这些错误信息里我没有得到什么帮助..2008-11-18 8:36:45 org.apache.catalina.core.ApplicationContext log
信息: HTMLManager: init: Associated with Deployer 'Catalina:type=Deployer,host=localhost'
2008-11-18 8:36:45 org.apache.catalina.core.ApplicationContext log
信息: HTMLManager: init: Global resources are available
2008-11-18 8:36:45 org.apache.catalina.core.ApplicationContext log
信息: HTMLManager: list: Listing contexts for virtual host 'localhost'
java.lang.NullPointerException
at com.conn.Selcity.<init>(Selcity.java:23)
at com.conn.Citylist.doGet(Citylist.java:30)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
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.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:595)
信息: HTMLManager: init: Associated with Deployer 'Catalina:type=Deployer,host=localhost'
2008-11-18 8:36:45 org.apache.catalina.core.ApplicationContext log
信息: HTMLManager: init: Global resources are available
2008-11-18 8:36:45 org.apache.catalina.core.ApplicationContext log
信息: HTMLManager: list: Listing contexts for virtual host 'localhost'
java.lang.NullPointerException
at com.conn.Selcity.<init>(Selcity.java:23)
at com.conn.Citylist.doGet(Citylist.java:30)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)
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.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:595)
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Connection conn;
Conn con; public Selcity() throws Exception {
super();
v = new Vector();
// data = new Data();
conn = con.getConn();
}
....................
con is null, How can you get something from null object?
at com.conn.Citylist.doGet(Citylist.java:30)
看下吧 错误就在这
我就是不明白,因为经验少所以不知道什么问这个问题好,跟踪调试也没有什么帮助,就是觉得我可以是少是
servlet的哪些知识少造成的,所以发出来让有经验的大家看看给建议..Conn.java
public class Conn{
String driver; // JDBC驱动程序,对应web.xml的driver属性
String url; // 数据库URL,对应web.xml的url属性
String user; // 用户名
String password; // 用户密码 Connection conn;
Statement stmt;
ResultSet rs; public Conn() {
super();
driver = "com.mysql.jdbc.Driver";
url =
"jdbc:mysql://localhost:3306/chinatravellinks";
user = "root";
password = null;
}
/**
* 功能:初始化连接数据库参数
* @param driver
* @param url
* @param user
* @param password
*/ /**
* 功能:连接数据库
* @return:Connection对象conn
* @throws Exception
*/
public Connection getConn() throws Exception {
try {
Class.forName(driver);
conn = (Connection) DriverManager
.getConnection(url, user, password);
return conn;
} catch (SQLException e) {
System.err.println(e.getMessage());
throw e;
}
} /**
* 功能:为执行SQL作准备,查询操作时专用 <br>
*
* @return:Statement对象stmt
*/
public Statement getStmtread() {
try {
conn = getConn();
stmt = (Statement) conn.createStatement(
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_READ_ONLY);
return stmt;
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
return null;
} /**
* 功能:为执行SQL作准备,非查询操作时用 <br>
*
* @return:Statement对象stmt
*/
public Statement getStmt() {
try {
conn = getConn();
stmt = (Statement) conn.createStatement();
return stmt;
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
return null;
} /**
* 功能:关闭数据库连接
*/
public void close() {
try {
if (rs != null) {
rs.close(); // 关闭结果集
rs = null;
}
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
try {
if (stmt != null) {
stmt.close(); // 关闭SQL语句对象
stmt = null;
}
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
try {
if (conn != null) {
conn.close(); // 关闭数据库
conn = null;
}
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
}
}
先看看 是否值提交传过来拉
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException { response.setContentType("text/html;charset=GB2312");
PrintWriter out = response.getWriter();
//在这把值打印出来
}
如果有值@Override
public PageBreak PageManage(String toPages) throws Exception {
PageBreak pageBreak = new PageBreak(this);
//看看这个有值没有
}
一步一步的试就可以拉
或者用单步调试最好
LZ你往简单的地方去想吧,最低等的异常..别想太复杂