spring - How to rewrite jdbcTemplate query using JDK8 features? -

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here's code. let's there many large images in db want keep 1 in memory @ time. how write using jdk 8 features lambda , streams?

i started using kept failing ( https://spring.io/guides/gs/relational-data-access/ , www.jooq.org/java-8-and-sql) , using resultsetextractor working intendent, there way without resultsetextractor?

 jdbctemplate.query(              "select id,image,mimetype images",             new resultsetextractor(){                   @override                   public list extractdata(resultset rs) throws sqlexception, dataaccessexception {                           while(rs.next()){                              createthumbnail( new imageholder(rs.getint("id"), rs.getbytes("image"), rs.getstring("mimetype") ));                         }                           return null;                     }               }     );

this nice looking stream/lambda version works holds many things in memory , gives oome sooner or later.

 jdbctemplate.query(               "select id,image,mimetype images",              (rs,rownum)->new imageholder(rs.getint("id"), rs.getbytes("image"),rs.getstring("mimetype"))     ).stream().foreach(                       imageholder -> createthumbnail(imageholder)     ) );

this loads rows before starts "streaming" them.

a solution move generation of thumbnail in first lambda, translating directly first example.

jdbctemplate.query(           "select id,image,mimetype images",          (rs,rownum)-> {              createthumbnail(new imageholder(                 rs.getint("id"),                 rs.getbytes("image"),                 rs.getstring("mimetype") ));          }) )

to have structure similar 1 tried achieve query method should return stream don't have collect before streaming.


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