jdbc 连接 oracle负载均衡（failover）

连接串如下：

String url="jdbc:oracle:thin:@(DESCRIPTION=(ADDRESS_LIST=(LOAD_BALANCE=OFF)(FAILOVER=ON)"

        +"(ADDRESS=(PROTOCOL=TCP)(HOST=Dong1)(PORT=1521))"
        +"(ADDRESS=(PROTOCOL=TCP)(HOST=Dong2)(PORT=1521)))"
        +"(CONNECT_DATA=(SERVICE_NAME=CALLDB)(SERVER=DEDICATED)))";