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copied!<p>Even if you use JDBC connection pool either application server provided or apache commons pooling, it is worthwhile to code a retry logic. Based on the configuration of your application server, the app server would purge all the pooled connections and recreate a fresh set of connections. Here is a sample:</p> <pre><code> Connection conn = null; Statement stmt = null; ResultSet rs = null; // // How many times do you want to retry the transaction // (or at least _getting_ a connection)? // int retryCount = 5; boolean transactionCompleted = false; do { try { conn = getConnection(); // assume getting this from a // javax.sql.DataSource, or the // java.sql.DriverManager retryCount = 0; stmt = conn.createStatement(); String query = "Some sample SQL"; rs = stmt.executeQuery(query); while (rs.next()) { } rs.close(); rs = null; stmt.close(); stmt = null; conn.close(); conn = null; transactionCompleted = true; } catch (SQLException sqlEx) { // // The two SQL states that are 'retry-able' // for a communications error. // // Only retry if the error was due to a stale connection, // communications problem // String sqlState = sqlEx.getSQLState(); if ("Substitute with Your DB documented sqlstate number for stale connection".equals(sqlState) ) { retryCount--; } else { retryCount = 0; } } finally { if (rs != null) { try { rs.close(); } catch (SQLException sqlEx) { // log this } } if (stmt != null) { try { stmt.close(); } catch (SQLException sqlEx) { // log this } } if (conn != null) { try { // // If we got here, and conn is not null, the // transaction should be rolled back, as not // all work has been done try { conn.rollback(); } finally { conn.close(); } } catch (SQLException sqlEx) { // // If we got an exception here, something // pretty serious is going on, so we better // pass it up the stack, rather than just // logging it. . . throw sqlEx; } } } } while (!transactionCompleted && (retryCount > 0)); } </code></pre>

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