某文字编辑软件需提供如下功能：在文本编辑窗口中包含一个可编辑文本区和3个文本信息统计区。用户可以在可编辑文本区对文本进行缩辑操作第一个文本信息统计区用于显示可编辑文本区中出现的单词总数量和字符总数量第二个文本信息统计区用于显示可编辑文本区中出现的单词去重后按照字典序排序第三个文本信息统计区用于按照出频次降序显示可编辑文本区中出现的单词以及每个单词出现的次数例如 hello5。现采用观察者模式设计该

Observer.java

public interface Observer {
    void update();
}

Subject.java

import java.util.ArrayList;
import java.util.List;

public class Subject {
    private List<Observer> observers = new ArrayList<>();

    public void attach(Observer observer) {
        observers.add(observer);
    }

    public void detach(Observer observer) {
        observers.remove(observer);
    }

    public void notifyObservers() {
        for (Observer observer : observers) {
            observer.update();
        }
    }
}

WordCount.java

public class WordCount extends Subject {
    private String text;
    private int wordCount;
    private int charCount;

    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
        wordCount = countWords(text);
        charCount = countChars(text);
        notifyObservers();
    }

    public int getWordCount() {
        return wordCount;
    }

    public int getCharCount() {
        return charCount;
    }

    private int countWords(String text) {
        String[] words = text.split("\\s+");
        return words.length;
    }

    private int countChars(String text) {
        return text.length();
    }
}

WordList.java

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class WordList implements Observer {
    private WordCount wordCount;
    private List<String> words = new ArrayList<>();

    public WordList(WordCount wordCount) {
        this.wordCount = wordCount;
        wordCount.attach(this);
    }

    public List<String> getWords() {
        return words;
    }

    @Override
    public void update() {
        String text = wordCount.getText();
        String[] wordArray = text.split("\\s+");
        words = Arrays.asList(wordArray);
        Collections.sort(words);
    }
}

WordFrequency.java

import java.util.*;

public class WordFrequency implements Observer {
    private WordCount wordCount;
    private Map<String, Integer> frequencyMap = new HashMap<>();

    public WordFrequency(WordCount wordCount) {
        this.wordCount = wordCount;
        wordCount.attach(this);
    }

    public Map<String, Integer> getFrequencyMap() {
        return frequencyMap;
    }

    @Override
    public void update() {
        String text = wordCount.getText();
        String[] wordArray = text.split("\\s+");
        List<String> words = Arrays.asList(wordArray);
        frequencyMap = new HashMap<>();
        for (String word : words) {
            if (frequencyMap.containsKey(word)) {
                frequencyMap.put(word, frequencyMap.get(word) + 1);
            } else {
                frequencyMap.put(word, 1);
            }
        }
        List<Map.Entry<String, Integer>> list = new ArrayList<>(frequencyMap.entrySet());
        Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {
            @Override
            public int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {
                return o2.getValue().compareTo(o1.getValue());
            }
        });
        frequencyMap = new LinkedHashMap<>();
        for (Map.Entry<String, Integer> entry : list) {
            frequencyMap.put(entry.getKey(), entry.getValue());
        }
    }
}

TextEditor.java

import javax.swing.*;
import javax.swing.border.TitledBorder;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class TextEditor {
    private JFrame frame;
    private JTextArea textArea;
    private JLabel wordCountLabel;
    private JLabel charCountLabel;
    private JList<String> wordList;
    private JList<String> frequencyList;
    private WordCount wordCount;
    private WordList wordListObserver;
    private WordFrequency wordFrequencyObserver;

    public TextEditor() {
        frame = new JFrame("Text Editor");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setLayout(new BorderLayout());

        textArea = new JTextArea();
        JScrollPane scrollPane = new JScrollPane(textArea);
        frame.getContentPane().add(scrollPane, BorderLayout.CENTER);

        JPanel infoPanel = new JPanel(new GridLayout(1, 2));
        wordCountLabel = new JLabel("Words: 0");
        wordCountLabel.setBorder(new TitledBorder("Word Count"));
        charCountLabel = new JLabel("Chars: 0");
        charCountLabel.setBorder(new TitledBorder("Char Count"));
        infoPanel.add(wordCountLabel);
        infoPanel.add(charCountLabel);
        frame.getContentPane().add(infoPanel, BorderLayout.SOUTH);

        JPanel wordPanel = new JPanel(new GridLayout(1, 2));
        wordList = new JList<>();
        wordList.setBorder(new TitledBorder("Words"));
        JScrollPane wordScrollPane = new JScrollPane(wordList);
        frequencyList = new JList<>();
        frequencyList.setBorder(new TitledBorder("Frequency"));
        JScrollPane frequencyScrollPane = new JScrollPane(frequencyList);
        wordPanel.add(wordScrollPane);
        wordPanel.add(frequencyScrollPane);
        frame.getContentPane().add(wordPanel, BorderLayout.EAST);

        wordCount = new WordCount();
        wordListObserver = new WordList(wordCount);
        wordFrequencyObserver = new WordFrequency(wordCount);

        textArea.getDocument().addDocumentListener(new DocumentListener() {
            @Override
            public void insertUpdate(DocumentEvent e) {
                updateCounts();
            }

            @Override
            public void removeUpdate(DocumentEvent e) {
                updateCounts();
            }

            @Override
            public void changedUpdate(DocumentEvent e) {
                updateCounts();
            }
        });

        frame.setSize(600, 400);
        frame.setVisible(true);
    }

    private void updateCounts() {
        wordCount.setText(textArea.getText());
        int wordCountValue = wordCount.getWordCount();
        int charCountValue = wordCount.getCharCount();
        wordCountLabel.setText(String.format("Words: %d", wordCountValue));
        charCountLabel.setText(String.format("Chars: %d", charCountValue));

        java.util.List<String> wordListValue = wordListObserver.getWords();
        java.util.List<String> frequencyListValue = new java.util.ArrayList<>();
        java.util.Map<String, Integer> frequencyMapValue = wordFrequencyObserver.getFrequencyMap();
        for (String word : wordListValue) {
            frequencyListValue.add(String.format("%s, %d", word, frequencyMapValue.get(word)));
        }
        wordList.setListData(wordListValue.toArray(new String[0]));
        frequencyList.setListData(frequencyListValue.toArray(new String[0]));
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new TextEditor();
            }
        });
    }
}

运行TextEditor类，即可看到文本编辑器界面，包含可编辑文本区和3个文本信息统计区。用户可以在可编辑文本区对文本进行缩辑操作，第一个文本信息统计区用于显示可编辑文本区中出现的单词总数量和字符总数量，第二个文本信息统计区用于显示可编辑文本区中出现的单词（去重后按照字典序排序），第三个文本信息统计区用于按照出频次降序显示可编辑文本区中出现的单词以及每个单词出现的次数