escaping - java resultset.getstring("col_name") query -

i have simple query regarding resultset.getstring() method in java jdbc.
suppose value in database column having \ javas escape character e.g. \n or \t etc.
when retrieve value getstring() see 1 more escape character getting added , actual meaning of \n string literal only.
had unescape java , use properly.

string s= rs.getstring("col_name"); 

when s contains `\n':

system.out.println(s) 

output:

\n 

after unescaping java using apache common stringescapeutils
output:

system.out.println("hi"+s+"hello"); hi hello 

my question adding \ before unescaping?? sorry if dumb question.

the jdbc driver no escaping in resultset. bad if does. @ simple example:

the database table x contain 1 column value. there 2 rows: 1 2 character string ('\' , 'n') , 1 witch 1 character string (the newline character). i've added string-length output clarification.

select *, length(value) x;  value | length  -------+--------  \n    |      2       +|      1        |  

this table read jdbc:

    connection db = drivermanager.getconnection( /* these parameters */ );      statement st = db.createstatement();     resultset rs = st.executequery("select value, length(value) x");     while(rs.next()){         string value = rs.getstring(1);         int length = rs.getint(2);          system.out.println("length="+length+", value='"+value+"'");     } 

you see: no explicit escaping anywhere in code far. , output is:

length=2, value='\n' length=1, value=' ' 

you see: there still nothing escaped - neither code nor jdbc.

but

things bit murky if mix in java literals: if this:

st.execute("insert x values ('\n')"); 

then guess happened? have row one character!

length=2, value='\n' length=1, value=' ' length=1, value=' ' 

this because java compiler translated 2 characters '\n' 1 newline character. hence jdbc driver , database see 1 character.

but if have read userinput , user have typed \ , n nobody de-escape , row have contained 2 characters.

next step

you say, explicit de-escaping using stringescapeutils. happen:

• the row 1 character pass unaltered db screen.
• the row 2 characters changed stringescapeutils string containing 1 characters. after both row same you.

summary

do not confuse string-literal escaping compiler escaping jdbc (which won't happen).

do not add unnecessary escaping layers.