利用apache commons组件实现WEB应用跨多数据库

时间：2015-01-13 10:34:04 阅读：345 评论：0 收藏：0 [点我收藏+]

1、前言

在一些多数据库的环境中，有时候应用系统需要同时访问多个数据库，在流行的spring+hibernate等架构中，涉及要修改和调整的内容会比较多；如果直接用jdbc，那么代码里就要充斥很多的连接、关闭数据库、以及从数据库中进行循环取结果的代码，感觉总是不够优化。

利用apachecommons 组件下的DBCP，dbUtils也能够编写相对比较优雅一点的代码。

本文主要提供更思路和方法，代码存在不够优化，架构存在不够清晰的情况，请辩证的看。

WEB应用涉及的东西有点多，写起来也挺繁琐的。如果有看不懂的地方，就多琢磨下吧，系统能正常运行的。

基于JDK1.6，ORACLE10g，tomcat6 开发和测试。

2、需要的文件

Oracle驱动：class12；commons-configuration-1.10.jar， commons-dbcp-1.4.jar，commons-dbutils-1.6.jar，commons-pool-1.6.jar在JRE5环境下，需要引入 struts2 core libraries库。

3、数据库表

两张

create table TB_STUDENT

(

ID INTEGER,

NAME VARCHAR2(256),

SEX VARCHAR2(256),

AGE VARCHAR2(256),

GRADE INTEGER,

CLASSNAME VARCHAR2(256)

)

Create table tb_user(

username VARCHAR2(256),

password VARCHAR2(256)

)

4、整体架构

1个web文件，index.jsp 放在WebRoot目录下

1个数据库配置文件，db.properties复制两份，一份放在工程根目录下（做测试用），另外一份放在src目录下，供运行正式用；

1个struts.xml文件，放在src目录下

4个package，action，bean，dao，utils

5、目录结构截图：

技术分享

6、utils包

包括三个，一个读取配置文件，一个实现数据库连接，另外一个是一个tb_user的简单对象，供连接测试使用。

package cn.mrcast.util;

import org.apache.commons.configuration.CompositeConfiguration;

importorg.apache.commons.configuration.ConfigurationException;

importorg.apache.commons.configuration.PropertiesConfiguration;

/**

* 通过commonsconfiguration进行简单的配置

*@author 范芳铭

public class ConfigurationUsage {

publicstatic void main(String[] args) {

StringjdbcUrl = propManager.getInstance().getProperty("jdbc.cms.url");

StringjdbcUsername = propManager.getInstance().getProperty(

"jdbc.cms.username");

StringjdbcPassword = propManager.getInstance().getProperty(

"jdbc.cms.password");

System.out.println("jdbcUrl:"+ jdbcUrl);

System.out.println("jdbcUsername:"+ jdbcUsername);

System.out.println("jdbcPassword:"+ jdbcPassword);

}

privateConfigurationUsage() {

}

privatestatic ConfigurationUsage propManager;

publicsynchronized static ConfigurationUsage getInstance() {

if(propManager == null) {

propManager= new ConfigurationUsage();

}

returnpropManager;

}

publicstatic CompositeConfiguration config = new CompositeConfiguration();

static{

try{

config.addConfiguration(newPropertiesConfiguration(

"db.properties"));

}catch (ConfigurationException e) {

e.printStackTrace();

}

publicString getProperty(String key) {

returnconfig.getString(key);

}

package cn.mrcast.util;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.Arrays;

import java.util.List;

import java.util.Map;

import java.util.Properties;

importorg.apache.commons.dbcp.BasicDataSource;

importorg.apache.commons.dbcp.BasicDataSourceFactory;

import org.apache.commons.dbutils.DbUtils;

importorg.apache.commons.dbutils.QueryRunner;

import org.apache.commons.dbutils.handlers.ArrayHandler;

importorg.apache.commons.dbutils.handlers.ArrayListHandler;

importorg.apache.commons.dbutils.handlers.BeanHandler;

importorg.apache.commons.dbutils.handlers.BeanListHandler;

import org.apache.commons.dbutils.handlers.ColumnListHandler;

importorg.apache.commons.dbutils.handlers.KeyedHandler;

importorg.apache.commons.dbutils.handlers.MapHandler;

importorg.apache.commons.dbutils.handlers.MapListHandler;

importorg.apache.commons.dbutils.handlers.ScalarHandler;

import org.apache.commons.lang.StringUtils;

/**

* 通过commonsdbUtils进行数据库的简单访问和实用,版本： dbUtils1.6,Oracle驱动：class12；QueryRunner 代码实例

*@author 范芳铭

public class DBUtils {

staticConfigurationUsage propManager = null;

privatestatic BasicDataSource dataSourceO2O = null;

privatestatic BasicDataSource dataSourceBM = null;

//连接O2O数据库

publicstatic void initO2O() {

if(dataSourceO2O != null) {

try{

dataSourceO2O.close();

}catch (Exception e) {

e.printStackTrace();

}

dataSourceO2O= null;

}

try{

Propertiesp = new Properties();

p.setProperty("driverClassName",propManager.getInstance().getProperty("jdbc.o2o.driverClassName"));

p.setProperty("url",propManager.getInstance().getProperty("jdbc.o2o.url"));

p.setProperty("password",propManager.getInstance().getProperty("jdbc.o2o.username"));

p.setProperty("username",propManager.getInstance().getProperty("jdbc.o2o.password"));

p.setProperty("maxActive",propManager.getInstance().getProperty("jdbc.o2o.maxActive"));

p.setProperty("maxIdle",propManager.getInstance().getProperty("jdbc.o2o.maxIdle"));

p.setProperty("maxWait",propManager.getInstance().getProperty("jdbc.o2o.maxWait"));

dataSourceO2O= (BasicDataSource) BasicDataSourceFactory

.createDataSource(p);

}catch (Exception e) {

e.printStackTrace();

}

//连接便民数据库

publicstatic void initBM() {

if(dataSourceBM != null) {

try{

dataSourceBM.close();

}catch (Exception e) {

e.printStackTrace();

}

dataSourceBM= null;

}

try{

Propertiesp = new Properties();

p.setProperty("driverClassName",propManager.getInstance().getProperty("jdbc.bm.driverClassName"));

p.setProperty("url",propManager.getInstance().getProperty("jdbc.bm.url"));

p.setProperty("password",propManager.getInstance().getProperty("jdbc.bm.username"));

p.setProperty("username",propManager.getInstance().getProperty("jdbc.bm.password"));

p.setProperty("maxActive",propManager.getInstance().getProperty("jdbc.bm.maxActive"));

p.setProperty("maxIdle",propManager.getInstance().getProperty("jdbc.bm.maxIdle"));

p.setProperty("maxWait",propManager.getInstance().getProperty("jdbc.bm.maxWait"));

dataSourceBM= (BasicDataSource) BasicDataSourceFactory

.createDataSource(p);

}catch (Exception e) {

e.printStackTrace();

}

publicstatic synchronized Connection getConnO2O() throws SQLException {

if(dataSourceO2O == null) {

initO2O();

}

Connectionconn = null;

if(dataSourceO2O != null) {

conn= dataSourceO2O.getConnection();

}

returnconn;

}

publicstatic synchronized Connection getConnBM() throws SQLException {

if(dataSourceBM == null) {

initBM();

}

Connectionconn = null;

if(dataSourceBM != null) {

conn= dataSourceBM.getConnection();

}

returnconn;

}

//内部使用和实例

privateQueryRunner runner = null;

publicDBUtils() {

initO2O();

runner= new QueryRunner(dataSourceO2O, true); //默认用O2O

}

publicstatic void main(String[] args) throws SQLException {

DBUtilsusage = new DBUtils();

usage.batch();

usage.fillStatement();

usage.query();

usage.closeDataSource();

}

privatevoid batch() {

Stringsql = "INSERT INTO tb_user (USERNAME, PASSWORD) values (?, ?)";

try{

System.out.println(StringUtils.center("TestQueryRunner batch", 50,

‘-‘));

int[]result = runner.batch(sql, new Object[][] {

{"范芳铭1", "ffm1" }, { "范芳铭2","ffm2" },

{"范芳铭3", "ffm3" }, { "范芳铭4","ffm" } });

System.out.printf("batch运行结果:", Arrays.toString(result));

}catch (SQLException ex) {

DbUtils.printStackTrace(ex);

}

privatevoid closeDataSource() throws SQLException {

((BasicDataSource)dataSourceO2O).close();

}

privatevoid fillStatement() throws SQLException {

Stringsql = "INSERT INTO tb_user (USERNAME, PASSWORD) VALUES (?, ?)";

Connectionconn = null;

try{

System.out.println(StringUtils.center("TestQueryRunner fillStatement", 50,

‘-‘));

conn= dataSourceO2O.getConnection();

PreparedStatementpsmt = conn.prepareStatement(sql);

runner.fillStatementWithBean(psmt,

newTb_user("范芳铭pstm", "ffm"), "username","password");

System.out.println("成功执行数据："+ psmt.executeUpdate() + " 条");

}catch (SQLException ex) {

DbUtils.printStackTrace(ex);

ex.printStackTrace();

}finally {

DbUtils.commitAndCloseQuietly(conn);

}

//列举一些主要的查询形态

privatevoid query() throws SQLException {

System.out.println(StringUtils

.center("TestQueryRunner query", 50, ‘-‘));

Stringsql = "SELECT * FROM tb_user WHERE rownum < ? ";

//把ResultSet第一行包装成Object[]

System.out.println(" Test QueryRunner query, ArrayHandler");

Object[]r1 = runner.query(sql, new ArrayHandler(), "3");

System.out.println(" " + Arrays.deepToString(r1));

//把ResultSet包装成List<Object[]>

System.out.println(" Test QueryRunner query,ArrayListHandler");

List<Object[]>r2 = runner.query(sql, new ArrayListHandler(), "3");

System.out.println(" " + Arrays.deepToString(r2.toArray()));

//把ResultSet第一行包装成一个List<JavaBean>；

System.out.println("Test QueryRunner query, BeanListHandler");

List<Tb_user>r4 = runner.query(sql, new BeanListHandler<Tb_user>(

Tb_user.class),"3");

System.out.println(" " + Arrays.deepToString(r4.toArray()));

//包装ResultSet，以Map<Object,Map<String,Object>>对象形式返回，第一个Object是指定的列值，第二个Map中String是列名且对大小写不敏感

System.out.println("TestQueryRunner query, KeyedHandler");

Map<Object,Map<String, Object>> r6 = runner.query(sql,

newKeyedHandler(2), "3");

System.out.println(" " + r6.toString());

//把ResultSet包装成List<Map<String,Object>>>，Map的key对大小写不敏感

System.out.println("TestQueryRunner query, MapListHandler");

List<Map<String,Object>> r8 = runner.query(sql, new MapListHandler(),

"3");

System.out.println(" " + r8.toString());

}

package cn.mrcast.util;

/**

* 通过commonsdbUtils进行数据库的简单访问和实用的javaBean

*QueryRunner 代码实例

*@author 范芳铭

public class Tb_user {

privateString username;

privateString password;

publicTb_user(){

}

publicTb_user(String username, String password) {

this.username= username;

this.password= password;

}

publicString getUsername() {

returnusername;

}

publicvoid setUsername(String username) {

this.username= username;

}

publicString getPassword() {

return password;

}

publicvoid setPassword(String password) {

this.password= password;

}

@Override

publicString toString(){

return"name:" + username + ",pass:" + password;

}

7、Bean包

就一个bean，student，在两个数据库中，对应的数据库的数据最好不一样，否则可能看不出效果。

package cn.mrcast.bean;

/**

* 通过commonsdbUtils进行数据库的简单访问和实用的javaBean

*QueryRunner 代码实例

*@author 范芳铭

public class Student {

privateint id;

privateString name;

private String sex;

private String age;

private int grade;

private String classname;

public int getId() {

returnid;

}

publicvoid setId(int id) {

this.id= id;

}

publicString getName() {

returnname;

}

publicvoid setName(String name) {

this.name= name;

}

publicString getSex() {

returnsex;

}

publicvoid setSex(String sex) {

this.sex= sex;

}

publicString getAge() {

returnage;

}

publicvoid setAge(String age) {

this.age= age;

}

publicint getGrade() {

returngrade;

}

publicvoid setGrade(int grade) {

this.grade= grade;

}

publicString getClassname() {

returnclassname;

}

publicvoid setClassname(String classname) {

this.classname= classname;

}

8、Action包

两个，一个访问A数据库，一个访问B数据库

package cn.mrcast.action;

import java.util.ArrayList;

import java.util.List;

importcom.opensymphony.xwork2.ActionSupport;

import cn.mrcast.bean.Student;

import cn.mrcast.dao.ShowAllDAO;

public class ShowAllAction extendsActionSupport {

List<Student>list = new ArrayList<Student>();

ShowAllDAOsd = new ShowAllDAO();

publicList<Student> getList() {

returnlist;

}

publicString execute() {

list= sd.useRunnerO2O_all();

return"success";

}

package cn.mrcast.action;

import java.util.ArrayList;

import java.util.List;

importcom.opensymphony.xwork2.ActionSupport;

import cn.mrcast.bean.Student;

import cn.mrcast.dao.ShowAllDAO;

public class ShowBMAction extendsActionSupport {

List<Student>list = new ArrayList<Student>();

ShowAllDAOsd = new ShowAllDAO();

publicList<Student> getList() {

returnlist;

}

publicString execute() {

list= sd.useRunnerBM_all();

return"success";

}

9、Dao包

一个类，包含了传统的JDBC使用的方式，以及新的方法作为对比

package cn.mrcast.dao;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

import org.apache.commons.dbutils.DbUtils;

importorg.apache.commons.dbutils.QueryRunner;

importorg.apache.commons.dbutils.handlers.BeanListHandler;

import cn.mrcast.bean.Student;

import cn.mrcast.util.DBUtils;

import cn.mrcast.util.Tb_user;

/**

* 通过commonsdbUtils进行数据库的简单访问和实用的javaBean,

* 放了一个传统的数据库访问对象获取的样例作为对比

*QueryRunner 代码实例

*@author 范芳铭

public class ShowAllDAO {

privateQueryRunner runnerO2O = null;

privateQueryRunner runnerBM = null;

//如果不用 runner的方法，比较繁琐，不推荐使用

publicList<Student> ShowAll() {

List<Student>list = new ArrayList<Student>();

Connectioncon = null;

try{

con= DBUtils.getConnO2O();

Stringsql = "select id,name,sex,age,grade,classname from tb_student";

PreparedStatementps = con.prepareStatement(sql);

ResultSetrs = ps.executeQuery();

while(rs.next()) {

Studentst = new Student();

st.setId(rs.getInt("id"));

st.setName(rs.getString("name"));

st.setSex(rs.getString("sex"));

st.setAge(rs.getString("age"));

st.setGrade(rs.getInt("grade"));

st.setClassname(rs.getString("classname"));

list.add(st);

}

}catch (SQLException e) {

System.out.println(e.getMessage());

}

returnlist;

}

publicList<Student> useRunnerO2O_all() {

List<Student>list = new ArrayList<Student>();

//oracle数据库连接初始化方法

runnerO2O= new QueryRunner(true);

Connectioncon = null;

try{

con= DBUtils.getConnO2O();

Stringsql = "select id,name,sex,age,grade,classname from tb_student";

list= runnerO2O.query(con,sql, new BeanListHandler<Student>(Student.class));

System.out.println(" " +Arrays.deepToString(list.toArray()));

}catch (SQLException e) {

System.out.println(e.getMessage());

}finally{

DbUtils.closeQuietly(con);

}

returnlist;

}

publicList<Student> useRunnerBM_all() {

List<Student>list = new ArrayList<Student>();

//oracle数据库连接初始化方法

runnerBM= new QueryRunner(true);

Connectioncon = null;

try{

con= DBUtils.getConnBM();

Stringsql = "select id,name,sex,age,grade,classname from tb_student";

list= runnerBM.query(con,sql, new BeanListHandler<Student>(Student.class));

System.out.println(" " + Arrays.deepToString(list.toArray()));

}catch (SQLException e) {

System.out.println(e.getMessage());

}finally{

DbUtils.closeQuietly(con);

}

returnlist;

}

10、数据库配置文件

jdbc.o2o.driverClassName=oracle.jdbc.driver.OracleDriver

jdbc.o2o.url=jdbc:oracle:thin:@192.168.1.1:1521:ffm

jdbc.o2o.username=ffm

jdbc.o2o.password=ffm

jdbc.o2o.maxActive=20

jdbc.o2o.maxIdle=5

jdbc.o2o.maxWait=200

jdbc.bm.driverClassName=oracle.jdbc.driver.OracleDriver

jdbc.bm.url=jdbc:oracle:thin:@192.168.1.2:1521:TEST

jdbc.bm.username=test

jdbc.bm.password=test

jdbc.bm.maxActive=20

jdbc.bm.maxIdle=5

jdbc.bm.maxWait=200

11、struts.xml配置文件

<?xml version="1.0"encoding="UTF-8" ?>

<!DOCTYPE struts PUBLIC "-//ApacheSoftware Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd">

<actionname="showall" class="cn.mrcast.action.ShowAllAction">

<resultname="success">/index.jsp</result>

</action>

<actionname="showBMall" class="cn.mrcast.action.ShowBMAction">

<resultname="success">/index.jsp</result>

</action>

</package>

</struts>

12、web文件Index.jsp

<%@ page language="java"import="java.util.*" pageEncoding="GBK"%>

<%@taglib uri="/struts-tags"prefix="s"%>

String path = request.getContextPath();

String basePath =request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

<!DOCTYPE HTML PUBLIC "-//W3C//DTDHTML 4.01 Transitional//EN">

<html>

<head>

<title>My JSP ‘index.jsp‘ startingpage</title>

<metahttp-equiv="pragma" content="no-cache">

<metahttp-equiv="cache-control" content="no-cache">

<metahttp-equiv="expires" content="0">

<metahttp-equiv="keywords"content="keyword1,keyword2,keyword3">

<!--

.STYLE1 {

font-size:18px;

font-weight:bold;

}

-->

</style>

</head>

<body>

<p class="STYLE1">连接两个数据库，找学生成绩统计</p>

</tr>

</table>

<s:iterator id="student" value="list">

<tr>

<s:else> 不及格</s:else>

</div></td>

</tr>

</s:iterator>

</td>

</tr>

</table>

</div>

</form>

</td>

</tr>

</table>

</div>

</form>

调试信息的输出：

<s:debug></s:debug>

</body>

</html>

利用apache commons组件实现WEB应用跨多数据库

标签：apache 多数据库 web 应用

原文地址：http://blog.csdn.net/ffm83/article/details/42672789

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