常用公共类代码一之数据库的连接

在项目中，我们经常会写到一些公共的代码，来让开发人员调用，减少代码重复，下面，我就将一些常用到的公共类贴出来和大家分享！！
一、数据库的连接，常用的方式有直接将那些要连接的参数放到java类中、将连接参数放到Properties文件中或者放到XML文件中，下面一一为大家描述
1、直接连接：
[java]
 普通的配置方式
 public static Connection getConnection(){
 Connection conn=null;
 try {
 Class.forName("com.mysql.jdbc.Driver");
 String url="jdbc:mysql://127.0.0.1:3306/xinyuandb";
 String username="root";
 String password="123456";
 conn=DriverManager.getConnection(url, username, password);
 } catch (ClassNotFoundException e) {
 e.printStackTrace();
 } catch (SQLException e) {
 e.printStackTrace();
 }
 return conn;
 } www.zzzyk.com

2、通过Properties文件创建连接，好处，很灵活，不用在代码里面进行更改
创建jdbc.properties文件
driver=com.mysql.jdbc.Driver
url=jdbc\:mysql\://127.0.0.1\:3306/xinyuandb
username=root
password=123456
[java]
 从properties文件中读取
 public static Connection getConnection(){
 Connection conn=null;
 Properties p=new Properties();
 try {
 //从当前线程加载
 p.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("jdbc.properties"));
 Class.forName(p.getProperty("driver"));
 conn=DriverManager.getConnection(p.getProperty("url"), p.getProperty("username"), p.getProperty("password"));
 } catch (IOException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 } catch (ClassNotFoundException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 } catch (SQLException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
 }
 return conn;
 }

3、通过XML文件读取
创建jdbc.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<config>
 <jdbc-config>
 <driver>com.mysql.jdbc.Driver</driver>
 <url>jdbc:mysql://127.0.0.1:3306/xinyuandb</url>
 <username>root</username>
 <password>123456</password>
 </jdbc-config>
</config>
创建javaBean类
package com.common.db;

public class JdbcBean {
 private String driver;
 private String url;
 private String username;
 private String password;
 public String getDriver() {
 return driver;
 }
 public void setDriver(String driver) {
 this.driver = driver;
 }
 public String getUrl() {
 return url;
 }
 public void setUrl(String url) {
 this.url = url;
 }
 public String getUsername() {
 return username;
 }
 public void setUsername(String username) {
 this.username = username;
 }
 public String getPassword() {
 return password;
 }
 public void setPassword(String password) {
 this.password = password;
 }
}

创建XML解析类
<pre name="code" class="java">package com.common.db;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

public class XmlConfigReader {
 private static XmlConfigReader instance;
 private JdbcBean bean=null;
 //调用构造函数进行XML文件解析
 private XmlConfigReader(){
 SAXReader reader=new SAXReader();
 try {
 Document doc=reader.read(Thread.currentThread().getContextClassLoader().getResourceAsStream("jdbc.xml"));
 Element root=doc.getRootElement();
 Element first=root.element("jdbc-config");

补充：软件开发 , Java ,