java - 连接mysql和Java的问题

Question

我正在尝试将 Java 代码连接到 mySQL。这是我得到的错误。我不明白为什么没有找到驱动程序，因为我已将连接器 jar 放在类路径中。

Class Not Found Exception:
No suitable driver found for jdbc:mysql://localhost/hpdata?user=root&password=12
3456
Exception in thread "main" java.lang.NullPointerException
    at edu.indiana.iucbrf.feature.featurespec.FeatureSpecRDB.open(FeatureSpe
cRDB.java:122)
    at edu.indiana.iucbrf.feature.featurespec.FeatureSpecRDB.<init>(FeatureS
pecRDB.java:66)
    at edu.indiana.iucbrf.domain.componentfactory.RDBComponentFactory.constr
uctProblemFeatureSpecCollection(RDBComponentFactory.java:112)
    at edu.indiana.iucbrf.domain.Domain.<init>(Domain.java:239)
    at edu.indiana.iucbrf.domain.Domain.<init>(Domain.java:197)
    at edu.indiana.iucbrf.examples.honeypotRDBTemplate.HDomainRDB.<in
it>(HDomainRDB.java:56)
    at edu.indiana.iucbrf.examples.hRDBTemplate.HSystemRDB.set
 upDomain(HSystemRDB.java:198)
    at edu.indiana.iucbrf.examples.hRDBTemplate.HSystemRDB.<in
it>(HSystemRDB.java:131)
    at edu.indiana.iucbrf.examples.hRDBTemplate.HTestClassRDB.
main(HTestClassRDB.java:65)

这是我的代码:

   private static void flush() {

  Class.forName("com.mysql.jdbc.Driver").newInstance();

    try {

   conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/hpdata?user=root&password=123456");  

      } catch (Exception e) {
          System.out.println("Class Not Found Exception:");
          System.out.println(e.getMessage());       
      }

Answer 1

try {
 String driverName = "com.mysql.jdbc.Driver";
 Class.forName(driverName);

 String serverName = "localhost";
 String mydatabase = "hpdata";
 String url = "jdbc:mysql :// " + serverName + "/" + mydatabase; 

 String username = "root";
 String password = "123456";
 connection = DriverManager.getConnection(url, username, password);
} catch(Exception e) {
 // appropriate action
}