连接池（C3P0，DBCP，Druid）

分手后的思念是犯贱 2023-01-13 08:54 228阅读 0赞

### 目录 ###

*   *  一、C3P0连接池
     *  二、DBCP连接池
     *  三、Druid连接池

## 一、C3P0连接池 ##

**c3p0-config.xml**（放在resources资源里）

<?xml version="1.0" encoding="UTF-8"?>
    <c3p0-config>  
       
        <named-config name="mysql">
            <property name="driverClass">com.mysql.jdbc.Driver</property>
            <property name="jdbcUrl">jdbc:mysql://localhost:3306/db1?characterEncoding=UTF-8</property>
            <property name="user">root</property>
            <property name="password">root</property>
            <property name="initialPoolSize">10</property>
            <property name="maxIdleTime">30</property>
            <property name="maxPoolSize">100</property>
            <property name="minPoolSize">10</property>
        </named-config>
        
    
    </c3p0-config>

**C3P0工具类**（放在utils包下）

public class C3P0Utils {
        
    
    //    //1.创建连接池对象
        //使用指定的配置
        public static ComboPooledDataSource dataSource=new ComboPooledDataSource("mysql");
    
        //获取连接的方法
        public static Connection getConnection() throws SQLException {
        
            return dataSource.getConnection();
        }
    
        //释放资源的方法
        public static void close(Connection connection, Statement statement) throws SQLException {
        
            if(connection!=null &&statement!=null){
        
                statement.close();
                statement.close();
            }
        }
        public static void close(Connection connection, Statement statement, ResultSet resultSet) throws SQLException {
        
            if(connection!=null &&statement!=null && resultSet!=null){
        
                resultSet.close();
                statement.close();
                statement.close();
            }
        }
    }

**通过C3P0连接池向数据库插入数据**

public class Test01 {
        
    
        public static void main(String[] args) throws SQLException {
        
    
            //1.从连接池拿到对象
            Connection connection= DBCPUtils.getConnection();
    
            //2.获取statement对象
            String sql="insert into user values (?,?)";
            PreparedStatement preparedStatement = connection.prepareStatement(sql);
    		//从用户那里拿到输入的语句
            Scanner s=new Scanner(System.in);
            System.out.println("请输入要插入的用户名");
            String name=s.next();
            System.out.println("请输入差的用户名的密码：");
            String password=s.next();
    		// 设置参数
            preparedStatement.setString(1,name);
            preparedStatement.setString(2,password);
    		//执行sql语句
            preparedStatement.executeUpdate();
    		//关闭流操作
            DBCPUtils.close(connection,preparedStatement);
    
        }
    }

## 二、DBCP连接池 ##

**DBCP工具类**

public class DBCPUtils {
        
    
        //1. 定义常量
        public static final String DRIVERNAME="com.mysql.jdbc.Driver";
        public static final String URL="jdbc:mysql://localhost:3306/db1?characterEncoding=UTF-8";
        public static final String USER="root";
        public static final String PASSWORD="root";
    
        //2.创建连接池对象
        public static BasicDataSource dataSource=new BasicDataSource();
    
        //3.使用静态代码块进行配置
        static{
        
            dataSource.setDriverClassName(DRIVERNAME);
            dataSource.setUrl(URL);
            dataSource.setUsername(USER);
            dataSource.setPassword(PASSWORD);
        }
    
        //4.连接
        public static Connection getConnection() throws SQLException {
        
            Connection connection=dataSource.getConnection();
            return connection;
        }
    
        //5.关闭流
        public static void close(Connection connection, Statement statement) throws SQLException {
        
            if(connection!=null && statement!=null){
        
                statement.close();
                connection.close();
            }
        }
        public static void close(Connection connection, Statement statement, ResultSet resultSet) throws SQLException {
        
            if(connection!=null && statement!=null && resultSet!=null){
        
                resultSet.close();
                statement.close();
                connection.close();
            }
        }
    }

**通过DBCP连接池登录数据库**

## 三、Druid连接池 ##

**druid.properties(放在resources里面)**

driverClassName=com.mysql.jdbc.Driver
    url=jdbc:mysql://localhost:3306/test?characterEncoding=UTF-8
    username=root
    password=root

**Druid工具类**

public class DruidUtils {
        
    
        //定义成员变量
        public static DataSource dataSource;
    
        //静态代码块
        static{
        
            try {
        
                //3. 创建属性集对象
                Properties properties = new Properties();
                //4.加载配置文件 Druid 连接池不能够主动加载配置文件，需要指定文件
                InputStream inputStream=DruidUtils.class.getClassLoader().getResourceAsStream("druid.properties");
                //5. Properties对象的Load方法 从字节流中读取配置信息
                properties.load(inputStream);
                //6. 通过工厂类获取连接池对象
                dataSource= DruidDataSourceFactory.createDataSource(properties);
            } catch (Exception e) {
        
                e.printStackTrace();
            }
        }
    
        //获取连接对象
        public static Connection getConnection(){
        
            try {
        
                return dataSource.getConnection();
            } catch (SQLException throwables) {
        
                throwables.printStackTrace();
                return null;
            }
        }
    
        //关闭连接方法
        public static  void close(Connection connection, Statement statement) throws SQLException {
        
            if(connection!=null&&statement!=null){
        
                statement.close();
                connection.close();
            }
        }
        public static  void close(Connection connection, Statement statement, ResultSet resultSet) throws SQLException {
        
            if(connection!=null&&statement!=null && resultSet!=null){
        
                resultSet.close();
                statement.close();
                connection.close();
            }
        }
    }