java.lang.NullPointerException

Java code

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.sql.DataSource;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.*;
import java.sql.SQLException;
import java.util.Properties;

import java.util.List;
import java.util.ArrayList;
import java.util.Iterator;
import myjdbc.util.WrapperUtil;

public class DatabaseOperation {
    private static DatabaseOperation dbo = null;
    private static final int FETCH_ALL = Integer.MAX_VALUE;
    private static final int NO_OFFSET = -1;
    private static final int DEFAULT_PAGE_SIZE = 20;
    private Connection conn = null;
    private PreparedStatement pst = null;
    private ResultSet rs = null;
    private DataSource ds = null;
    private static String staticTableConfigPath = "src/conf"; //
    private static String staticDataSourceName = "DataSource";
    //私有构在函数
    private DatabaseOperation() {
        try {
            Context ctx = getWeblogicServerInitialContext();
            ds = (DataSource) ctx.lookup(staticDataSourceName);
        } catch (NamingException ex) {
            ex.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //获得weblogic的上下文
    private final Context getWeblogicServerInitialContext() throws Exception {
        String url = "t3://127.0.0.1:7001";
        String user = null;
        String password = null;
        Properties properties;
        try {
            properties = new Properties();
            //  properties.put("tableConfigPath","F:/jbuilder_project/writebook/relation_manage/src/conf");
            properties.put(Context.INITIAL_CONTEXT_FACTORY,
                           "weblogic.jndi.WLInitialContextFactory");
            properties.put(Context.PROVIDER_URL, url);
            if (user != null) {
                properties.put(Context.SECURITY_PRINCIPAL, user);
                properties.put(Context.SECURITY_CREDENTIALS,
                               password == null ? "" : password);

            }
            return new javax.naming.InitialContext(properties);
        } catch (Exception e) {
            e.printStackTrace();
            throw e;
        }
    }
private void openConnection() {
        if (conn == null) {
            try {
                conn = ds.getConnection();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
 public static void main(String args[]) throws Exception {
        List result = new ArrayList();
        String sql = "select * from orderitem as a";
//    sql = sql.toLowerCase();
        DatabaseOperation database = DatabaseOperation.getInstance();
        //   database.openConnection();
        result = database.executeSQL(sql);
        System.out.println("asdf=====>" + result.size());

 数据挖掘实验室 

测试出现了错误
java.lang.NullPointerException

at   myjdbc.DatabaseOperation.openConnection(DatabaseOperation.java:88)

at   myjdbc.DatabaseOperation.getTotalPage(DatabaseOperation.java:182)

at   test.TestDatabaseOperation.testGetTotalPage(TestDatabaseOperation.java:25)

...(Click   for   full   stack   trace)...

可能这里错了   result   =   database.executeSQL(sql);
                System.out.println("asdf=====> "   +   result.size());

改成
if(result.next())
{System.out.println("asdf=====> "   +   result.size());
}
看看

不是吧       发生错误的不是这里啊

这种情况也有可能是由于加载驱动失败导致

你帮我看看啊         我有加附件的       那是整个数据库处理的类

看看你的   DataSource   设置,感觉是没有找到   "staticDataSourceName".

Create By Any-Extract(WL-AE) 数据挖掘实验室