JDBC从连接池获取连接

DBCP介绍

DBCP是Java开源连接池中常用的一种，它一般应用在使用数据库频繁的系统中，可以处理大量数据库连接请求。

简单配置

driverClassName=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/test
username=root
password=123456
maxActive=50
maxIdle=20
maxWait=60000

添加依赖

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-dbcp2</artifactId>
    <version>2.1.1</version>
</dependency>

代码展示

DBUtil工具类

import java.io.InputStream;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
import javax.sql.DataSource;
import org.apache.commons.dbcp2.BasicDataSourceFactory;
public class DBUtil {
    private static DataSource ds;
    private static Connection conn;
    static {
        try {
            Properties properties = new Properties();
            InputStream inStream = DBUtil.class.getResourceAsStream("dataSouce.properties");
            properties.load(inStream);
            ds = BasicDataSourceFactory.createDataSource(properties);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    // 获取连接
    public static Connection getConn() throws SQLException {
        if (conn == null || conn.isClosed()) {
            conn = ds.getConnection();
        }
        return conn;
    }
    // 回收连接
    public static void closeConn() {
        try {
            if (conn != null && !conn.isClosed()) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            conn = null;
        }
    }
}

操作数据库

import java.sql.Connection;
import java.sql.Statement;
public class Test {
    public static void main(String[] args) throws Exception {
        Connection conn = DBUtil.getConn();
        conn.setAutoCommit(false);
        Statement stmt = conn.createStatement();
        int rs = stmt.executeUpdate("DELETE FROM user WHERE name='qiang'");
        if (rs > 0) {
            System.out.println("更新成功！");
            conn.rollback();
        } else {
            System.out.println("更新失败！");
            conn.commit();
        } finally {
            stmt.close();
            DBUtil.closeConn();
        }     
    }
}