Java - Swing - 似乎无法让增量绘画工作(通过可执行 Jar 文件运行)

Question

我正在尝试构建元素周期表程序。我有几个类和一个充当数据库的 JSON 文件。我使用可执行 jar 文件有几个原因，其中最大的原因之一是 Applet 安全限制不适用于读取 JSON 文件等文件。

元素周期表图像将部分静态。目前的计划是把它画出来，并使用一个二维数组和光标的位置来确定其他操作。 (此类操作包括一个弹出菜单，显示有关元素的额外信息)

我的问题:我相信我所拥有的应该可以工作，但最后只显示了一个元素 block 。 (而且它甚至没有被正确绘制......这一小部分可能是我稍后可以找到的一些小错误)

下面是显示的内容:(这是元素周期表...有 118 个元素)

这是我的源文件:(主要源文件)

package PeriodicTable;

class PeriodicTable {
public static void main (String[] args) {
    Table table = new Table();
}
}

我的整体json结构如下:

JsonObject 持有 JsonArray(元素)

Elements 包含 118 个 JsonObjects(每个元素 1 个对象)

JsonObjects 保存其相应元素的信息

(到目前为止，基本上所有未显示在屏幕上的内容)

package PeriodicTable;

import javax.swing.JFrame;
import javax.swing.JPanel;

import javax.json.JsonArray;
import javax.json.JsonObject;

import java.awt.Toolkit;
import java.awt.Dimension;

import java.io.IOException;

class Table {
private JFrame frmMain;
private Element[][] aryElements;
Dimension dmsScreenSize;
int intScreenHeight, intScreenWidth;
DataBaseReader dbReader;
private int intElementsColumns = 18, intElementsRows = 9;//18 columns in the periodic table, 7 rows + the 2 F block rows, 6 and 7. Totals 9 rows

public Table(){
    dmsScreenSize = Toolkit.getDefaultToolkit().getScreenSize();
    intScreenWidth = (int)dmsScreenSize.getWidth();
    intScreenHeight = (int)dmsScreenSize.getHeight();
    frmMain = new JFrame("Periodic Table of the Elements");
    frmMain.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frmMain.setMinimumSize(dmsScreenSize);
    dbReader = new DataBaseReader();
    layout("Periodic Table");
    frmMain.setVisible(true);
}
void layout(String strLayout){ //Creates the specified table, at the time there is only one.
    switch(strLayout){
        case "Periodic Table":
            periodicTable();
            break;
    }
}
private void periodicTable() {
    aryElements = new Element[intElementsRows][intElementsColumns]; //creates a two-dimensional array of the class Element, hold 9 by 18 blocks
    try{
        JsonArray jAryElements = dbReader.readDataBase(); //obtains the Element array from Elements.JSON
        Element clsElement; //Define an element instance, but not create
        for(int index = 0; index < jAryElements.size(); index++){   //go through the Element array (called jAryElements), for every json object in this array...
            clsElement = new Element(jAryElements.getJsonObject(index));//create an instance of class Element with the current selected JsonObject
            frmMain.add(clsElement);                /*add that instance to the JFrame frmMain (Element extends JPanel)
                                        *(For below) Store that instance in the 2d array
                                        *storage location is dependant on the element's row and column in the periodic table*/
            aryElements[Integer.parseInt(element.getString("row"))-1][Integer.parseInt(element.getString("columnNumber"))-1] = clsElement;
        }
    }catch(IOException ioe){
        ioe.printStackTrace();
    }

}
}

(当前正在处理所有图形旁边)

package PeriodicTable;

import javax.json.JsonObject;

import javax.swing.JPanel;

import java.awt.Graphics;
import java.awt.Color;
import java.awt.Font;

class Element extends JPanel {
JsonObject element;
int intX, intY, intWidth, intHeight;
Font aFont, bFont, cFont;
Element(JsonObject elementForeign){
    element = elementForeign; //Store the json object from the database here
    intWidth = 50;  //width of an element
    intHeight = 71; //height of an element
    intX = 10+(intWidth*(Integer.parseInt(element.getString("columnNumber"))));
    /*<10+> add some space to the left of the entire grid of elements
    *<intWidth*(<some code>(<some code>("columnNumber")> 
    *   position would be equal to the element width multiplied by it's column. */
    intY = 50+(intHeight*(Integer.parseInt(element.getString("row")))); //Same as intX, but vertically
    aFont = new Font("TimesRoman", Font.BOLD, 10);//some fonts for text inside each element
    bFont = new Font("TimesRoman", Font.PLAIN, 9);
    cFont = new Font("TimesRoman", Font.BOLD, 17);
}
public void update(Graphics gr){ //Post to stop the program from clearing the screen
    paintComponent(gr);
}
public void paintComponent(Graphics gr){/*painting method. I've read someone describing the activation
                    *of this method to occur "magically" when ever something happens to the container
                    *such as resizing the main window.*/
    gr.setColor(getColor(""));              //The specifics for every piece of information to be drawn inside a element block
    gr.drawRect(intX, intY, intWidth, intHeight);
    gr.setColor(getColor(element.getString("group")));
    gr.fillRect(intX+1, intY+1, intWidth-2, intHeight-2);
    gr.setColor(getColor(""));
    gr.setFont(aFont);
    gr.drawString(element.getString("atomicNumber"), intX+4, intY+10);
    gr.drawString(element.getString("molarMass"), intX+4, intY+29);
    gr.setFont(bFont);
    gr.drawString(element.getString("electronegativity"), intX+4, intY+20);
    gr.drawString(element.getString("ionCharge1"), intX+4, intY+29);
    gr.drawString(element.getString("ionCharge2"), intX+4, intY+38);
    gr.drawString(element.getString("name"), intX+(intWidth/2)-((gr.getFontMetrics().stringWidth(element.getString("name")))/2), intY+56);
    gr.setColor(getColor(element.getString("naturalState")));
    gr.setFont(cFont);
    gr.drawString(element.getString("symbol"), intX+((intWidth/2)-((gr.getFontMetrics().stringWidth(element.getString("symbol")))/2)), intY+45);
    gr.setColor(getColor(element.getString("synthetic")));
    gr.drawRect(intX+(intWidth-(2*(intWidth/5)))-1, intY+1, intWidth/5, intWidth/5);
    gr.fillRect(intX+(intWidth-(2*(intWidth/5)))-1, intY+2, intWidth/5, intWidth/5);
    gr.setColor(getColor(element.getString("diatomic")));
    gr.drawRect(intX+(intWidth-(intWidth/5))-1, intY+1, intWidth/5, intWidth/5);
    gr.fillRect(intX+(intWidth-(intWidth/5))-1, intY+2, intWidth/5, intWidth/5);
}
private Color getColor(String strType){ //Returns a color depending on the situation (the string that is passed in)
    switch(strType){
        case "Hydrogen":
            return new Color(255,229,204);
        case "Alkali Metal":
            return new Color(255,102,102);
        case "Alkali Earth Metal":
            return new Color(255,204,204);
        case "Transition Metal":
            return new Color(153,255,153);
        case "Inner-Transition Metal":
            return new Color(0,255,0);
        case "Metalloid":
            return new Color(255,0,255);
        case "Post-Transition Metal":
            return new Color(255, 153,51);
        case "Halogen":
            return new Color(255,128,0);
        case "Noble Gas":
            return new Color(204,229,255);
        case "Unknown-Post-Transition Metal":
        case "Unknown-Halogen":
        case "Unknown-Noble Gas":
        case "false":
            return new Color(255,255,255);
        case "true":
            return new Color(255,255,0);
        case "Gas":
            return new Color(255,0,0);
        case "Liquid":
            return new Color(0,0,255);
        case "Solid":
        default:
            return new Color(0,0,0);
    }
}
}

我使用什么版本/程序/等等？

记事本

命令提示符

Java 8

javax.json-1.0.jar

程序将 javac、jar 和 java -jar 正常运行，数据库读取正常，我可以使用这些信息。因此，我不会提供有关这些内容的其他信息(除非有人询问)。

在此之前，我尝试过使用布局等，但我遇到了很多可笑的麻烦......最终我想到使用二维数组来保存信息。

我搜索了很多网站，包括:

How does paintComponent work?

http://www.oracle.com/technetwork/java/painting-140037.html

http://www.slideshare.net/martyhall/java-7-programming-tutorial-multithreaded-graphics-and-animation

Incremental graphics in Swing

Java clears screen when calling paint method - how to avoid that?

还有更多。虽然有些东西我不明白，但我确实学到了很多。

请注意，我对 Java 还很陌生，我的实际教育程度是高中在线计算机科学类(class)结束时的水平。尽管在从事这个额外项目的过程中，我在类(class)之外学到了很多东西。

清楚地陈述我的问题...

关于增量绘画为何不起作用的任何线索？我该如何解决这个问题？

Answer 1

这里出现了很多问题，但我立即想到的最大的 3 个问题是:

1. 您将重写 update(Graphics g) 方法，并在其中调用 paintComponent。您不应该在 Swing GUI 中重写此方法，这是 AWT 之类的事情，并且您当然不应该像您的代码那样更改其固有行为。
2. 您没有在覆盖中调用 super 的 PaintComponent 方法。
3. 最重要的是，您将元素组件直接添加到 JFrame 而不更改 JFrame 的默认 BorderLayout 布局管理器 - 您认为这会做什么？也许只显示最后输入的项目!

考虑创建一个使用更好布局的 JPanel，GridLayout 可能效果最好，并将您的元素组件添加到此 JPanel，然后将该 JPanel 添加到您的 GUI。

请注意，元素周期表中会有空元素的位置，对于这些空元素，请使用 JPanel 将空白 JLabels 添加到 GridLayout。

另一个问题:如果您要正确使用布局，那么您将希望每个元素在相对于该元素的坐标系中绘制其图像，而不是在表格中。换句话说，每个元素都会将其图像和文本放置在相同的相对位置。绝对位置会有所不同，因为每个元素在 JPanel 上都会占据自己不同的绝对位置。

<小时/><小时/>

就像对我自己的问题的编辑一样，我正在使用另一个问题的周期表数据显示，并尝试创建一个简化的周期表，其中没有镧系元素和锕系元素，并使用简单的 Swing GUI。

我创建了一个简单的 Element.java 类，它只保存元素内最基本的信息:

public class Element {
    private int atomicNumber;
    private String name;
    private String symbol;
    private int group;
    private int period;

    public Element(int atomicNumber, String name, String symbol, int group, int period) {
        this.atomicNumber = atomicNumber;
        this.name = name;
        this.symbol = symbol;
        this.group = group;
        this.period = period;
    }

    public int getAtomicNumber() {
        return atomicNumber;
    }

    public String getName() {
        return name;
    }

    public String getSymbol() {
        return symbol;
    }

    public int getGroup() {
        return group;
    }

    public int getPeriod() {
        return period;
    }

    @Override
    public String toString() {
        return "Element [atomicNumber=" + atomicNumber + ", name=" + name + ", symbol=" + symbol
                + ", group=" + group + ", period=" + period + "]";
    }

}

然后，我创建了此数据表 Elements.txt，将该文件放置在与类文件相同的目录中:

1, Hydrogen, H, 1, 1
2, Helium, He, 18, 1
3, Lithium, Li, 1, 2
4, Beryllium, Be, 2, 2
5, Boron, B, 13, 2
6, Carbon, C, 14, 2
7, Nitrogen, N, 15, 2
8, Oxygen, O, 16, 2
9, Fluorine, F, 17, 2
10, Neon, Ne, 18, 2
11, Sodium, Na, 1, 3
12, Magnesium, Mg, 2, 3
13, Aluminium, Al, 13, 3
14, Silicon, Si, 14, 3
15, Phosphorus, P, 15, 3
16, Sulfur, S, 16, 3
17, Chlorine, Cl, 17, 3
18, Argon, Ar, 18, 3
19, Potassium, K, 1, 4
20, Calcium, Ca, 2, 4
21, Scandium, Sc, 3, 4
22, Titanium, Ti, 4, 4
23, Vanadium, V, 5, 4
24, Chromium, Cr, 6, 4
25, Manganese, Mn, 7, 4
26, Iron, Fe, 8, 4
27, Cobalt, Co, 9, 4
28, Nickel, Ni, 10, 4
29, Copper, Cu, 11, 4
30, Zinc, Zn, 12, 4
31, Gallium, Ga, 13, 4
32, Germanium, Ge, 14, 4
33, Arsenic, As, 15, 4
34, Selenium, Se, 16, 4
35, Bromine, Br, 17, 4
36, Krypton, Kr, 18, 4
37, Rubidium, Rb, 1, 5
38, Strontium, Sr, 2, 5
39, Yttrium, Y, 3, 5
40, Zirconium, Zr, 4, 5
41, Niobium, Nb, 5, 5
42, Molybdenum, Mo, 6, 5
43, Technetium, Tc, 7, 5
44, Ruthenium, Ru, 8, 5
45, Rhodium, Rh, 9, 5
46, Palladium, Pd, 10, 5
47, Silver, Ag, 11, 5
48, Cadmium, Cd, 12, 5
49, Indium, In, 13, 5
50, Tin, Sn, 14, 5
51, Antimony, Sb, 15, 5
52, Tellurium, Te, 16, 5
53, Iodine, I, 17, 5
54, Xenon, Xe, 18, 5
55, Caesium, Cs, 1, 6
56, Barium, Ba, 2, 6
57, Lanthanum, La, 3, 6
72, Hafnium, Hf, 4, 6
73, Tantalum, Ta, 5, 6
74, Tungsten, W, 6, 6
75, Rhenium, Re, 7, 6
76, Osmium, Os, 8, 6
77, Iridium, Ir, 9, 6
78, Platinum, Pt, 10, 6
79, Gold, Au, 11, 6
80, Mercury, Hg, 12, 6
81, Thallium, Tl, 13, 6
82, Lead, Pb, 14, 6
83, Bismuth, Bi, 15, 6
84, Polonium, Po, 16, 6
85, Astatine, At, 17, 6
86, Radon, Rn, 18, 6
87, Francium, Fr, 1, 7
88, Radium, Ra, 2, 7
89, Actinium, Ac, 3, 7
104, Rutherfordium, Rf, 4, 7
105, Dubnium, Db, 5, 7
106, Seaborgium, Sg, 6, 7
107, Bohrium, Bh, 7, 7
108, Hassium, Hs, 8, 7
109, Meitnerium, Mt, 9, 7
110, Darmstadtium, Ds, 10, 7
111, Roentgenium, Rg, 11, 7
112, Copernicium, Cn, 12, 7
113, Nihonium, Nh, 13, 7
114, Flerovium, Fl, 14, 7
115, Moscovium, Mc, 15, 7
116, Livermorium, Lv, 16, 7
117, Tennessine, Ts, 17, 7
118, Oganesson, Og, 18, 7

然后 GUI 将使用 BoxLayout 为表格创建每个元素单元格，并使用 GridLayout 来保存和显示所有元素单元格:

import java.awt.Color;
import java.awt.Font;
import java.awt.GridLayout;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import javax.swing.*;

@SuppressWarnings("serial")
public class ElementsGui extends JPanel {

    private static final int MAX_GROUPS = 7;
    private static final int MAX_PERIODS = 18;

    public ElementsGui(List<Element> elements) {
        setLayout(new GridLayout(MAX_GROUPS, MAX_PERIODS));
        int prevGroup = 1;
        for (Element element : elements) {
            ElementPanel elementPanel = new ElementPanel(element);
            for (int i = prevGroup; i < element.getGroup() - 1; i++) {
                add(new JLabel());
            }
            add(elementPanel);
            prevGroup = element.getGroup();
        }
    }

    // a utility method for downloading the elements from the text file
    public static List<Element> extractElements(InputStream sourceStream) {
        List<Element> elements = new ArrayList<>();
        Scanner scan = new Scanner(sourceStream);
        while (scan.hasNextLine()) {
            String line = scan.nextLine();
            String[] tokens = line.split(", ");

            int atomicNumber = Integer.parseInt(tokens[0]);
            String name = tokens[1];
            String symbol = tokens[2];
            int group = Integer.parseInt(tokens[3]);
            int period = Integer.parseInt(tokens[4]);
            elements.add(new Element(atomicNumber, name, symbol, group, period));
        }
        scan.close();

        return elements;
    }

    private class ElementPanel extends JPanel {
        Element element;

        public ElementPanel(Element element) {
            this.element = element;
            JLabel nameLabel = new JLabel(element.getName(), SwingConstants.CENTER);
            JLabel symbolLabel = new JLabel(element.getSymbol(), SwingConstants.CENTER);
            JLabel atomNumbLabel = new JLabel("" + element.getAtomicNumber(), SwingConstants.CENTER);

            symbolLabel.setFont(symbolLabel.getFont().deriveFont(Font.BOLD, 32f));

            JPanel namePanel = new JPanel();
            JPanel symbolPanel = new JPanel();
            JPanel atomNumbPanel = new JPanel();

            namePanel.add(nameLabel);
            symbolPanel.add(symbolLabel);
            atomNumbPanel.add(atomNumbLabel);

            setBorder(BorderFactory.createLineBorder(Color.BLACK));
            setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
            add(namePanel);
            add(symbolPanel);
            add(atomNumbPanel);
        }

        public Element getElement() {
            return element;
        }

    }

    private static void createAndShowGui() {
        String path = "Elements.txt";
        InputStream sourceStream = ElementUtilities.class.getResourceAsStream(path);
        if (sourceStream == null) {
            String message = "\"" + path + "\"" + " not found. Program will abort";
            String title = "Path Error";
            JOptionPane.showMessageDialog(null, message, title, JOptionPane.ERROR_MESSAGE);
            System.exit(-1);
        }
        List<Element> elements = extractElements(sourceStream);

        ElementsGui mainPanel = new ElementsGui(elements);

        JFrame frame = new JFrame("Elements Gui");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(mainPanel);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }
}

这显示为: