QueryRunner类结果处理的八种方法

在连接数据库的时候(MySQL)时，会遇到的问题。

调用QueryRunner的方法是：

query(Connection con,String Sql,ResultSetHandler r,Object.params)

MapListHandler

将结果集每一行存储到Map集合中，键：列名；值：数据

public static void mapListHandler()throws SQLException{ QueryRunner qr = new QueryRunner(); String sql = "select * from db"; Lsit<Map<String,Object>> list = qr.query(con,sql,new MapListHandler()); for(Map<String,Object> map:list){ System.out.print(key+'..'+map.get(key)); } System.out.prinln(); }

MapHandler

将结果集的第一行数据，封存到Map集合中

public static void mapHandler()throws SQLException{ QueryRunner qr = new QueryRunner(); String sql = "select * from db"; Map map = qr.query(con,sql,new MapHandler()); for(String key:map.keySet()){ System.out.print(key+'..'+map.get(key)); } System.out.prinln(); }

ScalarHandler

查询后，只有一个结果

Public static void scalarHandler() throws SQLException(){ QueryRunner qr = new QueryRunner(); String sql = "select * from db"; long count = qr.query(con,sql,new ScalarHandler()); System.out.prinln(count); }

ColumnListHandler

结果集，指定列的数据存储到List集合中，

List每个列数据类型不同。

public static void columnListHandler()throws SQLException(){ QueryRunner qr = new QueryRunner(); String sql = "select * from db"; List<Object> list = qr.query(con,sql,new ColumnListHandler<Object>("name")); for(Object obj:list){ System.out.println(obj); } System.out.prinln(obj); }

BeanListHandler

结果集每一行数据，封装JavaBean对象

多个JavaBean对象，存储到List集合

public static void columnListHandler()throws SQLException(){ QueryRunner qr = new QueryRunner(); String sql = "select * from db"; List list = qr.query(con,sql,new BeanListHandler<Sort>(Sort.class)); for(Sort s:list){ System.out.println(s); } }

BeanHandler

将结果集的第一行数据,封装成JavaBean对象

public static void beanHandler()throws SQLException{ QueryRunner qr = new QueryRunner(); String sql = "SELECT * FROM sort "; Sort s = qr.query(con, sql, new BeanHandler<Sort>(Sort.class)); System.out.println(s); }

ArrayListHandler

将结果集的每一行,封装到对象数组中

public static void arrayListHandler()throws SQLException{ QueryRunner qr = new QueryRunner(); String sql = "SELECT * FROM sort"; List<Object[]> result= qr.query(con, sql, new ArrayListHandler()); for( Object[] objs : result){ for(Object obj : objs){ System.out.print(obj+" "); } System.out.println(); } }

ArrayHandler

将结果集的第一行存储到对象数组中 Object[]

public static void arrayHandler()throws SQLException{ QueryRunner qr = new QueryRunner(); String sql = "SELECT * FROM sort"; Object[] result = qr.query(con, sql, new ArrayHandler()); for(Object obj : result){ System.out.print(obj); } } }

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