java - C3P0 连接池获取 java.sql.SQLException : No suitable driver exception

Question

我在我的 Web 应用程序中使用 c3p0 连接池，当我运行这个应用程序时，我得到了 java.sql.SQLException: No suitable driver 异常，我使用 Datasource.java 类创建连接池，使用 Utils.java 从 datasouce.properties 文件中读取属性。

完全执行是(我得到 10 次)为什么会出现异常。我正在为 oracle 驱动程序使用 odbc6.jar 文件，请帮助我

2015-09-07 16:53:32 INFO  AbstractPoolBackedDataSource:527 - Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 10, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, contextClassLoaderSource -> caller, dataSourceName -> z8kflt9b1agzamcthrvgf|1d84bc10, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> null, extensions -> {}, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, forceSynchronousCheckins -> false, forceUseNamedDriverClass -> false, identityToken -> z8kflt9b1agzamcthrvgf|1d84bc10, idleConnectionTestPeriod -> 0, initialPoolSize -> 10, jdbcUrl -> jdbc:oracle:thin:@localhost:1521:LOCALDB, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 200, maxStatements -> 2100, maxStatementsPerConnection -> 0, minPoolSize -> 10, numHelperThreads -> 3, preferredTestQuery -> null, privilegeSpawnedThreads -> false, properties -> {user=******, password=******}, propertyCycle -> 0, statementCacheNumDeferredCloseThreads -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, userOverrides -> {}, usesTraditionalReflectiveProxies -> false ]
2015-09-07 16:54:02 WARN  BasicResourcePool:1911 - com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@295bc68c -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
java.sql.SQLException: No suitable driver
    at java.sql.DriverManager.getDriver(DriverManager.java:264)
    at com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource.java:285)
    at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:175)
    at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:220)
    at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:206)
    at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:203)
    at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1138)
    at com.mchange.v2.resourcepool.BasicResourcePool.doAcquireAndDecrementPendingAcquiresWithinLockOnSuccess(BasicResourcePool.java:1125)
    at com.mchange.v2.resourcepool.BasicResourcePool.access$700(BasicResourcePool.java:44)
    at com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask.run(BasicResourcePool.java:1870)
    at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:696)
2015-09-07 16:54:02 WARN  BasicResourcePool:1911 - com.mchange.v2.resourcepool.BasicResourcePool$ScatteredAcquireTask@78da5318 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 

JSP 文件:-

<%
    Datasource ds = Datasource.getInstance();
    Connection connection = ds.getConnection();
    try{
    Statement st = connection.createStatement();
    ResultSet rs = st.executeQuery("select * from app_userlist");
    while(rs.next()){
        System.out.println(rs.getInt(1));
    }
    }catch(Exception e){

    }
    %>

数据源.java

public class Datasource {       

private Datasource() throws IOException, SQLException {
    // load datasource properties   
    props = Utils.readProperties("datasource.properties");
    cpds = new ComboPooledDataSource();
    cpds.setJdbcUrl(props.getProperty("jdbcUrl"));
    cpds.setUser(props.getProperty("username"));
    cpds.setPassword(props.getProperty("password"));

    cpds.setInitialPoolSize(new Integer((String) props.getProperty("initialPoolSize")));
    cpds.setAcquireIncrement(new Integer((String) props.getProperty("acquireIncrement")));
    cpds.setMaxPoolSize(new Integer((String) props.getProperty("maxPoolSize")));
    cpds.setMinPoolSize(new Integer((String) props.getProperty("minPoolSize")));
    cpds.setMaxStatements(new Integer((String) props.getProperty("maxStatements")));

    Connection testConnection = null;
    Statement testStatement = null;

    // test connectivity and initialize pool
    try {
           testConnection = cpds.getConnection();
           testStatement = testConnection.createStatement();
           testStatement.executeQuery("select 1+1 from DUAL");
        } catch (SQLException e) {
            throw e;
        } finally {
            testStatement.close();
            testConnection.close();
    }

}

public static Datasource getInstance() throws IOException, SQLException {
    if (datasource == null) {
          datasource = new Datasource();
          return datasource;
        } else {
          return datasource;
        }
}

  public Connection getConnection() throws SQLException {
      return this.cpds.getConnection();
  } }

Utils.java

public class Utils {

   static public Properties readProperties(String filename) throws IOException{
      Properties props = new Properties();
      ClassLoader loader = Thread.currentThread().getContextClassLoader();
      InputStream stream = loader.getResourceAsStream(filename);
      props.load(stream);
      return props;
   } 
}

数据源.properties:-

driverClass =oracle.jdbc.OracleDriver
jdbcUrl =jdbc:oracle:thin:@localhost:1521:userdb
username =user
password =xxxx                                                 
factory="org.apache.naming.factory.BeanFactory"
type="com.mchange.v2.c3p0.ComboPooledDataSource"
maxPoolSize="50"   
minPoolSize="15"
acquireIncrement="3"
acquireRetryAttempts = "0"
acquireRetryDelay = "3000"
breakAfterAcquireFailure = "false"
maxConnectionAge = "60"
maxIdleTime = "30"
maxIdleTimeExcessConnections = "10"
idleConnectionTestPeriod = "15"
testConnectionOnCheckout = "true"
preferredTestQuery = "SELECT 1"
debugUnreturnedConnectionStackTraces = "true"  
autoCommitOnClose="true"

Answer 1

java.sql.SQLException: No suitable driver found

这个异常可能有两个原因:

• 根本没有加载 JDBC 驱动程序。
• URL 与任何加载的 JDBC 驱动程序都不匹配。