java.sql.SQLException：关闭语句：下一个

java.sql.SQLException: Closed statement: next

提问by CursedChico

I have the following method which uses JDBC to get data from the DB:

我有以下使用 JDBC 从数据库获取数据的方法：

public List<QueryHolder> getData(String Name) throws SQLException {
    OracleDataSource ds;
    ds = new OracleDataSource();

    String url="jdbc:oracle:thin:@192.***.*.**:1521/dbg";
    ds.setURL(url);
    Connection conn = null;
    conn=ds.getConnection("name","password");

    SQL_Str = "SELECT ASM4EVLENMEEHLIYETBELGESI.DAMATSOYAD,ASM4EVLENMEEHLIYETBELGESI.DAMATBABAADI,ASM4EVLENMEEHLIYETBELGESI.DAMATANNEADI FROM ASM4EVLENMEEHLIYETBELGESI where DAMATSOYAD like ('%"
            + Name + "%')";
    Statement ps = conn.createStatement();
    if (ps == null)
        throw new SQLException("Can't get data source");
    rs = ps.executeQuery(SQL_Str);
    ps.close();
    if (con != null) {
        con.close();
    }

    if (rs == null)
        throw new SQLException("Can't get data source");
    List<QueryHolder> list = new ArrayList<QueryHolder>();
    while (rs.next()) {                                 // <-- This is line 89.
        QueryHolder que = new QueryHolder();

        que.setSoyad(rs.getString("DAMATSOYAD"));
        que.setBabaadi(rs.getString("DAMATANNEADI"));
        que.setAnneadi(rs.getString("DAMATBABAADI"));

        list.add(que);
    }
    return list;
}

However, when I run this method, it throws the following exception:

但是，当我运行此方法时，它会引发以下异常：

java.sql.SQLException: Closed statement: next
    oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:113)
    oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:147)
    oracle.jdbc.driver.OracleResultSetImpl.next(OracleResultSetImpl.java:187)
    Que.Query.getData(Query.java:89)
    ...

How is this caused and how can I solve it?

这是怎么引起的，我该如何解决？

回答by Andrea

The execution of

的执行

ps.close();

is in the wrong place.

是在错误的地方。

You have to close the Statement after having iterate on its result set (that is, just close ps after the while loop).

您必须在迭代其结果集后关闭语句（即，在 while 循环后关闭 ps）。

回答by SparkOn

It is a good practice to keep you ps.close();or other closing statements in the finallyblock. Instead of handling Exceptionon the method label use try and catchinstead.

将您ps.close();或其他结束语保留在finally块中是一种很好的做法。而不是Exception对方法标签进行处理，而是使用try and catch。

the problem in your case is you closed the Statement before and trying to iterate through the ResultSet to just put your ps.close();after the whileblock

您的情况的问题是您之前关闭了 Statement 并尝试遍历 ResultSet 以将您ps.close();的放在while块之后

Edit: do it something like this

编辑：做这样的事情

public returnType methodname()
{
    try{
        //your boilerplate code
        return whateverYouWantToReturn;
    }
    catch(AppropriateExceptionClass e)
    {
        e.printStackTrace();
    }
    finally
    {
     //closing statements
    }
 return null;
}

回答by kunwar.sangram

Correct closing order :

正确的关闭顺序：

The following procedures should be done (in order)

应执行以下程序（按顺序）

1. ResultSet
2. PreparedStatement
3. Connection.

1. 结果集
2. 准备好的语句
3. 联系。

Edited code

编辑代码

Statement ps = conn.createStatement();
...
rs = ps.executeQuery(SQL_Str);
...

while (rs.next()) {                                 // <-- This is line 89.
    ...
}

ps.close();
con.close();
return list;