使用druid连接mysql报错，搞不清楚是哪里的问题，求解答！！!

Question

报错如下：
04-Dec-2019 19:16:27.521 淇℃伅 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory 鎶妛eb 搴旂敤绋嬪簭閮ㄧ讲鍒扮洰褰� [D:\javaEE\tomcat\webapps\manager]
04-Dec-2019 19:16:27.537 淇℃伅 [localhost-startStop-1] org.apache.catalina.startup.HostConfig.deployDirectory Deployment of web application directory [D:\javaEE\tomcat\webapps\manager] has finished in [16] ms
04-Dec-2019 19:16:40.134 淇℃伅 [http-nio-80-exec-9] com.alibaba.druid.support.logging.JakartaCommonsLoggingImpl.info {dataSource-1} inited
org.springframework.dao.EmptyResultDataAccessException: Incorrect result size: expected 1, actual 0
at org.springframework.dao.support.DataAccessUtils.requiredSingleResult(DataAccessUtils.java:71)
at org.springframework.jdbc.core.JdbcTemplate.queryForObject(JdbcTemplate.java:797)
at dao.UserDaoImpl.UserDaoImpl.findUserByUsernameAndPassword(UserDaoImpl.java:19)
at service.impl.UserServiceImpl.login(UserServiceImpl.java:13)
at Servlet.LoginServlet.doPost(LoginServlet.java:55)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:528)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:678)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:798)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:810)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1500)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)
配置文件：
driverClassName=com.mysql.cj.jdbc.Driver
url=jdbc:mysql://localhost:3306/day17
username=root
password=root
initialSize=5
maxActive=10
maxWait=3000
validationQuery:SELECT 1

testWhileIdle:true

testOnBorrow:false

testOnReturn:false
工具类如下：
/**

• JDBC工具类 使用Durid连接池
  */
  public class JDBCUtils {

  private static DataSource ds ;

  static {

  try {
      //1.加载配置文件
                 Properties pro = new Properties();
      //使用ClassLoader加载配置文件，获取字节输入流
      InputStream is = JDBCUtils.class.getClassLoader().getResourceAsStream("druid.properties");
      pro.load(is);
  
      //2.初始化连接池对象
      ds = DruidDataSourceFactory.createDataSource(pro);
  
  } catch (IOException e) {
      e.printStackTrace();
  } catch (Exception e) {
      e.printStackTrace();
  }
  

  }

  /**

  • 获取连接池对象 */ public static DataSource getDataSource(){ return ds; }

  /**

  • 获取连接Connection对象 */ public static Connection getConnection() throws SQLException { return ds.getConnection(); } }

Answer 1

原因：在使用JdbcTemplate的queryForObject方法时，当查不到数据时会抛出这个异常
解决方法：相应代码处加try catch捕获