java 连接sybase 事物处理报空指针,请指教

ConnSyBase类如下:
public class ConnSyBase {    private static ConnSyBase db = null;    //数据库库连接对象
    private static Connection conn = null;    private Statement stmt = null;    private boolean hadErrors = false;    private ConnSyBase() throws Exception {
        if (conn == null) {
            Class.forName("com.sybase.jdbc3.jdbc.SybDriver").newInstance();
            String url = "jdbc:sybase:Tds:XXXX:5000/myDB";//myDB为你的数据库名
            Properties sysProps = System.getProperties();
            sysProps.put("user", "sa"); //设置数据库访问用户名
            sysProps.put("password", ""); //密码
            Connection conn = DriverManager.getConnection(url, sysProps);
            System.out.println("--------success------------in connection");
            stmt = conn.createStatement();
        }
    }    public void beginTransaction() throws Exception {
        conn.setAutoCommit(false);
    }    public void commitTransaction() throws Exception {
        if (!hadErrors) {
            conn.commit();
        } else {
            conn.rollback();
            hadErrors = false;
        }
        hadErrors = true;
        conn.setAutoCommit(true);
    }    public void ErrorOccur() {
        hadErrors = true;    }    public static ConnSyBase getInstance() {
        if (db == null) {
            System.out.println("--------ok-----------");
            try {
                db = new ConnSyBase();
            } catch (Exception e) {
                conn = null;
                Log log = LogFactory.getLog("mylog");
                log.error("数据库连接出错－DataStore.java");
                return null;
            }
        }
        return db;
    }    //执行插入，删除和更新操作
    synchronized public void execute(String sql) throws SQLException {
        if (stmt != null)
            stmt.executeUpdate(sql);
        else {
            Log log = LogFactory.getLog("mylog");
            log.error("数据库插入出错");
        }
    }    //执行查询操作
    synchronized public ResultSet read(String sql) throws SQLException {
        if (stmt != null) {
            ResultSet tmp = null;
            tmp = stmt.executeQuery(sql);
            return tmp;
        } else {
            return null;
        }
    }    //执行查询个数操作
    synchronized public int readCount(String sql) throws SQLException {
        int nCount = 0;        try {
            if (stmt != null) {
                ResultSet tmp = null;
                if (tmp != null && tmp.next()) {
                    nCount = tmp.getInt(1);
                } else {
                    nCount = 0;
                }
            } else {
                nCount = 0;
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return nCount;
    }    //  终止数据库的连接
    synchronized public void stop() {
        try {
            if (conn != null) {
                conn.close();
                stmt.close();
            }
        } catch (Exception e) {
            Log log = LogFactory.getLog("mylog");
            log.error("数据库关闭出错-DataStore.java");
        } finally {
            conn = null;
        }
        System.out.println("----------connection-------is down");
    }
}

ConnSyBase dbSybase2 = ConnSyBase.getInstance();
这个没有取到Connection连接？

为什么没取到呢
不懂,继续问下
回答的有分，3楼的谢谢
sybase和其它的都一样的，应该
只是事物操作不会,能给我好的例子也行啊

一个singleton的ConnectionFactory，参考一下。import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class ConnectionFactory {
    private static String DB_DRIVER;
    private static String DB_URL;
    private static String DB_USER;
    private static String DB_PASSWORD;
    // 静态变量首先加载private构造
    private static ConnectionFactory ref = new ConnectionFactory();        /**
     * 一个 singleton
     *
     * */
    public static ConnectionFactory getInstance(){
        return ref;
    }    /**
     * 注册jdbc驱动
     *
     * */
    private ConnectionFactory() {
        try {
            Class.forName(DB_DRIVER);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }    /**
     * 获取数据库的一个连接
     *
     * */
    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(DB_URL, DB_USER, DB_PASSWORD);
    }    /**
     * 关闭ResultSet
     */
    public static void close(ResultSet rst) {
        if (rst != null) {
            try {
                rst.close();
                rst = null;
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }    /**
     * 关闭Statement
     */
    public static void close(Statement stmt) {
        if (stmt != null) {
            try {
                stmt.close();
                stmt = null;
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }    /**
     * 关闭Connection
     */
    public static void close(Connection conn) {
        if (conn != null) {
            try {
                conn.close();
                conn = null;
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }}

DB_DRIVER等信息可以到用类似下面的方法取得，楼主自己再改一下。

    Properties pros = new Properties();
    try {
        File file = new File("DBCONFIG.properties");
        pros.load(new FileInputStream(file));
        DB_DRIVER = pros.getProperty("DB_DRIVER");
        DB_URL = pros.getProperty("DB_URL");
        DB_USER = pros.getProperty("DB_USER");
        DB_PASSWORD = pros.getProperty("DB_PASSWORD");
    }
     catch(IOException e){
         e.printStatckTrace();
     }ps：楼主仔细看看你的
    public static ConnSyBase getInstance() {
        if (db == null) {
            System.out.println("--------ok-----------");
            try {
                db = new ConnSyBase();
            } catch (Exception e) {
                conn = null;
                Log log = LogFactory.getLog("mylog");
                log.error("数据库连接出错－DataStore.java");
                return null;
            }
        }
        return db;
    }
取得的是null吧！

其实你把构造里的这句
Connection conn = DriverManager.getConnection(url, sysProps);改成conn = DriverManager.getConnection(url, sysProps);
就ok了，conn被你覆盖了！

Class.forName("com.sybase.jdbc3.jdbc.SybDriver").newInstance();
            String url = "jdbc:sybase:Tds:XXXX:5000/myDB";//myDB为你的数据库名
            Properties sysProps = System.getProperties();
            sysProps.put("user", "sa"); //设置数据库访问用户名
            sysProps.put("password", ""); //密码
            Connection conn = DriverManager.getConnection(url, sysProps);
            System.out.println("--------success------------in connection");
            stmt = conn.createStatement();

你说的没错,但我现在改成你这样还是不行
报错在 public void beginTransaction() throws Exception {
conn.setAutoCommit(false);
}
java.lang.NullPointerException
at com.jandar.db.ConnSyBase.beginTransaction(ConnSyBase.java:50)

来看看你的代码：
1).
    //数据库库连接对象
    private static Connection conn = null;
这个conn是属于类的！2).
你的构造：
   private ConnSyBase() throws Exception {
        if (conn == null) {
            Class.forName("com.sybase.jdbc3.jdbc.SybDriver").newInstance();
            String url = "jdbc:sybase:Tds:XXXX:5000/myDB";//myDB为你的数据库名
            Properties sysProps = System.getProperties();
            sysProps.put("user", "sa"); //设置数据库访问用户名
            sysProps.put("password", ""); //密码             // ********** 注意这里，你这里声明了一个局域成员变量conn ，而属于类的conn还是null ！
            Connection conn = DriverManager.getConnection(url, sysProps);
            System.out.println("--------success------------in connection");
            stmt = conn.createStatement();
        }
    }3).
你的beginTransaction里
public void beginTransaction() throws Exception {
        // ************ 注意这里的conn 是null，当然会报NullPointerException了!!
        conn.setAutoCommit(false);
    }
楼主看出问题了吗？一起学习，一起仔细！

谢谢楼上的,结贴了
其实问题我已经找出来了,
一直在忙与写程序,现在过来揭贴
非常感谢bootupnow的指导

调试易

java 连接sybase 事物处理报空指针,请指教

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java 连接sybase 事物处理 报空指针,请指教

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java 连接sybase 事物处理报空指针,请指教