de.highbyte_le.weberknecht.db.DefaultWebDbConnectionProvider2.java Source code

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Here is the source code for de.highbyte_le.weberknecht.db.DefaultWebDbConnectionProvider2.java

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/*
 * DefaultWebDbConnectionProvider2.java
 * 
 * Copyright 2009 Patrick Mairif.
 * The program is distributed under the terms of the Apache License (ALv2).
 * 
 * charset=utf-8, tabstob=4
 */
package de.highbyte_le.weberknecht.db;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * provide DB connection from within web container.
 * 
 * <p>This connection provider throws {@link NamingException}s, if the connection is not configured.</p>
 * 
 * @author pmairif
 */
@SuppressWarnings("nls")
public class DefaultWebDbConnectionProvider2 implements DbConnectionProvider {
    private DataSource datasource = null;

    private DbType type;

    private int onErrorRetryCount = 5;

    /**
     * Logger for this class
     */
    private static final Log log = LogFactory.getLog(DefaultWebDbConnectionProvider2.class);

    public DefaultWebDbConnectionProvider2(String jdbcContextName) throws NamingException {
        //JNDI-Context
        Context ctx = new InitialContext();
        Context envCtx = (Context) ctx.lookup("java:comp/env");

        //JNDI-Lookup for jdbc connection
        this.datasource = (DataSource) envCtx.lookup(jdbcContextName);

        this.type = DbType.MYSQL; //FIXME implement some property handling for db type
    }

    public DefaultWebDbConnectionProvider2(DataSource dataSource, DbType type) {
        this.datasource = dataSource;
        this.type = type;
    }

    /**
     * is the database connection available, i. e. properly configured?
     * @return true, if it is available
     */
    @Override
    public boolean isAvailable() {
        return (this.datasource != null);
    }

    @Override
    public Connection getConnection() throws DBConnectionException {
        try {

            if (!isAvailable())
                throw new DBConnectionException("db connection is not available (e.g. not configured)");

            Connection con = null;
            boolean ok = false;
            int count = 0;
            while (!ok && count < onErrorRetryCount) {
                count++;
                con = this.datasource.getConnection();

                try {
                    Statement st = con.createStatement();
                    ResultSet rs = st.executeQuery("select true");
                    if (rs.next())
                        ok = true;
                } catch (SQLException e) {
                    log.warn("SQL exception while testing connection (attempt " + count + "): " + e.getMessage());
                    try {
                        con.close();
                    } catch (SQLException e1) {
                        /**/}
                    //and again
                }
            }

            return con;

        } catch (SQLException e) {
            log.error("getConnection() - SQLException: " + e.getMessage(), e);
            throw new DBConnectionException("sql exception: " + e.getMessage());
        }
    }

    @Override
    public DbType getType() {
        return type;
    }

    /**
     * @return the onErrorRetryCount
     */
    public int getOnErrorRetryCount() {
        return this.onErrorRetryCount;
    }

    /**
     * @param onErrorRetryCount the onErrorRetryCount to set
     */
    public void setOnErrorRetryCount(int onErrorRetryCount) {
        this.onErrorRetryCount = onErrorRetryCount;
    }
}