Spring JDBC Query添加到地图

Question

I'm using the Spring JDBC Framework ( like here ) to obtain two columns from the database. I have used the 'Mapper' to implement 'RowMapper' class and I execute the query like this:

List<Entity> rows = template.query(sql, new EntityMapper());

This is my Mapper Class:

public class EntityMapper implements RowMapper<Entity> {

@Override
public Entity mapRow(ResultSet rs, int rowNum) throws SQLException {
    Entity entity = new Entity();
    entity.setID(rs.getString("ID"));
    entity.setAccount(rs.getString("ACCOUNT"));

    return entity;
}

Instead of storing the results of the query into a <List> , I want to store them into a Map - accountsById I created in the same class. I want the ID that goes into the Map to be my key so that I can obtain the Id's with getID()

 public List<String> getID() {
    if (accountsByID.isEmpty()) {
        return Collections.EMPTY_LIST;
    } else {
        return new ArrayList<String>(accountsByID.keySet());
    }
}

How do I store my query rows into a map in spring and set ID as key, with value being account .

Answer 1

queryForList returns a List of LinkedHashMap objects.

In order to get Map We need to cast the result of queryForList method like below

       List list = template.queryForList(...);
        for (Object o : list) {
           Map m = (Map) o;
           <your code here which uses Map objects>
        }

More about the method here