代码如下:
rt com.alibaba.druid.pool.DruidDataSourceFactory;
import javax.sql.DataSource;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.util.Properties;
/*
利用druid连接池进行数据库查询操作(配置文件方式)
*/
public class Test03 {
public static void main(String[] args) throws Exception {
/*
导包
准备配置文件,只要是properties文件即可,需要自己加载该配置文件
创建连接池对象
获取连接
获取语句执行者进行后续的一系列操作
*/
//创建properties对象,将配置文件信息读取到该对象中
Properties pro = new Properties();
InputStream in = Test03.class.getClassLoader().getResourceAsStream("druid.properties");//获取输入流
pro.load(in);//读取配置文件的信息到ps中,抛出异常
DataSource dataSource = DruidDataSourceFactory.createDataSource(pro);//获取连接池
Connection connection = dataSource.getConnection();//获取连接
//查询出部门编号、部门名称、部门位置、每个部门的员工人数
String sql =" SELECT d.id,d.dname,d.loc,COUNT(*) FROM emp e JOIN dept d ON e.`dept_id`= d.`id` GROUP BY d.`id`;";
//查询经理的信息。显示员工姓名，员工工资，职务名称，职务描述，部门名称，部门位置，工资等级
String sql1 = "select e.ename,e.salary,j.jname,j.description,d.dname,d.loc,s.grade from emp e join job j join\n" +
"dept d join salarygrade s on e.`dept_id`= d.`id` and e.`job_id`=j.`id` where j.`jname`='经理'\n" +
"and e.`salary` between s.`losalary` and s.`hisalary`;";
//查询所有员工信息。显示员工姓名，员工工资，职务名称，职务描述，部门名称，部门位置，工资等级
String sql2 = " select e.ename,e.salary,j.jname,j.description,d.dname,d.loc,s.grade from emp e join job j join\n" +
" dept d join salarygrade s on e.`job_id`= j.`id` and e.`dept_id`= d.`id` where e.`salary` between \n" +
" s.`losalary` and s.`hisalary`;";
//获取语句执行者等一系列操作
PreparedStatement ps = connection.prepareStatement(sql);
PreparedStatement ps1 = connection.prepareStatement(sql1);
PreparedStatement ps2 = connection.prepareStatement(sql2);
ResultSet resultSet = ps.executeQuery();
ResultSet resultSet1 = ps1.executeQuery();
ResultSet resultSet2 = ps2.executeQuery();
while (resultSet.next()) {
int id = resultSet.getInt("id");
String dname = resultSet.getString("dname");
String loc = resultSet.getString("loc");
int count = resultSet.getInt("count(*)");
System.out.println("id="+id+" dname="+dname+" loc="+loc+" count="+count );
}
System.out.println("===================================================================");
while (resultSet1.next()) {
String ename = resultSet1.getString("ename");
int salary = resultSet1.getInt("salary");
String jname = resultSet1.getString("jname");
String description = resultSet1.getString("description");
String dname = resultSet1.getString("dname");
String loc = resultSet1.getString("loc");
int grade = resultSet1.getInt("grade");
System.out.println("ename="+ename+" salary="+salary+" jname="+jname+" description="+description
+" dname="+dname+" loc="+loc+" grade="+grade);
}
System.out.println("===================================================================");
while (resultSet2.next()) {
String ename = resultSet2.getString("ename");
int salary = resultSet2.getInt("salary");
String jname = resultSet2.getString("jname");
String description = resultSet2.getString("description");
String dname = resultSet2.getString("dname");
String loc = resultSet2.getString("loc");
int grade = resultSet2.getInt("grade");
System.out.println("ename="+ename+" salary="+salary+" jname="+jname+" description="+description
+" dname="+dname+" loc="+loc+" grade="+grade);
}
//释放资源
Utils11.closeResource(resultSet,ps,connection);
Utils11.closeResource(resultSet1,ps1,null);
Utils11.closeResource(resultSet2,ps2,null);
}
}
配置文件概况:
控制台打印效果: