Java 定制的Tomcat JNDI数据源

我有多个使用同一数据库的Web应用程序。直到最近，我一直在使用JNDI数据源，如下所示：

server.xml：

<Resource name="jdbc/dbPool" auth="Container" type="javax.sql.DataSource"
          maxActive="100" minIdle="10" maxIdle="30" maxWait="1000" 
          username="username" password="password" 
          driverClassName="oracle.jdbc.OracleDriver"
          factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
          url="jdbc:oracle:thin:@//localhost:1521/XE"/>

<Resource name="jdbc/dbPool" auth="Container" type="my.webapp.CustomDataSource"
          maxActive="100" minIdle="10" maxIdle="30" maxWait="1000" 
          username="username" password="password" 
          driverClassName="oracle.jdbc.OracleDriver"
          factory="my.webapp.CustomDataSourceFactory"
          dialect="org.hibernate.dialect.Oracle10gDialect"
          url="jdbc:oracle:thin:@//localhost:1521/XE"/>

现在我需要开始在JNDI资源中配置数据库方言（到目前为止已经硬编码）。我的Tomcat和服务器配置现在如下所示：

server.xml：

<Resource name="jdbc/dbPool" auth="Container" type="javax.sql.DataSource"
          maxActive="100" minIdle="10" maxIdle="30" maxWait="1000" 
          username="username" password="password" 
          driverClassName="oracle.jdbc.OracleDriver"
          factory="org.apache.tomcat.jdbc.pool.DataSourceFactory"
          url="jdbc:oracle:thin:@//localhost:1521/XE"/>

<Resource name="jdbc/dbPool" auth="Container" type="my.webapp.CustomDataSource"
          maxActive="100" minIdle="10" maxIdle="30" maxWait="1000" 
          username="username" password="password" 
          driverClassName="oracle.jdbc.OracleDriver"
          factory="my.webapp.CustomDataSourceFactory"
          dialect="org.hibernate.dialect.Oracle10gDialect"
          url="jdbc:oracle:thin:@//localhost:1521/XE"/>

这在某种程度上是可行的——当我重新启动Tomcat时，第一个webapp（例如使用jdbc/service1DB数据源的webapp）成功启动，并使用配置的方言正常运行，但所有其他webapp在数据源查找过程中都失败并出现错误。此外，当我在不重新启动Tomcat的情况下部署webapp时，也会发生相同的错误（即使是之前在重新启动Tomcat后成功启动的第一个webapp）：

这里可能有什么问题？

singleton=“false” 啊，我知道了

我确实注意到，CustomDataSource只创建了一个“实例”——重启后，日志中有一个很小的指示，说明创建了数据源，然后启动了第一个webapp，但在再次重启之前，没有为任何webapp再次创建数据源

我重新阅读了Tomcat的JNDI resources HOW-TO中的“添加定制资源工厂”一章，并注意到关于将singleton属性设置为false的评论（我以前读过，但认为这对我的案例并不重要）

我把它添加到我的数据源中。请注意底部的最后一个属性

<Resource name = "jdbc/dbPool"
          auth = "Container"
          type = "my.webapp.CustomDataSource"
          maxActive = "100"
          minIdle = "10"
          maxIdle = "30"
          maxWait = "1000"
          username = "username"
          password = "password"
          driverClassName = "oracle.jdbc.OracleDriver"
          factory = "my.webapp.CustomDataSourceFactory"
          dialect = "org.hibernate.dialect.Oracle10gDialect"
          url = "jdbc:oracle:thin:@//localhost:1521/XE"
          singleton = "false"
/>

---

而且它有效！我的所有网络应用程序都会启动并使用我配置的方言

您的

CustomDataSource

位于哪里？这是Tomcat如何处理类加载器的典型问题，尝试将类放在jar上，Tomcat/libIt中的jar与配置数据源查找的类（以及CustomDataSourceFactory）位于同一个包中。因此，它被包括在每个webapp的战争中。我将尝试这个方法，看看它是否有效，但如果可能的话，我宁愿避免使用这种方法。

public class CustomDataSourceFactory extends DataSourceFactory {

    private static final String PROP_DIALECT = "dialect";
    private static final String[] CUSTOM_PROPERTIES = new String[]{PROP_DIALECT};
    private static final String[] PROPERTIES = ArrayUtils.addAll(ALL_PROPERTIES, CUSTOM_PROPERTIES);

    @Override
    public Object getObjectInstance(Object obj, Name name, Context nameCtx, Hashtable<?, ?> environment) throws Exception {
        if (obj != null && obj instanceof Reference) {
            Reference ref = (Reference) obj;
            Properties properties = new Properties();

            for (int i = 0; i < PROPERTIES.length; ++i) {
                String propertyName = PROPERTIES[i];
                RefAddr ra = ref.get(propertyName);
                if (ra != null) {
                    String propertyValue = ra.getContent().toString();
                    properties.setProperty(propertyName, propertyValue);
                }
            }

            return this.createDataSource(properties, nameCtx);
        } else {
            return null;
        }
    }

    public javax.sql.DataSource createDataSource(Properties properties, Context context) throws Exception {
        PoolConfiguration poolProperties = parsePoolProperties(properties);
        if (poolProperties.getDataSourceJNDI() != null && poolProperties.getDataSource() == null) {
            this.performJNDILookup(context, poolProperties);
        }

        String dialect = properties.getProperty(PROP_DIALECT);
        if (dialect == null) {
            log.error("Dialect is unspecified");
            return null;
        }

        CustomDataSource dataSource = new CustomDataSource(dialect, poolProperties);
        dataSource.createPool();
        return dataSource;
    }
}

@NoArgsConstructor
public class CustomDataSource extends DataSource {

    @Getter
    @Setter
    private String dialect;

    public CustomDataSource(String dialect, PoolConfiguration poolProperties) {
        super(poolProperties);
        this.dialect = dialect;
    }
}

"org.springframework.jdbc.datasource.lookup.DataSourceLookupFailureException":"Failed to look up JNDI DataSource with name 'java:comp/env/jdbc/service2DB'; nested exception is javax.naming.NamingException: The local resource link [service2DB] that refers to global resource [jdbc/dbPool] was expected to return an instance of [my.webapp.CustomDataSource] but returned an instance of [my.webapp.CustomDataSource]"

<Resource name = "jdbc/dbPool"
          auth = "Container"
          type = "my.webapp.CustomDataSource"
          maxActive = "100"
          minIdle = "10"
          maxIdle = "30"
          maxWait = "1000"
          username = "username"
          password = "password"
          driverClassName = "oracle.jdbc.OracleDriver"
          factory = "my.webapp.CustomDataSourceFactory"
          dialect = "org.hibernate.dialect.Oracle10gDialect"
          url = "jdbc:oracle:thin:@//localhost:1521/XE"
          singleton = "false"
/>