连接池的作用是限制最大连接数并且能保持几个长连接,这样可以提高连接速度,不用非常频繁的连接和断开,更重要的是能限制最大连接数目,这样完全可以避免出现连接没有断开,连接数超过最大连接数而把数据库连死的情况,一般我认为都应该用连接池给你一个连接池的程序DBConn.java连接池程序import java.sql.*;
import java.io.*;
import javax.naming.*;public class DBConn {
private Connection myConn = null;
private Statement stmt = null;
private ResultSet rs = null; public Connection getConn() throws Exception {
Context initContext = new InitialContext();
Context envContext = (Context) initContext.lookup("java:comp/env"); //获取连接池对象
javax.sql.DataSource ds = (javax.sql.DataSource) envContext.lookup(
"jdbc/Provision"); //类型转换
myConn = ds.getConnection();
return myConn;
} public boolean makeConn() throws Exception { //完成连接数据库的功能
Context initContext = new InitialContext();
Context envContext = (Context) initContext.lookup("java:comp/env"); //获取连接池对象
javax.sql.DataSource ds = (javax.sql.DataSource) envContext.lookup(
"jdbc/Provision"); //类型转换
myConn = ds.getConnection();
return (myConn != null);
} public boolean sqlQuery(String sql) throws Exception { //执行select语句 stmt = myConn.createStatement();
rs = stmt.executeQuery(sql);
return (rs != null);
} public boolean getNext() throws Exception { //看数据库的下一个数据是否为空
return (rs.next());
} public String getString(String inCol) throws Exception { //取得对应数据库字段的数据
return rs.getString(inCol);
} public int getInt(String inCol) throws Exception { //取得对应数据库整型字段的数据
return rs.getInt(inCol);
} public void sqlUpdate(String sql) throws Exception { //执行update、delete、insert的sql语句
stmt = null;
stmt = myConn.createStatement();
stmt.executeUpdate(sql);
} public void closeAll() throws Exception {
if (rs != null)
rs.close();
if (stmt != null)
stmt.close();
if (myConn != null)
myConn.close();
} public void closeConn() throws Exception { //关闭所有的与数据库相关的操作
if (stmt != null)
stmt.close();
if (myConn != null)
myConn.close();
} public void closeRs() throws Exception {
if (rs != null)
rs.close();
} public void closeStmt() throws Exception {
if (stmt != null)
stmt.close();
} public void closeConnect() throws Exception {
if (myConn != null)
myConn.close();
}}调用方法DBConn dbconn; //数据库对象
Connection conn; //数据连接对象
dbconn = new DBConn();
conn = dbconn.getConn();
//用户通过短信订购直接调用addbusi_ret
strSQL = "{ call mobuser.addbusi_ret(?,?,?,?) }";
cstmt_add_sms = conn.prepareCall(strSQL);
//用户通过web或者wap订购
strSQL="{ call mobuser.pro_check_reg(?,?,?,?) }";
cstmt_add_web = conn.prepareCall(strSQL);
//取消定购
strSQL = "{ call mobuser.cancelbusi(?,?,?) }";
cstmt_cancel = conn.prepareCall(strSQL);
import java.io.*;
import javax.naming.*;public class DBConn {
private Connection myConn = null;
private Statement stmt = null;
private ResultSet rs = null; public Connection getConn() throws Exception {
Context initContext = new InitialContext();
Context envContext = (Context) initContext.lookup("java:comp/env"); //获取连接池对象
javax.sql.DataSource ds = (javax.sql.DataSource) envContext.lookup(
"jdbc/Provision"); //类型转换
myConn = ds.getConnection();
return myConn;
} public boolean makeConn() throws Exception { //完成连接数据库的功能
Context initContext = new InitialContext();
Context envContext = (Context) initContext.lookup("java:comp/env"); //获取连接池对象
javax.sql.DataSource ds = (javax.sql.DataSource) envContext.lookup(
"jdbc/Provision"); //类型转换
myConn = ds.getConnection();
return (myConn != null);
} public boolean sqlQuery(String sql) throws Exception { //执行select语句 stmt = myConn.createStatement();
rs = stmt.executeQuery(sql);
return (rs != null);
} public boolean getNext() throws Exception { //看数据库的下一个数据是否为空
return (rs.next());
} public String getString(String inCol) throws Exception { //取得对应数据库字段的数据
return rs.getString(inCol);
} public int getInt(String inCol) throws Exception { //取得对应数据库整型字段的数据
return rs.getInt(inCol);
} public void sqlUpdate(String sql) throws Exception { //执行update、delete、insert的sql语句
stmt = null;
stmt = myConn.createStatement();
stmt.executeUpdate(sql);
} public void closeAll() throws Exception {
if (rs != null)
rs.close();
if (stmt != null)
stmt.close();
if (myConn != null)
myConn.close();
} public void closeConn() throws Exception { //关闭所有的与数据库相关的操作
if (stmt != null)
stmt.close();
if (myConn != null)
myConn.close();
} public void closeRs() throws Exception {
if (rs != null)
rs.close();
} public void closeStmt() throws Exception {
if (stmt != null)
stmt.close();
} public void closeConnect() throws Exception {
if (myConn != null)
myConn.close();
}}调用方法DBConn dbconn; //数据库对象
Connection conn; //数据连接对象
dbconn = new DBConn();
conn = dbconn.getConn();
//用户通过短信订购直接调用addbusi_ret
strSQL = "{ call mobuser.addbusi_ret(?,?,?,?) }";
cstmt_add_sms = conn.prepareCall(strSQL);
//用户通过web或者wap订购
strSQL="{ call mobuser.pro_check_reg(?,?,?,?) }";
cstmt_add_web = conn.prepareCall(strSQL);
//取消定购
strSQL = "{ call mobuser.cancelbusi(?,?,?) }";
cstmt_cancel = conn.prepareCall(strSQL);
那么它有没有不同数据库之间编写代码的不同呢?比如mysql oracle and ms sqlserver在编写连接池的时候不同?
DBConnectionManager.javapackage ChatServer;
import java.io.*;
import java.sql.*;
import java.util.*;
import java.util.Date;
/**
*管理类DBConnectionManager支持对一个或多个有属性文件定义的数据库连接
*池的访问,客户程序可以调用getInstance()方法访问本类的唯一实例
*/
public class DBConnectionManager {
static private DBConnectionManager instance; //唯一实例
static private int clients;
private Vector drivers = new Vector(); //数据库驱动
private PrintWriter log;
private Hashtable pools = new Hashtable(); //
/**
*返回唯一实例,如果是第一次调用此方法,则创建实例
*
*/
static synchronized public DBConnectionManager getInstance() {
if (instance == null) {
instance = new DBConnectionManager();
}
clients++;
return instance;
}
/**
*构造函数私有以防止其它对象创建本类实例
*/
private DBConnectionManager() {
init();
}
/**
*将连接对象返回给由名字指定的连接池
*
*@param name 在属性文件中定义的连接池名字
*@param con连接对象
*/
public void freeConnection(String name, Connection con) {
DBConnectionPool pool = (DBConnectionPool) pools.get(name);
if (pool != null) {
pool.freeConnection(con);
}
} /**
*获得一个可用的(空闲)连接,如果没有可用连接,且已有连接数小于最大连接数限制,
*则创建并返回新连接
*
*@param name 在属性文件中定义的连接池名字
*@return Connection 可用连接或null
*/
public Connection getConnection(String name) {
DBConnectionPool pool = (DBConnectionPool) pools.get(name);
if (pool != null) {
return pool.getConnection();
}
return null;
}
public Connection getConnection(String name, long time) {
DBConnectionPool pool = (DBConnectionPool) pools.get(name);
if (pool != null) {
return pool.getConnection(time);
}
return null;
}
/**
*关闭所有连接,撤销驱动程序的注册
*/
public synchronized void release() {
//等待直到最后一个客户程序调用
if (--clients != 0) {
return;
}
Enumeration allPools = pools.elements();
while (allPools.hasMoreElements()) {
DBConnectionPool pool = (DBConnectionPool) allPools.nextElement();
pool.release();
}
Enumeration allDrivers = drivers.elements();
while (allDrivers.hasMoreElements()) {
Driver driver = (Driver) allDrivers.nextElement();
try {
DriverManager.deregisterDriver(driver);
log("撤销JDBC驱动程序" + driver.getClass().getName() + "的注册");
}
catch (SQLException e) {
log(e, "无法撤销下列JDBC驱动程序的注册:" + driver.getClass().getName());
}
}
}
/**
*根据指定属性创建连接池实例
*
*@param props连接池属性
*/
private void createPools(Properties props) {
Enumeration propNames = props.propertyNames();
while (propNames.hasMoreElements()) {
String name = (String) propNames.nextElement();
if (name.endsWith(".url")) {
String poolName = name.substring(0, name.lastIndexOf("."));
String url = props.getProperty(poolName + ".url"); if (url == null) {
log("没有为连接池" + poolName + "指定URL");
continue;
}
String user = props.getProperty(poolName + ".user");
String password = props.getProperty(poolName + ".password");
String maxconn = props.getProperty(poolName + ".maxconn", "0");
int max;
try {
max = Integer.valueOf(maxconn).intValue();
}
catch (NumberFormatException e) {
log("错误的最大连接数限制:" + maxconn + ".连接池" + poolName);
max = 0;
}
DBConnectionPool pool = new DBConnectionPool(poolName, url, user,
password, max);
pools.put(poolName, pool);
log("成功创建连接池" + poolName);
}
}
} /**
*读取属性完成初始化
*/
private void init() {
Properties dbProps = new Properties();
try {
FileInputStream is = new FileInputStream("conf\\db.properties");
dbProps.load(is); }
catch (Exception e) {
System.err.println("不能读取属性文件" + "请确保db.properties在classPath指定的路径中");
return;
}
String logFile = dbProps.getProperty("logfile", "DBConnectionManager.log");
try {
log = new PrintWriter(new FileWriter(logFile, true), true);
}
catch (IOException e) {
System.err.println("无法打开日志文件:" + logFile);
log = new PrintWriter(System.err);
}
loadDrivers(dbProps);
createPools(dbProps); }
/**
*装载和注册所有JDBC驱动程序
*
*@param props属性
*/
private void loadDrivers(Properties props) {
String driverClasses = props.getProperty("drivers");
StringTokenizer st = new StringTokenizer(driverClasses);
while (st.hasMoreElements()) {
String driverClassName = st.nextToken().trim();
try {
Driver driver = (Driver) Class.forName(driverClassName).newInstance();
DriverManager.registerDriver(driver);
drivers.addElement(driver);
log("成功注册JDBC驱动程序" + driverClassName);
}
catch (Exception e) {
log("无法注册JDBC驱动程序" + driverClassName + ",错误:" + e);
}
}
}
/**
*将文本信息写入日志文件
*/
private void log(String msg) {
log.println(new Date() + ":" + msg);
}
/**
*将文本信息与异常写入日志文件
*/
private void log(Throwable e, String msg) {
log.println(new Date() + ":" + msg);
e.printStackTrace(log);
}
/**
*此类定义了一个连接池,它能够根据要求创建新连接,直到预定的最大连接数为止,
*在返回连接给客户程序之前,它能够验证连接的有效性。
*/
class DBConnectionPool {
private int checkedOut;
private Vector freeConnections = new Vector();
private int maxConn;
private String name;
private String password;
private String URL;
private String user; /**
*创建新的连接池
*
*@param name连接池名称
*@param URL数据库的JDBC URL
*@param user数据库账号,或null
*@param password密码,或null
*@param maxConn此连接池允许建立的最大连接数
*/
public DBConnectionPool(String name, String URL, String user,
String password, int maxConn) {
this.name = name;
this.URL = URL;
this.user = user;
this.password = password;
this.maxConn = maxConn;
}
/**
*将不再使用的连接返回给连接池
*
*@param con客户程序释放的连接
*/
public synchronized void freeConnection(Connection con) {
//将指定连接加入到向量末尾
freeConnections.addElement(con);
checkedOut--;
notifyAll();
} /**
*从连接池获得一个可用连接,如果没有空闲的连接且当前连接数小于最大连接数限制,
*则创建新连接,如原来登记为可用连接不再有效,则从向量删除之,然后递归调用自
*己以尝试新的可用连接
*/
public synchronized Connection getConnection() {
Connection con = null;
if (freeConnections.size() > 0) {
//获取向量中第一个可用连接
con = (Connection) freeConnections.firstElement();
freeConnections.removeElementAt(0);
try {
if (con.isClosed()) {
log("从连接池" + name + "删除一个无效连接");
//递归调用自己,尝试再次获取可用连接
con = getConnection();
}
}
catch (SQLException e) {
log("从连接池" + name + "删除一个无效连接");
//递归调用自己,尝试再次获取可用连接
con = getConnection();
}
}
else if (maxConn == 0 || checkedOut < maxConn) {
con = newConnection();
}
if (con != null) {
checkedOut++;
}
return con;
} /**
*从连接池获取可用连接,可以指定客户程序能够等待的最长时间
*参见前一个getConnection()方法
*
*@param timeout 以毫秒计的等待时间限制
*/
public synchronized Connection getConnection(long timeout) {
long startTime = new Date().getTime();
Connection con;
while ( (con = getConnection()) == null) {
try {
wait(timeout);
}
catch (InterruptedException e) {}
if ( (new Date().getTime() - startTime) >= timeout) {
//wait()返回的原因是超时
return null;
}
}
return con;
} /**
*关闭所有连接
*/
public synchronized void release() {
Enumeration allConnections = freeConnections.elements();
while (allConnections.hasMoreElements()) {
Connection con = (Connection) allConnections.nextElement();
try {
con.close();
log("关闭连接池" + name + "中的一个连接");
}
catch (SQLException e) {
log(e, "无法关闭连接池" + name + "中的连接");
}
}
freeConnections.removeAllElements();
} /**
*创建新的连接
*/
private Connection newConnection() {
Connection con = null;
try {
if (user == null) {
con = DriverManager.getConnection(URL);
}
else {
con = DriverManager.getConnection(URL, user, password);
} log("连接池" + name + "创建一个新的连接");
}
catch (SQLException e) {
log(e, "无法创建下列URL的连接:" + URL);
System.err.println(e.getMessage());
System.out.println("url=" + URL + "\nuser=" + user + "\npassword=" +
password);
return null;
}
return con;
}
}
}
/**
* <p>Title:连接数据库的程序 </p>
* <p>Description: </p>
* <p>Copyright: Copyright (c) 2005</p>
* <p>Company: </p>
* @author not attributable
* @version 1.0
*/
import java.io.*;
import java.util.*;
import java.sql.*;
public class ConnectDB{
String strDB;
String strUsr;
String strPasswd;
Connection conn = null;
Properties prop;
private String CONF = "conf\\db.conf";
public ConnectDB(String dbConf) {
CONF = dbConf;
try //获取数据库配置文件
{
prop = new Properties();
prop.load(new FileInputStream(CONF));
System.out.println("成功读取数据库配置文件:" + CONF);
}
catch(IOException e)
{
e.printStackTrace();
System.out.println("数据库配置文件读取错误!系统将要退出!");
System.exit(-1);
}
//从配置文件中读取配置信息
strDB = prop.getProperty("DBNAME").trim();
strUsr = prop.getProperty("DBUSER").trim();
strPasswd = prop.getProperty("DBPASSWORD").trim();
}
public Connection getConn()
{
try {
DriverManager.registerDriver(new oracle.jdbc.OracleDriver());
conn = DriverManager.getConnection(strDB, strUsr, strPasswd);
conn.setAutoCommit(false);
System.out.println("数据库连结正常!");
return conn;
}
catch (SQLException e) {
System.out.println("数据库连接错误!错误类型:" + e.toString());
return null;
}
}
}配置文件#驱动程序
drivers=oracle.jdbc.driver.OracleDriver
#日志文件
logfile=log\\connPoolLog.txt
#webdb1_unicom连接池
#登陆用户:webuser
webdb1_unicom.url=jdbc:oracle:thin:@211.154.171.116:1521:WEBDB1
webdb1_unicom.maxconn=3
webdb1_unicom.user=CHATSERVER
webdb1_unicom.password=chat_server
#webdb1_unicom连接池
#登陆用户:webuser
webdb1_mobcom.url=jdbc:oracle:thin:@211.136.82.145:1521:WEBDB1
webdb1_mobcom.maxconn=3
webdb1_mobcom.user=CPSERVER
webdb1_mobcom.password=CPSERVER
只要修改drivers就可以修改了你可以仔细看一下原来我是做SP的,短信,WAP我都做过,不过我现在不做了
呵呵!
我也讨厌做SP