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[英]JNDI Connection works on Tomcat, but doesn't work on Websphere
[英]JNDI Can't Create a JDBC Connection on Tomcat 6
嘗試查看頁面時出現此錯誤:
SQLException: Cannot create JDBC driver of class '' for connect URL 'null'
我有以下/WEB-INF/web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app>
<display-name>WSwartzendruber.net</display-name>
<description>Personal Website</description>
<!-- Servlet stuff -->
<servlet>
<servlet-name>PostgresTest</servlet-name>
<servlet-class>PostgresTest</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>PostgresTest</servlet-name>
<url-pattern>/servlets/postgrestest</url-pattern>
</servlet-mapping>
<!-- JNDI -->
<resource-ref>
<description>PostgreSQL Data Source</description>
<res-ref-name>jdbc/db_website</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
</web-app>
我在/META-INF/context.xml中有這個:
<?xml version="1.0" encoding="UTF-8"?>
<Context reloadable="true">
<Resource name="jdbc/db_website" auth="Container" type="javax.sql.DataSource" driverClassName="org.postgresql.Driver" url="jdbc:postgresql://localhost:5432/db_website" username="website"/>
</Context>
這是測試代碼:
import java.io.*;
import java.sql.*;
import javax.naming.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.sql.*;
import org.wswartzendruber.website.access.*;
public class PostgresTest extends HttpServlet
{
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException
{
response.setContentType("text/plain");
try
{
Context initialContext = new InitialContext();
Context context = (Context)initialContext.lookup("java:comp/env");
DataSource dataSource = (DataSource)context.lookup("jdbc/db_website");
Connection connection = dataSource.getConnection();
NewsCategory[] newsCategory = NewsCategory.getNewsCategories(connection);
connection.close();
}
catch (NamingException e)
{
response.getWriter().println("ERROR: We have naming problems!");
}
catch (SQLException se)
{
response.getWriter().println("ERROR: SQLException: " + se.getMessage());
}
catch (AccessException ae)
{
response.getWriter().println("ERROR: AccessException: " + ae.getMessage());
}
}
}
我不知所措。 我已經有/usr/share/tomcat-6/lib/postgresql-8.4-702.jdbc4.jar了。 將其移動到/ WEB-INF / lib沒什么區別。 在我看來,它可以在WEB-INF / web.xml中看到資源條目,但無法從META-INF / context.xml中提取詳細信息。 在此分配密碼似乎也沒有什么區別。
你們有什么我都願意。
更新 :這是完整的堆棧跟蹤:
Sep 19, 2010 7:01:36 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet PostgresTest threw exception
java.io.IOException: org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
at PostgresTest.doGet(PostgresTest.java:23)
at javax.servlet.http.HttpServlet.service(Unknown Source)
at javax.servlet.http.HttpServlet.service(Unknown Source)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Unknown Source)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(Unknown Source)
at org.apache.catalina.core.StandardWrapperValve.invoke(Unknown Source)
at org.apache.catalina.core.StandardContextValve.invoke(Unknown Source)
at org.apache.catalina.core.StandardHostValve.invoke(Unknown Source)
at org.apache.catalina.valves.ErrorReportValve.invoke(Unknown Source)
at org.apache.catalina.core.StandardEngineValve.invoke(Unknown Source)
at org.apache.catalina.connector.CoyoteAdapter.service(Unknown Source)
at org.apache.jk.server.JkCoyoteHandler.invoke(Unknown Source)
at org.apache.jk.common.HandlerRequest.invoke(Unknown Source)
at org.apache.jk.common.ChannelSocket.invoke(Unknown Source)
at org.apache.jk.common.ChannelSocket.processConnection(Unknown Source)
at org.apache.jk.common.ChannelSocket$SocketConnection.runIt(Unknown Source)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(Unknown Source)
at java.lang.Thread.run(Thread.java:636)
Caused by: org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot create JDBC driver of class '' for connect URL 'null'
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1452)
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1371)
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
at PostgresTest.doGet(PostgresTest.java:17)
... 17 more
Caused by: java.lang.NullPointerException
at org.postgresql.Driver.parseURL(Driver.java:567)
at org.postgresql.Driver.acceptsURL(Driver.java:412)
at java.sql.DriverManager.getDriver(DriverManager.java:268)
at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1437)
... 20 more
異常的“由...引起” /“根本原因”部分包含有關失敗原因的信息。 您不應僅打印異常消息,而忽略異常詳細信息的剩余部分。 您應該拋出整個異常,或者至少打印整個stacktrace。
快速解決方案:將您的try
替換為
try {
Context initialContext = new InitialContext();
Context context = (Context)initialContext.lookup("java:comp/env");
DataSource dataSource = (DataSource)context.lookup("jdbc/db_website");
Connection connection = dataSource.getConnection();
NewsCategory[] newsCategory = NewsCategory.getNewsCategories(connection);
connection.close();
} catch (Exception e) {
throw new ServletException(e);
}
然后重試。 整個堆棧跟蹤應該顯示在服務器的默認錯誤頁面中。 或者,如果您已自定義了不顯示跟蹤的錯誤頁面,請在服務器日志中查找該頁面。
按照注釋進行更新 :您可以僅將ServletException
添加到throws
子句中。 根據stacktrace的說明, context.xml
的資源已正確定位,驅動程序已正確加載,但是未傳遞URL,就像未在<Resource>
指定URL一樣。
您確定要提供您認為正在提供的<Resource>
嗎? 您是否沒有另一個具有相同名稱的<Resource>
,但是在Tomcat/conf/context.xml
沒有url
?
是的,我也遇到了這個問題。如果我將該段放入tomcat / conf / context.xml,它可以工作。我不知道為什么
在WebRoot / META-INF文件夾中添加context.xml並放入
<!-- Default set of monitored resources -->
<WatchedResource>WEB-INF/web.xml</WatchedResource>
<Resource name="jdbc/ecms" auth="Container" type="javax.sql.DataSource"
maxActive="100" maxIdle="30" maxWait="10000"
username="root" password="root123#" driverClassName="com.mysql.jdbc.Driver"
url="jdbc:mysql://localhost:3306/ecms"/>
在web.xml頁面中寫
<resource-ref>
<description>DB Connection</description>
<res-ref-name>jdbc/ecms</res-ref-name>
<res-type>javax.sql.DataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>
形成一個新的Java類並編寫
package com.common;
import java.sql.Connection;
import java.sql.SQLException;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.servlet.ServletException;
import javax.sql.DataSource;
public class DataSourceq {
public Connection dbc() throws NamingException, SQLException, ServletException{
try {
InitialContext initialContext = new InitialContext();
Context context = (Context)initialContext.lookup("java:comp/env");
//The JDBC Data source that we just created
DataSource ds = (DataSource) context.lookup("jdbc/ecms");
Connection connection = ds.getConnection();
return connection;
}
catch (Exception e) {
throw new ServletException(e);
}
}
}
為您的數據源類創建對象並調用
DataSourceq dq = new DataSourceq();
Connection con = dq.dbc();
並執行查詢,它將成功運行
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