8.druid连接池

一、连接参数的配置，为了程序方便修改采用database.properties文件的方式。

#连接的配置
driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/videomanager
username=root
password=123
#<!-- 初始传输连接数 -->
initialSize=30
#最大连接数
maxActive=50
#<!-- 最小空闲连接数 -->
minIdle=5
#<!-- 如果超出最大连接数开始等待毫秒数，可能因为这个设置会报错 -->
maxWait=5000

二、通过database.properties创建DruidUtil连接池

package com.cqkj.utils;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
import javax.sql.DataSource;
import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidDataSourceFactory;


public class DruidUtil {
    static DataSource dataSource = null;
    static Connection con = null;
    static PreparedStatement  pst =  null;
    static ResultSet rs =  null;
    
    
    static{
        //实例化配置对象
        Properties properties = new Properties();
        try {                                                    //创建InputStream流    
              InputStream in = DruidUtil.class.getClassLoader().getResourceAsStream("database.properties");
                    //加载配置文件内容
              properties.load(in);
              dataSource = (DruidDataSource)DruidDataSourceFactory.createDataSource(properties);    
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    
    //加载驱动、获取链接
    public static Connection getConnection() {
        try {
            con = dataSource.getConnection();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return con;
    }
    
    //执行查询sql
    public static ResultSet query(String sql,Object[] obj) {
        try {
            con = getConnection();
            pst = con.prepareStatement(sql);
            if(obj != null) {
                for (int i = 0; i < obj.length; i++) {
                    pst.setObject(i+1, obj[i]);
                }
            }
            rs = pst.executeQuery();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return rs;
    }
    
    //执行增删改sql
    public static int update(String sql,Object[] obj) {
        int num = 0;
        try {
            con = getConnection();
            pst = con.prepareStatement(sql);
            if(obj != null) {
                for (int i = 0; i < obj.length; i++) {
                    pst.setObject(i+1, obj[i]);
                }
            }
            num = pst.executeUpdate();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return num;
    }
    
    
    public static void main(String[] args) {
        try {
            String sql = "select * from user";
            Object[] obj = {};
            rs = query(sql,obj);
            while(rs.next()) {
                String name = rs.getString(3);
                System.out.println(name);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}