JAVA小应用程序Applet设计(计算器)实验报告(附完整代码)

小应用程序Applet设计一、课题内容和要求内容：设计和编写一个可以用鼠标操作的Applet小应用程序和相应的HTML 页面，观察Applet的执行过程，测试程序鼠标用户交互操作的效果。

要求：要求学生能在学习和理解课堂学习内容中JAVA小应用程序的基础上，通过实验，培养学生将JAVA小应用程序相关知识点（包括JAVA Applet和低级事件处理模型）有机结合，设计基于WEB浏览器的小应用程序的能力。

二、设计思路分析class App:一个Java Applet计算器的主类public void init():完成初始化appletpublic boolean action():实现事件处理的方法public void doOperator():运算及运算结果输出操作public void doForeScreen():数字和小数点输出到文本框操作public void doClear():清空操作三、概要设计public class App extends Applet {TextField tfAnswer;Button b0, b1, b2, b3, b4, b5, b6, b7, b8, b9;Button bPoint, bEqual, bPlus, bMinus, bClear, bMulti, bDivision;String OperatorCurrent, OperatorPre;String ForeScreen, BackScreen;boolean isFloat = false;public void init();public boolean action(Event e, Object o);public void doOperator()public void doForeScreen(String s);public void doClear();}事件处理:运算及运算结果输出:四、详细设计Java代码：import java.awt.*;import java.applet.*;public class App extends Applet {TextField tfAnswer;// 定义变量Button b0, b1, b2, b3, b4, b5, b6, b7, b8, b9;Button bPoint, bEqual, bPlus, bMinus, bClear, bMulti, bDivision;String OperatorCurrent, OperatorPre;String ForeScreen, BackScreen;boolean isFloat = false;public void init() {// 初始化OperatorCurrent = new String("");OperatorPre = new String("");ForeScreen = new String("0");// 保证输入字符串不为空防止计算错误BackScreen = new String("");setBackground(Color.gray);setLayout(null);// 设为空布局便于自定义组件位置tfAnswer = new TextField();// 设置文本框样式tfAnswer.setBounds(20, 20, 175, 40);tfAnswer.setFont(new Font(BackScreen, Font.BOLD, 28));add(tfAnswer);tfAnswer.setText(ForeScreen);bClear = new Button("C");// 设置按钮样式bClear.setBounds(20, 70, 40, 40);add(bClear);bDivision = new Button("/");bDivision.setBackground(Color.green);bDivision.setBounds(65, 70, 40, 40);add(bDivision);bMulti = new Button("*");bMulti.setBackground(Color.green);bMulti.setBounds(110, 70, 40, 40);add(bMulti);bMinus = new Button("-");bMinus.setBackground(Color.green);bMinus.setBounds(155, 70, 40, 40);add(bMinus);b7 = new Button("7");b7.setBounds(20, 115, 40, 40);b7.setBackground(Color.orange);add(b7);b8 = new Button("8");b8.setBackground(Color.orange);b8.setBounds(65, 115, 40, 40);add(b8);b9 = new Button("9");b9.setBackground(Color.orange);b9.setBounds(110, 115, 40, 40);add(b9);bPlus = new Button("+");bPlus.setBackground(Color.green);bPlus.setBounds(155, 115, 40, 85);add(bPlus);b4 = new Button("4");b4.setBackground(Color.orange);b4.setBounds(20, 160, 40, 40);add(b4);b5 = new Button("5");b5.setBackground(Color.orange);b5.setBounds(65, 160, 40, 40);add(b5);b6 = new Button("6");b6.setBackground(Color.orange);b6.setBounds(110, 160, 40, 40);add(b6);b1 = new Button("1");b1.setBackground(Color.orange);b1.setBounds(20, 205, 40, 40);add(b1);b2 = new Button("2");b2.setBackground(Color.orange);b2.setBounds(65, 205, 40, 40);add(b2);b3 = new Button("3");b3.setBackground(Color.orange);b3.setBounds(110, 205, 40, 40);add(b3);bEqual = new Button("=");bEqual.setBackground(Color.green);bEqual.setBounds(155, 205, 40, 85);add(bEqual);b0 = new Button("0");b0.setBackground(Color.orange);b0.setBounds(20, 250, 85, 40);add(b0);bPoint = new Button(".");bPoint.setBackground(Color.orange);bPoint.setBounds(110, 250, 40, 40);add(bPoint);}public boolean action(Event e, Object o) {// 实现事件处理的方法String s = new String("");if ((e.target == b0) || (e.target == b1) || (e.target == b2)|| (e.target == b3) || (e.target == b4) || (e.target == b5)|| (e.target == b6) || (e.target == b7) || (e.target == b8)|| (e.target == b9)) {// 获取数字按钮数据并在控制台和文本框输出if (e.target != bPoint) {// 获取数字s = (String) o;doForeScreen(s);}}if ((e.target == bPoint) && !ForeScreen.contains(".")) {// 保证原数不含小数点的情况下获取小数点并在控制台和文本框输出s = (String) o;if (ForeScreen.equals(""))// 原来没有输入数据则用0.{doForeScreen("0.");} else// 原来有输入数据则用.{doForeScreen(s);}}if (e.target == bClear) {// 清除按钮进行清除操作doClear();}if ((e.target == bMulti) || (e.target == bDivision)|| (e.target == bPlus) || (e.target == bMinus)|| (e.target == bEqual)) {// 加减乘除等于按钮获取运算操作符并进行运算操作if (ForeScreen != "") {// 重新输入数字进行运算操作OperatorCurrent = ((String) o);doOperator();} else {// 没有重新输入数字则作为上一运算符--->保证不输入连续的同一运算符OperatorPre = ((String) o);}}return true;}public void doOperator() {// 运算及运算结果输出操作double dFore, dBack;Double d;if (OperatorPre.equals("")) {// 上一运算符没有则直接输出BackScreen = ForeScreen;// 输入的数据转入后台并清空，用后台输出它ForeScreen = "";tfAnswer.setText(BackScreen);repaint();} else {// 上一运算符存在则运算后输出dFore = (new Double(ForeScreen)).doubleValue();dBack = (new Double(BackScreen)).doubleValue();ForeScreen = "";// 运算结果转入后台并清空，用后台输出它BackScreen = tfAnswer.getText();if (OperatorPre.equals("+")) {d = new Double((dBack + dFore));BackScreen = d.toString();}if (OperatorPre.equals("-")) {d = new Double((dBack - dFore));BackScreen = d.toString();}if (OperatorPre.equals("*")) {d = new Double((dBack * dFore));BackScreen = d.toString();}if (OperatorPre.equals("/")) {d = new Double((dBack / dFore));BackScreen = d.toString();}tfAnswer.setText(BackScreen);repaint();}OperatorPre = OperatorCurrent;// 现运算符变上一运算符repaint();}public void doForeScreen(String s) {// 数字和小数点输出到文本框操作ForeScreen += s;if (ForeScreen.length() > 1 && ForeScreen.startsWith("0")&& !ForeScreen.contains("."))// 以0开头的长度大于一的非小数去掉开头的0ForeScreen = ForeScreen.substring(1);tfAnswer.setText(ForeScreen);repaint();}public void doClear() {// 清空操作OperatorCurrent = "";OperatorPre = "";ForeScreen = "0";BackScreen = "";isFloat = false;tfAnswer.setText(ForeScreen);repaint();}}Html代码：<!DOCTYPE html><html lang="en"><head><meta charset="UTF-8"><title>"JavaApplet计算器"</title></head><body><div><applet code="App.class" width="215" height="310"></applet></div></body></html>五、测试数据及其结果分析1正常输入：1.88+99=C .666/33=C 7.33*26=0.5-1-3=2结果：输出正常。