连接池快速入门

目录

数据库连接的背景

数据库连接池

DataSource

自定义数据库连接池

演示

测试

数据库连接的背景

数据库连接池

DataSource

自定义数据库连接池

演示

package demo02.myDataSourse;
import demo02.utils.JDBCUtils;
 
import javax.sql.DataSource;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.SQLFeatureNotSupportedException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.logging.Logger;
 
//自定义数据库连接池
public class demoDataSourse implements DataSource{
    //1.准备容器，用于保存多个连接对象
    private static List pool = Collections.synchronizedList(new ArrayList<>());
    //2.定义静态代码块，通过工具类获取10个连接对象
    static{
        for(int i=1;i<=10;i++){
            Connection con = JDBCUtils.getConnection();
            pool.add(con);
        }
    }
    //3.重写getConnection(),用于获取一个连接对象
    @Override
    public Connection getConnection() throws SQLException {
        if(pool.size()>0){
            Connection con = pool.remove(0);
            return con;
        }else{
            throw new RuntimeException("连接数量已用尽");
        }
    }
    //4.定义getSize方法，获取连接池容器的大小
    public int getSize(){
        return pool.size();
    }
    @Override
    public Connection getConnection(String username, String password) throws SQLException {
        return null;
    }
 
    @Override
    public  T unwrap(Class iface) throws SQLException {
        return null;
    }
 
    @Override
    public boolean isWrapperFor(Class iface) throws SQLException {
        return false;
    }
 
    @Override
    public PrintWriter getLogWriter() throws SQLException {
        return null;
    }
 
    @Override
    public void setLogWriter(PrintWriter out) throws SQLException {
 
    }
 
    @Override
    public void setLoginTimeout(int seconds) throws SQLException {
 
    }
 
    @Override
    public int getLoginTimeout() throws SQLException {
        return 0;
    }
 
    @Override
    public Logger getParentLogger() throws SQLFeatureNotSupportedException {
        return null;
    }
}

测试

package demo02.myDataSourse;
 
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
 
public class demoDataSourseTest {
    public static void main(String[] args) throws Exception {
        //1.创建连接池对象
        demoDataSourse dataSourse = new demoDataSourse();
 
        System.out.println("使用之前的数量" + dataSourse.getSize());
 
        //2.通过连接池对象获取连接对象
        Connection con = dataSourse.getConnection();
        //3.查询学生表的全部信息
        String sql = "SELECT * FROM student";
        PreparedStatement pst = con.prepareStatement(sql);
        //4.执行sql语句,接收结果集
        ResultSet rs = pst.executeQuery();
        //5.处理结果集
        while(rs.next()){
            System.out.println(rs.getInt("sid")+"\t"+rs.getString("name")+"\t"+rs.getInt("age")+"\t"+rs.getDate("birthday"));
        }
        //6.释放资源
        rs.close();
        pst.close();
        con.close();//用完以后，未归还进行关闭连接；归还后面再讲
 
        System.out.println("使用之后的数量" + dataSourse.getSize());
    }
}