优化以下代码，以免花费更多时间不执行查询

Question

I have the below code which is a simple jdbc java program which fetch the results upon execution of the query and retrieve the results and further store them in a resultset

The Statement.execute() method allows us to execute any kind of query like select, update. It returns boolean. If the return value is true, then it executed select query, get the ResultSet object and read the resulted records. If it returns false, then it can be update query, call getUpdateCount() method to get total records updated

public static void main(String a[]){

        Connection con = null;
        try {
            Class.forName("oracle.jdbc.driver.OracleDriver");
            con = DriverManager.
                    getConnection("jdbc:oracle:thin:@<hostname>:<port num>:<DB name>"
                        ,"user","password");
            Statement stmt = con.createStatement();
            //The query can be update query or can be select query
            String query = "select * from emp";
            boolean status = stmt.execute(query);
            if(status){
                //query is a select query.
                ResultSet rs = stmt.getResultSet();
                while(rs.next()){
                    System.out.println(rs.getString(1));
                }
                rs.close();
            } else {
                //query can be update or any query apart from select query
                int count = stmt.getUpdateCount();
                System.out.println("Total records updated: "+count);
            }
        } catch (ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally{
            try{
                if(con != null) con.close();
            } catch (Exception ex){}
        }
    }

Now my query is to I have to optimize this program in such a way like

1)It should print the time taken by query to execute at runtime

2) need to add the condition in such a way ...if the query takes more than 1 min then it should stop at that time means some counter should be there which will keep track of the time that it should not be more than 1 min

Please advise how to achieve

Answer 1

• Log System.currentTimeMillis() (which returns the current time in milliseconds) as the last thing before executing your query. Subtract as soon as the execute() returns.

• And, use Statement.setQueryTimeout(int seconds) to specify your timeout value as

   stmt.setQueryTimeout(60); long start = System.currentTimeMillis(); boolean status = stmt.execute(query); System.out.println("Took " + (start - System.currentTimeMillis()) + " ms");