how to implementing this simple logic in spring batch? - spring-batch

Question

i tried to make this as simple as possible. i`m new to spring batch, i have a small isuue with understanding how to relate spring items together especially when it comes to multi-steps jobs however this is my logic not code(simplified) and i dont know to impliment it in spring batch so i thought this might be the right structure
reader_money
reader_details
tasklet
reader_profit
tasklet_calculation
writer
however please correct me if i`m wrong and provide some code if possible.
thank you very much
LOGIC:
sql = "select * from MONEY where id= user input"; //the user will input the condition
while (records are available) {
int currency= resultset(currency column);
sql= "select * from DETAILS where D_currency = currency";
while (records are available) {
int amount= resultset(amount column);
string money_flag= resultset(money_type column);
sql= "select * from PROFIT where Mtypes = money_type";
while (records are available) {
int revenue= resultset(revenue);
if (money_type== 1) {
int net_profit= revenue * 3.75;
sql = "update PROFIT set Nprofit = net_profit";
}
else (money_type== 2) {
int net_profit = (revenue - 5 ) * 3.7 ;
sql = "update PROFIT set Nprofit = net_profit";
}
}
sql="update DETAILS set detail_falg = 001 ";
}
sql = "update MONEY set currency_flag = 009";
}

Answer 1

to fit this into a 'conventional' spring batch configuration, you would need to flatten the three loops into one if possible.
perhaps a sql statement that would return it in one loop similiar to;
select p.revenue, d.amount from PROFIT p, DETAILS d, MONEY m where p.MTypes = d.money_type and d.D_currency = m.currency and m.id = :?
once you've "flattened" it, you then fall into the more 'conventional' read/process/write of a chunk pattern where the reader retrieves a record from the resultset, the processor performs the money_type logic, and the writer then executes the 'update' statement.

Answer 2

Check for the use of ItemReaderAdapter where you could place all your SQL in some kind of DAO that could return a list of aggregated object containing all the info you need for your calculation.
Or
You could use the CompositeItemReader pattern. You basicaly define multiple ItemReader into one master ItemReader. The read() method will invoke all the inner ItemReader before going to the Processor /writer phase.
I could post you some example.. but i have to leave :-(..
Leave a comment if you need some example