【官方正版】javascript與jquery網(wǎng)頁(yè)

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在連接數(shù)據(jù)庫(kù)的時(shí)候(MySQL)時(shí)，會(huì)遇到的問(wèn)題。

調(diào)用QueryRunner的方法是：

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

MapListHandler

將結(jié)果集每一行存儲(chǔ)到Map集合中，鍵：列名；值：數(shù)據(jù)

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

將結(jié)果集的第一行數(shù)據(jù)，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

查詢(xún)后，只有一個(gè)結(jié)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

結(jié)果集，指定列的數(shù)據(jù)存儲(chǔ)到List集合中，

List每個(gè)列數(shù)據(jù)類(lèi)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

結(jié)果集每一行數(shù)據(jù)，封裝JavaBean對(duì)象

多個(gè)JavaBean對(duì)象，存儲(chǔ)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

將結(jié)果集的第一行數(shù)據(jù),封裝成JavaBean對(duì)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

將結(jié)果集的每一行,封裝到對(duì)象數(shù)組中

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

將結(jié)果集的第一行存儲(chǔ)到對(duì)象數(shù)組中 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);

}

}

}

java 11官方入門(mén)(第8版)教材

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