MySQL SQLException: 找不到合适的驱动程序

Question

提问by Eliezer

I have a Java class that accesses a MySQL database through JDBC that I use in a JSP running on Tomcat, and I am getting No Driver Found Exception.

我有一个 Java 类，它通过我在 Tomcat 上运行的 JSP 中使用的 JDBC 访问 MySQL 数据库，但我收到了 No Driver Found Exception。

I have a method:

我有一个方法：

private static Statement makeStatement() {
   try{
    com.mysql.jdbc.Driver d = null;
    try{d = new com.mysql.jdbc.Driver();}catch(Exception e){
      System.out.println("ERROR BY NEW DRIVER " + e.toString() + 
      "\n");e.printStackTrace();}
    Connection con = DriverManager.getConnection(url, user, password);
    return con.createStatement();
   }catch(java.sql.SQLException ex){
      System.out.println("ERROR IN makeStatement " + "\nERROR - " +
      ex.toString() +  "\n ERROR CODE:\n " + ex.getErrorCode() + 
      "\nSQLSTATE:\n " + ex.getSQLStat        e());ex.printStackTrace();}
    return null;
 }

That throws an error at Connection con = DriverManager.getConnection(url, user, password);Here is my printout from catalina.out:

这会引发错误，Connection con = DriverManager.getConnection(url, user, password);这是我从 catalina.out 打印出来的：

  Received Parameters

ERROR IN makeStatement 
ERROR - java.sql.SQLException: No suitable driver found for 
 ERROR CODE:
 0
SQLSTATE:
 08001
java.sql.SQLException: No suitable driver found for 
        at java.sql.DriverManager.getConnection(DriverManager.java:602)
        at java.sql.DriverManager.getConnection(DriverManager.java:185)
        at message.Message.makeStatement(Message.java:72)
        at message.Message.query(Message.java:79)
        at message.Message.getName(Message.java:225)
        at org.apache.jsp.message_jsp._jspService(message_jsp.java:288)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:548)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
        at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
        at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
        at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
        at java.lang.Thread.run(Thread.java:619)
ERROR IN QUERY java.lang.NullPointerException
ERROR in getName java.lang.NullPointerException
-----------------------------------

  Received Parameters

        newMessage      =  
        newpassword     = 
        verifypassword  = 
        sendinfo        = 
        username        = Eli
        newusername     = 
        login   = login
        password        = tree
ERROR IN makeStatement 
ERROR - java.sql.SQLException: No suitable driver found for 
 ERROR CODE:
 0
SQLSTATE:
 08001
java.sql.SQLException: No suitable driver found for 
        at java.sql.DriverManager.getConnection(DriverManager.java:602)
        at java.sql.DriverManager.getConnection(DriverManager.java:185)
        at message.Message.makeStatement(Message.java:72)
        at message.Message.query(Message.java:79)
        at message.Message.validUser(Message.java:195)
        at org.apache.jsp.message_jsp._jspService(message_jsp.java:123)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:548)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
        at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
        at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
        at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
        at java.lang.Thread.run(Thread.java:619)
ERROR IN QUERY java.lang.NullPointerException
ERROR in validUser java.lang.NullPointerException
ERROR IN makeStatement 
ERROR - java.sql.SQLException: No suitable driver found for 
 ERROR CODE:
 0
SQLSTATE:
 08001
java.sql.SQLException: No suitable driver found for 
        at java.sql.DriverManager.getConnection(DriverManager.java:602)
        at java.sql.DriverManager.getConnection(DriverManager.java:185)
        at message.Message.makeStatement(Message.java:72)
        at message.Message.query(Message.java:79)
        at message.Message.getName(Message.java:225)
        at org.apache.jsp.message_jsp._jspService(message_jsp.java:288)
        at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:331)
        at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:329)
        at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:265)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:174)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:548)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
        at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
        at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
        at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
        at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
        at java.lang.Thread.run(Thread.java:619)
ERROR IN QUERY java.lang.NullPointerException
ERROR in getName java.lang.NullPointerException

The only error that matters is the one in makeStatement()as that failing causes all the other errors. I have quadruple checked that I have the correct jar files in my WEB-INF/lib directory and I have restarted Tomcat more times than I would ever want to. I have a separate webapp that uses makeStatement()in a different .java file, and that webapp runs fine. Even weirder is that I have this in the .java:

唯一重要的错误是错误，makeStatement()因为失败会导致所有其他错误。我已经四次检查我的 WEB-INF/lib 目录中是否有正确的 jar 文件，并且我重新启动 Tomcat 的次数比我想要的要多。我有一个单独的 webapp，它makeStatement()在不同的 .java 文件中使用，并且该 webapp 运行良好。更奇怪的是，我在 .java 中有这个：

static {
  System.err.println("\n\nTEST MYSQL ACCESS: dump all relevant tables:");
  dump();
  System.err.println("END OF MYSQL ACCESS ACCESS.");
}

 public static void dump() {
   try {
     readUsers();
     for (UserRecord u: users)
     System.err.println(u.username+" "+u.password);
   } catch (Exception e) {System.err.println(e);}
 }

where readUsers()reads all the users from the database using makeStatement(). This actually works and all the users in the database are printed (not shown here for obvious reasons :) ) and then the driver not found error occurs.

其中readUsers()使用makeStatement(). 这实际上是有效的，并且数据库中的所有用户都被打印出来（由于明显的原因，这里没有显示:)）然后发生驱动程序未找到错误。

Answer 1

回答by BalusC

java.sql.SQLException: No suitable driver found

java.sql.SQLException：找不到合适的驱动程序

This exception can have 2 causes:

此异常可能有两个原因：

The JDBC driver is not loaded at all.
URL does not match any of the loaded JDBC drivers.

JDBC 驱动程序根本没有加载。
URL 与任何加载的 JDBC 驱动程序都不匹配。

Since the driver seems to be loaded (although in an incorrect manner), it look like that the URL is plain wrong. Ensure that the value of your urlvariable matches the following format

由于驱动程序似乎已加载（尽管以不正确的方式加载），因此 URL 似乎是完全错误的。确保您的url变量值符合以下格式

jdbc:mysql://localhost:3306/dbname

也可以看看：

Connect Java to a MySQL database

将 Java 连接到 MySQL 数据库

Unrelatedto the concrete problem: Java code doesn't belong in a JSP file. Work on that as well. Your exception handling is also terrible, you should throwthe exception (so that it blocks executing the remnant of the code) instead of printing the message/trace and then continue with the code.

与具体问题无关：Java 代码不属于 JSP 文件。也在这方面努力。您的异常处理也很糟糕，您应该抛出异常（以便它阻止执行剩余的代码），而不是打印消息/跟踪，然后继续执行代码。

Answer 2

回答by Parag Sarda

I had to removemysql-connector-java-*.jar from WEB-INF/lib and addit into tomcat6/lib folder. (tomcat6 is where tomcat was installed.) I do not know why this worked but it worked for me.

我必须从 WEB-INF/lib 中删除mysql-connector-java-*.jar并将其添加到 tomcat6/lib 文件夹中。（tomcat6 是安装 tomcat 的地方。）我不知道这为什么有效，但它对我有用。

Answer 3

回答by John Kane

Did you register your class with the Driver? For example:

您是否在 Driver 上注册了您的课程？例如：

Class.forName("net.sourceforge.jtds.jdbc.Driver");
DriverManager.getConnection(url,user,password);

Answer 4

回答by heavi5ide

Are you passing an emtpy url string to getConnection()? The error message starts out

您是否将一个空的 url 字符串传递给 getConnection()？错误信息开始

No suitable driver found for ERROR

No suitable driver found for [blank]? Seems like you're not passing a url here.

没有找到适合 [空白] 的驱动程序？似乎您没有在这里传递网址。

Answer 5

回答by Thilina101

Go to library folder of your project and right click it,then go to 'Add Library' option.Now add the mysql.jdbc.Driver

转到项目的库文件夹并右键单击它，然后转到“添加库”选项。现在添加 mysql.jdbc.Driver

MySQL SQLException: 找不到合适的驱动程序

提问by Eliezer

回答by BalusC

See also:

也可以看看：

回答by Parag Sarda

回答by John Kane

回答by heavi5ide

回答by Thilina101

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MySQL SQLException: 找不到合适的驱动程序

提问by Eliezer

回答by BalusC

See also:

也可以看看：

回答by Parag Sarda

回答by John Kane

回答by heavi5ide

回答by Thilina101

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