单行数据处理:
ScalarHandler ArrayHandler MapHandler BeanHandler
多行数据处理:BeanListHandler AbstractListHandler(ArrayListHandler MapListHandler ColumnListHandler)
AbstractKeyedHandler(KeyedHandler BeanMapHandler)
可供扩展的类:
BaseResultSetHandler
一、ScalarHandler:获取结果集第一行某列;泛型决定返回值类型,默认返回Object;
String sql="select * from book where id=?";
1.Float name = runner.query(sql, new ScalarHandler
2.Float name = runner.query(sql, new ScalarHandler
3.Float name = runner.query(sql, new ScalarHandler
二、ArrayHandler:获取结果集第一行;返回值默认为Object[];
String sql="select * from book where id=?";
1.Object[] o = runner.query(sql, new ArrayHandler(),1);//获取结果集第一行,并且将每列封装成Object[]的元素;
for (Object object : o) {
System.out.println(String.valueOf(object));
}
三、MapHandler:获取结果集第一行,将其封装成LinkHashMap,返回值Map
String sql = “select * form book where id=?”;
Map
Set set = map.keySet();
for (Iterator iterator = set.iterator(); iterator.hasNext();) {
Object object = (Object) iterator.next();
System.out.println(map.get(object));
}
System.out.println(map.get("ID"));//注意 map的key是不区分大小写的
四、BeanHandler
注意:要保证数据库表的字段和javabean(User)的属性一致,并且不区分大小写
String sql = "select * from users";
User user = runner.query(sql,new BeanHandler
System.out.println(user);
五、BeanListHandler:将结果集的每一行数据转换为Javabean,再将这个Javabean添加到ArrayList中。
String sql = "select * from book where id
List
for (Iterator
Book book = (Book) iterator.next();
System.out.println(book);
六、AbstractListHandler。。。
七、ArrayListHandler (extends AbstractListHandler
,然后再将Object[]添加到ArrayList 里面;
String sql = "select id,name,price from book where id
List
for (Iterator
Object[] objects = (Object[]) iterator.next();
for(Objectobject:objects){
System.out.print(object);
}
System.out.println();
}
八、MapListHandler (extends AbstractListHandler
String sql = "select id,name,price from book where id
List list = runner.query(sql, new MapListHandler(),5);
for (Iterator iterator = list.iterator(); iterator.hasNext();) {
Map map = (Map) iterator.next();
System.out.println(map.toString());
}
九、ColumnListHandler
1.List list = runner.query(sql, new ColumnListHandler
2.List list = runner.query(sql, new ColumnListHandler
十、KeyedHandler
String sql = "select * from book where id
Map
System.out.println(map);
十一、BeanMapHandler
String sql = "select * from book where id<5";
Map
Set set = map.keySet();
for(Objectobject:set){
System.out.println(map.get(object));
}