java - 噩梦 java 泄漏......带有循环和 jdbc

Question

当我在探查器中运行以下代码时，我得到一个 char[] 和 byte[]，它们会不断累积，直到程序因 Java 堆内存不足异常而崩溃。有人能告诉我为什么吗？也许我在做一些根本性的错误。

package testleak;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;
import javax.swing.Timer;

    public class TestLeak
    {
        static String DB_USERNAME = "userName";
        static String DB_SUBSCRIPTION_EXPIRATION = "subscriptionExpiration";
        static String DB_REMOTE_ACCESS_ENABLED = "remoteAccessEnabled";
        static String DB_LOCAL_USERNAME = "root";
        static String DB_LOCAL_PASS = "root";
        public static void main(String[] args)
        {
            Timer timer = new Timer(2000, new ActionListener()
            {
                @Override
                public void actionPerformed(ActionEvent evt)
                {
                    TestLeak tester = new TestLeak();
                    try
                    {
                       tester.go();
                    }
                    catch (NumberFormatException n)
                    {
                    }
                    tester = null;
                }
            });
            timer.start();
            while (true)
            {
                //keep the program from ending...
            }

        }
        private void go() throws NumberFormatException
        {
            ResultSet results = null;
            Connection conn = null;
            Properties connectionProps = new Properties();
            try
            {
                connectionProps.put("user", "root");
                connectionProps.put("password", "root");
                conn = DriverManager.getConnection("jdbc:mysql://localhost:8889/myDataBase",
                        connectionProps);
                connectionProps = null;
                try
                {
                    String rawQuery = new String("SELECT " + TestLeak.DB_USERNAME + ", "
                            + TestLeak.DB_REMOTE_ACCESS_ENABLED
                            + ", " + TestLeak.DB_SUBSCRIPTION_EXPIRATION + " FROM myTable");
                    Statement statement = conn.createStatement();
                    try
                    {
                        statement.executeQuery(rawQuery);
                        results = statement.getResultSet();
                        rawQuery = null;
                        try
                        {
                            while (results.next())
                            {
                                String auth = new String(results.getString(TestLeak.DB_REMOTE_ACCESS_ENABLED));
                                if (auth.equals("1"))
                                {
                                    Long subExpires = Long.valueOf(results.getString(TestLeak.DB_SUBSCRIPTION_EXPIRATION));
                                    if (subExpires > System.currentTimeMillis())
                                    {
                                        System.out.println(results.getString(TestLeak.DB_USERNAME));
                                        System.out.println();
                                    }
                                    subExpires = null;
                                }
                                auth = null;
                            }
                        }
                        finally
                        {
                            results.close();
                        }
                    }
                    finally
                    {
                        statement.close();
                    }
                }
                finally
                {
                    conn.close();
                }
            }
            catch (SQLException e)
            {
                System.out.println(e.getMessage());
            }
        }
    }

我想我正在释放所有东西，但一定有什么东西阻止了所有物体被释放。为什么在 go() 方法结束时所有对象都不符合垃圾回收条件？每次我在探查器中调用垃圾收集时，我都会得到另一个幸存的一代。谢谢。

Answer 1

我会改变这个:

                        statement.executeQuery(rawQuery);
                        results = statement.getResultSet();

为此:

                        results = statement.executeQuery(rawQuery);

后者肯定是 API 批准的执行此操作的方法，虽然我不能肯定地说前者是一个问题，但它确实似乎可以创建两个单独的结果-集合，其中你只能关闭一个。