Merge pull request #1932 from xiaoshan00/master

修复自定义的ValidConnectionChecker被覆盖的问题

src/main/java/com/alibaba/druid/pool/DruidDataSource.java

@@ -1107,6 +1107,10 @@ public class DruidDataSource extends DruidAbstractDataSource implements DruidDat
     }
 
     private void initValidConnectionChecker() {
+        if (this.validConnectionChecker != null) {
+            return;
+        }
+
         String realDriverClassName = driver.getClass().getName();
         if (JdbcUtils.isMySqlDriver(realDriverClassName)) {
             this.validConnectionChecker = new MySqlValidConnectionChecker();

src/test/java/com/alibaba/druid/bvt/pool/DruidDataSourceTestValidConnectionChecker.java

@@ -0,0 +1,56 @@
+package com.alibaba.druid.bvt.pool;
+
+import com.alibaba.druid.pool.DruidDataSource;
+import com.alibaba.druid.pool.ValidConnectionChecker;
+import org.junit.Assert;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.Properties;
+
+/**
+ * 给对象 {@link DruidDataSource} 已经设置了自定义的 validConnectionChecker的情况下,
+ * 使用MySQL等已知的Driver的时候, 会用内置的checker覆盖自定义的checker.
+ * 由于测试用例{@link DruidDataSourceTest5}使用的是mock driver, 导致并不能测试自定义checker被修改的问题.
+ * 此处单独列出Test Case. 由于需要用到真实的MySQL Driver, 以main函数方式提供测试用例.
+ * 如需运行此用例, 请先修改连接信息.
+ */
+public class DruidDataSourceTestValidConnectionChecker {
+
+    public static void main(String[] args) throws SQLException {
+        DruidDataSource dataSource = new DruidDataSource();
+
+        ValidConnectionChecker checker = new ValidConnectionChecker() {
+            @Override
+            public boolean isValidConnection(Connection c, String query, int validationQueryTimeout) throws Exception {
+                return true;
+            }
+
+            @Override
+            public void configFromProperties(Properties properties) {
+            }
+        };
+
+        // 运行测试用例之前请先修改连接信息.
+        String jdbcUrl = "jdbc:mysql://localhost:3306/test";
+        String user = "test";
+        String password = "test";
+
+        Assert.assertTrue("运行此用例之前请先修改上面的连接信息, 并注释此行", false);
+
+        String driverClass = "com.mysql.jdbc.Driver";
+
+        dataSource.setUrl(jdbcUrl);
+        dataSource.setUsername(user);
+        dataSource.setPassword(password);
+        dataSource.setDriverClassName(driverClass);
+
+        dataSource.setValidConnectionChecker(checker);
+        Assert.assertEquals(checker, dataSource.getValidConnectionChecker());
+
+        dataSource.init();
+
+        // 已经设置了自定义的validConnectionChecker的情况下, 即使加载了MySQL Driver之后checker对象也不应该发生变化.
+        Assert.assertEquals(checker, dataSource.getValidConnectionChecker());
+    }
+}