数据库访问 threadlocal模式[参考easydbo]

JDBCContext类主要解决数据连接的问题

public class JDBCContext {

    

    private static final Log log = LogFactory.getLog(JDBCContext.class);

    //private Database database;

    private DataSource datasource;

    protected Connection connection;

    private boolean isValid = true;

    private static ThreadLocal<JDBCContext> jdbcContext;

    /**

     * 私有构造函数

     * @param database

     */

    private JDBCContext(DataSource datasource){        

        this.datasource = datasource;

        createConnection();        

    }

    public static JDBCContext getJdbcContext(DataSource datasource)

    {        

        

        if(jdbcContext==null)jdbcContext=new JDBCContextThreadLocal(datasource);

        

        JDBCContext context = (JDBCContext) jdbcContext.get();

        if (context == null) {

            

            context = new JDBCContext(datasource);

            

        }

        return context;

    }

    

    private void createConnection(){        

        try{

            

            if(connection == null || connection.isClosed() == true){

                log.debug("Create a connection");

                

                //connection=datasource.getConnection();

                //isValid = true;

                

                if(datasource != null){

                    

                        //Class.forName(datasource.getdBType().getDriverclass()).newInstance();

                        //connection = DriverManager.getConnection(datasource.getUrl(), datasource.getUser(),datasource.getPassword());

                    connection=datasource.getConnection();

                    isValid = true;

                    

                }

                else{

                    log.error("DataSource is invalid");

                    isValid = false;

                    return;

                }

            }else{

                log.debug("The current connection is valid.");

            }

        }catch(Exception e){

            e.printStackTrace();

        }

        

    }

    

    /**

     * 释放当前连接；

     */

    public void releaseConnection(){

        try{

            if(connection != null && connection.isClosed() == false){

                connection.close();

                // 添加代码 by chenying                

                jdbcContext.remove();

                isValid = false;

                log.debug("The connection is closed.");

            }

        }catch(SQLException e){

            e.printStackTrace();

        }

    }

    

    /**

     * @return

     */

    public Connection getConnection(){

        

        log.debug("Get a Connection!");

        try{

        if(connection==null || connection.isClosed())createConnection();

        }

        catch(Exception e)

        {

            e.printStackTrace();

        }

        return connection;

    }

    /**

     * @return

     */

    public boolean isValid(){

        return isValid;

    }

    

    

    /**

     * 内部类

     * @author Administrator

     *

     */

    private static class JDBCContextThreadLocal extends ThreadLocal<JDBCContext> {

        public DataSource datasource;

        public JDBCContextThreadLocal(DataSource datasource)

        {

            this.datasource=datasource;

        }

        protected synchronized JDBCContext initialValue() {            

            return new JDBCContext(datasource);            

        }

    }



}