JDBC获取数据库信息

当同一个项目部署到不同数据库环境时，程序中涉及sql语句执行时，由于各种数据库的差异，可能会产生异常。则就需要获取数据库信息做适当处理。

public class DBUtils {
    private static Log logger = LogFactory.getLog(DBUtils.class);

    private static String dbName;

    private static final String DBTYPE_DB2 = "DB2";

    private static final String DBTYPE_SYBASE = "Sybase";

    private static final String DBTYPE_ORACLE = "Oracle";

    private static final String DBTYPE_SQLSERVER = "SqlServer";

    private static final String DBTYPE_MYSQL = "MySQL";

/*    private static Cache dbTypeJudgeCache = DBCache.DBTypeJudgeCache;*/

    private static String getDatabaseProductName() {
        WebApplicationContext webContext = (WebApplicationContext)ComponentFactory.getApplicationContext();
        DataSource ds = (DataSource) webContext.getBean("dataSource");
        if (dbName != null) {
            return dbName;
        }
        Connection con = null;
        try {
            con = DataSourceUtils.getConnection(ds);
        } catch (DataAccessException ex) {
            logger.error("获取数据库连接失败", ex);
        }

        if (con != null) {
            try {
                DatabaseMetaData dbmd = con.getMetaData();
                if (dbmd != null) {
                    dbName = dbmd.getDatabaseProductName();
                    if (dbName != null && dbName.startsWith("DB2/")) {
                        dbName = DBUtils.DBTYPE_DB2;
                    } else if (dbName != null && dbName.startsWith("Oracle")) {
                        dbName = DBUtils.DBTYPE_ORACLE;
                    } else if (dbName != null
                            && dbName.startsWith("Microsoft SQL Server")) {
                        dbName = DBUtils.DBTYPE_SQLSERVER;
                    } else if (dbName != null
                            && (dbName.equals("Adaptive Server Enterprise") || dbName
                                    .equals("Adaptive Server Anywhere"))) {
                        dbName = DBUtils.DBTYPE_SYBASE;
                    } else if (dbName != null && dbName.startsWith("MySQL")) {
                        dbName = DBUtils.DBTYPE_MYSQL;
                    }
                } else {
                    logger.warn("获取数据库类型出错");
                }
            } catch (SQLException se) {
                logger.error("获取数据库类型出错", se);
            } finally {
                DataSourceUtils.closeConnectionIfNecessary(con, ds);
            }
        }
        return dbName;
    }

    private static String getDbType() {
        String dbType = null;
        try {
            dbType = DBUtils.getDatabaseProductName();
        } catch (Exception e) {
            // 异常不处理;
        }
        if (dbType == null) {
            dbType = "";
        } else {
            dbType = dbType.trim();
        }
        return dbType;
    }

    // 下面四个方法最好能有更好的办法使每次进来的时候只比较一次，不用每次进来都比较
    public static boolean dbTypeIsDB2() {
        Boolean is_db2 = new Boolean(false);
        logger.debug("使用CACHE前 " + is_db2);
        is_db2 = new Boolean(DBUtils.getDbType().equalsIgnoreCase(DBUtils.DBTYPE_DB2));
        return is_db2.booleanValue();
    }

    public static boolean dbTypeIsORACLE() {
        Boolean is_oracle = new Boolean(false);
        is_oracle = new Boolean(DBUtils.getDbType().equalsIgnoreCase(DBUtils.DBTYPE_ORACLE));
        return is_oracle.booleanValue();
    }

    public static boolean dbTypeIsSYBASE() {
        Boolean is_sybase = new Boolean(false);
        is_sybase = new Boolean(DBUtils.getDbType().equalsIgnoreCase(DBUtils.DBTYPE_SYBASE));
        return is_sybase.booleanValue();
    }

    public static boolean dbTypeIsSQLSERVER() {
        Boolean is_sqlserver = new Boolean(false);
        is_sqlserver = new Boolean(DBUtils.getDbType().equalsIgnoreCase(DBUtils.DBTYPE_SQLSERVER));
        return is_sqlserver.booleanValue();
    }

    public static boolean dbTypeIsMYSQL() {
        Boolean is_mysql = new Boolean(false);
        is_mysql = new Boolean(DBUtils.getDbType().equalsIgnoreCase(DBUtils.DBTYPE_MYSQL));
        return is_mysql.booleanValue();
    }
}