Apache的DBUtils框架的查询结果处理器的使用（ResultSetHandler接口的子类）

1。导包

(1).commons-dbcp-1.4.jar

(2)commons-dbutils-1.4.jar

(3)commons-pool-1.5.6.jar

(4)mysql-connector-java-5.0.8-bin.jar

2。数据库配置文件：

#\u8FDE\u63A5\u8BBE\u7F6E
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/day18
username=root
password=admin

#<!-- \u521D\u59CB\u5316\u8FDE\u63A5 -->
initialSize=10

#\u6700\u5927\u8FDE\u63A5\u6570\u91CF
maxActive=50

#<!-- \u6700\u5927\u7A7A\u95F2\u8FDE\u63A5 -->
maxIdle=20

#<!-- \u6700\u5C0F\u7A7A\u95F2\u8FDE\u63A5 -->
minIdle=5

#<!-- \u8D85\u65F6\u7B49\u5F85\u65F6\u95F4\u4EE5\u6BEB\u79D2\u4E3A\u5355\u4F4D 6000\u6BEB\u79D2/1000\u7B49\u4E8E60\u79D2 -->
maxWait=60000

#JDBC\u9A71\u52A8\u5EFA\u7ACB\u8FDE\u63A5\u65F6\u9644\u5E26\u7684\u8FDE\u63A5\u5C5E\u6027\u5C5E\u6027\u7684\u683C\u5F0F\u5FC5\u987B\u4E3A\u8FD9\u6837\uFF1A[\u5C5E\u6027\u540D=property;]
#\u6CE8\u610F\uFF1A"user" \u4E0E "password" \u4E24\u4E2A\u5C5E\u6027\u4F1A\u88AB\u660E\u786E\u5730\u4F20\u9012\uFF0C\u56E0\u6B64\u8FD9\u91CC\u4E0D\u9700\u8981\u5305\u542B\u4ED6\u4EEC\u3002
connectionProperties=useUnicode=true;characterEncoding=utf8

#\u6307\u5B9A\u7531\u8FDE\u63A5\u6C60\u6240\u521B\u5EFA\u7684\u8FDE\u63A5\u7684\u81EA\u52A8\u63D0\u4EA4\uFF08auto-commit\uFF09\u72B6\u6001\u3002
defaultAutoCommit=true

#driver default \u6307\u5B9A\u7531\u8FDE\u63A5\u6C60\u6240\u521B\u5EFA\u7684\u8FDE\u63A5\u7684\u53EA\u8BFB\uFF08read-only\uFF09\u72B6\u6001\u3002
#\u5982\u679C\u6CA1\u6709\u8BBE\u7F6E\u8BE5\u503C\uFF0C\u5219\u201CsetReadOnly\u201D\u65B9\u6CD5\u5C06\u4E0D\u88AB\u8C03\u7528\u3002\uFF08\u67D0\u4E9B\u9A71\u52A8\u5E76\u4E0D\u652F\u6301\u53EA\u8BFB\u6A21\u5F0F\uFF0C\u5982\uFF1AInformix\uFF09
defaultReadOnly=

#driver default \u6307\u5B9A\u7531\u8FDE\u63A5\u6C60\u6240\u521B\u5EFA\u7684\u8FDE\u63A5\u7684\u4E8B\u52A1\u7EA7\u522B\uFF08TransactionIsolation\uFF09\u3002
#\u53EF\u7528\u503C\u4E3A\u4E0B\u5217\u4E4B\u4E00\uFF1A\uFF08\u8BE6\u60C5\u53EF\u89C1javadoc\u3002\uFF09NONE,READ_UNCOMMITTED, READ_COMMITTED, REPEATABLE_READ, SERIALIZABLE
defaultTransactionIsolation=REPEATABLE_READ

3。工具类：

package com.itheima.util;

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSourceFactory;

public class DBCPUtil {

private static DataSource dataSource;
static{
try {
InputStream in = DBCPUtil.class.getClassLoader().getResourceAsStream("dbcpconfig.properties");
Properties props = new Properties();
props.load(in);
dataSource = BasicDataSourceFactory.createDataSource(props);
} catch (Exception e) {
throw new ExceptionInInitializerError(e);
}
}
public static DataSource getDataSource(){
return dataSource;
}

public static Connection getConnection(){
try {
return dataSource.getConnection();
} catch (SQLException e) {
throw new RuntimeException(e);
}
}
}

4。查询结果的实现

ResultSetHandlerDemo.java文件：

package com.itheima.dbutil;

import java.util.List;
import java.util.Map;

import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.ArrayHandler;
import org.apache.commons.dbutils.handlers.ArrayListHandler;
import org.apache.commons.dbutils.handlers.ColumnListHandler;
import org.apache.commons.dbutils.handlers.KeyedHandler;
import org.apache.commons.dbutils.handlers.MapHandler;
import org.apache.commons.dbutils.handlers.MapListHandler;
import org.apache.commons.dbutils.handlers.ScalarHandler;
import org.junit.Test;

import com.itheima.util.DBCPUtil;

public class ResultSetHandlerDemo {
private QueryRunner qr = new QueryRunner(DBCPUtil.getDataSource());
//ArrayHandler:适合结果只有一条的情况。把第一条记录的每列的值封装到一个Object[]数组中
@Test
public void test1() throws Exception{
Object[] objs = qr.query("select * from student", new ArrayHandler());
for(Object obj:objs)
System.out.println(obj);
}
//ArrayListHandler:适合结果有多条的情况。把每列的值封装到Object[]数组中，把Object[]放到List中
@Test
public void test2() throws Exception{
List<Object[]> list = qr.query("select * from student", new ArrayListHandler());
for(Object[] objs:list){
System.out.println("----------------");
for(Object obj:objs){
System.out.println(obj);
}
}
}
//ColumnListHandler:适合取某列的值。把取到值封装到List中
@Test
public void test3() throws Exception{
List<Object> list = qr.query("select * from student", new ColumnListHandler("name"));
for(Object obj:list){
System.out.println(obj);
}
}
//KeyedHandler:查询多条记录。每条记录封装到一个Map中，key：字段名，value：字段值。再把Map作为value放到另外一个Map中，该Map的key为指定的列值作为key。
@Test
public void test4() throws Exception{
Map<Object,Map<String,Object>> bmap = qr.query("select * from student", new KeyedHandler("id"));
for(Map.Entry<Object,Map<String,Object>> bme:bmap.entrySet()){
System.out.println("--------------------");
for(Map.Entry<String, Object> lme:bme.getValue().entrySet()){
System.out.println(lme.getKey()+"="+lme.getValue());
}
}
}
//MapHandler:适合一条结果。封装到一个Map中，key：字段名，value：字段值
@Test
public void test5() throws Exception{
Map<String,Object> map = qr.query("select * from student", new MapHandler());
for(Map.Entry<String, Object> lme:map.entrySet()){
System.out.println(lme.getKey()+"="+lme.getValue());
}
}
//MapListHandler:适合多条结果。把每条封装到一个Map中，key：字段名，value：字段值，在把Map封装到List中
@Test
public void test6() throws Exception{
List<Map<String,Object>> list = qr.query("select * from student", new MapListHandler());
for(Map<String,Object> map:list){
System.out.println("--------------------");
for(Map.Entry<String, Object> lme:map.entrySet()){
System.out.println(lme.getKey()+"="+lme.getValue());
}
}
}
//ScalarHandler:适合取结果只有一行和一列的情况。
@Test
public void test7() throws Exception{
Object obj = qr.query("select count(*) from student", new ScalarHandler(1));
//      System.out.println(obj.getClass().getName());
Long l = (Long)obj;
System.out.println(l.intValue());
System.out.println(obj);
}
}

运行结果：

test()1:

5
yajg1
2016-09-12

test2():

----------------
5
yajg1
2016-09-12----------------
6
zhangsan
2016-09-12
----------------
15
yajg1
2016-09-12

test3():

yajg1
zhangsan
yajg1

test4():

--------------------
id=5
birthday=2016-09-12
name=yajg1
--------------------
id=6
birthday=2016-09-12
name=zhangsan
--------------------
id=15
birthday=2016-09-12
name=yajg1

test5():

id=5
birthday=2016-09-12
name=yajg1

test6():

--------------------
id=5
birthday=2016-09-12
name=yajg1
--------------------
id=6
birthday=2016-09-12
name=zhangsan
--------------------
id=15
birthday=2016-09-12
name=yajg1

test7():

3
3