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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> list = qr.query(con,sql,new MapListHandler());

for(Map 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 list = qr.query(con,sql,new ColumnListHandler("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.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.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 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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