SQLITE_BUSY 数据库被锁定java [英] SQLITE_BUSY the database is locked java

问题描述

我创建了一个使用 sqlite 数据库的 java 软件.整个数据库运行顺利，但是在运行应用程序一段时间后，我收到以下消息(来自 try catch 块):

I have create a java software which make use of sqlite database. The whole database works smoothly however after some time of running the application I am reveiving the following message (from a try catch block):

java.sql.SQLException: [SQLITE_BUSY] 数据库文件被锁定(数据库被锁定)

java.sql.SQLException: [SQLITE_BUSY] The database file is locked (database is locked)

每次出现异常时，我都通过关闭软件解决了我的问题.但是，有没有办法关闭我的数据库，以免每次都关闭软件?

I ve solved my problems by closing the software every time the exception rising. However is there a way to close my database instead so as not to close the software every time?

我有很多疑问，但我的问题总是出现在特定点:

I ve got plenty of queries however my prob arises always in a specific point:

        try {
            String query = "select * from StudentsSession where userId=? and course=? and level=?";
            PreparedStatement pst = connectionUsers.prepareStatement(query);
            pst.setString(1, saveUser.getText());
            pst.setString(2, textSubjectQTest);
            st.setString(3, showCurrentLevelLabel.getText());
            ResultSet rs = pst.executeQuery();
            while (rs.next()) {
                count = count + 1;
            }
            pst.close();
            rs.close();

        } catch (Exception a) {
            System.out.println(a);
        }
        try {
            String countS, tmpS;
            countS = String.valueOf(count);
            sessionId.setText(countS);
            long unixTime = System.currentTimeMillis() / 1000L;
            tmpS = String.valueOf(unixTime);
            date.setText(tmpS);
            course.setText(textSubjectQTest);

            String query = "insert into StudentsSession (userId,date,course,level,trial,score) values (?,?,?,?,?,-1)";
            PreparedStatement pst = connectionUsers.prepareStatement(query);
            pst.setString(1, saveUser.getText());
            pst.setString(2, tmpS);
            pst.setString(3, textSubjectQTest);
            pst.setString(4, showCurrentLevelLabel.getText());
            pst.setString(5, countS);
            pst.executeUpdate();
            pst.close();

        } catch (Exception a) {

            System.out.println(a);
            System.exit(0);
        }

        String file1 = "";
        ResultSet ts4;
        try {

            sessionId3 = "";
            String query3 = "select * from studentssession where userid = ?  and course = ? and level = ?";
            PreparedStatement pst__1 = connectionUsers.prepareStatement(query3);
            pst__1.setString(1, saveUser.getText());
            pst__1.setString(2, textSubjectQTest);
            pst__1.setString(3, showCurrentLevelLabel.getText());
            ts4 = pst__1.executeQuery();

            while (ts4.next()) {
                sessionId3 = ts4.getString("sessionId");
            }
            pst__1.close();
            ts4.close();
            obj = new CaptureVideoFromWebCamera();

            file1 = "videos/" + userTextFieldS.getText();

            file1 = file1 + "_" + sessionId3;
            file1 = file1 + ".wmv";

            obj.start(file1);

        } catch (Exception e4) {
            e4.getCause();
        }

有时此代码会引发异常.

Sometimes this code rise the exception.

推荐答案

你的 try catch 错了，你尝试关闭 try 块中的 ResultSet 和 Statemnt一个 finally 块.这可能会导致泄漏.

Your try catch are wrong, you try to close the ResultSet and Statemnt in the try block instead of a finally block. This could lead to leaks.

你应该这样做，最后.

PreparedStatement pst  = null;
ResultSet rs = null;
try {
        pst = connectionUsers.prepareStatement(query);
        ...  
        rs = pst.executeQuery();
        ...                    
    } catch (Exception a) {
        a.printStackTrace();
    } finally {
        if(rs != null){
             try{
                  rs.close();
             } catch(Exception e){
                 e.printStackTrace();
             }
        }
        if(pst != null){
            try{
                pst.close();
            } catch(Exception e){
                e.printStackTrace();
            }
        }
    }

或者您可以查看 Try-with-resource.

Or you could look to the Try-with-resource.

这可能是一个原因.

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