java - 我已将 java mysql 连接器添加到我的项目中，但我的项目仍然无法使用它

Question

这是我的类，它用于获取连接

// Database credentials
static final String JDBC_DRIVER = "com.mysql.cj.jdbc.Driver";
static final String DB_URL = "jdbc:mysql://localhost:3306/pornism";
static final String USER = "root";
static final String PASS = "1";
static final String HOST_NAME = "localhost";
static final String DB_NAME = "pornism";

// Connection and Statement of current session

public static Connection getConnection() throws ClassNotFoundException {
    try {
        String connectionURL = "jdbc:mysql://" + HOST_NAME + ":3306/" + DB_NAME;
        Connection conn = DriverManager.getConnection(connectionURL,USER,PASS);
        System.out.println("Successfull!!");
        return conn;
    } catch (SQLException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        return null;
    }
}

这就是我尝试连接时所显示的内容

    java.sql.SQLException: No suitable driver found for jdbc:mysql://localhost:3306/crewup
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at data.Database.getConnection(Database.java:22)
at prototype.LoginMethod.doPost(LoginMethod.java:45)
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:543)
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:688)
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:609)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:818)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1623)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)

我已经将 mysql 连接器添加到我的项目中: Eclipse build path

谁能告诉我为什么它不起作用？我试图找到。

Answer 1

您必须设置Class.forName。

尝试下面的代码片段。

public static Connection getConnection() throws ClassNotFoundException {
  try {
      Class.forName(JDBC_DRIVER);  // Add this line.
      String connectionURL = "jdbc:mysql://" + HOST_NAME + ":3306/" + DB_NAME;
      Connection conn = DriverManager.getConnection(connectionURL,USER,PASS);
      System.out.println("Successfull!!");
      return conn;
  } catch (SQLException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      return null;
  }
}