Spring Batch FlatFileItemWriter - output customization

Question

I would have the need to produce a CSV File with the following requirements:

• Every field is surrounded by double quotes
• Double quotes are escaped with backslash
• Backslash is escaped with backslash

Input:

• Field1
• Field2With\Backslash"DoubleQuotes"And|Pipe
• Field3

Expected output:

"Field1"|"Field2With\\Backslash\"DoubleQuotes\"And|Pipe"|"Field3"

Is it possible to obtain such an output?

Answer 1

Best solution is to implement quoting and escaping in a subclass of DelimitedLineAggregator.

Answer 2

Basically, you just want to process your fields before writing it. You could do it with these 2 ways

Let's say this method processes your field

public String escape(String str) {
    str = "\"" + str + "\"";
    str = str.replace("|", "\\|");
    str = str.replace("\\", "\\\\");
    return str;
}

1 - Process it during processor - preferred

@Override
public A process(B b) throws Exception {
    A a = new A();
    //Process b to a...    

    a.setField1(escape(a.getField1)); //For each fields
    return a;
}

2 - Process it before writing in custom Writer

public class EscapeFlatFileItemWriter<A> extends FlatFileItemWriter<A> {

    @Override
    public void write(List<? extends A> items) throws Exception {
        for (A a : items) {
            a.setField1(escape(a.getField1)); //For each fields
        }
        super.write(items);
    }
}