1 package cn.itcast.dbutil;
2
3 import java.sql.SQLException;
4 import java.util.List;
5 import java.util.Map;
6
7 import org.apache.commons.dbutils.QueryRunner;
8 import org.apache.commons.dbutils.handlers.ArrayHandler;
9 import org.apache.commons.dbutils.handlers.ArrayListHandler;
10 import org.apache.commons.dbutils.handlers.BeanHandler;
11 import org.apache.commons.dbutils.handlers.BeanListHandler;
12 import org.apache.commons.dbutils.handlers.ColumnListHandler;
13 import org.apache.commons.dbutils.handlers.KeyedHandler;
14 import org.apache.commons.dbutils.handlers.MapHandler;
15 import org.apache.commons.dbutils.handlers.MapListHandler;
16 import org.apache.commons.dbutils.handlers.ScalarHandler;
17 import org.junit.Test;
18
19 import cn.itcast.domain.Account;
20 import cn.itcast.util.DBCPUtil;
21
22 //查询练习
23 public class DbUtilDemo2 {
24 private QueryRunner qr = new QueryRunner(DBCPUtil.getDataSource());
25 @Test//BeanHandler
26 public void test1() throws SQLException{
27 Account a = qr.query("select * from account where id=?", new BeanHandler<Account>(Account.class), 1);
28 System.out.println(a);
29 }
30 @Test//BeanListHandler
31 public void test2() throws SQLException{
32 List<Account> list = qr.query("select * from account", new BeanListHandler<Account>(Account.class));
33 for(Account a:list)
34 System.out.println(a);
35 }
36
37 @Test//ArrayHandler：把结果集中的第一行数据转成对象数组。只适合结果集有一条记录的情况
38 public void test3() throws SQLException{
39 //该数组中每个元素就是记录的每列的值
40 Object objs[] = qr.query("select * from account where id=?", new ArrayHandler(),1);
41 for(Object o:objs)
42 System.out.println(o);
43 }
44 @Test//ArrayListHandler：把结果集中的每一行数据都转成一个数组，再存放到List中。
45 public void test4() throws SQLException{
46 //该数组中每个元素就是记录的每列的值
47 List<Object[]> list = qr.query("select * from account", new ArrayListHandler());
48 for(Object[] objs:list){
49 System.out.println("-----------------");
50 for(Object o:objs)
51 System.out.println(o);
52 }
53 }
54 @Test//ColumnListHandler：将结果集中某一列的数据存放到List中
55 public void test5() throws SQLException{
56 List<Object> list = qr.query("select * from account", new ColumnListHandler("id"));
57 for(Object o:list)
58 System.out.println(o);
59 }
60 @Test//KeyedHandler(name)：将结果集中的每一行数据都封装到一个Map<列名,列值>里，再把这些map再存到一个map里，其key为指定的key。
61 public void test6() throws SQLException{
62 Map<Object, Map<String,Object>> bmap= qr.query("select * from account", new KeyedHandler("id"));
63 for(Map.Entry<Object, Map<String,Object>> bme:bmap.entrySet()){
64 System.out.println("-----------------");
65 Map<String,Object> lmap = bme.getValue();
66 for(Map.Entry<String,Object> lme:lmap.entrySet()){
67 System.out.println(lme.getKey()+"="+lme.getValue());
68 }
69 }
70 }
71 @Test//MapHandler：将结果集中的第一行数据封装到一个Map里，key是列名，value就是对应的值。
72 public void test7() throws SQLException{
73 Map<String,Object> map= qr.query("select * from account where id=?", new MapHandler(),1);
74 for(Map.Entry<String, Object> me:map.entrySet()){
75 System.out.println(me.getKey()+"="+me.getValue());
76 }
77 }
78 @Test//MapListHandler：将结果集中的每一行数据都封装到一个Map里，然后再存放到List
79 public void test8() throws SQLException{
80 List<Map<String,Object>> list= qr.query("select * from account", new MapListHandler());
81 for(Map<String,Object> map:list){
82 System.out.println("-----------------");
83 for(Map.Entry<String, Object> me:map.entrySet()){
84 System.out.println(me.getKey()+"="+me.getValue());
85 }
86 }
87 }
88 @Test//ScalarHandler 适合取一条一列的记录。比如记录总数
89 public void test9() throws SQLException{
90 Object obj = qr.query("select count(*) from account", new ScalarHandler(1));
91 System.out.println(obj.getClass().getName());
92 int num = ((Long)obj).intValue();
93 System.out.println(num);
94 }
95 }