jdbc ResultSet已关闭 [英] jdbc ResultSet closed

问题描述

我有以下来源。

在insertMessage（..）中，它调用selectMessage来检查是否存在重复记录。

In insertMessage(..), it calls selectMessage to check whether duplicate record exists or not.

但是会发生此错误。
在我的大脑中，它运行正常，因为datasource给了我新的连接......也许

But this error occurs. In my brain, it works fine because datasource gives me new Connection...maybe

java.sql.SQLException: ResultSet closed
    at org.sqlite.RS.checkOpen(RS.java:63)
    at org.sqlite.RS.findColumn(RS.java:108)
    at org.sqlite.RS.getString(RS.java:317)
    at org.apache.commons.dbcp.DelegatingResultSet.getString(DelegatingResultSet.java:263)
    at org.apache.commons.dbcp.DelegatingResultSet.getString(DelegatingResultSet.java:263)
    at org.springframework.context.support.CachedMessageSourceDao.selectMessage(CachedMessageSourceDao.java:68)
    at org.springframework.context.support.CachedMessageSourceDao.insertMessage(CachedMessageSourceDao.java:94)
    at MessageSourceDemo.main(MessageSourceDemo.java:11)

---

---

public String selectMessage(String code, String language) {
    Connection conn = null;
    PreparedStatement pstmt = null;
    ResultSet rs = null;
    String value = null;

    String sql = "SELECT code, value, language FROM " + TABLE + " where code=? and language=? and flag = '" + FLAG_OK + "'";

    try {
        conn = dataSource.getConnection();
        conn.setAutoCommit(true);
        pstmt = conn.prepareStatement(sql);
        pstmt.setString(1, code);
        pstmt.setString(2, language);
        rs = pstmt.executeQuery();
        rs.next();

        String _code = rs.getString("code");
        String _value = rs.getString("value");
        String _language = rs.getString("language");
        Locale _locale = new Locale(_language);
        value = _value;

    } catch(SQLException ex) {

        ex.printStackTrace();

    } finally {

        try {
            if(rs != null);
            if(pstmt != null) pstmt.close();
            if(conn != null) conn.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
    return value;
}

public synchronized void insertMessage(String code, String value, String language) throws SQLException {
    //Duplicate Message Check
    **if(selectMessage(code, language) != null) throw new SQLException("Duplicate message exists for code: " + code + " and" + "language: " + language);**

    String sql = "INSERT INTO " + TABLE + " (code, value, language, flag) values (?, ?, ?, '" + FLAG_OK + "')";

    Connection conn = null;
    PreparedStatement pstmt = null;

    try {
        conn = dataSource.getConnection();
        conn.setAutoCommit(true);
        pstmt = conn.prepareStatement(sql);
        pstmt.setString(1, code);
        pstmt.setString(2, value);
        pstmt.setString(3, language);
        pstmt.execute();

    } catch(SQLException ex) {

        ex.printStackTrace();

    } finally {

        try {

            if(pstmt != null) pstmt.close();
            if(conn != null) conn.close();

        } catch (SQLException e) {

            e.printStackTrace();

        }

    }

    notifyMessageChange(); //Realtime apply to MessageSource
}

推荐答案

您的结果集可能没有任何记录，这就是 next（）关闭它的原因。

Your resultset probably didn't have any record, which is the reason why next() closed it.

next（）返回一个布尔值，检查它。

next() returns a boolean, check it.

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