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标题: 一个小java程序的小问题 [打印本页]

作者: 小文文化 时间: 2017-10-13 14:31
标题: 一个小java程序的小问题
我有以下几个java程序：
以下是dbcpconfig.properties程序：
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf-8
username=root
password=123

initialSize=10

maxIdle=20

minIdle=5

maxActive=50

maxWait=60000

cooectionProperties=useUnicode=true;characterEncoding=utf8
以下是jdbcutils.java程序：
package utils;

import java.beans.PropertyDescriptor;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

import javax.sql.DataSource;

import org.apache.commons.dbcp2.BasicDataSourceFactory;

public class jdbcutils {

   private static DataSource ds = null;

   static
   {
   InputStream in = (InputStream) jdbcutils.class.getClassLoader().getResourceAsStream("dbcpconfig.properties");
   Properties conf = new Properties();
   try
   {
   conf.load(in);
   BasicDataSourceFactory bdsf = new BasicDataSourceFactory();
   ds = bdsf.createDataSource(conf);
   }
   catch(Exception e)
   {
   e.printStackTrace();
   }
   }

   public static Connection getconn() throws SQLException
   {
   return ds.getConnection();
   }

   public static void del(Connection conn,Statement st,ResultSet rs)
   {
   if(rs!=null)
{
try {
rs.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

if(st!=null)
{
try {
st.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

if(conn!=null)
{
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
   }

}
以下是customerdaoimpl.java程序（这只是我javaee项目其中一个程序）：
package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import utils.jdbcutils;

import bean.customer;
import bean.queryresult;

public class customerdaoimpl implements customerdao {

@Override
public void add(customer c) {
// TODO Auto-generated method stub
Connection conn=null;
PreparedStatement st=null;
ResultSet rs=null;
String sql;
try {
        conn=jdbcutils.getconn();
        sql="insert into customer(name,gender,age,cellphone,live,type,descr) values(?,?,?,?,?,?,?)";
        //System.out.println(sql);
        st=conn.prepareStatement(sql);
        st.setString(1,c.getName());
        st.setString(2, c.getGender());
        st.setInt(3,c.getAge());
        st.setString(4,c.getCellphone());
        st.setString(5, c.getLive());
        st.setString(6, c.getType());
        st.setString(7, c.getDescr());
        int i=st.executeUpdate();
        if(i<1)
        {
        System.out.println("插入客户失败");
        }
        else
        {
     System.out.println("插入客户成功");
        }
}
   catch (Exception e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
}
      finally
      {
        jdbcutils.del(conn, st, rs);
      }
}

@Override
public void updata(customer c) {
// TODO Auto-generated method stub
Connection conn=null;
PreparedStatement st=null;
ResultSet rs=null;
String sql;
try {
        conn=jdbcutils.getconn();
        sql="update customer set name=?,gender=?,age=?,cellphone=?,live=?,type=?,descr=? where id=?";
        st=conn.prepareStatement(sql);
        st.setString(1,c.getName());
        st.setString(2,c.getGender());
        st.setInt(3,c.getAge());
        st.setString(4,c.getCellphone());
        st.setString(5,c.getLive());
        st.setString(6,c.getType());
        st.setString(7,c.getDescr());
        st.setInt(8,c.getId());
     int i=st.executeUpdate();
   if(i<1)
   {
   System.out.println("修改客户失败");
   }
   else
   {
System.out.println("修改客户成功");
   }
}
   catch (Exception e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
}
      finally
      {
        jdbcutils.del(conn, st, rs);
      }
}

@Override
public void del(int id) {
// TODO Auto-generated method stub
Connection conn=null;
PreparedStatement st=null;
ResultSet rs=null;
String sql;
try {
        conn=jdbcutils.getconn();
        conn=jdbcutils.getconn();
        sql="delete from customer where id=?";
        st=conn.prepareStatement(sql);
        st.setInt(1, id);
        int i=st.executeUpdate();
        if(i<1)
   {
   System.out.println("删除客户失败");
   }
   else
   {
System.out.println("删除客户成功");
   }
}
   catch (Exception e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
}
      finally
      {
        jdbcutils.del(conn, st, rs);
      }
}

@Override
public customer find(int id) {
// TODO Auto-generated method stub
Connection conn=null;
PreparedStatement st=null;
ResultSet rs=null;
String sql;
customer c = new customer();
try {
        conn=jdbcutils.getconn();
     sql="select * from customer where id=?";
        st=conn.prepareStatement(sql);
        st.setInt(1,id);
        rs=st.executeQuery();
        if(!rs.next())
        {
        throw new RuntimeException("没有"+id+"号客户");
        }
        else
        {
           c.setId(rs.getInt("id"));
        c.setName(rs.getString("name"));
        c.setGender(rs.getString("gender"));
        c.setAge(rs.getInt("age"));
        c.setCellphone(rs.getString("cellphone"));
        c.setLive(rs.getString("live"));
        c.setType(rs.getString("type"));
        c.setDescr(rs.getString("descr"));
        return c;
        }
}
   catch (Exception e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
}
      finally
      {
        jdbcutils.del(conn, st, rs);
      }
}

@Override
public List<customer> getall() {
// TODO Auto-generated method stub
Connection conn=null;
PreparedStatement st=null;
ResultSet rs=null;
String sql;
List<customer> lc = new ArrayList<customer>();
try {
        conn=jdbcutils.getconn();
        sql="select * from customer";
        st=conn.prepareStatement(sql);
        rs=st.executeQuery();
        while(rs.next())
        {
        customer c = new customer();
        c.setId(rs.getInt("id"));
        c.setName(rs.getString("name"));
        c.setGender(rs.getString("gender"));
        c.setAge(rs.getInt("age"));
        c.setCellphone(rs.getString("cellphone"));
        c.setLive(rs.getString("live"));
        c.setType(rs.getString("type"));
        c.setDescr(rs.getString("descr"));
        lc.add(c);
        }
        return lc;
}
   catch (Exception e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
}
      finally
      {
        jdbcutils.del(conn, st, rs);
      }
}

public queryresult pagequery(int startindex,int pagesize)
{

Connection conn=null;
PreparedStatement st=null;
ResultSet rs=null;
String sql;
List<customer> lc = new ArrayList<customer>();
queryresult qr = new queryresult();
try {
        conn=jdbcutils.getconn();
        sql="select * from customer limit ?,?";
        st=conn.prepareStatement(sql);
        st.setInt(1, startindex);
        st.setInt(2, pagesize);
        rs=st.executeQuery();
        while(rs.next())
        {
        customer c = new customer();
        c.setId(rs.getInt("id"));
        c.setName(rs.getString("name"));
        c.setGender(rs.getString("gender"));
        c.setAge(rs.getInt("age"));
        c.setCellphone(rs.getString("cellphone"));
        c.setLive(rs.getString("live"));
        c.setType(rs.getString("type"));
        c.setDescr(rs.getString("descr"));
        lc.add(c);
        }
     qr.setList(lc);
     sql="select count(*) from customer";
     st=conn.prepareStatement(sql);
     rs=st.executeQuery();
     if(rs.next())
     {
     qr.setTotalrecord(rs.getInt(1));
     }
     return qr;
}
   catch (Exception e) {
// TODO Auto-generated catch block
throw new RuntimeException(e);
}
      finally
      {
        jdbcutils.del(conn, st, rs);
      }

}

}
以下是test1.java程序：
package unit;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import utils.jdbcutils;

import dao.customerdao;
import dao.customerdaoimpl;
import bean.customer;

public class test1 extends common {

/**
   * @param args
   */
public static void main(String[] args) {
   Connection conn=null;
   PreparedStatement st=null;
   ResultSet rs=null;
   try {
//System.out.println(jdbcutils.getconn());
         conn = jdbcutils.getconn();
st=conn.prepareStatement("select * from customer");
rs=st.executeQuery();
while(rs.next())
{
System.out.println(rs.getString("name"));
}
//System.out.println(conn);
//System.out.println(st);
//System.out.println(rs);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally
{
jdbcutils.del(conn, st, rs);
}
}

}
运行test1.java程序时，程序能够运行正常，把数据库的数据正确输出，没有问题，但在firefox浏览器运行javeee项目（即customerdaoimpl .java程序所在的javeee项目）时，就出现以下错误：
ava.sql.SQLException: Cannot create JDBC driver of class '' for connect URL 'jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf-8'
at org.apache.commons.dbcp2.BasicDataSource.createConnectionFactory(BasicDataSource.java:2161)
at org.apache.commons.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:2033)
at org.apache.commons.dbcp2.BasicDataSource.getLogWriter(BasicDataSource.java:1588)
at org.apache.commons.dbcp2.BasicDataSourceFactory.createDataSource(BasicDataSourceFactory.java:595)
at utils.jdbcutils.<clinit>(jdbcutils.java:30)
at dao.customerdaoimpl.pagequery(customerdaoimpl.java:217)
at service.customerserimpl.pagequery(customerserimpl.java:50)

at ccon.getallservlet.doGet(getallservlet.java:29)
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:222)
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:99)
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:1002)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.sql.SQLException: No suitable driver
at java.sql.DriverManager.getDriver(Unknown Source)
at org.apache.commons.dbcp2.BasicDataSource.createConnectionFactory(BasicDataSource.java:2145)

... 24 more
java.lang.RuntimeException: java.lang.NullPointerException
at dao.customerdaoimpl.pagequery(customerdaoimpl.java:248)
at service.customerserimpl.pagequery(customerserimpl.java:50)

at ccon.getallservlet.doGet(getallservlet.java:29)
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:222)
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:99)
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:1002)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
at utils.jdbcutils.getconn(jdbcutils.java:40)
at dao.customerdaoimpl.pagequery(customerdaoimpl.java:217)

... 19 more
为什么都是同一个jdbcutils.java在普通java程序就很正常，但在javaee项目中就运行出错了？那位高手能够解决掉这个问题？

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