Question

Eclipse显示警告消息“资源泄漏，预备状态未在以下位置关闭”

对我而言，看起来finally块负责关闭preparedstatement和rs对象。知道为什么eclipse仍在抱怨资源泄漏吗？

String ruleGrpId = null;
        int finalRuleID = 0;

        String saveRule1 = "INSERT INTO ..";
        String saveRule2 = "INSERT INTO ";

        String saveRule3 = "select ..._name = ?";

        PreparedStatement preparedstatement = null;
        ResultSet rs = null;

        try {
            if (objSomeRule.getRule() == 0) {

                preparedstatement = con.prepareStatement(saveRule1);
                preparedstatement.setString(1, ruleId);

                preparedstatement.executeUpdate();

                //Eclipse complains here
                preparedstatement = con.prepareStatement(saveRule2);

                preparedstatement.setInt(1, ruleID_2);
                preparedstatement.setString(2, ruleID_3);

                rs =  preparedstatement.executeQuery();

                if(rs.next()){
                    finalRuleID = rs.getInt(1);
                }else{
                    //complains here
                    preparedstatement = con.prepareStatement(saveRule3);
                    preparedstatement.setString(1, ruleID_4);
                    //complains here
                    rs =  preparedstatement.executeQuery();
                    if(rs.next()){
                        finalRuleID = rs.getInt("rulegroup_id");
                    }
                }
                objSomeRule.setRuleID(finalRuleID);

            }

        } finally {

            if(preparedstatement != null){
                preparedstatement.close();
            }

            if(rs != null){
                rs.close();
            }
        }

        return finalRuleID;
    }

Answer 1

所以，你说当没有记录创建另一个preparedStatement时。

 if(rs.next())
 {
      finalRuleID = rs.getInt(1);
 }
 else
 {
    //close here first
    if(preparedstatement != null)
    {
       preparedstatement.close();
    }

    if(rs != null){
       rs.close();
    }

    preparedstatement = con.prepareStatement(saveRule3);
    // your code

但是，你还没有关闭前一个。我不确定，你为什么这样做，但是，假设你需要这样做。然后，你应该先关闭前一个。

Answer 2

您创建了3个PreparedStatement的不同实例：

preparedstatement = con.prepareStatement(saveRule1);

preparedstatement = con.prepareStatement(saveRule2);

preparedstatement = con.prepareStatement(saveRule3);

您的变量preparedStatement仅保留您打开的最后一个变量而且你没有引用你之前打开的其他人因此，在finally部分中，您只能关闭最后一个PreparedStatement：

preparedstatement.close();

类似的问题在于您的ResultSet。您创建了2个实例，但只关闭了其中的一个。

Answer 3

重用变量preparedStatement和rs会阻止对变量的旧对象值调用close()。 Try-with-resources是一个很好的解决方案，因为close()会被自动调用，即使抛出异常或在深层嵌套的try中执行返回也是如此。

    String ruleGrpId = null;
    int finalRuleID = 0;
    String saveRule1 = "INSERT INTO ..";
    String saveRule2 = "INSERT INTO ";
    String saveRule3 = "select ..._name = ?";

    if (objSomeRule.getRule() == 0) {
        try (PreparedStatement ps1 = con.prepareStatement(saveRule1)) {
            ps1.setString(1, ruleId);
            ps1.executeUpdate();
        }
        try (PreparedStatement ps2 = con.prepareStatement(saveRule2)) {
            ps2.setInt(1, ruleID_2);
            ps2.setString(2, ruleID_3);

            try (ResultSet rs2 =  ps2.executeQuery()) {

                if (rs2.next()) {
                    finalRuleID = rs2.getInt(1);
                } else {
                    try (Preparedstatement ps3 = con.prepareStatement(saveRule3)) {
                        ps3.setString(1, ruleID_4);
                        //complains here
                        try (ResultSet rs3 =  ps3.executeQuery()) {
                            if (rs3.next()) {
                                finalRuleID = rs3.getInt("rulegroup_id");
                            }
                        }
                    }
                }
            }
            objSomeRule.setRuleID(finalRuleID);
        }
    }

如果最后一个SELECT查询打算检索先前INSERT的AUTOINCREMENT ID，那么使用getGeneratedKeys

可以更安全（多用户）和更好

PreparedStatement和ResultSet上的资源泄漏

3 个答案: