扫java盲区知识点之JDBC（2021-10-24）Druid数据库连接池

与c3p0不同，Druid的配置文件是properties形式的。而且Druid不像c3p0那样可以自动加载配置文件，Druid需要手动去指定配置文件，所以Druid的配置文件可以叫任意名称，并且可以放置在任意目录下。
　1、导入druid-1.0.9.jar和mysql连接器。
　
2、配置文件druid.properties

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/test
username=root
password=root
initialSize=5
maxActive=10
maxWait=3000

3、工具类

package utils;

import com.alibaba.druid.pool.DruidDataSourceFactory;

import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class JdbcUtils_Druid {
    private static DataSource ds;
    static {
        try{
            Properties prop = new Properties();
            prop.load(JdbcUtils_Druid.class.getClassLoader().getResourceAsStream("druid.properties"));
            ds = DruidDataSourceFactory.createDataSource(prop);
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    //获取连接对象
    public static Connection getConnection() throws SQLException {
        return ds.getConnection();
    }

    //释放资源
    public static void close(Connection conn, Statement st){
        close(conn,st,null);
    }

    public static void close(Connection conn, Statement st, ResultSet rs){
        if(st!=null){
            try {
                st.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        if(conn!=null){
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        if(rs!=null){
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    //获取连接池
    public static DataSource getDataSource(){
        return ds;
    }
}

4、测试类

package druidtest;

import utils.JdbcUtils_Druid;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

public class TestDruid2 {
    public static void main(String[] args) {
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try{
            conn = JdbcUtils_Druid.getConnection();
            String sql = "select * from test1 where id = ?";
            ps = conn.prepareStatement(sql);
            ps.setInt(1,1);
            rs = ps.executeQuery();
            while (rs.next()){
                int id = rs.getInt("id");
                String name = rs.getString("name");
                System.out.println("name:"+name+",id="+id);
            }

        }catch (Exception e){
            e.printStackTrace();
        }finally {
            JdbcUtils_Druid.close(conn,ps,rs);
        }

    }
}