一、JDBC
package com.direct.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class JDBCutil {
/*
* 目前使用的JDBC连接数据库，存在问题：
* 每次连接和释放需要比较多的资源
* 资源浪费比较严重，系统的性能下滑
*
* 连接池的原理：
* 提前设定好，数据库的连接对象，当用户连接数据库时，直接从
* “池子”中取出一个连接即可。
* 当用户使用完毕后，“关闭连接”不是物理关闭，而是把连接放回连接池中
*/
private static final String DRIVER="com.mysql.jdbc.Driver";
private static final String URL="jdbc:mysql://localhost:3306/countryside_buy?userUnicode=true&characterEncoding=utf-8";
private static final String USER="root";
private static final String PWD="123456";
static{
try {
Class.forName(DRIVER);
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
//获得链接
public Connection createConn(){
Connection conn = null;
try {
conn = DriverManager.getConnection(URL, USER, PWD);
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
//关闭连接
public void closeJ(Connection conn,PreparedStatement ps,ResultSet rs) throws SQLException{
if(rs!=null) rs.close();
if(ps!=null) ps.close();
if(conn!=null) conn.close();
}
}
二，DBCP
2.1 dbcp.properties
username=root
password=123456
driverClassName=com.mysql.jdbc.Driver
maxActive=2000
maxIdle=520
maxWait=5000
url=jdbc:mysql://localhost:3306/countryside_buy
2.2 DBCPutil
package com.direct.util;
import java.sql.Connection;
import java.sql.SQLException;
import java.util.ResourceBundle;
import javax.sql.DataSource;
import org.apache.commons.dbcp.BasicDataSource;
/*
* DBCP使用步骤：
* 1，下载需要的jar包，放入web项目的lib下面
* 2，在src下面建立配置文件 .properties
* 3, 建立连接数据库工具，获取配置信息，
* 4，commons-dbcp.jar
* commons-pool-1.5.3.jar
* musql-connector-java-5.1.7.jar
*/
public class DBCPutil {
//数据源
private static DataSource ds= null;
//基本数据源
static BasicDataSource bds = new BasicDataSource();
public static Connection getconn() throws SQLException{
if (ds==null) {
ResourceBundle rs = ResourceBundle.getBundle("dbcp");
String username = rs.getString("username");
String password = rs.getString("password");
String driverClassName = rs.getString("driverClassName");
String maxActive = rs.getString("maxActive");
String maxIdle = rs.getString("maxIdle");
String maxWait = rs.getString("maxWait");
String url = rs.getString("url");
bds.setMaxActive(Integer.parseInt(maxActive));
bds.setMaxIdle(Integer.parseInt(maxIdle));
bds.setMaxWait(Integer.parseInt(maxWait));
bds.setUrl(url);
bds.setUsername(username);
bds.setPassword(password);
bds.setDriverClassName(driverClassName);
ds = bds;
return ds.getConnection();
}
return ds.getConnection();
}
//测试
public static void main(String[] args) {
try {
System.out.println(getconn());
} catch (SQLException e) {
e.printStackTrace();
}
}
}
三，JNDI
1，所需放在tomcat安装路径的lib目录下 commons.pool-1.5.3.jar 和 mysql-connector-java-5.1.7-bin.jar
2，tomcat中找到config文件夹下的context.xml
在标签<Context>中添加
<Resource
name="jndiDemo"
auth="Container"
type="javax.sql.DataSource"
driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/countryside_buy"
username="root"
password="123456"
maxActive="100"
maxIdle="30"
maxWait="3000"
/>
3，项目的web.xml中添加映射
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<!-- 配置JNDI -->
<resource-ref>
<res-ref-name>jndiDemo</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>JndiServlet</servlet-name>
<servlet-class>com.direct.servlet.JndiServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>JndiServlet</servlet-name>
<url-pattern>/JndiServlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>register.jsp</welcome-file>
</welcome-file-list>
</web-app>
4，jndi类
package com.direct.util;
import java.sql.Connection;
import java.sql.SQLException;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
public class JNDIutil {
/*
* JNDI是tomcat提供的一种标准的连接池
* 1，将驱动放入项目中tomcat的lib目录下
* 2，修改配置文件（tomcat中找到config文件夹下的context.xml）
* 3，在web.xml下配置
*/
public static Connection conn(){
Connection connection = null;
try {
//获得对数据源的引用
Context context = new InitialContext();
DataSource ds = (DataSource)context.lookup("java:comp/env/jndiDemo");
//获得数据库连接对象
connection = ds.getConnection();
} catch (NamingException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return connection;
}
}
5，servlet 测试jndi
package com.direct.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.direct.util.JNDIutil;
public class JndiServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
System.out.println(new JNDIutil().conn());
//jdbc:mysql://localhost:3306/countryside_buy, UserName=root@localhost, MySQL-AB JDBC Driver
}
}
最后开启服务器，访问 jndiServlet 后台即可得到连接，并输出连接地址