有段html代码  <table border="0" cellpadding="5" cellspacing="0" width="100%" class="ms-listviewtable"><tr><th class="ms-vh2">No</th><th class="ms-vh2">Name</th><th class="ms-vh2">Description</th><th class="ms-vh2">File Revision</th><th class="ms-vh2">File Size</th></tr><tr><td class="ms-vb2">1</td><td class="ms-vb2"><a href="http://sharenet.hqcec.com/dms/default.aspx?link=pw%3A%5C%5Cpw-int-hqbj%3Apw%5CDocuments%5C5043E%5C(C)%3A%20Exchange%20Area%5C02.%20Engineering%5C03%20Water%20Process%5C0002-00-15-B-E-3-33-001_PB%5C0002-00-15-121-B-E-3-33-001_PB%20COVER.doc" target="_blank">0002-00-15-121-B-E-3-33-001_PB COVER.doc</a></td><td class="ms-vb2">0002-00-15-121-B-E-3-33-001_PB COVER</td><td class="ms-vb2"></td><td class="ms-vb2">180224</td></tr><tr><td class="ms-vb2">2</td><td class="ms-vb2"><a href="http://sharenet.hqcec.com/dms/default.aspx?link=pw%3A%5C%5Cpw-int-hqbj%3Apw%5CDocuments%5C5043E%5C(C)%3A%20Exchange%20Area%5C02.%20Engineering%5C03%20Water%20Process%5C0002-00-15-B-E-3-33-001_PB%5C0002-00-15-121-B-E-3-33-001_PB.xls" target="_blank">0002-00-15-121-B-E-3-33-001_PB.xls</a></td><td class="ms-vb2">0002-00-15-121-B-E-3-33-001_PB</td><td class="ms-vb2"></td><td class="ms-vb2">204800</td></tr></table>  想办法取出所有<a>标签求里的href的值，后台实现