如何释放javaFX浏览器中webEngine消耗的内存

Question

我正在使用这个 SimpleSwingBrowser。它消耗太多内存并且不会释放该内存。我不断地在任务管理器中看到消耗的内存，并且它仅在访问三个站点时增加到 500MB，并且还在不断增加。

所以我想在浏览器切换到下一页时释放所有内存。意味着必须处理或清除上一页消耗的所有内存。

    import javafx.application.Platform;
    import javafx.beans.value.ChangeListener;
    import javafx.beans.value.ObservableValue;
    import javafx.embed.swing.JFXPanel;
    import javafx.event.EventHandler;
    import javafx.scene.Scene;
    import javafx.scene.web.WebEngine;
    import javafx.scene.web.WebEvent;
    import javafx.scene.web.WebView;

    import javax.swing.*;
    import java.awt.*;
    import java.awt.event.*;
    import java.net.MalformedURLException;
    import java.net.URL;

    import static javafx.concurrent.Worker.State.FAILED;

    public class SimpleSwingBrowser extends JFrame {

    private final JFXPanel jfxPanel = new JFXPanel();
    private WebEngine engine;

    private final JPanel panel = new JPanel(new BorderLayout());
    private final JLabel lblStatus = new JLabel();


    private final JButton btnGo = new JButton("Go");
    private final JTextField txtURL = new JTextField();
    private final JProgressBar progressBar = new JProgressBar();

    public SimpleSwingBrowser() {
        super();
        initComponents();
    }


    private void initComponents() {
        createScene();

        ActionListener al = new ActionListener() {
            @Override 
            public void actionPerformed(ActionEvent e) {
                loadURL(txtURL.getText());
            }
        };

        btnGo.addActionListener(al);
        txtURL.addActionListener(al);

        progressBar.setPreferredSize(new Dimension(150, 18));
        progressBar.setStringPainted(true);

        JPanel topBar = new JPanel(new BorderLayout(5, 0));
        topBar.setBorder(BorderFactory.createEmptyBorder(3, 5, 3, 5));
        topBar.add(txtURL, BorderLayout.CENTER);
        topBar.add(btnGo, BorderLayout.EAST);

        JPanel statusBar = new JPanel(new BorderLayout(5, 0));
        statusBar.setBorder(BorderFactory.createEmptyBorder(3, 5, 3, 5));
        statusBar.add(lblStatus, BorderLayout.CENTER);
        statusBar.add(progressBar, BorderLayout.EAST);

        panel.add(topBar, BorderLayout.NORTH);
        panel.add(jfxPanel, BorderLayout.CENTER);
        panel.add(statusBar, BorderLayout.SOUTH);

        getContentPane().add(panel);

        setPreferredSize(new Dimension(1024, 600));
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();

    }

    private void createScene() {

        Platform.runLater(new Runnable() {
            @Override 
            public void run() {

                WebView view = new WebView();
                engine = view.getEngine();

                engine.titleProperty().addListener(new ChangeListener<String>() {
                    @Override
                    public void changed(ObservableValue<? extends String> observable, String oldValue, final String newValue) {
                        SwingUtilities.invokeLater(new Runnable() {
                            @Override 
                            public void run() {
                                SimpleSwingBrowser.this.setTitle(newValue);
                            }
                        });
                    }
                });

                engine.setOnStatusChanged(new EventHandler<WebEvent<String>>() {
                    @Override 
                    public void handle(final WebEvent<String> event) {
                        SwingUtilities.invokeLater(new Runnable() {
                            @Override 
                            public void run() {
                                lblStatus.setText(event.getData());
                            }
                        });
                    }
                });

                engine.locationProperty().addListener(new ChangeListener<String>() {
                    @Override
                    public void changed(ObservableValue<? extends String> ov, String oldValue, final String newValue) {
                        SwingUtilities.invokeLater(new Runnable() {
                            @Override 
                            public void run() {
                                txtURL.setText(newValue);
                            }
                        });
                    }
                });

                engine.getLoadWorker().workDoneProperty().addListener(new ChangeListener<Number>() {
                    @Override
                    public void changed(ObservableValue<? extends Number> observableValue, Number oldValue, final Number newValue) {
                        SwingUtilities.invokeLater(new Runnable() {
                            @Override 
                            public void run() {
                                progressBar.setValue(newValue.intValue());
                            }
                        });
                    }
                });

                engine.getLoadWorker()
                        .exceptionProperty()
                        .addListener(new ChangeListener<Throwable>() {

                            public void changed(ObservableValue<? extends Throwable> o, Throwable old, final Throwable value) {
                                if (engine.getLoadWorker().getState() == FAILED) {
                                    SwingUtilities.invokeLater(new Runnable() {
                                        @Override public void run() {
                                            JOptionPane.showMessageDialog(
                                                    panel,
                                                    (value != null) ?
                                                    engine.getLocation() + "\n" + value.getMessage() :
                                                    engine.getLocation() + "\nUnexpected error.",
                                                    "Loading error...",
                                                    JOptionPane.ERROR_MESSAGE);
                                        }
                                    });
                                }
                            }
                        });

                jfxPanel.setScene(new Scene(view));
            }
        });
    }

    public void loadURL(final String url) {
        Platform.runLater(new Runnable() {
            @Override 
            public void run() {
                String tmp = toURL(url);

                if (tmp == null) {
                    tmp = toURL("http://" + url);
                }

                engine.load(tmp);
            }
        });
    }

    private static String toURL(String str) {
        try {
            return new URL(str).toExternalForm();
        } catch (MalformedURLException exception) {
                return null;
        }
    }



    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            public void run() {
                SimpleSwingBrowser browser = new SimpleSwingBrowser();
                browser.setVisible(true);
                browser.loadURL("http://oracle.com");
           }     
       });
    }
}

Answer 1

那是一个实际的 'problem-kind of restriction' 和 Java.Even 如果你把 System.gc() which is not recommended,it is not sure that the garbage collector will release memory.One way is to set 调用 Object 到 null，所以它被标记为被清除。

即使您有大量元素并删除它们，您也可能会发现 ram 消耗是相同的。有时 Java 默认使用更多内存，因此您的应用不会延迟。

您需要等待垃圾收集器完成工作并使用策略创建新对象。如果对象已保留 too long("mention that Java8 is different permgen not exists") you have a possibility that it will never been collected from gc. Sometimes it might take 1 minute to release for example 200 MiB 内存。

像WebViewer这样的一些元素消耗很多RAM.You可以在Firefox中看到相同的内容，但过一会儿就会清除它。

如何释放javaFX浏览器中webEngine消耗的内存

How to release the consumed memory by the webEngine in javaFX browser

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