GWT 股票交易所应用程序示例

17 Mar 2025 | 5 分钟阅读

在 GWT 股票交易所中，我们将使用所有基本组件、面板和布局，使用名为股票交易所的 Google Web Toolkit 来设计一个 Web 应用程序。

该应用程序可用于添加股票市场的内容，其值将在特定时间间隔后更改。计算出的值包括价格，以及变化， 并且还可以删除内容。

Panel 和 Widget 的使用如下

HTML 面板
Flex Table
Flow 面板
计时器

创建的文件

StockExchange.gwt.xml GWT 模块定义
StockExchange.html 主机页面
StockExchange.css 应用程序样式表
web.xml Java Web 应用程序描述符
StockExchange.java GWT 入口点类
GreetingService.java, GreetingServiceAsync.java, GreetingServiceImpl.java GWT 示例 RPC 类
gwt-servlet.jar GWT 服务器运行时库
StockExchangeTest.java Exchange 的启动器测试用例

StockExchange.html

<!doctype html>
<!-- The DOCTYPE declaration above will set the     -->
<!-- browser's rendering engine into                -->
<!-- "Standards Mode". Replacing this declaration   -->
<!-- with a "Quirks Mode" doctype is not supported. -->
<html>
  <head>
   <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    <!--     -->
    <!-- Consider inlining CSS to reduce the number of requested files -->
    <!--     -->
    <link type="text/css" rel="stylesheet" href="StockExchange.css">
    <!--     -->
    <!-- Any title is fine       -->
    <!--     -->
    <title>Stock Exchange</title>
   
    <!--     -->
    <!-- This script loads your compiled module.   -->
    <!-- If you add any GWT meta tags, they must   -->
    <!-- be added before this line.                -->
    <!--    -->
    <script type="text/javascript" language="javascript" src="stockexchange/stockexchange.nocache.js"></script>
	
  </head>
  <!--      -->
  <!-- The body can have arbitrary html, or     -->
  <!-- you can leave the body empty if you want  -->
  <!-- to create a completely dynamic UI.       -->
  <!--      -->
  <body>
     <h1>Stock Exchange</h1>
     <div id="stockList"></div>
    <iframe src="javascript:''" id="__gwt_historyFrame" tabIndex='-1' 
	style="position:absolute;width:0;height:0;border:0"></iframe>
    <!-- RECOMMENDED if your web app will not function without JavaScript enabled -->
    <noscript>
      <div style="width: 22em; position: absolute; left: 50%; margin-left: -11em; 
	  color: red; background-color: white; border: 1px solid red; padding: 4px; font-family: sans-serif">
        Your web browser must have JavaScript enabled
        in order for this application to display correctly.
      </div>
    </noscript>
  </body>
</html>

StockExchange.java

package com.gwt.sample.stockexchange.client;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.FlexTable;
import com.google.gwt.user.client.ui.HorizontalPanel;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.event.dom.client.KeyCodes;
import com.google.gwt.event.dom.client.KeyDownEvent;
import com.google.gwt.event.dom.client.KeyDownHandler;
import com.google.gwt.user.client.Window;
import java.util.ArrayList;
import com.google.gwt.user.client.Timer;
import com.google.gwt.user.client.Random;
import com.google.gwt.i18n.client.NumberFormat;
import com.google.gwt.i18n.client.DateTimeFormat;
import java.util.Date;
/**
 * Entry point classes define <code>onModuleLoad()</code>.
 */
public class StockExchange implements EntryPoint {
	  private VerticalPanel mainPanel = new VerticalPanel();
	  private FlexTable stocksFlexTable = new FlexTable();
	  private HorizontalPanel addPanel = new HorizontalPanel();
	  private TextBox newSymbolTextBox = new TextBox();
	  private Button addStockButton = new Button("Add");
	  private Label lastUpdatedLabel = new Label();
	  private ArrayList<String> stocks = new ArrayList<String>();
	  private static final int REFRESH_INTERVAL = 5000; // m
	/**
	 * This is the entry point method.
	 */
	public void onModuleLoad() {
		stocksFlexTable.setText(0, 0, "Symbol");
	    stocksFlexTable.setText(0, 1, "Price");
	    stocksFlexTable.setText(0, 2, "Change");
	    stocksFlexTable.setText(0, 3, "Remove");
	 // Assemble Add Stock panel.
	    addPanel.add(newSymbolTextBox);
	    addPanel.add(addStockButton);
	    // Assemble Main panel.
	    mainPanel.add(stocksFlexTable);
	    mainPanel.add(addPanel);
	    mainPanel.add(lastUpdatedLabel);
	 // Associate the Main panel with the HTML host page.
	    RootPanel.get("stockList").add(mainPanel);
	 // Move cursor focus to the input box.
	    newSymbolTextBox.setFocus(true);
	    // Setup timer to refresh list automatically.
	      Timer refreshTimer = new Timer() {
	        @Override
	        public void run() {
	          refreshWatchList();
	        }
	      };
	      refreshTimer.scheduleRepeating(REFRESH_INTERVAL)
	    // Listen for mouse events on the Add button.
	    addStockButton.addClickHandler(new ClickHandler() {
	      public void onClick(ClickEvent event) {
	        addStock();
	      }
	    });
	    // Listen for keyboard events in the input box.
	      newSymbolTextBox.addKeyDownHandler(new KeyDownHandler() {
	        public void onKeyDown(KeyDownEvent event) {
	          if (event.getNativeKeyCode() == KeyCodes.KEY_ENTER) {
	            addStock();
	          }
	        }
	      });
	  }
	  /**
	   * Add stock to FlexTable. Executed when the user clicks the addStockButton or
	   * presses enter in the newSymbolTextBox.
	   */
	  private void addStock() {
	      final String symbol = newSymbolTextBox.getText().toUpperCase().trim();
	      newSymbolTextBox.setFocus(true);
	      // Stock code must be between 1 and 10 chars that are numbers, letters, or dots.
	      if (!symbol.matches("^[0-9A-Z\\.]{1,10}$")) {
	        Window.alert("'" + symbol + "' is not a valid symbol.");
	        newSymbolTextBox.selectAll();
	        return;
	      }
	      newSymbolTextBox.setText("");
	   // Don't add the stock if it's already in the table.
	      if (stocks.contains(symbol))
	        return;
	   // Add the stock to the table.
	      int row = stocksFlexTable.getRowCount();
	      stocks.add(symbol);
	      stocksFlexTable.setText(row, 0, symbol);
	   // Add a button to remove this stock from the table.
	      Button removeStockButton = new Button("x");
	      removeStockButton.addClickHandler(new ClickHandler() {
	        public void onClick(ClickEvent event) {
	          int removedIndex = stocks.indexOf(symbol);
	          stocks.remove(removedIndex);
	          stocksFlexTable.removeRow(removedIndex + 1);
	        }
	      });
	      stocksFlexTable.setWidget(row, 3, removeStockButton);
	      // Get the stock price.
	      refreshWatchList();
	    }
	  private void refreshWatchList() {
		     final double MAX_PRICE = 100.0; // $100.00
		     final double MAX_PRICE_CHANGE = 0.02; // +/- 2%
		     StockPrice[] prices = new StockPrice[stocks.size()];
		     for (int i = 0; i < stocks.size(); i++) {
		       double price = Random.nextDouble() * MAX_PRICE;
		       double change = price * MAX_PRICE_CHANGE
		           * (Random.nextDouble() * 2.0 - 1.0);
		       prices[i] = new StockPrice(stocks.get(i), price, change);
		     }
		     updateTable(prices);
		    }
	  private void updateTable(StockPrice[] prices) {
		  for (int i = 0; i < prices.length; i++) {
		        updateTable(prices[i]);
		      }
		// Display timestamp showing last refresh.
	      DateTimeFormat dateFormat = DateTimeFormat.getFormat(
	        DateTimeFormat.PredefinedFormat.DATE_TIME_MEDIUM);
	      lastUpdatedLabel.setText("Last update : " 
	        + dateFormat.format(new Date()));
		}
	  private void updateTable(StockPrice price) {
		     // Make sure the stock is still in the stock table.
		     if (!stocks.contains(price.getSymbol())) {
		       return;
		     }
		     int row = stocks.indexOf(price.getSymbol()) + 1;
		     // Format the data in the Price and Change fields.
		     String priceText = NumberFormat.getFormat("#,##0.00").format(
		         price.getPrice());
		     NumberFormat changeFormat = NumberFormat.getFormat("+#,##0.00;-#,##0.00");
		     String changeText = changeFormat.format(price.getChange());
		     String changePercentText = changeFormat.format(price.getChangePercent());
		     // Populate the Price and Change fields with new data.
		     stocksFlexTable.setText(row, 1, priceText);
		     stocksFlexTable.setText(row, 2, changeText + " (" + changePercentText
		         + "%)");
		    }
}

StockPrice.java

package com.gwt.sample.stockexchange.client;
public class StockPrice {
  private String symbol;
  private double price;
  private double change;
  public StockPrice() {
  }
  public StockPrice(String symbol, double price, double change) {
    this.symbol = symbol;
    this.price = price;
    this.change = change;
  }
  public String getSymbol() {
    return this.symbol;
  }
  public double getPrice() {
    return this.price;
  }
  public double getChange() {
    return this.change;
  }
  public double getChangePercent() {
    return 10.0 * this.change / this.price;
  }
  public void setSymbol(String symbol) {
    this.symbol = symbol;
  }
  public void setPrice(double price) {
    this.price = price;
  }
  public void setChange(double change) {
    this.change = change;
  }
}

StockExchange.gwt.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--
  When updating your version of GWT, you should also update this DTD reference,
  so that your app can take advantage of the latest GWT module capabilities.
-->
<!DOCTYPE module PUBLIC "-//Google Inc.//DTD Google Web Toolkit 2.7.0//EN"
  "http://gwtproject.org/doctype/2.7.0/gwt-module.dtd">
<module rename-to='stockexchange'>
  <!-- Inherit the core Web Toolkit stuff.  -->
  <inherits name='com.google.gwt.user.User'/>
  <!-- Inherit the default GWT style sheet.  You can change   -->
  <!-- the theme of your GWT application by uncommenting    -->
  <!-- any one of the following lines. -->
  <inherits name='com.google.gwt.user.theme.clean.Clean'/>
  <!-- <inherits name='com.google.gwt.user.theme.standard.Standard'/> -->
  <!-- <inherits name='com.google.gwt.user.theme.chrome.Chrome'/> -->
  <!-- <inherits name='com.google.gwt.user.theme.dark.Dark'/>     -->
  <!-- Other module inherits   -->
  <!-- Specify the app entry point class.   -->
  <entry-point class='com.gwt.sample.stockexchange.client.StockExchange'/>
  <!-- Specify the paths for translatable code -->
  <source path='client'/>
  <source path='shared'/>
  <!-- allow Super Dev Mode -->
  <add-linker name="xsiframe"/>
</module>

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