鸿蒙 简易计算器实现案例教程【鸿蒙专题8】
作者：徐庆
前言：
各位同学大家好，有段时间没有给大家更新文章了，具体多久我也不记得哈，今天是周日有时间就撸了一个鸿蒙的简易计算器的案例分享给大家 希望能帮助到各位同学学习和工作 那么废话不多说我们正式开始
准备工作
华为鸿蒙系统开发初体验 ：?[https://www.jianshu.com/p/f94c847c7fdc]
效果图：
image.png
具体实现
- 代码结构
image.png
- 1 slice MainAbilitySlice：计算器交互界面，用于完成界面元素渲染、按钮事件绑定动作。
- 2 utils
- MathUtil：用于计算表达式结果的工具类，封装有运算符权重获取、表达式计算等方法。
- 3 resources resources\base\layout：存放xml布局文件。resources\base\media：存放图片资源文件。resources\base\graphic：存放xml样式文件。
- 4 MainAbility：HAP的入口ability，由DevEco Studio自动生成。
- 5 MyApplication：表示HAP的类，由DevEco Studio自动生成。
- 6 config.json：应用的配置文件，由DevEco Studio自动生成。
- 应用初始化 计算器应用使用的是自定义的按键，为避免用户在输入数学表达式时，系统自动弹出软键盘，本应用在初始化时，会在入口类MainAbility禁止应用弹出软键盘。
getWindow().setLayoutFlags(WindowManager.LayoutConfig.MARK_ALT_FOCUSABLE_IM,
WindowManager.LayoutConfig.MARK_ALT_FOCUSABLE_IM);
随后会在计算器交互界面类MainAbilitySlice中，完成界面渲染和按键点击事件绑定。
@Override
public void onStart(Intent intent) {
super.onStart(intent);
super.setUIContent(ResourceTable.Layout_ability_main);
initView();
initListener();
}
- 主页面布局 布局文件 ability_main.xml
<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
xmlns:ohos="http://schemas.huawei.com/res/ohos"
ohos:height="match_parent"
ohos:orientation="vertical"
ohos:alignment="bottom"
ohos:background_element="$graphic:background_ability_main"
ohos:width="match_parent">
<DirectionalLayout
ohos:id="$+id:result_console"
ohos:height="match_content"
ohos:left_margin="15vp"
ohos:right_margin="15vp"
ohos:bottom_margin="50vp"
ohos:width="match_parent">
<TextField
ohos:id="$+id:input_text"
ohos:height="60vp"
ohos:width="match_parent"
ohos:text_size="48vp"
ohos:bubble_height="0"
ohos:multiple_lines="false"
ohos:text_alignment="right"/>
<Text
ohos:id="$+id:pre_result"
ohos:margin="3vp"
ohos:height="42vp"
ohos:width="match_parent"
ohos:text_size="36vp"
ohos:text_color="#555555"
ohos:scrollable="true"
ohos:text_alignment="right"/>
</DirectionalLayout>
<DirectionalLayout
ohos:id="$+id:calculate_keyboard"
ohos:height="match_content"
ohos:padding="8vp"
ohos:margin="8vp"
ohos:background_element="$graphic:background_keyboard"
ohos:width="match_parent">
<DirectionalLayout
ohos:height="match_content"
ohos:width="match_parent"
ohos:alignment="center"
ohos:orientation="horizontal">
<Text
ohos:id="$+id:number_cancel"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:text_color="blue"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="C"/>
<Text
ohos:id="$+id:divide"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="35vp"
ohos:text_color="blue"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="÷"/>
<Text
ohos:id="$+id:multiply"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="35vp"
ohos:text_color="blue"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="×"/>
<Image
ohos:id="$+id:delete"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="28vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:image_src="$media:brief_del_bt"
/>
</DirectionalLayout>
<DirectionalLayout
ohos:height="match_content"
ohos:width="match_parent"
ohos:alignment="center"
ohos:orientation="horizontal">
<Text
ohos:id="$+id:seven"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="7"/>
<Text
ohos:id="$+id:eight"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="8"/>
<Text
ohos:id="$+id:nine"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="9"/>
<Text
ohos:id="$+id:minus"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_color="blue"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="-"/>
</DirectionalLayout>
<DirectionalLayout
ohos:height="match_content"
ohos:width="match_parent"
ohos:alignment="center"
ohos:orientation="horizontal">
<Text
ohos:id="$+id:four"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="4"/>
<Text
ohos:id="$+id:five"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="5"/>
<Text
ohos:id="$+id:six"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="6"/>
<Text
ohos:id="$+id:plus"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_color="blue"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="+"/>
</DirectionalLayout>
<DirectionalLayout
ohos:height="match_content"
ohos:width="match_parent"
ohos:orientation="horizontal"
ohos:alignment="center">
<DirectionalLayout
ohos:height="match_content"
ohos:width="match_content">
<DirectionalLayout
ohos:height="match_content"
ohos:width="match_parent"
ohos:alignment="center"
ohos:orientation="horizontal">
<Text
ohos:id="$+id:one"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="1"/>
<Text
ohos:id="$+id:two"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="2"/>
<Text
ohos:id="$+id:three"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="3"/>
</DirectionalLayout>
<DirectionalLayout
ohos:height="match_content"
ohos:width="match_parent"
ohos:alignment="center"
ohos:orientation="horizontal">
<Text
ohos:id="$+id:divide_remainder"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="%"/>
<Text
ohos:id="$+id:zero"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="0"/>
<Text
ohos:id="$+id:radix_point"
ohos:text_alignment="center"
ohos:height="70vp"
ohos:width="70vp"
ohos:text_size="30vp"
ohos:background_element="$graphic:background_round"
ohos:margin="8vp"
ohos:text="."/>
</DirectionalLayout>
</DirectionalLayout>
<Text
ohos:id="$+id:equal_sign"
ohos:text_alignment="center"
ohos:height="150vp"
ohos:width="70vp"
ohos:text_size="35vp"
ohos:text_color="#FFFFFF"
ohos:background_element="$graphic:background_denghao"
ohos:margin="8vp"
ohos:text="="/>
</DirectionalLayout>
</DirectionalLayout>
</DirectionalLayout>
布局预览效果
我们从布局文件结构·可以看出来 多层线性布局嵌套来实现了整个 计算器键盘的布局 以及输入框和显示结果的text
- 逻辑实现
package com.example.counter_demo.slice;
import com.example.counter_demo.utils.MathUtil;
import com.example.counter_demo.ResourceTable;
import ohos.aafwk.ability.AbilitySlice;
import ohos.aafwk.content.Intent;
import ohos.agp.components.Component;
import ohos.agp.components.Text;
import ohos.agp.components.TextField;
import java.util.EmptyStackException;
import java.util.regex.Pattern;
/**
* MainAbilitySlice
*
* @since 2021年8月22日11:55:18
*
*/
public class MainAbilitySlice extends AbilitySlice {
/**
* number component
*/
private static int[] numberComponentIds = {ResourceTable.Id_seven, ResourceTable.Id_eight, ResourceTable.Id_nine,
ResourceTable.Id_four, ResourceTable.Id_five, ResourceTable.Id_six, ResourceTable.Id_one,
ResourceTable.Id_two, ResourceTable.Id_three, ResourceTable.Id_zero, ResourceTable.Id_radix_point
};
/**
* operator component
*/
private static int[] operatorComponentIds = {ResourceTable.Id_divide, ResourceTable.Id_multiply,
ResourceTable.Id_minus, ResourceTable.Id_divide_remainder, ResourceTable.Id_plus
};
private TextField inputText;
private Text preResult;
@Override
public void onStart(Intent intent) {
super.onStart(intent);
super.setUIContent(ResourceTable.Layout_ability_main);
initView();
initListener();
}
private void initView() {
if (findComponentById(ResourceTable.Id_input_text) instanceof TextField) {
inputText = (TextField) findComponentById(ResourceTable.Id_input_text);
inputText.requestFocus();
}
if (findComponentById(ResourceTable.Id_pre_result) instanceof Text) {
preResult = (Text) findComponentById(ResourceTable.Id_pre_result);
}
}
private void initListener() {
findComponentById(ResourceTable.Id_number_cancel).setClickedListener(new Component.ClickedListener() {
@Override
public void onClick(Component component) {
preResult.setText("");
inputText.setText("");
}
});
findComponentById(ResourceTable.Id_delete).setClickedListener(new Component.ClickedListener() {
@Override
public void onClick(Component component) {
if (inputText.getText().isEmpty()) {
return;
}
inputText.setText(inputText.getText().substring(0, inputText.getText().length() - 1));
}
});
findComponentById(ResourceTable.Id_equal_sign).setClickedListener(new Component.ClickedListener() {
@Override
public void onClick(Component component) {
calculateResult(inputText.getText(), false);
}
});
for (int componentId : numberComponentIds) {
findComponentById(componentId).setClickedListener(new Component.ClickedListener() {
@Override
public void onClick(Component component) {
bindNumberClickListener(componentId);
}
});
}
for (int componentId : operatorComponentIds) {
findComponentById(componentId).setClickedListener(new Component.ClickedListener() {
@Override
public void onClick(Component component) {
bindOperatorClickListener(componentId);
}
});
}
}
private void bindNumberClickListener(int componentId) {
String oldValue = inputText.getText();
String inputValue = "";
if (findComponentById(componentId) instanceof Text) {
Text text = (Text) findComponentById(componentId);
inputValue = text.getText();
}
if (oldValue.isEmpty() && ".".equals(inputValue)) {
return;
}
if ("0".equals(oldValue) && !".".equals(inputValue)) {
inputText.setText(inputValue);
} else {
inputText.append(inputValue);
}
calculateResult(inputText.getText(), true);
}
private void bindOperatorClickListener(int componentId) {
String oldValue = inputText.getText();
String inputValue = "";
if (findComponentById(componentId) instanceof Text) {
Text text = (Text) findComponentById(componentId);
inputValue = text.getText();
}
if (oldValue.isEmpty()) {
inputText.setText(inputValue);
} else if (MathUtil.isOperator(oldValue.substring(oldValue.length() - 1))
&& MathUtil.isOperator(inputValue)) {
String newValue = oldValue.substring(0, oldValue.length() - 1) + inputValue;
inputText.setText(newValue);
} else {
inputText.append(inputValue);
}
calculateResult(inputText.getText(), true);
}
private void calculateResult(String exp, Boolean isAutoCalculate) {
if (exp.isEmpty()) {
return;
}
// 只有数字 不计算
String pattern = "(\\d*\\.?\\d*)|(0\\.\\d*[1-9])";
boolean isMatch = Pattern.matches(pattern, exp);
if (isMatch) {
return;
}
// 末位是运算符 不计算
if (MathUtil.isOperator(exp.substring(exp.length() - 1))) {
return;
}
String resultValue;
try {
resultValue = MathUtil.getResultString(exp);
} catch (NumberFormatException | ArithmeticException | EmptyStackException e) {
preResult.setText("错误");
return;
}
if (isAutoCalculate) {
preResult.setText(resultValue);
return;
}
preResult.setText("");
inputText.setText(resultValue);
}
@Override
public void onActive() {
super.onActive();
}
@Override
public void onForeground(Intent intent) {
super.onForeground(intent);
}
}
我们定义了2个数组来统一初始化我们的运算键位控件和我们数字控件 并且添加点击事件，然后配合我们MathUtil 工具类来处理结果
- cancel 清零复位键处理
findComponentById(ResourceTable.Id_number_cancel).setClickedListener(new Component.ClickedListener() {
@Override
public void onClick(Component component) {
preResult.setText("");
inputText.setText("");
}
});
当用户点击到cancel键的时候我们将输入框的内容和显示文本上的内容全部都set成空字符串
- delete删除键处理
findComponentById(ResourceTable.Id_delete).setClickedListener(new Component.ClickedListener() {
@Override
public void onClick(Component component) {
if (inputText.getText().isEmpty()) {
return;
}
inputText.setText(inputText.getText().substring(0, inputText.getText().length() - 1));
}
});
当用户点击到delete我们采用的 末尾删除 这个时候我们只需要通过字符串截取即可实现
具体 MathUtil 工具类实现
package com.example.counter_demo.utils;
import java.math.BigDecimal;
import java.util.Stack;
/**
* MathUtil
*
* @since 2021年8月22日11:55:02
* 类说明：数学运算工具类
*/
public class MathUtil {
// 数字栈中分隔数字时使用
private static String separateStr = "@";
// 保留小数位数
private static final int DECIMAL_DIGIT = 6;
// 不包含指定字符
private static final int NOT_CONTAIN = -1;
// 高优先级
private static final int HIGH_PRIORITY = 2;
// 低优先级
private static final int LOW_PRIORITY = 1;
private MathUtil() {
}
public static String getResultString(String exp) {
Stack<String> numStack = new Stack<>();
numStack.push(separateStr); // 数字用@分开，数字栈中@号 为了便于区分小数
Stack<String> oprStack = new Stack<>();
String[] strings = exp.split("");
for (String singleStr : strings) {
if (isOperator(singleStr)) {
spiltExp(numStack, oprStack, singleStr);
} else {
numStack.push(singleStr);
}
}
while (!oprStack.isEmpty()) {
combineString(numStack);
compute(numStack, oprStack);
}
numStack.pop();
String resultValue = numStack.peek();
return resultValue;
}
private static void spiltExp(Stack<String> numStack, Stack<String> oprStack, String singleStr) {
// 运算符间的字符拼接成一个数字
combineString(numStack);
if (!oprStack.isEmpty()) {
// 先处理优先级高的运算符
while (!oprStack.isEmpty() && priority(singleStr) <= priority(oprStack.peek())) {
combineString(numStack);
compute(numStack, oprStack);
}
}
oprStack.push(singleStr);
}
private static void compute(Stack<String> numStack, Stack<String> oprStack) {
BigDecimal result = null;
numStack.pop();
BigDecimal rightNumber = new BigDecimal(numStack.pop());
numStack.pop();
BigDecimal leftNumber = new BigDecimal(numStack.pop());
String operator = oprStack.pop();
switch (operator) {
case "-":
result = leftNumber.subtract(rightNumber);
break;
case "+":
result = leftNumber.add(rightNumber);
break;
case "%":
result = leftNumber.divideAndRemainder(rightNumber)[1];
break;
case "×":
result = leftNumber.multiply(rightNumber);
break;
case "÷":
result = leftNumber.divide(rightNumber, DECIMAL_DIGIT, BigDecimal.ROUND_HALF_UP);
break;
default:
break;
}
numStack.push(result.stripTrailingZeros().toPlainString());
numStack.push(separateStr);
}
private static void combineString(Stack<String> stack) {
if (separateStr.equals(stack.peek())) {
return;
}
StringBuilder numberBuilder = new StringBuilder();
while (true) {
String string = stack.peek();
if (separateStr.equals(string)) {
break;
}
numberBuilder.insert(0, string);
stack.pop();
}
stack.push(numberBuilder.toString());
stack.push(separateStr);
numberBuilder.delete(0, numberBuilder.length());
}
/**
* Determines whether a string is an operator.
*
* @param singleStr Character string to be judged
* @return Judgment Result
*/
public static boolean isOperator(String singleStr) {
String operators = "-+×÷%";
if (operators.indexOf(singleStr) > NOT_CONTAIN) {
return true;
}
return false;
}
private static int priority(String str) {
String highOperator = "×÷%";
if (highOperator.indexOf(str) > NOT_CONTAIN) {
return HIGH_PRIORITY;
}
return LOW_PRIORITY;
}
}
工具类是借鉴了java里面数据学运算的设计 有兴趣的同学可以自己看一下这里不展开讲 到此简易计算器demo已经讲完了。
最后总结
这一章主要是讲解鸿蒙里面一些常用的案例 由于鸿蒙采用了java js作为基础语言来开发 非常成熟的语言那么我们在java以及js里面比较成熟的 数学运算设计可以直接借鉴的 我们配合上UI 布局就可以实现类似的简易计算器，有兴趣的可以私下多研究看看用js ui如何实现 这里就不展开讲了. 最后希望我的文章能帮助到各位解决问题 ，以后我还会贡献更多有用的代码分享给大家。各位同学如果觉得文章还不错 ，麻烦给关注和star，小弟在这里谢过啦
项目地址
码云 ：https://gitee.com/qiuyu123/counter_demo
今天的文章就分享到这儿，如果大家喜欢的话，我将会在接下来的一段时间里，持续分享更多优质内容。
本文参与 腾讯云自媒体同步曝光计划，分享自微信公众号。
原始发表：2022-01-24，如有侵权请联系 cloudcommunity@tencent.com 删除
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