dbUtils结果集处理器

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <c3p0-config>
 3     <!-- 这是默认配置信息 -->
 4     <default-config> 
 5         <!-- 连接四大参数配置 -->
 6         <property name="jdbcUrl">jdbc:mysql://localhost:3306/test</property>
 7         <property name="driverClass">com.mysql.jdbc.Driver</property>
 8         <property name="user">root</property>
 9         <property name="password">abcd@1234</property>
10         <!-- 池参数配置 -->
11         <property name="acquireIncrement">3</property>
12         <property name="initialPoolSize">10</property>
13         <property name="minPoolSize">2</property>
14         <property name="maxPoolSize">10</property>
15     </default-config>
16     
17     <!-- 专门为oracle提供的配置信息 -->
18     <named-config name="oracle-config"> 
19         <property name="jdbcUrl">jdbc:mysql://localhost:3306/mydb1</property>
20         <property name="driverClass">com.mysql.jdbc.Driver</property>
21         <property name="user">root</property>
22         <property name="password">123</property>
23         <property name="acquireIncrement">3</property>
24         <property name="initialPoolSize">10</property>
25         <property name="minPoolSize">2</property>
26         <property name="maxPoolSize">10</property>
27     </named-config>
28 
29 </c3p0-config>

 1 package cn.itcast.utils;
 2 
 3 import java.sql.Connection;
 4 import java.sql.SQLException;
 5 
 6 import javax.sql.DataSource;
 7 
 8 import com.mchange.v2.c3p0.ComboPooledDataSource;
 9 
10 public class JdbcUtils {
11     // 配置文件的默认配置！要求你必须给出c3p0-config.xml！！！
12     private static ComboPooledDataSource dataSource = new ComboPooledDataSource();
13     
14     /**
15      * 使用连接池返回一个连接对象
16      * @return
17      * @throws SQLException
18      */
19     public static Connection getConnection() throws SQLException {
20         return dataSource.getConnection();
21     }
22     
23     /**
24      * 返回连接池对象！
25      * @return
26      */
27     public static DataSource getDataSource() {
28         return dataSource;
29     }
30 }

  1 package cn.itcast.dbutils;
  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.BeanHandler;
  9 import org.apache.commons.dbutils.handlers.BeanListHandler;
 10 import org.apache.commons.dbutils.handlers.MapHandler;
 11 import org.apache.commons.dbutils.handlers.MapListHandler;
 12 import org.apache.commons.dbutils.handlers.ScalarHandler;
 13 import org.junit.Test;
 14 
 15 import cn.itcast.jdbc.JdbcUtils;
 16 
 17 public class Demo3 {
 18     @Test
 19     public void fun1() throws SQLException {
 20         QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
 21         String sql = "insert into t_stu values(?,?,?,?)";
 22         Object[] params = {1002, "liSi", 88, "female"};
 23         
 24         qr.update(sql, params);
 25     }
 26     
 27     @Test
 28     public void fun2() throws SQLException {
 29         // 创建QueryRunner，需要提供数据库连接池对象
 30         QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
 31         // 给出sql模板
 32         String sql = "select * from t_stu where sid=?";
 33         // 给出参数
 34         Object[] params = {1001};
 35         
 36 //        ResultSetHandler<Stu> rsh = new ResultSetHandler<Stu>() {
 37 //
 38 //            @Override
 39 //            public Stu handle(ResultSet rs) throws SQLException {
 40 //                // TODO Auto-generated method stub
 41 //                return null;
 42 //            }
 43 //        };
 44         // 执行query()方法，需要给出结果集处理器，即ResultSetHandler的实现类对象
 45         // 我们给的是BeanHandler，它实现了ResultSetHandler
 46         // 它需要一个类型，然后它会把rs中的数据封装到指定类型的javabean对象中，然后返回javabean
 47         Stu stu = qr.query(sql, new BeanHandler<Stu>(Stu.class), params);
 48         System.out.println(stu);
 49     }
 50     
 51     /**
 52      * BeanListHandler的应用，它是多行处理器
 53      * 每行对象一个Stu对象！
 54      * @throws Exception
 55      */
 56     @Test
 57     public void fun3() throws Exception {
 58         QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
 59         String sql = "select * from t_stu";
 60         List<Stu> stuList = qr.query(sql, new BeanListHandler<Stu>(Stu.class));
 61         
 62         System.out.println(stuList);
 63     }
 64     
 65     /**
 66      * MapHandler的应用，它是单行处理器，把一行转换成一个Map对象
 67      * @throws SQLException 
 68      */
 69     @Test
 70     public void fun4() throws SQLException  {
 71         QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
 72         String sql = "select * from t_stu where sid=?";
 73         Object[] params = {1001};
 74         Map map = qr.query(sql, new MapHandler(), params);
 75         
 76         System.out.println(map);
 77     }
 78     
 79     /**
 80      * MapListHandler，它是多行处理器，把每行都转换成一个Map，即List<Map>
 81      * @throws SQLException
 82      */
 83     @Test
 84     public void fun5() throws SQLException  {
 85         QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
 86         String sql = "select * from t_stu";
 87         List<Map<String,Object>> mapList = qr.query(sql, new MapListHandler());
 88         
 89         System.out.println(mapList);
 90     }
 91     
 92     /**
 93      * ScalarHandler，它是单行单列时使用，最为合适！
 94      * @throws SQLException
 95      */
 96     @Test
 97     public void fun6() throws SQLException {
 98         QueryRunner qr = new QueryRunner(JdbcUtils.getDataSource());
 99         String sql = "select count(*) from t_stu";
100         /*
101          * Integer、Long、BigInteger
102          */
103         Number cnt = (Number)qr.query(sql, new ScalarHandler());
104         
105         long c = cnt.longValue();
106         System.out.println(c);
107     }
108 }