使用druid 连接池时，Driver 初始化空指针问题

springboot-starter-data-authorization/src/main/java/com/codingapi/springboot/authorization/jdbc/AuthorizationJdbcDriver.java

@@ -6,52 +6,131 @@
 import java.sql.*;
 import java.util.Enumeration;
 import java.util.Properties;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.logging.Logger;
 
 public class AuthorizationJdbcDriver implements Driver {
 
-    private Driver driver;
+    /**
+     * Cache driver by URL to avoid repeated traversal.
+     * Thread-safe since multiple connections may be created concurrently.
+     */
+    private final ConcurrentHashMap<String, Driver> driverCache = new ConcurrentHashMap<>();
+
+    /**
+     * Cached reference to any non-self driver (for methods without URL).
+     */
+    private volatile Driver anyDriverCache;
 
     @Override
     public Connection connect(String url, Properties info) throws SQLException {
-        return new ConnectionProxy(driver.connect(url, info));
+        Driver targetDriver = getTargetDriver(url);
+        if (targetDriver == null) {
+            return null;
+        }
+        return new ConnectionProxy(targetDriver.connect(url, info));
     }
 
     @Override
     public boolean acceptsURL(String url) throws SQLException {
+        return getTargetDriver(url) != null;
+    }
+
+    /**
+     * Get target driver for the given URL.
+     * Uses cached result if available, otherwise finds and caches.
+     */
+    private Driver getTargetDriver(String url) throws SQLException {
+        // Fast path: check cache first
+        Driver cached = driverCache.get(url);
+        if (cached != null) {
+            return cached;
+        }
+
+        // Cache miss: find and cache
+        Driver found = findDriver(url);
+        if (found != null) {
+            driverCache.putIfAbsent(url, found);
+        }
+        return found;
+    }
+
+    /**
+     * Find the target driver that accepts the URL from DriverManager.
+     */
+    private Driver findDriver(String url) throws SQLException {
         Enumeration<Driver> drivers = DriverManager.getDrivers();
         while (drivers.hasMoreElements()) {
             Driver driver = drivers.nextElement();
-            if (driver.acceptsURL(url)) {
-                this.driver = driver;
-                return true;
+            if (driver != this && driver.acceptsURL(url)) {
+                return driver;
             }
         }
-        return false;
+        return null;
     }
 
     @Override
     public DriverPropertyInfo[] getPropertyInfo(String url, Properties info) throws SQLException {
-        return driver.getPropertyInfo(url, info);
+        Driver driver = getTargetDriver(url);
+        if (driver != null) {
+            return driver.getPropertyInfo(url, info);
+        }
+        return new DriverPropertyInfo[0];
     }
 
     @Override
     public int getMajorVersion() {
-        return driver.getMajorVersion();
+        return getAnyDriver().getMajorVersion();
     }
 
     @Override
     public int getMinorVersion() {
-        return driver.getMinorVersion();
+        return getAnyDriver().getMinorVersion();
     }
 
     @Override
     public boolean jdbcCompliant() {
-        return driver.jdbcCompliant();
+        Driver driver = getAnyDriver();
+        return driver != null && driver.jdbcCompliant();
     }
 
     @Override
     public Logger getParentLogger() throws SQLFeatureNotSupportedException {
-        return driver.getParentLogger();
+        return getAnyDriver().getParentLogger();
+    }
+
+    /**
+     * Get any registered driver other than this one.
+     * Caches the first found result since driver set doesn't change at runtime.
+     */
+    private Driver getAnyDriver() {
+        // Double-checked locking for lazy initialization
+        Driver cached = anyDriverCache;
+        if (cached != null) {
+            return cached;
+        }
+        synchronized (this) {
+            cached = anyDriverCache;
+            if (cached != null) {
+                return cached;
+            }
+            anyDriverCache = findAnyDriver();
+            return anyDriverCache;
+        }
+    }
+
+    /**
+     * Find any registered driver other than this one.
+     * Used for methods that don't have URL available.
+     */
+    private Driver findAnyDriver() {
+        Enumeration<Driver> drivers = DriverManager.getDrivers();
+        while (drivers.hasMoreElements()) {
+            Driver driver = drivers.nextElement();
+            if (driver != this) {
+                return driver;
+            }
+        }
+        throw new IllegalStateException("No JDBC driver found");
     }
 }