基于 gwt 的简易计算器

看了一些关于 Google Web Toolkit 的资料，搞出了一个简易的计算器来。

分两个类写，一个显示（Calculator），一个计算（Operator）。
Calculator 类

public class Calculator implements EntryPoint {
	
	final VerticalPanel calculator = new VerticalPanel();   // 计算器管理面板

	public void onModuleLoad() {
		final TextBox valueBox = new TextBox();             // 计算结果显示区
		final Grid calculatorGrid = new Grid(4, 4);         // 管理 Button 的网格
		final String[] strBtns = new String[] { "7", "8", "9", "+", "4", "5",
				"6", "-", "1", "2", "3", "*", "0", "C", "/", "=" };      // Button 的显示值
		for (int i = 0; i < strBtns.length; i++) {
			calculatorGrid.setWidget(i / 4, i % 4, createButton(strBtns[i]));
		} // end for i

		valueBox.setText("0");
		valueBox.setReadOnly(true);
		valueBox.setSize("135pt", "25pt");
		valueBox.setTextAlignment(TextBoxBase.ALIGN_RIGHT);
		calculatorGrid.setCellSpacing(2);
		calculator.setTitle("Calculator");
		calculator.setHorizontalAlignment(HasHorizontalAlignment.ALIGN_CENTER);
		calculator.setVerticalAlignment(HasVerticalAlignment.ALIGN_BOTTOM);
		calculator.setBorderWidth(5);
		
		calculator.add(valueBox);
		calculator.add(calculatorGrid);
		RootPanel.get().add(calculator);
	}

	// 创建 Button，并添加相关属性和事件
	public Button createButton(String text) {
		Button button = new Button(text);
		button.setSize("30pt", "30pt");
		// 添加 Button 的 onClick 事件
		button.addClickListener(new ClickListener() {
			public void onClick(Widget widget) {
				String numSign = ((Button) widget).getText();
				String value = "";
				if ("0123456789".indexOf(numSign) != -1) {
					value = Operator.numClick(numSign);
				} else if ("+-*/".indexOf(numSign) != -1) {
					value = Operator.signClick(numSign);
				} else if ("C".indexOf(numSign) != -1) {
					value = Operator.cleanClick(numSign);
				} else if ("=".indexOf(numSign) != -1) {
					value = Operator.amountClick();
				}
				((TextBox)(calculator.getWidget(0))).setText(value);
			}
		});
		return button;
	}
}

Operator
所有要传递的数据均需继承 com.google.gwt.user.client.rpc.IsSerializable 接口。

public class Operator implements IsSerializable {
	private static String old_Value = "0";         // 保存符号之前的值
	private static String sign = "";               // 保存计算符号
	private static String textValue = "0";         // 保存 valueBox 当前或将要显示的值

	public static String getOld_Value() {
		return old_Value;
	}

	public static String textValue() {
		return textValue;
	}

	// 保存显示值
	public static String numClick(String num) {
		if (textValue.equals("0") || textValue.equals("Error")) {
			textValue = num;
		} else {
			textValue += num;
		}
		return textValue;
	}

	// 保存计算符号
	public static String signClick(String signStr) {
		sign = signStr;
		old_Value = textValue;
		textValue = "0";
		return old_Value;
	}

	// 清空现有数据
	public static String cleanClick(String clean) {
		sign = "";
		old_Value = "0";
		textValue = "0";
		return textValue;
	}

	// 计算方法，并返回结果
	public static String amountClick() {
		if (sign.equals("+")) {
			textValue = String.valueOf(Integer.decode(old_Value)
					+ Integer.decode(textValue));
		} else if (sign.equals("-")) {
			textValue = String.valueOf(Integer.decode(old_Value)
					- Integer.decode(textValue));
		} else if (sign.equals("*")) {
			textValue = String.valueOf(Integer.decode(old_Value)
					* Integer.decode(textValue));
		} else if (sign.equals("/")) {
			if (old_Value.equals("0")) {
				textValue = "Error";
			} else {
				textValue = String.valueOf(Integer.decode(old_Value)
						/ Integer.decode(textValue));
			}
		}
		sign = "";
		old_Value = "0";
		return textValue;
	}
}

XML 配置文件

<module>
	<!-- 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.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='org.gwt.calculator.client.Calculator'/>
	
	<!-- Specify the application specific style sheet.              -->
	<stylesheet src='Calculator.css' />  
</module>