我正在尝试创建我的第一个连接池。我正在使用 Tomcat 7 和 MySQL DB 创建一个 Java Web 应用程序，并且我想创建一个可能实现连接池的 Servelet。我尝试了一个网络代码，但出现了一个持久的 HTTP 500 问题。我搜索了很多，但仍然没有解决方案，所以请不要链接其他讨论，因为我已经全部检查过了！这是我的代码：对于 context.xml ：
<?xml version="1.0" encoding="UTF-8"?>
<Context antiJARLocking="true" path="/My_First_WEB"
reloadable="true"
docBase="\My_First_WEB" >
<Resource
name="jdbc/TutoPool"
auth="Container"
type="javax.sql.DataSource"/>
<ResourceParams name="jdbc/TutoPool">
<parameter>
<name>username</name>
<value>root</value>
</parameter>
<parameter>
<name>password</name>
<value>""</value>
</parameter>
<parameter>
<name>driverClassName</name>
<value>com.mysql.jdbc.Driver</value>
</parameter>
<parameter>
<name>url</name>
<value>jdbc:mysql://localhost/TutoPool</value>
</parameter>
<parameter>
<name>maxActive</name>
<value>8</value>
</parameter>
<parameter>
<name>maxIdle</name>
<value>8</value>
</parameter>
<parameter>
<name>maxWait</name>
<value>10000</value>
</parameter>
<parameter>
<name>validationQuery</name>
<value>select 1</value>
</parameter>
<parameter>
<name>removeAbandoned</name>
<value>true</value>
</parameter>
<parameter>
<name>removeAbandonedTimeout</name>
<value>20</value>
</parameter>
<parameter>
<name>logAbandoned</name>
<value>true</value>
</parameter>
</ResourceParams>
</Context>
web.xml 如下：
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" 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_3_0.xsd">
<servlet>
<servlet-name>TutoPool</servlet-name>
<servlet-class>MyServelets.TutoPool</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>TutoPool</servlet-name>
<url-pattern>/TutoPool</url-pattern>
</servlet-mapping>
<resource-ref>
<description>
reference a la ressource BDD pour le pool
</description>
<res-ref-name>jdbc/TutoPool</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
<session-config>
<session-timeout>
30
</session-timeout>
</session-config>
最后 TutoPool.java 如下：
package MyServelets;
import java.io.*;
import java.sql.*;
import javax.naming.*;
import javax.servlet.ServletException;
import javax.servlet.UnavailableException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import javax.sql.DataSource;
@WebServlet(name = "TutoPool", urlPatterns = {"/TutoPool"})
public class TutoPool extends HttpServlet {
private DataSource ds; //la source de données
/**
* Processes requests for both HTTP
* <code>GET</code> and
* <code>POST</code> methods.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
try {
/* TODO output your page here. You may use following sample code. */
out.println("<html>");
out.println("<head>");
out.println("<title>Servlet TutoPool</title>");
out.println("</head>");
out.println("<body>");
out.println("<h1>Servlet TutoPool at " + request.getContextPath() + "</h1>");
out.println("</body>");
out.println("</html>");
} finally {
out.close();
}
}
// <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
/**
* Handles the HTTP
* <code>GET</code> method.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html><head></head>");
out.println("<body>");
Connection con=null;
Statement s=null;
ResultSet rs=null;
try {
//récupération de la Connection depuis le DataSource
con = ds.getConnection();
s = con.createStatement();
rs = s.executeQuery("SELECT * FROM table1");
while (rs.next()) {
out.println(rs.getString(1) + " ");
out.println(rs.getString(2) + "<br/>");
}
} catch (SQLException e) {
response.sendError(500, "Exception sur l'accès à la BDD " + e);
}finally {
if (rs != null)
{
try {
rs.close();
} catch (SQLException e) {}
rs = null;
}
if (s != null) {
try {
s.close();
} catch (SQLException e) {}
s = null;
}
if (con != null) {
try {
con.close();
} catch (SQLException e) {}
con = null;
}
}
out.println("</body>");
out.println("</html>");
out.close();
}
/**
* Returns a short description of the servlet.
*
* @return a String containing servlet description
*/
@Override
public String getServletInfo() {
return "Short description";
}// </editor-fold>
/**
*
* @throws ServletException
*/
@Override
public void init() throws ServletException {
try {
//récupération de la source de donnée
Context initCtx = new InitialContext();
ds = (DataSource) initCtx.lookup("java:comp/env/jdbc/TutoPool");
} catch (Exception e) {
throw new UnavailableException(e.getMessage());
}
}
}
最后出现的错误是：
type Rapport d''état
message Exception sur l'accès à la BDD org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
description Le serveur a rencontré une erreur interne (Exception sur l'accès à la BDD org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null') qui l'a empêché de satisfaire la requête.
我已经检查了图书馆中的 mysql-connector，这应该可以工作！还是没有。请问，有人对此有想法吗？我在这里淹死了！！：（ 谢谢。