improved postgres support

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

@@ -70,6 +70,7 @@ import com.alibaba.druid.pool.vendor.MySqlValidConnectionChecker;
 import com.alibaba.druid.pool.vendor.OracleExceptionSorter;
 import com.alibaba.druid.pool.vendor.OracleValidConnectionChecker;
 import com.alibaba.druid.pool.vendor.PGExceptionSorter;
+import com.alibaba.druid.pool.vendor.PGValidConnectionChecker;
 import com.alibaba.druid.pool.vendor.SybaseExceptionSorter;
 import com.alibaba.druid.proxy.DruidDriver;
 import com.alibaba.druid.proxy.jdbc.DataSourceProxyConfig;
@@ -887,12 +888,14 @@ public class DruidDataSource extends DruidAbstractDataSource
 
     private void initValidConnectionChecker() {
         String realDriverClassName = driver.getClass().getName();
-        if (realDriverClassName.equals("com.mysql.jdbc.Driver")) {
+        if (realDriverClassName.equals(JdbcConstants.MYSQL_DRIVER)) {
             this.validConnectionChecker = new MySqlValidConnectionChecker();
-        } else if (realDriverClassName.equals("oracle.jdbc.driver.OracleDriver")) {
+        } else if (realDriverClassName.equals(JdbcConstants.ORACLE_DRIVER)) {
             this.validConnectionChecker = new OracleValidConnectionChecker();
-        } else if (realDriverClassName.equals("com.microsoft.jdbc.sqlserver.SQLServerDriver")) {
+        } else if (realDriverClassName.equals(JdbcConstants.SQL_SERVER_DRIVER)) {
             this.validConnectionChecker = new MSSQLValidConnectionChecker();
+        } else if (realDriverClassName.equals(JdbcConstants.POSTGRESQL_DRIVER)) {
+            this.validConnectionChecker = new PGValidConnectionChecker();
         }
     }
 

src/main/java/com/alibaba/druid/pool/vendor/PGValidConnectionChecker.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 1999-2011 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.druid.pool.vendor;
+
+import java.io.Serializable;
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+import com.alibaba.druid.pool.DruidPooledConnection;
+import com.alibaba.druid.pool.ValidConnectionChecker;
+import com.alibaba.druid.pool.ValidConnectionCheckerAdapter;
+import com.alibaba.druid.proxy.jdbc.ConnectionProxy;
+import com.alibaba.druid.support.logging.Log;
+import com.alibaba.druid.support.logging.LogFactory;
+import com.alibaba.druid.util.JdbcUtils;
+
+public class PGValidConnectionChecker extends ValidConnectionCheckerAdapter implements ValidConnectionChecker, Serializable {
+
+    private static final long serialVersionUID     = -2227528634302168877L;
+
+    private static final Log  LOG                  = LogFactory.getLog(PGValidConnectionChecker.class);
+
+    private String            defaultValidateQuery = "SELECT 'x' FROM DUAL";
+
+    public PGValidConnectionChecker(){
+        configFromProperties(System.getProperties());
+    }
+
+    public boolean isValidConnection(Connection conn, String validateQuery, int validationQueryTimeout) {
+        if (validateQuery == null || validateQuery.isEmpty()) {
+            validateQuery = this.defaultValidateQuery;
+        }
+
+        try {
+            if (conn.isClosed()) {
+                return false;
+            }
+        } catch (SQLException ex) {
+            // skip
+            return false;
+        }
+
+        try {
+            if (conn instanceof DruidPooledConnection) {
+                conn = ((DruidPooledConnection) conn).getConnection();
+            }
+
+            if (conn instanceof ConnectionProxy) {
+                conn = ((ConnectionProxy) conn).getRawObject();
+            }
+
+            Statement stmt = null;
+            ResultSet rs = null;
+            try {
+                stmt = conn.createStatement();
+                rs = stmt.executeQuery(validateQuery);
+                return true;
+            } catch (SQLException e) {
+                return false;
+            } catch (Exception e) {
+                LOG.warn("Unexpected error in ping", e);
+                return false;
+            } finally {
+                JdbcUtils.close(rs);
+                JdbcUtils.close(stmt);
+            }
+        } catch (Exception e) {
+            LOG.warn("Unexpected error in pingDatabase", e);
+            return false;
+        }
+    }
+}

src/main/java/com/alibaba/druid/util/JdbcConstants.java

@@ -28,10 +28,12 @@ public interface JdbcConstants {
     public static final String DB2_DRIVER        = "COM.ibm.db2.jdbc.app.DB2Driver";
 
     public static final String POSTGRESQL        = "postgresql";
+    public static final String POSTGRESQL_DRIVER = "org.postgresql.Driver";
 
     public static final String SYBASE            = "sybase";
 
     public static final String SQL_SERVER        = "sqlserver";
+    public static final String SQL_SERVER_DRIVER = "com.microsoft.jdbc.sqlserver.SQLServerDriver";
 
     public static final String ORACLE            = "oracle";
     public static final String ORACLE_DRIVER     = "oracle.jdbc.driver.OracleDriver";