类的使用---进阶编程篇(四)
很多讲解编程的书籍在介绍类的时候就直接介绍属性,字段,方法,事件等等,然后说下多态性,继承性,等等,所有的这些东西对于初学者来说实在是虚无缥缈,对于什么地方该用类,该怎么设计类仍然是很模糊的,需要经验大量的编程实践才能摸索到里面的经验,所以本节在讲解的时候,会侧重于举例子来说明,为什么需要使用类,怎么使用类,至于类的继承也会针对特定的情况来说明,让大家对于类有个清晰的概念。
为什么需要使用类
理解这个问题对于学习编程的人非常的关键,对于有经验的人来说,可能会回答,类可以分离功能,形成功能模块,进而实现模块开发,易于调试和代码维护。对于初学者来说,鬼知道你在说什么啊!根本理解不了,需要多写几次类以后才能深刻的理解这些思想,所以此处会从更基础的情况进行说明,假设我们有一台设备,上面有5个参数需要实时在软件上显示,作为初学者,我们会这么写:(1s定时器模拟了读取设备的场景)
代码如下所示:
1 using System; 2 using System.Collections.Generic; 3 using System.ComponentModel; 4 using System.Data; 5 using System.Drawing; 6 using System.Linq; 7 using System.Text; 8 using System.Threading.Tasks; 9 using System.Windows.Forms; 10 11 namespace WindowsFormsApp1 12 { 13 public partial class Form1 : Form 14 { 15 public Form1() 16 { 17 InitializeComponent(); 18 } 19 20 private Timer TimerReadMachine = null; 21 22 private void Form1_Load(object sender, EventArgs e) 23 { 24 //初始化时钟 25 TimerReadMachine = new Timer(); 26 TimerReadMachine.Interval = 1000; 27 TimerReadMachine.Tick += TimerReadMachine_Tick; 28 } 29 30 private void TimerReadMachine_Tick(object sender, EventArgs e) 31 { 32 Random r = new Random(); 33 label1.Text = "温度1:" + r.Next(100, 300) + " ℃"; 34 label2.Text = "温度2:" + r.Next(100, 300) + " ℃"; 35 label3.Text = "温度3:" + r.Next(100, 300) + " ℃"; 36 label4.Text = "温度4:" + r.Next(100, 300) + " ℃"; 37 label5.Text = "温度5:" + r.Next(100, 300) + " ℃"; 38 } 39 40 private void Form1_Shown(object sender, EventArgs e) 41 { 42 //启动定时器 43 TimerReadMachine.Start(); 44 } 45 46 private void Form1_FormClosing(object sender, FormClosingEventArgs e) 47 { 48 if (MessageBox.Show("是否真的退出窗口?", "退出确认", MessageBoxButtons.YesNo) == DialogResult.No) 49 { 50 e.Cancel = true; 51 } 52 } 53 54 private void Form1_FormClosed(object sender, FormClosedEventArgs e) 55 { 56 } 57 58 59 private void button1_Click(object sender, EventArgs e) 60 { 61 Button button = new Button(); 62 button.Location = new System.Drawing.Point(328, 42); 63 button.Name = "button2"; 64 button.Size = new System.Drawing.Size(75, 23); 65 button.TabIndex = 0; 66 button.Text = "button2"; 67 button.UseVisualStyleBackColor = true; 68 button.Click += Button_Click; 69 70 this.Controls.Add(button); 71 } 72 73 private void Button_Click(object sender, EventArgs e) 74 { 75 MessageBox.Show("你点击了button2"); 76 } 77 78 79 80 } 81 }
上述的代码有部分是上一章节的代码,所以自行忽略,如果碰到上述的情况,只是将数据显示一下就完事了还算简单了,但实际情况更加复杂,通常需要缓存这五个温度的数据,一遍根据需要进行获取计算其他的需求,比如说,温度的幅度区间,最大值最小值,温度的平均值,温度变大了还是变小了判定,等等情况,所以我们会将代码改成下面这样的:
1 using System; 2 using System.Collections.Generic; 3 using System.ComponentModel; 4 using System.Data; 5 using System.Drawing; 6 using System.Linq; 7 using System.Text; 8 using System.Threading.Tasks; 9 using System.Windows.Forms; 10 11 namespace WindowsFormsApp1 12 { 13 public partial class Form1 : Form 14 { 15 public Form1() 16 { 17 InitializeComponent(); 18 } 19 20 private Timer TimerReadMachine = null; 21 22 private void Form1_Load(object sender, EventArgs e) 23 { 24 //初始化时钟 25 TimerReadMachine = new Timer(); 26 TimerReadMachine.Interval = 1000; 27 TimerReadMachine.Tick += TimerReadMachine_Tick; 28 } 29 30 int Temperature1 = 0; 31 int Temperature2 = 0; 32 int Temperature3 = 0; 33 int Temperature4 = 0; 34 int Temperature5 = 0; 35 36 private void TimerReadMachine_Tick(object sender, EventArgs e) 37 { 38 Random r = new Random(); 39 int temp1 = r.Next(100, 300); 40 int temp2 = r.Next(100, 300); 41 int temp3 = r.Next(100, 300); 42 int temp4 = r.Next(100, 300); 43 int temp5 = r.Next(100, 300); 44 label1.Text = "温度1:" + temp1 + " ℃ " + (temp1 > Temperature1 ? "变大了" : "变小了"); 45 label2.Text = "温度2:" + temp2 + " ℃ " + (temp2 > Temperature2 ? "变大了" : "变小了"); 46 label3.Text = "温度3:" + temp3 + " ℃ " + (temp3 > Temperature3 ? "变大了" : "变小了"); 47 label4.Text = "温度4:" + temp4 + " ℃ " + (temp4 > Temperature4 ? "变大了" : "变小了"); 48 label5.Text = "温度5:" + temp5 + " ℃ " + (temp5 > Temperature5 ? "变大了" : "变小了"); 49 50 Temperature1 = temp1; 51 Temperature2 = temp2; 52 Temperature3 = temp3; 53 Temperature4 = temp4; 54 Temperature5 = temp5; 55 } 56 57 private void Form1_Shown(object sender, EventArgs e) 58 { 59 //启动定时器 60 TimerReadMachine.Start(); 61 } 62 63 private void Form1_FormClosing(object sender, FormClosingEventArgs e) 64 { 65 if (MessageBox.Show("是否真的退出窗口?", "退出确认", MessageBoxButtons.YesNo) == DialogResult.No) 66 { 67 e.Cancel = true; 68 } 69 } 70 71 private void Form1_FormClosed(object sender, FormClosedEventArgs e) 72 { 73 } 74 75 76 private void button1_Click(object sender, EventArgs e) 77 { 78 Button button = new Button(); 79 button.Location = new System.Drawing.Point(328, 42); 80 button.Name = "button2"; 81 button.Size = new System.Drawing.Size(75, 23); 82 button.TabIndex = 0; 83 button.Text = "button2"; 84 button.UseVisualStyleBackColor = true; 85 button.Click += Button_Click; 86 87 this.Controls.Add(button); 88 } 89 90 private void Button_Click(object sender, EventArgs e) 91 { 92 MessageBox.Show("你点击了button2"); 93 } 94 95 96 97 } 98 }
效果如下:
在实际的开发中,一台设备的参数通常是几十个或是上百个的数量级,或许你会说,我可以定义100个label啊,假设要监视100台设备呢,还要定义10000个label吗,显示是不可能的,再想想如果以后碰到需要追加一个参数的时候怎么办(或许你会说,我会和工艺部门再三确认这些参数是不是足够了,别人也保证了以后不再添加参数,事实上这根本没什么卵用),再添加一台设备呢,你还要再定义那么多数据吗?
为了解决上述留下来的编程困难,我们需要用到类的知识来解决,我们想要一种什么样子的解决方案呢,首先肯定不希望重复定义那么多的参数吧,定义一台设备也就算了,2台的话,勉强复制下算了,超过10台,即时是复制粘贴也会受不了,其次希望多一台设备的情况下,稍微修改下代码就可以实现。
我们把一台设备定义一个类,那么属性就很多解决了,无非就是5个参数点,那么这个类就设计完成了:
1 public class HslMachine 2 { 3 public int Temperature1 { get; set; } 4 public int Temperature2 { get; set; } 5 public int Temperature3 { get; set; } 6 public int Temperature4 { get; set; } 7 public int Temperature5 { get; set; } 8 }
设计好类后,接着开始改造代码,把原先的代码改造成使用类完成的:
1 using System; 2 using System.Collections.Generic; 3 using System.ComponentModel; 4 using System.Data; 5 using System.Drawing; 6 using System.Linq; 7 using System.Text; 8 using System.Threading.Tasks; 9 using System.Windows.Forms; 10 11 namespace WindowsFormsApp1 12 { 13 public partial class Form1 : Form 14 { 15 public Form1() 16 { 17 InitializeComponent(); 18 } 19 20 private Timer TimerReadMachine = null; 21 22 private void Form1_Load(object sender, EventArgs e) 23 { 24 //初始化时钟 25 TimerReadMachine = new Timer(); 26 TimerReadMachine.Interval = 1000; 27 TimerReadMachine.Tick += TimerReadMachine_Tick; 28 } 29 30 HslMachine machine1 = new HslMachine(); 31 32 private void TimerReadMachine_Tick(object sender, EventArgs e) 33 { 34 Random r = new Random(); 35 int temp1 = r.Next(100, 300); 36 int temp2 = r.Next(100, 300); 37 int temp3 = r.Next(100, 300); 38 int temp4 = r.Next(100, 300); 39 int temp5 = r.Next(100, 300); 40 label1.Text = "温度1:" + temp1 + " ℃ " + (temp1 > machine1.Temperature1 ? "变大了" : "变小了"); 41 label2.Text = "温度2:" + temp2 + " ℃ " + (temp2 > machine1.Temperature2 ? "变大了" : "变小了"); 42 label3.Text = "温度3:" + temp3 + " ℃ " + (temp3 > machine1.Temperature3 ? "变大了" : "变小了"); 43 label4.Text = "温度4:" + temp4 + " ℃ " + (temp4 > machine1.Temperature4 ? "变大了" : "变小了"); 44 label5.Text = "温度5:" + temp5 + " ℃ " + (temp5 > machine1.Temperature5 ? "变大了" : "变小了"); 45 46 machine1.Temperature1 = temp1; 47 machine1.Temperature2 = temp2; 48 machine1.Temperature3 = temp3; 49 machine1.Temperature4 = temp4; 50 machine1.Temperature5 = temp5; 51 } 52 53 private void Form1_Shown(object sender, EventArgs e) 54 { 55 //启动定时器 56 TimerReadMachine.Start(); 57 } 58 59 private void Form1_FormClosing(object sender, FormClosingEventArgs e) 60 { 61 if (MessageBox.Show("是否真的退出窗口?", "退出确认", MessageBoxButtons.YesNo) == DialogResult.No) 62 { 63 e.Cancel = true; 64 } 65 } 66 67 private void Form1_FormClosed(object sender, FormClosedEventArgs e) 68 { 69 } 70 71 72 private void button1_Click(object sender, EventArgs e) 73 { 74 Button button = new Button(); 75 button.Location = new System.Drawing.Point(328, 42); 76 button.Name = "button2"; 77 button.Size = new System.Drawing.Size(75, 23); 78 button.TabIndex = 0; 79 button.Text = "button2"; 80 button.UseVisualStyleBackColor = true; 81 button.Click += Button_Click; 82 83 this.Controls.Add(button); 84 } 85 86 private void Button_Click(object sender, EventArgs e) 87 { 88 MessageBox.Show("你点击了button2"); 89 } 90 91 92 93 } 94 95 96 public class HslMachine 97 { 98 public int Temperature1 { get; set; } 99 public int Temperature2 { get; set; } 100 public int Temperature3 { get; set; } 101 public int Temperature4 { get; set; } 102 public int Temperature5 { get; set; } 103 } 104 }
或许你会说,你看嘛,根本没有方便多少,而且写的代码还更多了,在只有一台设备的情况下,确实如你所说,代码更难了,却没有实现更多的功能。但是,,,,,但是,,,,,你想想,如果你再增加一台设备呢???
1 HslMachine machine1 = new HslMachine(); 2 HslMachine machine2 = new HslMachine();
这样就解决拉!!!!!再增加一台的话,那就再实例化一个对象,可能你又会说,我要是有100台设备,还要实例化100个对象吗,要是如果10000台设备呢?接下来激动人心的时刻到了,假设我们有10000台设备,应该怎么做呢?
1 private HslMachine[] hslMachines = new HslMachine[10000];//声明10000台设备的对象
这样一来,就算你有1亿台设备我也能实例化完成(假设一台设备1万元,总值1万亿,所以几乎不可能),需要注意的是,这个数组对象虽然实例化完成了,1万台设备还需要自己实例化,不然就是空引用。当设备比较多的时候,再初始化数据的地方我们也要修改,不然每台设备都这么写就要复制很多次了,这里精简的过程就是方法的提炼,我们让设备类支持自我初始化,所以新增一个方法:
1 public class HslMachine
2 {
3 public int Temperature1 { get; set; }
4 public int Temperature2 { get; set; }
5 public int Temperature3 { get; set; }
6 public int Temperature4 { get; set; }
7 public int Temperature5 { get; set; }
8
9 /// <summary>
10 /// 初始化数据
11 /// </summary>
12 /// <param name="r">假想r是传进来的设备底层数据</param>
13 public void Initialization(Random r)
14 {
15 int temp1 = r.Next(100, 300);
16 int temp2 = r.Next(100, 300);
17 int temp3 = r.Next(100, 300);
18 int temp4 = r.Next(100, 300);
19 int temp5 = r.Next(100, 300);
20
21 Temperature1 = temp1;
22 Temperature2 = temp2;
23 Temperature3 = temp3;
24 Temperature4 = temp4;
25 Temperature5 = temp5;
26 }
27 }
但是这样做了又发生一个问题,我们在窗体程序中就不知道一个数据的状态是变大变小还是不变了,所以我们需要改造温度的数据。使得温度的数据也是一个类,这样可以使得温度数据包含更多的特性,甚至是最大值,最小值,参数名称
1 public class MachineParameter 2 { 3 public string ParameterName { get; set; } 4 public int Temperature { get; set; } 5 public int Status { get; set; } 6 7 public int TemperatureMax { get; set; } = int.MinValue; 8 9 public int TemperatureMin { get; set; } = int.MaxValue; 10 } 11 12 public class HslMachine 13 { 14 public MachineParameter Temperature1 = new MachineParameter() 15 { 16 ParameterName = "温度1" 17 }; 18 public MachineParameter Temperature2 = new MachineParameter() 19 { 20 ParameterName = "温度2" 21 }; 22 public MachineParameter Temperature3 = new MachineParameter() 23 { 24 ParameterName = "温度3" 25 }; 26 public MachineParameter Temperature4 = new MachineParameter() 27 { 28 ParameterName = "温度4" 29 }; 30 public MachineParameter Temperature5 = new MachineParameter() 31 { 32 ParameterName = "温度5" 33 }; 34 35 /// <summary> 36 /// 初始化数据 37 /// </summary> 38 /// <param name="r">假想r是传进来的设备底层数据</param> 39 public void Initialization(Random r) 40 { 41 int temp1 = r.Next(100, 300); 42 int temp2 = r.Next(100, 300); 43 int temp3 = r.Next(100, 300); 44 int temp4 = r.Next(100, 300); 45 int temp5 = r.Next(100, 300); 46 47 SetValue(Temperature1, temp1); 48 SetValue(Temperature2, temp2); 49 SetValue(Temperature3, temp3); 50 SetValue(Temperature4, temp4); 51 SetValue(Temperature5, temp5); 52 } 53 54 private void SetValue(MachineParameter para,int value) 55 { 56 if(para.Temperature>value) 57 { 58 para.Status = 1; 59 } 60 else if(para.Temperature == value) 61 { 62 para.Status = 0; 63 } 64 else 65 { 66 para.Status = -1; 67 } 68 69 70 if (para.TemperatureMax < value) para.TemperatureMax = value; 71 if (para.TemperatureMin > value) para.TemperatureMin = value; 72 73 para.Temperature = value; 74 } 75 }
到此为止,设备的类已经初具成形了,如果参数想要支持更多的特性,也方便进行扩充,如果再添加一些其他的参数信息,这个类编写的就相当棒了。接下来就是显示了,这次假设有50台设备,只显示一台设备,不同的设备进行手动切换显示,并显示参数变大变小区别。界面重新调整:
然后界面的代码重新设计:
1 namespace WindowsFormsApp1 2 { 3 public partial class Form1 : Form 4 { 5 public Form1() 6 { 7 InitializeComponent(); 8 } 9 10 private Timer TimerReadMachine = null; 11 12 private void Form1_Load(object sender, EventArgs e) 13 { 14 //初始化时钟 15 TimerReadMachine = new Timer(); 16 TimerReadMachine.Interval = 1000; 17 TimerReadMachine.Tick += TimerReadMachine_Tick; 18 19 int[] datas = new int[hslMachines.Length]; 20 //设备实例化 21 for (int i = 0; i < hslMachines.Length; i++) 22 { 23 hslMachines[i] = new HslMachine(); 24 datas[i] = i + 1; 25 } 26 //初始化组合框 27 comboBox1.SelectedIndexChanged += ComboBox1_SelectedIndexChanged; 28 comboBox1.DataSource = datas; 29 } 30 31 private void ComboBox1_SelectedIndexChanged(object sender, EventArgs e) 32 { 33 //选择发生了变化 34 ShowSpecifiedMachine(); 35 } 36 37 private HslMachine[] hslMachines = new HslMachine[50];//声明10000台设备的对象 38 39 private void TimerReadMachine_Tick(object sender, EventArgs e) 40 { 41 Random r = new Random(); 42 43 for (int i = 0; i < hslMachines.Length; i++) 44 { 45 hslMachines[i].Initialization(r); 46 } 47 48 ShowSpecifiedMachine(); 49 } 50 51 private void ShowSpecifiedMachine() 52 { 53 int i = comboBox1.SelectedIndex; 54 HslMachine machine = hslMachines[i]; 55 ShowTemperatureChange(label1, label10, machine.Temperature1); 56 ShowTemperatureChange(label2, label9, machine.Temperature2); 57 ShowTemperatureChange(label3, label8, machine.Temperature3); 58 ShowTemperatureChange(label4, label7, machine.Temperature4); 59 ShowTemperatureChange(label5, label6, machine.Temperature5); 60 } 61 62 private void ShowTemperatureChange(Label label_1, Label label_2,MachineParameter para) 63 { 64 label_1.Text = para.ParameterName + ":" + para.Temperature + " ℃ "; 65 switch (para.Status) 66 { 67 case -1: label_2.BackColor = Color.LimeGreen; break; 68 case 1: label_2.BackColor = Color.Tomato; break; 69 default: label_2.BackColor = SystemColors.Control; break; 70 } 71 } 72 73 private void Form1_Shown(object sender, EventArgs e) 74 { 75 //启动定时器 76 TimerReadMachine.Start(); 77 } 78 79 private void Form1_FormClosing(object sender, FormClosingEventArgs e) 80 { 81 if (MessageBox.Show("是否真的退出窗口?", "退出确认", MessageBoxButtons.YesNo) == DialogResult.No) 82 { 83 e.Cancel = true; 84 } 85 } 86 87 private void Form1_FormClosed(object sender, FormClosedEventArgs e) 88 { 89 } 90 91 92 private void button1_Click(object sender, EventArgs e) 93 { 94 Button button = new Button(); 95 button.Location = new System.Drawing.Point(328, 42); 96 button.Name = "button2"; 97 button.Size = new System.Drawing.Size(75, 23); 98 button.TabIndex = 0; 99 button.Text = "button2"; 100 button.UseVisualStyleBackColor = true; 101 button.Click += Button_Click; 102 103 this.Controls.Add(button); 104 } 105 106 private void Button_Click(object sender, EventArgs e) 107 { 108 MessageBox.Show("你点击了button2"); 109 } 110 111 112 113 }
至此,已经将软件开发思路大致讲完,后面的类的多态性需要另开一片文章讲解,一个好的软件系统需要花大量的时间不停的去优化,调整,路漫漫其修远兮。