c3p0连接池和DBCP连接池及其DBUtils对数据库的操作

一：c3p0连接池：

使用c3p0连接池，使用外部文件，外部文件的命名为c3p0-config.xml.在lib里面添加c3p0-XXX.jar包

我们连接数据库里面的数据库名、用户名、密码 全部都使用在xml文件里面：

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
//默认加载
  <default-config>
    <property name="driverClass">com.mysql.jdbc.Driver</property>
	<property name="jdbcUrl">jdbc:mysql:///数据库名</property>
	<property name="user">root</property>
	<property name="password">123456</property>
	<property name="initialPoolSize">5</property>
	<property name="maxPoolSize">20</property>
  </default-config>
  //指定加载
  <named-config name="oracle"> 
    <property name="driverClass">com.mysql.jdbc.Driver</property>
	<property name="jdbcUrl">jdbc:mysql:///web_07</property>
	<property name="user">root</property>
	<property name="password">123</property>
  </named-config>
  

</c3p0-config>

使用

ComboPooledDataSource DataSource = new ComboPooledDataSource();来加载c3p0-config.xml文件，且默认加载

ComboPooledDataSource datasource = new ComboPooledDataSource("oracle");指定加载，这样简单地就完成了数据库的连接。但是我们得对数据库操作，所以定义一个工具类：

package utils;

import java.sql.Connection;
import java.sql.SQLException;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;
public class c3p0Utils {
	ComboPooledDataSource DataSource = new ComboPooledDataSource();
	public DataSource getDataSource() {
		return DataSource;
	}
	public Connection getConnection() {
		Connection conn = null;
		try {
			conn = DataSource.getConnection();
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return conn;
	}

}

测试类：

@Test
	public void login1() {
		ComboPooledDataSource datasource = new ComboPooledDataSource();
		//ComboPooledDataSource datasource = new ComboPooledDataSource("oracle");
		try {
			conn = datasource.getConnection();
			String sql = "insert into t_user values(null,?,?,?,?,?,?)";
			preps = conn.prepareStatement(sql);
			preps.setString(1, "lis");
			preps.setString(2, "123234");
			preps.setInt(3, 22);
			preps.setInt(4, 23);
			preps.setString(5, "123");
			preps.setInt(6, 23);
			int row = preps.executeUpdate();
			if (row > 0) {
				System.out.println("添加成功！");
			} else {
				System.out.println("添加失败！");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			try {
				JDBCUtils.release(conn, preps, null);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}

二.DBCP连接池

DBCP的外部配置文件XXX.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/数据库名?useUnicode=true&characterEncoding=utf8
username=root
password=root

它的加载方法和JDBC的差不多，所以直接写出工具类：

package 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.util.Properties;
import java.util.ResourceBundle;

import javax.sql.DataSource;

import org.apache.commons.dbcp.BasicDataSourceFactory;

public class JDBCUtils2 {
	public static DataSource dataSource;
	public static String driver;
	public static String url;
	public static String username;
	public static String password;

	static {

		try {

			InputStream is = JDBCUtils2.class.getClassLoader().getResourceAsStream("db.properties");
			Properties prop = new Properties();
			prop.load(is);
			dataSource = BasicDataSourceFactory.createDataSource(prop);
			driver = prop.getProperty(driver);
			url = prop.getProperty(url);
			username = prop.getProperty(username);
			password = prop.getProperty(password);
		} catch (Exception e) {
			e.printStackTrace();
		}

	}

	public static Connection getConnection() {
		Connection conn = null;
		try {
			Class.forName(driver);
			conn = DriverManager.getConnection(url, username, password);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return conn;
	}

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

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

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

}

三：DBUtils对数据库的操作

BDUtils是JDBC的简化开发工具包，需要的jar包：c3p0-XXX.jar,commons-dbcp-XX.jar,commons-dbutils-XX.jar,commons-pool-XXX.jar,在对数据库的增删改时，会出现很多的冗余代码，我们使用DBUtils大大的减少了冗余代码：

import java.sql.SQLException;
import org.apache.commons.dbutils.QueryRunner;
import org.junit.Test;
import utils.c3p0Utils;
public class TestMyConnection {

	
	@Test
	public void login1() {
		try {
			QueryRunner runner = new QueryRunner(c3p0Utils.getDataSource());
			String sql = "insert into t_user values(null,?,?,?,?,?,?)";
			Object[] params  = {"wer","75",32,31,"567",12};
			int row = runner.update(sql,params);
			if (row > 0) {
				System.out.println("添加成功");
			}else {
				System.out.println("添加失败");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

而在进行查的时候，需要我们进行创建一个javaBean,一个类对应一张数据库表，类中的属性对于着一个字段，在进行查的时候，将数据库中的数据存在JavaBean中：所以在进行查的时候，创建一个JavaBean.

这就是查询当前表中有多少条数据：

@Test
	public void login1() {
		try {
			QueryRunner runner = new QueryRunner(c3p0Utils.getDataSource());
			String sql = "select count(*) from t_user";
			Object[] params = {};
			Long nn=(Long) runner.query(sql, new ScalarHandler());
			
			System.out.println(nn);
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

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提取码：d3bk