JDBC数据源连接池配置及应用

JDBC数据源连接池配置及应用

使用JDBC建立数据库连接的两种方式:

1.在代码中使用DriverManager获得数据库连接。这种方式效率低，并且其性能、可靠性和稳定性随着用户访问量得增加逐渐下降。

2.使用配置数据源的方式连接数据库，该方式其实质就是在上述方法的基础上增加了数据库连接池，这种方式效率高。

数据源连接池的方式连接数据库与在代码中使用DriverManager获得数据库连接存在如下差别：

1）数据源连接池的方式连接数据库是在程序中,通过向一个JNDI(java Naming and  Directory Interface)服务器查询,即调用Context接口的lookup()方法,来得到DataSource对象,然后调用DataSource对象的getConnection()方法建立连接

2）为了能重复利用数据库连接对象,提高对请求的响应时间和服务器的性能,采用连接池技术.连接池技术预先建立多个数据库连接对象,然后将连接对象保存到连接池中,当客户请求到来时,从池中取出一个连接对象为客户服务,当请求完成时,客户程序调用close()方法,将连接对象放回池中.

3）在代码中使用DriverManager获得数据库连接的方式中,客户程序得到的连接对象是物理连接,调用连接对象的close()方法将关闭连接,而采用连接池技术,客户程序得到的连接对象是连接池中物理连接的一个句柄,调用连接对象的close()方法,物理连接并没有关闭,数据源的实现只是删除了客户程序中的连接对象和池中的连接对象之间的联系.

为了测试方便可以在数据库（这里以mysql 5为例）中建立一个USER表：

CREATE TABLE `user` (

`id` int(10) unsigned NOT NULL AUTO_INCREMENT,

`username` varchar(50) DEFAULT NULL,

`password` varchar(50) DEFAULT NULL,

`email` varchar(50) DEFAULT NULL,

PRIMARY KEY (`id`),

);

导入数据库的驱动的jar包到tomcat的lib目录下（这里以mysql5为例，所用到的jar包为：mysql-connector-java-5.0.8-bin.jar）。

1.在代码中使用DriverManager获得数据库连接。这种方式效率低，并且其性能、可靠性和稳定性随着用户访问量得增加逐渐下降。

oracle数据库连接的Java代码如下：

import java.sql.Connection;

import java.sql.DriverManager;

/**

* 获取数据库连接

*/

public class DBConnection {

/** Oracle数据库连接URL*/

private final static String DB_URL = "jdbc:oracle:thin:@127.0.0.1:1521:orcl";

/** Oracle数据库连接驱动*/

private final static String DB_DRIVER = "oracle.jdbc.driver.OracleDriver";

/** 数据库用户名*/

private final static String DB_USERNAME = "root";

/** 数据库密码*/

private final static String DB_PASSWORD = "admin";

/**

* 获取数据库连接

* @return

*/

public Connection getConnection(){

/** 声明Connection连接对象*/

Connection conn = null;

try{

/** 使用Class.forName()方法自动创建这个驱动程序的实例且自动调用DriverManager来注册它*/

Class.forName(DB_DRIVER);

/** 通过DriverManager的getConnection()方法获取数据库连接*/

conn = DriverManager.getConnection(DB_URL,DB_USERNAME,DB_PASSWORD);

}catch(Exception ex){

ex.printStackTrace();

}

return conn;

}

/**

* 关闭数据库连接

*

* @param connect

*/

public void closeConnection(Connection conn){

try{

if(conn!=null){

/** 判断当前连接连接对象如果没有被关闭就调用关闭方法*/

if(!conn.isClosed()){

conn.close();

}

}

}catch(Exception ex){

ex.printStackTrace();

}

}

}

mysql数据库连接的jsP代码如下：

<%@page import="java.sql.*, com.mysql.jdbc.Driver"%>

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

<%

//com.mysql.jdbc.Driver

Class.forName(Driver.class.getName()).newInstance();

String url = "jdbc:mysql://localhost:3306/demo?useUnicode=true&characterEncoding=UTF8";

String user = "root";

String password = "123";

Connection conn = DriverManager.getConnection(url, user, password);

Statement stmt = conn.createStatement();

String sql = "select * from user";

ResultSet rs = stmt.executeQuery(sql);

while(rs.next()) {

out.print("
" + "====================" + "
");

out.print(rs.getLong("id") + " ");

out.print(rs.getString("username") + " ");

out.print(rs.getString("password") + " ");

out.print(rs.getString("email") + " ");

}

%>

2.使用配置数据源的方式连接数据库，该方式其实质就是在上述方法的基础上增加了数据库连接池，这种方式效率高。

1）mysql数据库数据源连接池的JSP代码如下：

<%@page import="java.sql.*, javax.naming.*, javax.sql.DataSource"%>

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

<%

Context initCtx = new InitialContext();

DataSource ds = (DataSource)initCtx.lookup("java:comp/env/jdbc/demoDB");

Connection conn = ds.getConnection();

Statement stmt = conn.createStatement();

String sql = "select * from user";

ResultSet rs = stmt.executeQuery(sql);

while(rs.next()) {

out.print("
" + "====================" + "
");

out.print(rs.getLong("id") + " ");

out.print(rs.getString("username") + " ");

out.print(rs.getString("password") + " ");

out.print(rs.getString("email") + " ");

}

%>

2） 添加如下代码到tomcat的conf目录下的server.xml中：

type="javax.sql.DataSource"

driverClassName="com.mysql.jdbc.Driver"

url="jdbc:mysql://localhost:3306/demo"

username="root"

password="123"

maxActive="50"

maxIdle="30"

maxWait="10000" />

3）在web工程目录下的web.xml的根节点下配置如下内容：

mysqlDB Connection

jdbc/demoDB

javax.sql.DataSource

Container

完成上述步骤数据源的连接池配置已经完成，但是为了提高项目的可移植性，最好将上述第二步的内容放入到工程的META-INF目录的context.xml中（这个文件需要自行建立）：

<Context>

type="javax.sql.DataSource"

driverClassName="com.mysql.jdbc.Driver"

url="jdbc:mysql://localhost:3306/demo"

username="root"

password="123"

maxActive="50"

maxIdle="30"

maxWait="10000" />

3.使用配置数据源的数据库连接池时的数据库操作工具类

代码如下：

package db.utils;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.ResultSetMetaData;

import java.sql.SQLException;

import java.sql.Statement;

import java.text.DateFormat;

import java.util.ArrayList;

import java.util.Date;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import javax.naming.InitialContext;

import javax.sql.DataSource;

//import org.apache.log4j.Logger;

/**

* 数据库操作辅助类

*/

public class DbUtils {

//private static Logger logger = Logger.getLogger("DbUtils");

/**

* 该语句必须是一个 SQL INSERT、UPDATE 或 DELETE 语句

* @param sql

* @param paramList：参数，与SQL语句中的占位符一一对应

* @return

* @throws Exception

*/

public int execute(String sql, List

if(sql == null || sql.trim().equals("")) {

//logger.info("parameter is valid!");

}

Connection conn = null;

PreparedStatement pstmt = null;

int result = 0;

try {

conn = getConnection();

pstmt = DbUtils.getPreparedStatement(conn, sql);

setPreparedStatementParam(pstmt, paramList);

if(pstmt == null) {

return -1;

}

result = pstmt.executeUpdate();

} catch (Exception e) {

//logger.info(e.getMessage());

throw new Exception(e);

} finally {

closeStatement(pstmt);

closeConn(conn);

}

return result;

}

/**

* 将查询数据库获得的结果集转换为Map对象

* @param sql：查询语句

* @param paramList：参数

* @return

*/

public List

if(sql == null || sql.trim().equals("")) {

//logger.info("parameter is valid!");

return null;

}

Connection conn = null;

PreparedStatement pstmt = null;

ResultSet rs = null;

List

try {

conn = getConnection();

pstmt = DbUtils.getPreparedStatement(conn, sql);

setPreparedStatementParam(pstmt, paramList);

if(pstmt == null) {

return null;

}

rs = getResultSet(pstmt);

queryList = getQueryList(rs);

} catch (RuntimeException e) {

//logger.info(e.getMessage());

System.out.println("parameter is valid!");

throw new Exception(e);

} finally {

closeResultSet(rs);

closeStatement(pstmt);

closeConn(conn);

}

return queryList;

}

private void setPreparedStatementParam(PreparedStatement pstmt, List

if(pstmt == null || paramList == null || paramList.isEmpty()) {

return;

}

DateFormat df = DateFormat.getDateTimeInstance();

for (int i = 0; i < paramList.size(); i++) {

if(paramList.get(i) instanceof Integer) {

int paramValue = ((Integer)paramList.get(i)).intValue();

pstmt.setInt(i+1, paramValue);

} else if(paramList.get(i) instanceof Float) {

float paramValue = ((Float)paramList.get(i)).floatValue();

pstmt.setFloat(i+1, paramValue);

} else if(paramList.get(i) instanceof Double) {

double paramValue = ((Double)paramList.get(i)).doubleValue();

pstmt.setDouble(i+1, paramValue);

} else if(paramList.get(i) instanceof Date) {

pstmt.setString(i+1, df.format((Date)paramList.get(i)));

} else if(paramList.get(i) instanceof Long) {

long paramValue = ((Long)paramList.get(i)).longValue();

pstmt.setLong(i+1, paramValue);

} else if(paramList.get(i) instanceof String) {

pstmt.setString(i+1, (String)paramList.get(i));

}

}

return;

}

/**

* 获得数据库连接

* @return

* @throws Exception

*/

private Connection getConnection() throws Exception {

InitialContext cxt = new InitialContext();

DataSource ds = (DataSource) cxt.lookup(jndiName);

if ( ds == null ) {

throw new Exception("Data source not found!");

}

return ds.getConnection();

}

private static PreparedStatement getPreparedStatement(Connection conn, String sql) throws ExcijzoDeption {

if(conn == null || sql == null || sql.trim().equals("")) {

return null;

}

PreparedStatement pstmt = conn.prepareStatement(sql.trim());

return pstmt;

}

/**

* 获得数据库查询结果集

* @param pstmt

* @return

* @throws Exception

*/

private ResultSet getResultSet(PreparedStatement pstmt) throws Exception {

if(pstmt == null) {

return null;

}

ResultSet rs = pstmt.executeQuery();

return rs;

}

/**

* @param rs

ijzoD* @return

* @throws Exception

*/

private List

if(rs == null) {

return null;

}

ResultSetMetaData rsMetaData = rs.getMetaData();

int columnCount = rsMetaData.getColumnCount();

List

while (rs.next()) {

Map dataMap = new HashMap();

for (int i = 0; i < columnCount; i++) {

dataMap.put(rsMetaData.getColumnName(i+1), rs.getObject(i+1));

}

dataList.add(dataMap);

}

return dataList;

}

/**

* 关闭数据库连接

* @param conn

*/

private void closeConn(Connection conn) {

if(conn == null) {

return;

}

try {

conn.close();

} catch (SQLException e) {

//logger.info(e.getMessage());

}

}

/**

* 关闭

* @param stmt

*/

private void closeStatement(Statement stmt) {

if(stmt == null) {

return;

}

try {

stmt.close();

} catch (SQLException e) {

//logger.info(e.getMessage());

}

}

/**

* 关闭

* @param rs

*/

private void closeResultSet(ResultSet rs) {

if(rs == null) {

return;

}

try {

rs.close();

} catch (SQLException e) {

//logger.info(e.getMessage());

}

}

private String jndiName = "java:/comp/env/jdbc/demoDB";

public void setJndiName(String jndiName) {

this.jndiName = jndiName;

}

}

总结：使用配置数据源的方式连接数据库，这种方式效率高且性能稳定，推荐使用。

type="javax.sql.DataSource"

driverClassName="com.mysql.jdbc.Driver"

url="jdbc:mysql://localhost:3306/demo"

username="root"

password="123"

maxActive="50"

maxIdle="30"

maxWait="10000" />

3）在web工程目录下的web.xml的根节点下配置如下内容：

mysqlDB Connection

jdbc/demoDB

javax.sql.DataSource

Container

完成上述步骤数据源的连接池配置已经完成，但是为了提高项目的可移植性，最好将上述第二步的内容放入到工程的META-INF目录的context.xml中（这个文件需要自行建立）：

<Context>

type="javax.sql.DataSource"

driverClassName="com.mysql.jdbc.Driver"

url="jdbc:mysql://localhost:3306/demo"

username="root"

password="123"

maxActive="50"

maxIdle="30"

maxWait="10000" />

3.使用配置数据源的数据库连接池时的数据库操作工具类

代码如下：

package db.utils;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.ResultSetMetaData;

import java.sql.SQLException;

import java.sql.Statement;

import java.text.DateFormat;

import java.util.ArrayList;

import java.util.Date;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import javax.naming.InitialContext;

import javax.sql.DataSource;

//import org.apache.log4j.Logger;

/**

* 数据库操作辅助类

*/

public class DbUtils {

//private static Logger logger = Logger.getLogger("DbUtils");

/**

* 该语句必须是一个 SQL INSERT、UPDATE 或 DELETE 语句

* @param sql

* @param paramList：参数，与SQL语句中的占位符一一对应

* @return

* @throws Exception

*/

public int execute(String sql, List

if(sql == null || sql.trim().equals("")) {

//logger.info("parameter is valid!");

}

Connection conn = null;

PreparedStatement pstmt = null;

int result = 0;

try {

conn = getConnection();

pstmt = DbUtils.getPreparedStatement(conn, sql);

setPreparedStatementParam(pstmt, paramList);

if(pstmt == null) {

return -1;

}

result = pstmt.executeUpdate();

} catch (Exception e) {

//logger.info(e.getMessage());

throw new Exception(e);

} finally {

closeStatement(pstmt);

closeConn(conn);

}

return result;

}

/**

* 将查询数据库获得的结果集转换为Map对象

* @param sql：查询语句

* @param paramList：参数

* @return

*/

public List

if(sql == null || sql.trim().equals("")) {

//logger.info("parameter is valid!");

return null;

}

Connection conn = null;

PreparedStatement pstmt = null;

ResultSet rs = null;

List

try {

conn = getConnection();

pstmt = DbUtils.getPreparedStatement(conn, sql);

setPreparedStatementParam(pstmt, paramList);

if(pstmt == null) {

return null;

}

rs = getResultSet(pstmt);

queryList = getQueryList(rs);

} catch (RuntimeException e) {

//logger.info(e.getMessage());

System.out.println("parameter is valid!");

throw new Exception(e);

} finally {

closeResultSet(rs);

closeStatement(pstmt);

closeConn(conn);

}

return queryList;

}

private void setPreparedStatementParam(PreparedStatement pstmt, List

if(pstmt == null || paramList == null || paramList.isEmpty()) {

return;

}

DateFormat df = DateFormat.getDateTimeInstance();

for (int i = 0; i < paramList.size(); i++) {

if(paramList.get(i) instanceof Integer) {

int paramValue = ((Integer)paramList.get(i)).intValue();

pstmt.setInt(i+1, paramValue);

} else if(paramList.get(i) instanceof Float) {

float paramValue = ((Float)paramList.get(i)).floatValue();

pstmt.setFloat(i+1, paramValue);

} else if(paramList.get(i) instanceof Double) {

double paramValue = ((Double)paramList.get(i)).doubleValue();

pstmt.setDouble(i+1, paramValue);

} else if(paramList.get(i) instanceof Date) {

pstmt.setString(i+1, df.format((Date)paramList.get(i)));

} else if(paramList.get(i) instanceof Long) {

long paramValue = ((Long)paramList.get(i)).longValue();

pstmt.setLong(i+1, paramValue);

} else if(paramList.get(i) instanceof String) {

pstmt.setString(i+1, (String)paramList.get(i));

}

}

return;

}

/**

* 获得数据库连接

* @return

* @throws Exception

*/

private Connection getConnection() throws Exception {

InitialContext cxt = new InitialContext();

DataSource ds = (DataSource) cxt.lookup(jndiName);

if ( ds == null ) {

throw new Exception("Data source not found!");

}

return ds.getConnection();

}

private static PreparedStatement getPreparedStatement(Connection conn, String sql) throws ExcijzoDeption {

if(conn == null || sql == null || sql.trim().equals("")) {

return null;

}

PreparedStatement pstmt = conn.prepareStatement(sql.trim());

return pstmt;

}

/**

* 获得数据库查询结果集

* @param pstmt

* @return

* @throws Exception

*/

private ResultSet getResultSet(PreparedStatement pstmt) throws Exception {

if(pstmt == null) {

return null;

}

ResultSet rs = pstmt.executeQuery();

return rs;

}

/**

* @param rs

ijzoD* @return

* @throws Exception

*/

private List

if(rs == null) {

return null;

}

ResultSetMetaData rsMetaData = rs.getMetaData();

int columnCount = rsMetaData.getColumnCount();

List

while (rs.next()) {

Map dataMap = new HashMap();

for (int i = 0; i < columnCount; i++) {

dataMap.put(rsMetaData.getColumnName(i+1), rs.getObject(i+1));

}

dataList.add(dataMap);

}

return dataList;

}

/**

* 关闭数据库连接

* @param conn

*/

private void closeConn(Connection conn) {

if(conn == null) {

return;

}

try {

conn.close();

} catch (SQLException e) {

//logger.info(e.getMessage());

}

}

/**

* 关闭

* @param stmt

*/

private void closeStatement(Statement stmt) {

if(stmt == null) {

return;

}

try {

stmt.close();

} catch (SQLException e) {

//logger.info(e.getMessage());

}

}

/**

* 关闭

* @param rs

*/

private void closeResultSet(ResultSet rs) {

if(rs == null) {

return;

}

try {

rs.close();

} catch (SQLException e) {

//logger.info(e.getMessage());

}

}

private String jndiName = "java:/comp/env/jdbc/demoDB";

public void setJndiName(String jndiName) {

this.jndiName = jndiName;

}

}

总结：使用配置数据源的方式连接数据库，这种方式效率高且性能稳定，推荐使用。

type="javax.sql.DataSource"

driverClassName="com.mysql.jdbc.Driver"

url="jdbc:mysql://localhost:3306/demo"

username="root"

password="123"

maxActive="50"

maxIdle="30"

maxWait="10000" />

3.使用配置数据源的数据库连接池时的数据库操作工具类

代码如下：

package db.utils;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.ResultSetMetaData;

import java.sql.SQLException;

import java.sql.Statement;

import java.text.DateFormat;

import java.util.ArrayList;

import java.util.Date;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import javax.naming.InitialContext;

import javax.sql.DataSource;

//import org.apache.log4j.Logger;

/**

* 数据库操作辅助类

*/

public class DbUtils {

//private static Logger logger = Logger.getLogger("DbUtils");

/**

* 该语句必须是一个 SQL INSERT、UPDATE 或 DELETE 语句

* @param sql

* @param paramList：参数，与SQL语句中的占位符一一对应

* @return

* @throws Exception

*/

public int execute(String sql, List

if(sql == null || sql.trim().equals("")) {

//logger.info("parameter is valid!");

}

Connection conn = null;

PreparedStatement pstmt = null;

int result = 0;

try {

conn = getConnection();

pstmt = DbUtils.getPreparedStatement(conn, sql);

setPreparedStatementParam(pstmt, paramList);

if(pstmt == null) {

return -1;

}

result = pstmt.executeUpdate();

} catch (Exception e) {

//logger.info(e.getMessage());

throw new Exception(e);

} finally {

closeStatement(pstmt);

closeConn(conn);

}

return result;

}

/**

* 将查询数据库获得的结果集转换为Map对象

* @param sql：查询语句

* @param paramList：参数

* @return

*/

public List

if(sql == null || sql.trim().equals("")) {

//logger.info("parameter is valid!");

return null;

}

Connection conn = null;

PreparedStatement pstmt = null;

ResultSet rs = null;

List

try {

conn = getConnection();

pstmt = DbUtils.getPreparedStatement(conn, sql);

setPreparedStatementParam(pstmt, paramList);

if(pstmt == null) {

return null;

}

rs = getResultSet(pstmt);

queryList = getQueryList(rs);

} catch (RuntimeException e) {

//logger.info(e.getMessage());

System.out.println("parameter is valid!");

throw new Exception(e);

} finally {

closeResultSet(rs);

closeStatement(pstmt);

closeConn(conn);

}

return queryList;

}

private void setPreparedStatementParam(PreparedStatement pstmt, List

if(pstmt == null || paramList == null || paramList.isEmpty()) {

return;

}

DateFormat df = DateFormat.getDateTimeInstance();

for (int i = 0; i < paramList.size(); i++) {

if(paramList.get(i) instanceof Integer) {

int paramValue = ((Integer)paramList.get(i)).intValue();

pstmt.setInt(i+1, paramValue);

} else if(paramList.get(i) instanceof Float) {

float paramValue = ((Float)paramList.get(i)).floatValue();

pstmt.setFloat(i+1, paramValue);

} else if(paramList.get(i) instanceof Double) {

double paramValue = ((Double)paramList.get(i)).doubleValue();

pstmt.setDouble(i+1, paramValue);

} else if(paramList.get(i) instanceof Date) {

pstmt.setString(i+1, df.format((Date)paramList.get(i)));

} else if(paramList.get(i) instanceof Long) {

long paramValue = ((Long)paramList.get(i)).longValue();

pstmt.setLong(i+1, paramValue);

} else if(paramList.get(i) instanceof String) {

pstmt.setString(i+1, (String)paramList.get(i));

}

}

return;

}

/**

* 获得数据库连接

* @return

* @throws Exception

*/

private Connection getConnection() throws Exception {

InitialContext cxt = new InitialContext();

DataSource ds = (DataSource) cxt.lookup(jndiName);

if ( ds == null ) {

throw new Exception("Data source not found!");

}

return ds.getConnection();

}

private static PreparedStatement getPreparedStatement(Connection conn, String sql) throws ExcijzoDeption {

if(conn == null || sql == null || sql.trim().equals("")) {

return null;

}

PreparedStatement pstmt = conn.prepareStatement(sql.trim());

return pstmt;

}

/**

* 获得数据库查询结果集

* @param pstmt

* @return

* @throws Exception

*/

private ResultSet getResultSet(PreparedStatement pstmt) throws Exception {

if(pstmt == null) {

return null;

}

ResultSet rs = pstmt.executeQuery();

return rs;

}

/**

* @param rs

ijzoD* @return

* @throws Exception

*/

private List

if(rs == null) {

return null;

}

ResultSetMetaData rsMetaData = rs.getMetaData();

int columnCount = rsMetaData.getColumnCount();

List

while (rs.next()) {

Map dataMap = new HashMap();

for (int i = 0; i < columnCount; i++) {

dataMap.put(rsMetaData.getColumnName(i+1), rs.getObject(i+1));

}

dataList.add(dataMap);

}

return dataList;

}

/**

* 关闭数据库连接

* @param conn

*/

private void closeConn(Connection conn) {

if(conn == null) {

return;

}

try {

conn.close();

} catch (SQLException e) {

//logger.info(e.getMessage());

}

}

/**

* 关闭

* @param stmt

*/

private void closeStatement(Statement stmt) {

if(stmt == null) {

return;

}

try {

stmt.close();

} catch (SQLException e) {

//logger.info(e.getMessage());

}

}

/**

* 关闭

* @param rs

*/

private void closeResultSet(ResultSet rs) {

if(rs == null) {

return;

}

try {

rs.close();

} catch (SQLException e) {

//logger.info(e.getMessage());

}

}

private String jndiName = "java:/comp/env/jdbc/demoDB";

public void setJndiName(String jndiName) {

this.jndiName = jndiName;

}

}

总结：使用配置数据源的方式连接数据库，这种方式效率高且性能稳定，推荐使用。

版权声明：本文内容由网络用户投稿，版权归原作者所有，本站不拥有其著作权，亦不承担相应法律责任。如果您发现本站中有涉嫌抄袭或描述失实的内容，请联系我们jiasou666@gmail.com 处理，核实后本网站将在24小时内删除侵权内容。