Java 从web应用程序访问MS Access数据库

我在尝试访问MS access DB中的表时遇到以下错误

我已经分别创建了数据库

下面是代码

public String ValidateLogin(String un, String pw)
{
    try
    {

        //  Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
            String url = "jdbc:ucanaccess://D:/questions1.accdb";
            Connection con = DriverManager.getConnection(url, "", "");
            Statement s =con.createStatement();

            String query="select count(*) from Users where UserName="+un;
            System.out.println(query);
            s.execute(query);

            ResultSet rs= s.getResultSet();
            if(rs==null)
            {
                result="failure";
            }
            else
            {
                String a1=rs.getString(3);
                if(a1.equals(pw))
                {
                    result="success";
                }
                else
                {
                    result="failure";
                }
            }
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    return result;
}

当我尝试查找记录数时，它工作正常。但是当我试图为一个用户获取记录时，它给了我错误

请告诉我需要做什么

net.ucanaccess.jdbc.UcanaccessSQLException: UCAExc:::3.0.4 user lacks privilege or object not found: AAA
    at net.ucanaccess.jdbc.UcanaccessStatement.execute(UcanaccessStatement.java:154)
    at com.infy.dao.LoginActionDAO.ValidateLogin(LoginActionDAO.java:32)
    at com.infy.HelloWorldAction.execute(HelloWorldAction.java:33)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:452)
    at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:291)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:254)
    at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:176)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:263)
    at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:133)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:207)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:190)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:142)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:166)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:190)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:187)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:248)
    at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488)
    at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:395)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.sql.SQLSyntaxErrorException: user lacks privilege or object not found: AAA
    at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
    at org.hsqldb.jdbc.Util.sqlException(Unknown Source)
    at org.hsqldb.jdbc.JDBCStatement.fetchResult(Unknown Source)
    at org.hsqldb.jdbc.JDBCStatement.execute(Unknown Source)
    at net.ucanaccess.jdbc.Execute.executeWrapped(Execute.java:56)
    at net.ucanaccess.jdbc.AbstractExecute.executeBase(AbstractExecute.java:152)
    at net.ucanaccess.jdbc.Execute.execute(Execute.java:46)
    at net.ucanaccess.jdbc.UcanaccessStatement.execute(UcanaccessStatement.java:152)
    ... 66 more
Caused by: org.hsqldb.HsqlException: user lacks privilege or object not found: AAA
    at org.hsqldb.error.Error.error(Unknown Source)
    at org.hsqldb.error.Error.error(Unknown Source)
    at org.hsqldb.ExpressionColumn.checkColumnsResolved(Unknown Source)
    at org.hsqldb.QueryExpression.resolve(Unknown Source)
    at org.hsqldb.ParserDQL.compileCursorSpecification(Unknown Source)
    at org.hsqldb.ParserCommand.compilePart(Unknown Source)
    at org.hsqldb.ParserCommand.compileStatements(Unknown Source)
    at org.hsqldb.Session.executeDirectStatement(Unknown Source)
    at org.hsqldb.Session.execute(Unknown Source)
    ... 72 more

---

你得到了错误

net.ucanaccess.jdbc.UcanaccessSQLException:ucaesc:：：3.0.4用户缺少权限或找不到对象：AAA

因为您的代码正在构造SQL查询

从UserName=AAA的用户中选择count（*）

而

AAA

被解释为列名，而不是字符串值

正确的解决方案是使用

PreparedStatement

执行参数化查询，它看起来更像这样：

String query=“从用户名=？”的用户中选择*”；
PreparedStatement s=con.prepareStatement（查询）；
s、 设置管柱（1，un）；
结果集rs=s.executeQuery（）；
如果（rs.next（））{
//找到匹配的行，请继续处理
}否则{
//未找到匹配行，因此通知用户和/或日志错误
}

使用

PreparedStatement

而不是（错误地！）在查询字符串中串联值。基本问题是，用户名值周围没有引号，因此它被视为列名而不是值，但实际上应该使用预先准备好的语句。谢谢标记！！：）你是对的。