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Java连载142-使用数据库连接池批量查询数据

一、创建一个数据库连接池

  • 首先建立工程 chaper03, 然后在src目录下创建 xml 文件
  • 该文件中定义了数据的密码的属性，用于连接数据库
<?xml version="1.0" encoding="UTF-8"?>

<c3p0-config>
<named-config name="qfedu">
<propertyname="driverClass">com.mysql.jdbc.Driver</property>
<property name="jdbcUrl" >jdbc:mysql:192.168.1.9:3306?encodingCharacter=utf8&amp;//</property>
<property name="user">root</property>
<property name="password">nicaibudao</property>
<property name="acquireIncrement">5</property>
<property name="initialPoolSize">20</property>
<property name="minPoolSize">10</property>
<property name="maxPoolSize">40</property>
<property name="maxStatement">0</property>
<property name="maxStatementPerConnection">5</property>
</named-config>


</c3p0-config>

  • 然后创建一个com.qfedu.utils的包，创建一个工具类 C3P0Utils，用于连接数据库等操作
package com.qfedu.utils;
import java.sql.Connection;
import java.sql.SQLException;
import javax.sql.DataSource;
import com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3P0Utils {
private static ComboPooledDataSource dataSource = new ComboPooledDataSource("qfedu");


<span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> DataSource <span class="hljs-title function_">getDataSource</span><span class="hljs-params">()</span> {
	<span class="hljs-keyword">return</span> dataSource;
}



}

  • 书写查询语句
package com.qfedu.test;
import java.sql.SQLException;
import java.util.List;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.ColumnListHandler;
import com.qfedu.utils.C3P0Utils;

public class TestDBUtils_ColumnListHandler {
public static void main(String[] args) throws SQLException{
QueryRunner queryRunner = new QueryRunner(C3P0Utils.getDataSource());


	<span class="hljs-type">String</span> <span class="hljs-variable">sql</span> <span class="hljs-operator">=</span> <span class="hljs-string">"select * from students"</span>;
	List&lt;Object&gt; list = (List&lt;Object&gt;) queryRunner.query(sql, <span class="hljs-keyword">new</span> <span class="hljs-title class_">ColumnListHandler</span>(<span class="hljs-string">"s_name"</span>));
	
	System.out.println(list);
}



}

二、源码：