IDEA使用C3P0连接Mysql数据库

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
  <!--
  C3P0的缺省(默认)配置，
  如果在代码中“ComboPooledDataSource ds = new ComboPooledDataSource();”这样写就表示使用的是C3P0的缺省(默认)配置信息来创建数据源
  -->
  <default-config>
    <property name="driverClass">com.mysql.cj.jdbc.Driver</property>
    <property name="jdbcUrl">jdbc:mysql://localhost:3306/book_test?useSSL=false&amp;serverTimezone=CTT&amp;characterEncoding=utf8</property>
    <property name="user">root</property>
    <property name="password">123456</property>
    <property name="acquireIncrement">5</property>
    <property name="initialPoolSize">10</property>
    <property name="minPoolSize">5</property>
    <property name="maxPoolSize">20</property>
  </default-config>
  <!--
  C3P0的命名配置，
  如果在代码中“ComboPooledDataSource ds = new ComboPooledDataSource("MySQL");”这样写就表示使用的是name是MySQL的配置信息来创建数据源
  -->
  <named-config name="MySQL">
    <property name="driverClass">com.mysql.cj.jdbc.Driver</property>
    <property name="jdbcUrl">jdbc:mysql://localhost:3306/book_test?useSSL=false&amp;serverTimezone=CTT&amp;characterEncoding=utf8</property>
    <property name="user">root</property>
    <property name="password">123456</property>
    <property name="acquireIncrement">5</property>
    <property name="initialPoolSize">10</property>
    <property name="minPoolSize">5</property>
    <property name="maxPoolSize">20</property>
  </named-config>
</c3p0-config>

/**
 * @author 蓝多多的小仓库
 * @title: C3P0_Utils
 * @projectName ldd_firstpro
 * @description: ldd_annotation
 * @date 2022/1/13 15:23
 */
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class C3P0_Utils {
  private static ComboPooledDataSource dataSource = null;
  //在静态代码块中创建数据库连接池
  static{
    try{
      dataSource = new ComboPooledDataSource("MySQL");//使用C3P0的命名配置来创建数据源
      System.out.println(dataSource);
    }catch (Exception e) {
      throw new ExceptionInInitializerError(e);
    }
  }
  public static Connection getConnection() throws SQLException{
    //从数据源中获取数据库连接
    return dataSource.getConnection();
  }
  // 释放资源
  public static void release(Connection conn,Statement st,ResultSet rs){
    if(rs!=null){
      try{
        //关闭存储查询结果的ResultSet对象
        rs.close();
      }catch (Exception e) {
        e.printStackTrace();
      }
      rs = null;
    }
    if(st!=null){
      try{
        //关闭负责执行SQL命令的Statement对象
        st.close();
      }catch (Exception e) {
        e.printStackTrace();
      }
    }
    if(conn!=null){
      try{
        //将Connection连接对象还给数据库连接池
        conn.close();
      }catch (Exception e) {
        e.printStackTrace();
      }
    }
  }
}

/**
 * @author 蓝多多的小仓库
 * @title: DataSourceTest
 * @projectName ldd_firstpro
 * @description: ldd_annotation
 * @date 2022/1/13 15:24
 */
import java.math.BigDecimal;
import java.sql.Connection;
import java.sql.Date;
import java.sql.ResultSet;
import java.sql.Statement;
public class DataSourceTest {
  public void c3p0DataSourceTest() {
    Connection conn = null;
    Statement st = null;
    ResultSet rs = null;
    try {
      //获取数据库连接
      conn = C3P0_Utils.getConnection();
      String sql = "select * from bookinfo";     // 查询数据的sql语句
      st = (Statement) conn.createStatement();    //创建用于执行静态sql语句的Statement对象，st属局部变量
      rs = st.executeQuery(sql);    //执行sql查询语句，返回查询数据的结果集
      System.out.println("最后的查询结果为：");
      while(rs.next()){ //遍历结果集，取出数据
        int book_id = rs.getInt("book_id");
        String book_name = rs.getString("book_name");
        BigDecimal price = rs.getBigDecimal("price");
        Date public_date = rs.getDate("public_date");
        String store = rs.getString("store");
        //输出数据
        System.out.print("图书编号："+book_id);
        System.out.print("，图书名称："+book_name);
        System.out.print("，价格"+price);
        System.out.print("，出版日期"+public_date);
        System.out.print(",库存"+store);
        System.out.println();
      }
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      //释放资源
      C3P0_Utils.release(conn, st, rs);
    }
  }
  public static void main(String[] args) {
    new DataSourceTest().c3p0DataSourceTest();
  }
}