX5f-9o1vgP2EXwfjgl7AY.woff2) format('woff2');unicode-range:U+0400-045F,U+0490-0491,U+04B0-04B1,U+2116;}@font-face{font-family:'Open Sans';font-style:normal;font-weight:300;src:local('Open Sans Light'),local('OpenSans-Light'),url(http://fonts.gstatic.com/s/opensans/v13/DXI1ORHCpsQm3Vp6mXoaTRWV49_lSm1NYrwo-zkhivY.woff2) format('woff2');unicode-range:U+1F00-1FFF;}@font-face{font-family:'Open Sans';font-style:normal;font-weight:300;src:local('Open Sans Light'),local('OpenSans-Light'),url(http://fonts.gstatic.com/s/opensans/v13/DXI1ORHCpsQm3Vp6mXoaTaaRobkAwv3vxw3jMhVENGA.woff2) format('woff2');";

然后将正则规则修改为

Pattern pattern = Pattern.compile("(?<=url\\()[^\\)]+"); 

这样就能匹配如下内容了

http://fonts.gstatic.com/s/opensans/v13/DXI1ORHCpsQm3Vp6mXoaTa-j2U0lmluP9RWlSytm3ho.woff2
http://fonts.gstatic.com/s/opensans/v13/DXI1ORHCpsQm3Vp6mXoaTZX5f-9o1vgP2EXwfjgl7AY.woff2
http://fonts.gstatic.com/s/opensans/v13/DXI1ORHCpsQm3Vp6mXoaTRWV49_lSm1NYrwo-zkhivY.woff2
http://fonts.gstatic.com/s/opensans/v13/DXI1ORHCpsQm3Vp6mXoaTaaRobkAwv3vxw3jMhVENGA.woff2

正则中使用了零宽度断言