十万火急

[liuhangsheng]

前台报错
exception
org.apache.jasper.JasperException: An exception occurred processing JSP page /article.jsp at line 7

4: <%!
5: private void tree(List<Article> articles, Connection conn, int id, int grade) {
6: String sql = "select * from article where pid = " + id;
7: Statement stmt = DB.createStmt(conn);
8: ResultSet rs = DB.executeQuery(stmt, sql);
9: try {
10: while(rs.next()) {

DB.java的一些相关方法
public static Statement createStmt(Connection conn) {
Statement stmt = null;
try {
stmt = conn.createStatement();
} catch (SQLException e) {
e.printStackTrace();
}
return stmt;
}


后台报错:

严重: Servlet.service() for servlet [jsp] in context with path [/BBS] threw exception [An exception occurred processing JSP page /article.jsp at line 7

4: <%!
5: private void tree(List<Article> articles, Connection conn, int id, int grade) {
6: String sql = "select * from article where pid = " + id;
7: Statement stmt = DB.createStmt(conn);
8: ResultSet rs = DB.executeQuery(stmt, sql);
9: try {
10: while(rs.next()) {


Stacktrace:] with root cause
java.lang.NullPointerException
at com.bjsxt.bbs.DB.createStmt(DB.java:29)
at org.apache.jsp.article_jsp.tree(article_jsp.java:24)
at org.apache.jsp.article_jsp._jspService(article_jsp.java:96)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:395)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:339)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)




急啊，这个问题我也是弄半天了，好无奈啊

[newlifely]

问题解决了吗？ org.apache.jasper.JasperException: An exception occurred processing JSP page /article.jsp at line 7 7: Statement stmt = DB.createStmt(conn); --- java.lang.NullPointerException at com.bjsxt.bbs.DB.createStmt(DB.java:29) 后台报错空指针，定位在第七行，应该是DB这个对象没有引入 导下包试试 <%@ page import="java.sql.*,java.util.*" %> ps：是不是在学习马士兵的视频？

[醉解风情]

Connection 导入；List 导入； DB导入 <%@ page import="java.sql.*,java.util.*" %>

[qq_32670627]

conn为空

[自由自在_Yu]

Statement stmt = DB.createStmt(conn); 空指针异常，DB=null?

[xwn_2016]

DB这个类没有import?

[BadMoree]

导入这个类在页面 <%@ page import="java.util.*" %>

[双木L]

DB对象为空？是对象没有建立，还是相应的jar包没有导入导致DB对象为null的

[liuhangsheng]

引用 5 楼 newlifely 的回复:

问题解决了吗？ org.apache.jasper.JasperException: An exception occurred processing JSP page /article.jsp at line 7 7: Statement stmt = DB.createStmt(conn); --- java.lang.NullPointerException at com.bjsxt.bbs.DB.createStmt(DB.java:29) 后台报错空指针，定位在第七行，应该是DB这个对象没有引入 导下包试试 <%@ page import="java.sql.*,java.util.*" %> ps：是不是在学习马士兵的视频？

解决了