1、DBCP

DBCP（DataBase Connection Pool）数据库连接池，由Apache公司开发。连接池的运用避免了反复建立连接造成的资源浪费，预先建立一些连接放在数据库连接池中，需要时取出，不需要时放入连接池。

（1）导包：需要导入两个jar包：commons-pool-1.5.6和commons-dbcp-1.4.jar

（2）DBCP工具类：

import java.io.IOException;

import java.io.InputStream;

import java.util.Properties;

import org.apache.commons.dbcp.BasicDataSource;

public class JDBCUtils {

    private static BasicDataSource datasource = new BasicDataSource();

    /*

     * BasicDataSource类，实现了datasource接口

     */

    static {// 静态代码块,对象BasicDataSource对象中的配置,自定义

        InputStream in = JDBCUtils.class.getClassLoader().getResourceAsStream("DBCP.properties");

        Properties pro = new Properties();

        try {

            pro.load(in);

        } catch (IOException e) {

            e.printStackTrace();

        }

        // 数据库基本的连接信息，必须要设置（必须项）

        datasource.setDriverClassName(pro.getProperty("driver"));

        datasource.setUrl(pro.getProperty("url"));

        datasource.setUsername(pro.getProperty("username"));

        datasource.setPassword(pro.getProperty("password"));

        // 对象连接池中的连接数量配置,可以不设置（基本项）

        datasource.setInitialSize();// 初始化的连接数

        datasource.setMaxActive();// 最大连接数量

        datasource.setMaxIdle();// 最大空闲数

        datasource.setMinIdle();// 最小空闲

    }

    // 返回BasicDataSource类的对象

    public static BasicDataSource getDataSource() {

        return datasource;

    }

}
import java.sql.SQLException;

import java.util.List;

import org.apache.commons.dbutils.QueryRunner;

import org.apache.commons.dbutils.handlers.ArrayListHandler;

public class Test {

    public static void main(String[] args) {

        QueryRunner qr = new QueryRunner(JDBCUtils.getDataSource());//参数为数据源

        try {

            String sql = "select * from Student";

            List<Object[]> list = qr.query(sql, new ArrayListHandler());

            for (Object[] objs : list) {//list集合

                for (Object obj : objs) {

                    System.out.print(obj + "\t");

                }

                System.out.println();

            }

        } catch (SQLException ex) {

            System.out.println(ex);

            throw new RuntimeException("数据查询失败");

        }

    }

}

（3）配置文件：

2、C3P0

（1）导入jar包：

（2）配置文件：

<?xml version="1.0" encoding="UTF-8"?>

<c3p0-config>

    <default-config>

        <property name="driverClass">com.mysql.jdbc.Driver</property>

        <property name="jdbcUrl">jdbc:mysql://localhost:3306/student mangement system</property>

        <property name="user">root</property>

        <property name="password">root</property>

        <property name="initialPoolSize">5</property>

        <property name="maxPoolSize">20</property>

    </default-config>

    <named-config name="zhai">

        <property name="driverClass">com.mysql.jdbc.Driver</property>

        <property name="jdbcUrl">jdbc:mysql://localhost:3306/student mangement system</property>

        <property name="user">root</property>

        <property name="password">root</property>

    </named-config>

</c3p0-config>

（3）C3P0工具类：

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import com.mchange.v2.c3p0.ComboPooledDataSource;

import com.mysql.jdbc.Statement;

public class C3P0Utils {

    private static ComboPooledDataSource dataSource = new ComboPooledDataSource(

            "zhai");

    public static ComboPooledDataSource getDataSource() {

        return dataSource;

    }

    public static Connection getConnection() {

        try {

            return dataSource.getConnection();

        } catch (SQLException e) {

            throw new RuntimeException(e);

        }

    }

    public static void close(Connection con, Statement stat) {

        if (stat != null) {

            try {

                stat.close();

            } catch (SQLException e) {

                e.printStackTrace();

                System.out.println("stat流关闭异常！");

            }

        }

        if (con != null) {

            try {

                con.close();

            } catch (SQLException e) {

                e.printStackTrace();

                System.out.println("con流关闭异常！");

            }

        }

    }

    public static void close(Connection con, Statement stat, ResultSet rs) {

        if (rs != null) {

            try {

                rs.close();

            } catch (SQLException e) {

                e.printStackTrace();

                System.out.println("rs流关闭异常！");

            }

        }

        if (stat != null) {

            try {

                stat.close();

            } catch (SQLException e) {

                e.printStackTrace();

                System.out.println("stat流关闭异常！");

            }

        }

        if (con != null) {

            try {

                con.close();

            } catch (SQLException e) {

                e.printStackTrace();

                System.out.println("con流关闭异常！");

            }

        }

    }

}

（4）测试：用Prepared实现查询

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

public class Test {

    public static void main(String[] args) {

        Connection con = null;

        PreparedStatement ps = null;

        ResultSet rs = null;

        try {

            // 2.从池子中获取连接

            con = C3P0Utils.getConnection();

            String sql = "select * from student ";

            ps = con.prepareStatement(sql);// 获取预处理对象

            rs = ps.executeQuery();

            System.out.println("     " + "学号" + "   " + "班级" + "   " + "平时成绩"

                    + "  " + "期末成绩");

            while (rs.next()) {

                System.out.println(rs.getString(1) + "  " + rs.getString(2)

                        + "  " + rs.getString(3) + "  " + rs.getString(4));

            }

        } catch (Exception e) {

            throw new RuntimeException(e);

        } finally {

            C3P0Utils.close(con, null, rs);

        }

    }

}

用JDBCUtils实现查询：

建立JavaBean：

public class Student {

private String studentno;

private String sname;

private String sex;

private String birthday;

private String classno;

private String point;

private String phone;

private String email;

public String getStudentno() {

    return studentno;

}

public void setStudentno(String studentno) {

    this.studentno = studentno;

}

public String getSname() {

    return sname;

}

public void setSname(String sname) {

    this.sname = sname;

}

public String getSex() {

    return sex;

}

public void setSex(String sex) {

    this.sex = sex;

}

public String getBirthday() {

    return birthday;

}

public void setBirthday(String birthday) {

    this.birthday = birthday;

}

@Override

public String toString() {

    return "Student [studentno=" + studentno + ", sname=" + sname + ", sex="

            + sex + ", birthday=" + birthday + ", classno=" + classno

            + ", point=" + point + ", phone=" + phone + ", email=" + email

            + "]";

}

public String getClassno() {

    return classno;

}

public void setClassno(String classno) {

    this.classno = classno;

}

public String getPoint() {

    return point;

}

public void setPoint(String point) {

    this.point = point;

}

public String getPhone() {

    return phone;

}

public void setPhone(String phone) {

    this.phone = phone;

}

public String getEmail() {

    return email;

}

public void setEmail(String email) {

    this.email = email;

}

}

测试：

import java.sql.Connection;

import java.sql.SQLException;

import java.util.List;

import org.apache.commons.dbutils.QueryRunner;

import org.apache.commons.dbutils.handlers.BeanListHandler;

public class Test1 {

    public static void main(String[] args) {

        Connection con = null;

        try {

            con = C3P0Utils.getConnection();

            QueryRunner qr = new QueryRunner();

            String sql = "Select * from Student ";

            Object[] select = { };

            List<Student> list = qr.query(con, sql,

                    new BeanListHandler<Student>((Student.class)), select);

            // 将记录封装到一个装有Object[]的List集合中

            for (Student s : list) {

                System.out.println(s);

            }

        } catch (SQLException e) {

            throw new RuntimeException(e);

        }

    }

}

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