这是python书中的一个例子。当我运行它时，我没有得到任何输出。有人能帮我吗？感谢!!!
from urllib import urlopen
from BeautifulSoup import BeautifulSoup
text = urlopen('https://python.org/community/jobs').read()
soup = BeautifulSoup(text)
jobs = set()
for header in soup('h3'):
links = header('a', 'reference')
if not links: continue
link = links[0]
jobs.add('%s (%s)' % (link.string, link['href']))
print jobs.add('%s (%s)' % (link.string, link['href']))
print '\n'.join(sorted(jobs, key=lambda s: s.lower()))
reedit-- 首先，我只考虑了网址是错误的，但忽略了我想要得到的HTML信息不存在。可能这就是为什么我得到空输出。
答案 0 :(得分：1)
如果您打开页面并检查html，您会注意到没有包含链接的import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotEquals;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.Random;
import org.junit.Test;
/**
*
* @author Tristan Everitt
*/
public class AlphaNumericStringComparatorTester
{
@Test
public void testHumanNaturalSort1()
{
List<String> randomList = Arrays.asList("z1.doc", "z10.doc", "z100.doc", "z101.doc", "z102.doc", "z11.doc", "z12.doc", "z13.doc", "z14.doc", "z15.doc", "z16.doc", "z17.doc", "z18.doc",
"z19.doc", "z2.doc", "z20.doc", "z3.doc", "z4.doc", "z5.doc", "z6.doc", "z7.doc", "z8.doc", "z9.doc", "z1.2.doc", "z1.3.doc");
Collections.shuffle(randomList, new Random());
List<String> expected = Arrays.asList("z1.doc", "z1.2.doc", "z1.3.doc", "z2.doc", "z3.doc", "z4.doc", "z5.doc", "z6.doc", "z7.doc", "z8.doc", "z9.doc", "z10.doc", "z11.doc", "z12.doc",
"z13.doc", "z14.doc", "z15.doc", "z16.doc", "z17.doc", "z18.doc", "z19.doc", "z20.doc", "z100.doc", "z101.doc", "z102.doc");
assertNotEquals(expected, randomList);
Collections.sort(randomList, new AlphaNumericStringComparator());
assertEquals(expected, randomList);
}
@Test
public void testHumanNaturalSort2()
{
List<String> randomList = Arrays.asList("z1.doc", "z10.doc", "z100.doc", "z101.doc", "z102.doc", "z11.doc", "z12.doc", "z13.doc", "z14.doc", "z15.doc", "z16.doc", "z17.doc", "z18.doc",
"z19.doc", "z2.doc", "z20.doc", "z3.doc", "z4.doc", "z5.doc", "z6.doc", "z7.doc", "z8.doc", "z9.doc", "z1.2.doc", "z1.3.doc");
Collections.shuffle(randomList, new Random());
List<String> expected = Arrays.asList("z1.doc", "z1.2.doc", "z1.3.doc", "z2.doc", "z3.doc", "z4.doc", "z5.doc", "z6.doc", "z7.doc", "z8.doc", "z9.doc", "z10.doc", "z11.doc", "z12.doc",
"z13.doc", "z14.doc", "z15.doc", "z16.doc", "z17.doc", "z18.doc", "z19.doc", "z20.doc", "z100.doc", "z101.doc", "z102.doc");
assertNotEquals(expected, randomList);
Collections.sort(randomList, new AlphaNumericStringComparator());
assertEquals(expected, randomList);
}
@Test
public void testHumanNaturalSort3()
{
List<String> randomList = Arrays.asList("yr1", "yr10", "yr11", "yr12", "yr13", "yr2", "yr 3", "yr 3.4", "yr 4", "yr5", "yr6", "yr7", "yr8", "yr 9");
Collections.shuffle(randomList, new Random());
List<String> expected = Arrays.asList("yr1", "yr2", "yr 3", "yr 3.4", "yr 4", "yr5", "yr6", "yr7", "yr8", "yr 9", "yr10", "yr11", "yr12", "yr13");
assertNotEquals(expected, randomList);
Collections.sort(randomList, new AlphaNumericStringComparator());
assertEquals(expected, randomList);
}
@Test
public void testHumanNaturalSort4()
{
List<String> randomList = Arrays.asList("1-2", "1-02", "1-20", "10-20", "fred", "jane", "pic01", "pic2", "pic02", "pic02a", "pic3", "pic4", "pic 4 else", "pic 5", "pic05", "pic 5",
"pic 5 something", "pic 6", "pic 7", "pic100", "pic100a", "pic120", "pic121", "pic02000", "tom", "x2-g8", "x2-y7", "x2-y08", "x8-y8");
Collections.shuffle(randomList, new Random());
List<String> expected = Arrays.asList("1-2", "1-02", "1-20", "10-20", "fred", "jane", "pic01", "pic02", "pic2", "pic02a", "pic3", "pic4", "pic 4 else", "pic 5", "pic05", "pic 5",
"pic 5 something", "pic 6", "pic 7", "pic100", "pic100a", "pic120", "pic121", "pic02000", "tom", "x2-g8", "x2-y7", "x2-y08", "x8-y8");
assertNotEquals(expected, randomList);
Collections.sort(randomList, new AlphaNumericStringComparator());
assertEquals(expected, randomList);
}
}
标签。这就是你没有输出的原因。
所以<h3>一直在继续。
这可能是因为该网页已移至https://www.python.org/jobs/，因此页面上包含链接的if not links: continue代码不再存在。
如果您将此代码的网址指向新网页。我建议花一些时间熟悉页面源代码。例如，它为其链接使用<h3>而不是<h2>标记。