菜鸟求救高人!servlet中调用类总是报异常!
int_1 2012-07-18 09:28:45 配置文件和类(service1)测试正常,在JUnit测试中可以返回值,但是在servlet中调用service1类,始终出错,不是空指针就是下面的异常。
请看代码:
这是service1部分:
package com.yb.web;
import java.io.FileInputStream;
import java.io.IOException;
import java.sql.*;
import java.util.ArrayList;
import java.util.Properties;
public class Service1 {
/**
* @param args
*/
private static Connection ct=null;
private static PreparedStatement ps=null;
private static ResultSet rs=null;
private static ArrayList<JavaBean> al=null;
private static FileInputStream fis=null;
private static Properties pp=null;
private static String url="";
private static String user="";
private static String passw="";
private static String driver="";
//加载驱动,仅需一次。
static{
try {
//建立输入流,引入配置文件。
fis = new FileInputStream("peizhi.properties");
pp = new Properties();
pp.load(fis);
url=pp.getProperty("url");
user=pp.getProperty("user");
passw=pp.getProperty("passw");
driver=pp.getProperty("driver");
//加载驱动
Class.forName(driver);
} catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}finally{
//关闭输入流
try {
fis.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
fis=null;
}
}
}
public static Connection getConnection(){
//建立连接
try {
ct=DriverManager.getConnection(url,user,passw);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return ct;
}
//建立连接的方法
public static String chaxun(){
int i=0;
String pin="";
try{
//建立连接
ct=getConnection();
//建立语句对象
ps=ct.prepareStatement("select url,wenzi from info limit 0,10");
//回收结果
rs=ps.executeQuery();
//装箱
al=new ArrayList<JavaBean>();
while(rs.next()){
JavaBean jb =new JavaBean();
jb.setUrl(rs.getString(1));
jb.setWenzi(rs.getString(2));
al.add(jb);
for(i = 0; i<al.size(); i++) {
JavaBean jb=(JavaBean)al.get(i);
//height = Math.floor(Math.random()*200 + 200);
pin+="这是第"+(i+1)+"个文件"+jb.getUrl()+jb.getWenzi();
}
catch(Exception e){
e.printStackTrace();
}
finally{
//关闭资源
close(rs,ps,ct);
}
return pin;
}
//关闭资源方法
public static void close(ResultSet rs,PreparedStatement ps,Connection ct){
if(rs!=null){
try {
rs.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(ps!=null){
try {
ps.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(ct!=null){
try {
ct.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
以下是servlet代码:
package com.yb.controller;
import com.yb.web.Service1;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Myserv extends HttpServlet{
//private static final long serialVersionUID = 1L;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try {
PrintWriter pw = response.getWriter();//就是在这个地方总是出错!!
String pin = Service1.chaxun();//就是在这个地方总是出错!!
pw.print(pin);
} catch (IOException e) {
e.printStackTrace();
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}
严重: Servlet.service() for servlet [Myserv] in context with path [/firstweb] threw exception [Servlet execution threw an exception] with root cause
java.lang.NoClassDefFoundError: Could not initialize class com.yb.web.Service1
at com.yb.controller.Myserv.doGet(Myserv.java:25)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)