有效沟通问答-【官方】百战程序员_IT在线教育培训机构

class XinchengRoomsSpider(scrapy.Spider):
    name = 'xincheng_rooms'
    allowed_domains = ['anjuke.com']
    start_urls = ['https://xa.anjuke.com/sale/xinchengqu/p{}/'.format(num) for num in range(1,11)]

    def parse(self, response):
        #new_url = re.search('href="(https://xa.anjuke.com/prop/view/.+)?.+"',response.text).group(0)
        new_url = response.xpath('//a[@class="houseListTitle"]/@href').extract()
        for url in new_url:
            yield scrapy.Request(url,callback=self.parse_info)

老师我这个是安居客的 new_url用xpath_helper都可以找到但是调试的时候返回的都是空

Python 全系列/第十四阶段：Python 爬虫开发/动态数据抓取 557楼

问题：老师用Oracle进行操作时，应该代码没有问题，因为插入操作能执行成功，但是遇到的问题是进行删除操作，console空值台什么也不显示，删除也失败了，再进行插入操作，此时插入操作也不成功，但console什么也不显示，（重启eclipse时，插入操作能够完成，但是一执行删除操作，则所有操作全不能进行了）这是什么原因？

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
public class JDBCDemo {
 private static final String URL= "jdbc:oracle:thin:@localhost:1521:ORCL";
 private static final String USERNAME ="BJSXT";
 private static final String PWD = "oracle"; 
 //实现增删改查
 public static void update() throws SQLException {
  Connection conn=null;
  Statement state=null;
  //a.导入驱动，加载具体的驱动类
  try {
   Class.forName("oracle.jdbc.OracleDriver");
   //b.与数据库进行连接
   conn = DriverManager.getConnection(URL,USERNAME,PWD);
   //发送sql,执行(增删改，查)
   state = conn.createStatement();
   //插入
   String sql="insert into T_USERS values(8,'WangYaXing',25)";
   
   //修改数据
   //String sql = "update T_USERS set name='李四' where id = 1;";
   
   //删除数据
  // String sql = "delete from T_USERS where name='WangYaXin'";
   
   //执行sql
   int count = state.executeUpdate(sql);
   //处理结果
   if(count>0) {
    System.out.println("操作成功！");
   }
   
  } catch (ClassNotFoundException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }catch(SQLException e) {
   e.printStackTrace();
  }finally {
   try {
    if(state!=null) {
     state.close(); //对象为空
    }
    if(conn!=null) {
     conn.close();
    }
    
   } catch (SQLException e) {
    // TODO: handle exception
    e.printStackTrace();
   }
  }
 }
 
 public static void main(String[] args) throws SQLException {
  update();
 }
}

JAVA 全系列/第三阶段：数据库编程/JDBC技术（旧） 558楼

这个p值是怎么算的？为什么等于0.012和0.01？

Python 全系列/第十七阶段：数据分析-数学知识（旧）/统计学基础 559楼

time
():
    ()

():
    ()

():
    (func):
        :
            f = ()
            f.write(func.)
            f.write()
            f.write(time.asctime())
            ()
            ()


        e:
            (e)

        :
            f.close()
        func()
    writeLogin
wi = writeLogout()
wi(f2)

老师，这种方法可以实现用闭包引入日志功能吗？和课程中的方法比有什么不妥的地方吗？麻烦老师了

Python 全系列/第四阶段：函数式编程和核心特性/生成器和装饰器 560楼

io 可以具体解释一下吗。。。。。。？

Python 全系列/第三阶段：Python 网络与并发编程/并发编程 561楼

疑问：

在11分12秒的时候，使用的是select count(distinct(ifnull(mgr,1))) from emp;进行对所有领导人数进行统计，但是说的是董事长为空，但当存在多个空值时，ifnull返回的都是1，distinct只会返回1个，这样count计数的时候还是1个，就是说多个空值最终只会当做是一个进行计算，我这样理解是对的吗？

Python 全系列/第五阶段：数据库编程/mysql的使用 562楼

老师，我这里点击登陆按钮，然后console下就会报错？

Python 全系列/第九阶段：Flask百战电商后台系统/Flask百战电商后台项目 563楼

老师请问下,newInstance只能调用无参数构造,但为什么可以这么创建对象

JAVA 全系列/第二阶段：JAVA 基础深化和提高/反射技术（旧） 564楼

为什么我这样子敲，b那行显示不出来呢

Python 全系列/第一阶段：Python入门/编程基本概念 565楼

一》怎么按照老师的代码写的，在写获取根元素的代码是不支持

JAVA 全系列/第二阶段：JAVA 基础深化和提高/手写服务器项目（旧） 566楼

老师我在测试dao层的时候这个StudentDao变量爆红，我试着启动测试程序的时候，出错了，

"C:\Program Files\Java\jdk1.8.0_321\bin\java.exe" -ea -Didea.test.cyclic.buffer.size=1048576 "-javaagent:F:\IntelliJ IDEA 2021.3\lib\idea_rt.jar=53014:F:\IntelliJ IDEA 2021.3\bin" -Dfile.encoding=UTF-8 -classpath "F:\IntelliJ IDEA 2021.3\lib\idea_rt.jar;F:\IntelliJ IDEA 2021.3\plugins\junit\lib\junit5-rt.jar;F:\IntelliJ IDEA 2021.3\plugins\junit\lib\junit-rt.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\cldrdata.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\jfxrt.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\nashorn.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\sunpkcs11.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\ext\zipfs.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\jce.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\jfxswt.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\resources.jar;C:\Program Files\Java\jdk1.8.0_321\jre\lib\rt.jar;D:\ssm_demo\ssm_dao\target\test-classes;D:\ssm_demo\ssm_dao\target\classes;D:\maven_repository\org\mybatis\mybatis\3.5.7\mybatis-3.5.7.jar;D:\maven_repository\mysql\mysql-connector-java\8.0.26\mysql-connector-java-8.0.26.jar;D:\maven_repository\com\google\protobuf\protobuf-java\3.11.4\protobuf-java-3.11.4.jar;D:\maven_repository\com\alibaba\druid\1.2.8\druid-1.2.8.jar;D:\maven_repository\org\mybatis\mybatis-spring\2.0.6\mybatis-spring-2.0.6.jar;D:\maven_repository\org\springframework\spring-jdbc\5.2.12.RELEASE\spring-jdbc-5.2.12.RELEASE.jar;D:\maven_repository\org\springframework\spring-beans\5.2.12.RELEASE\spring-beans-5.2.12.RELEASE.jar;D:\maven_repository\org\springframework\spring-core\5.2.12.RELEASE\spring-core-5.2.12.RELEASE.jar;D:\maven_repository\org\springframework\spring-jcl\5.2.12.RELEASE\spring-jcl-5.2.12.RELEASE.jar;D:\maven_repository\org\springframework\spring-context\5.2.12.RELEASE\spring-context-5.2.12.RELEASE.jar;D:\maven_repository\org\springframework\spring-aop\5.2.12.RELEASE\spring-aop-5.2.12.RELEASE.jar;D:\maven_repository\org\springframework\spring-expression\5.2.12.RELEASE\spring-expression-5.2.12.RELEASE.jar;D:\maven_repository\org\springframework\spring-web\5.2.12.RELEASE\spring-web-5.2.12.RELEASE.jar;D:\maven_repository\org\springframework\spring-webmvc\5.2.12.RELEASE\spring-webmvc-5.2.12.RELEASE.jar;D:\maven_repository\org\springframework\spring-tx\5.2.12.RELEASE\spring-tx-5.2.12.RELEASE.jar;D:\maven_repository\org\aspectj\aspectjweaver\1.8.7\aspectjweaver-1.8.7.jar;D:\maven_repository\org\apache\taglibs\taglibs-standard-spec\1.2.5\taglibs-standard-spec-1.2.5.jar;D:\maven_repository\org\apache\taglibs\taglibs-standard-impl\1.2.5\taglibs-standard-impl-1.2.5.jar;D:\maven_repository\javax\servlet\servlet-api\2.5\servlet-api-2.5.jar;D:\maven_repository\javax\servlet\jsp\jsp-api\2.0\jsp-api-2.0.jar;D:\maven_repository\junit\junit\4.12\junit-4.12.jar;D:\maven_repository\org\hamcrest\hamcrest-core\1.3\hamcrest-core-1.3.jar;D:\maven_repository\org\springframework\spring-test\5.2.12.RELEASE\spring-test-5.2.12.RELEASE.jar;D:\maven_repository\log4j\log4j\1.2.12\log4j-1.2.12.jar" com.intellij.rt.junit.JUnitStarter -ideVersion5 -junit4 com.itbz.dao.StudentDaoTest

三月 25, 2022 10:30:54 上午 org.springframework.test.context.support.AbstractTestContextBootstrapper getDefaultTestExecutionListenerClassNames

信息: Loaded default TestExecutionListener class names from location [META-INF/spring.factories]: [org.springframework.test.context.web.ServletTestExecutionListener, org.springframework.test.context.support.DirtiesContextBeforeModesTestExecutionListener, org.springframework.test.context.support.DependencyInjectionTestExecutionListener, org.springframework.test.context.support.DirtiesContextTestExecutionListener, org.springframework.test.context.transaction.TransactionalTestExecutionListener, org.springframework.test.context.jdbc.SqlScriptsTestExecutionListener, org.springframework.test.context.event.EventPublishingTestExecutionListener]

三月 25, 2022 10:30:54 上午 org.springframework.test.context.support.AbstractTestContextBootstrapper getTestExecutionListeners

信息: Using TestExecutionListeners: [org.springframework.test.context.web.ServletTestExecutionListener@6eebc39e, org.springframework.test.context.support.DirtiesContextBeforeModesTestExecutionListener@464bee09, org.springframework.test.context.support.DependencyInjectionTestExecutionListener@f6c48ac, org.springframework.test.context.support.DirtiesContextTestExecutionListener@13deb50e, org.springframework.test.context.transaction.TransactionalTestExecutionListener@239963d8, org.springframework.test.context.jdbc.SqlScriptsTestExecutionListener@3abbfa04, org.springframework.test.context.event.EventPublishingTestExecutionListener@57fffcd7]

三月 25, 2022 10:30:54 上午 org.apache.ibatis.logging.commons.JakartaCommonsLoggingImpl warn

警告: No MyBatis mapper was found in '[com.itbaizhan.dao]' package. Please check your configuration.

log4j:ERROR Could not find value for key log4j.appender.LOGFILE

log4j:ERROR Could not instantiate appender named "LOGFILE".

三月 25, 2022 10:30:54 上午 org.springframework.test.context.TestContextManager prepareTestInstance

严重: Caught exception while allowing TestExecutionListener [org.springframework.test.context.support.DependencyInjectionTestExecutionListener@f6c48ac] to prepare test instance [com.itbz.dao.StudentDaoTest@2e55dd0c]

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'com.itbz.dao.StudentDaoTest': Unsatisfied dependency expressed through field 'studentDao'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.itbz.dao.StudentDao' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:643)

at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119)

at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399)

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1420)

at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireBeanProperties(AbstractAutowireCapableBeanFactory.java:392)

at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:119)

at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:83)

at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:244)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:227)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:289)

at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:291)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:246)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)

at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)

at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)

at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)

at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)

at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)

at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)

at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)

at org.junit.runners.ParentRunner.run(ParentRunner.java:363)

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)

at org.junit.runner.JUnitCore.run(JUnitCore.java:137)

at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:69)

at com.intellij.rt.junit.IdeaTestRunner$Repeater$1.execute(IdeaTestRunner.java:38)

at com.intellij.rt.execution.junit.TestsRepeater.repeat(TestsRepeater.java:11)

at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:35)

at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:235)

at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:54)

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.itbz.dao.StudentDao' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1717)

at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1273)

at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1227)

at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640)

... 29 more