利用svg绘制铁路线

<?xml version="1.0"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.0//EN"
"http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd">
<svg width="800" height="300" >
<defs>
<symbol id="sym">
<polyline points="100 100 250 90 400 80 500 90 550 100 600 110"/>
</symbol>
</defs>
<g >
<use xlink:href="#sym" style="fill:none;stroke:black;stroke-width:20"/>
<use xlink:href="#sym" style="fill:none;stroke:white;stroke-width:18;
stroke-dasharray:50 50;stroke-dashoffset :50"/>
</g>
</svg>