JDBC连接的问题。

你仔细看代码了么？
sing.getConnection();

新建立的连接
stmt已存在继续使用
java.sql.SQLException: 关闭的连接
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:111)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:145)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:207)
at oracle.jdbc.driver.OracleStatement.ensureOpen(OracleStatement.java:3512)
at oracle.jdbc.driver.OracleStatement.executeUpdateInternal(OracleStatement.java:1586)
at oracle.jdbc.driver.OracleStatement.executeUpdate(OracleStatement.java:1570)
at com.gmtoa.struts.sysManagement.holidays.impl.HoliDaysOperImpl.processData(HoliDaysOperImpl.java:235)
at com.gmtoa.struts.sysManagement.holidays.impl.HoliDaysOperImpl.addHolidaysData(HoliDaysOperImpl.java:212)
at com.gmtoa.struts.sysManagement.holidays.action.HoliDaysOperAction.addHolidaysData(HoliDaysOperAction.java:124)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:270)
at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:187)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at com.medi.filter.Filter.doFilter(Filter.java:22)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:831)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:652)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1203)
at java.lang.Thread.run(Thread.java:619)
retStr = no

public int processData(Statement stm,String sql){
try {
return stm.executeUpdate(sql);
} catch (SQLException e) {
e.printStackTrace();
}
return 0;
}

stmt 也需要关闭，记得关闭链接的顺序是由大到小的，con--->stmt ---->res

因为你的stmt和conn都是static的。第一次stmt基于conn生成，当第一次关闭conn时，你并没有关闭stmt，而且，你的create stmt的过程只判断了stmt是不是null，并没有判断它有效无效。你的commitData中只close了conn，并没有使stmt＝null。所以第二次调用create stmt时，stmt并不为null，所以并没有重新create stmt，但是这个stmt所基于的conn已经被你关喽哇，所以报这个错了。
你稍微修改下：    public static void releaseStatement(Statement stmt){
        try {
            if (stmt != null){
                stmt.close();
                stmt = null;
            }
        } catch (SQLException se){
            System.out.println("Close the statement encounter error!\n" + se.getMessage());
        }
    }
    public void commitData(){
        SingletonConnection sing = SingletonConnection.getInstance();
        Connection conn = sing.getConnection();
        //Statement stmt = sing.createStatement(conn);
        SingletonConnection.commitData(conn);
        SingletonConnection.printCount();
        SingletonConnection.releaseStatement(stmt); // 这个注释调的留着，用来关闭stmt
        SingletonConnection.releaseConnection(conn);
    }

正确的顺序是，先关闭resultset，然后关闭statement，然后关闭connection，不过只要你再关闭之前判断了是否为空就不那么重要了。

1.你的 SingletonConnection 单例模式写得没问题，但是newInstance得操作应该放在构造函数中。2.createStatement 和 releaseStatement 两个方法所处理的Statement对象不是同一个对象。
当你调用releaseStatement 并清除传递过去的stmt时，并没有清空SingletonConnection 的成员变量stmt。
你调用createStatement 方法，判断stmt 时条件if(stmt == null)始终是false！  每次数据库会话Statement都重新建立；不能利旧的
    public Statement createStatement(Connection conn){
        try{
            System.out.println("新建立的Statement");
                    count_stmt++;
            return conn.createStatement();
        } catch (SQLException e) {
            e.printStackTrace();
            return null;
        }
    }     protected SingletonConnection() {
        try {
            Class.forName(DB_DRIVER); //指定JDBC数据库驱动程序
        }
        catch(java.lang.ClassNotFoundException e) {//捕获异常
            e.printStackTrace();
        }
    }    删除 private static Statement stmt = null; 对象 releaseStatement 方法    public String addHolidaysData(){
        //获取连接
        SingletonConnection sing = SingletonConnection.getInstance();
        Connection conn = sing.getConnection();
        //获取Statement
        Statement stmt = sing.createStatement(conn);
        try {
    stmt.executeQuery("select * from t_user");
} catch (SQLException e) {
    e.printStackTrace();
}
sing.commitData(conn);
        stmt.close();
        sing.releaseConnection(conn);
        return null;
    }还是用连接池吧！

那关闭连接顺序是错误的。
rs-stmt-conn
从小到大。现在已经解决了。
在我关闭连接时把 count_stmt初始化为0 ，当第二次请求时判断count_stmt是否=0
等于0时创建一个statement否则继续使用。

调试易

JDBC连接的问题。

解决方案 »