《模式——工程化实现及扩展》(设计模式C# 版)《创建者模式 Builder》——正文完整示例
转自:《模式——工程化实现及扩展》(设计模式C# 版)
http://www.cnblogs.com/callwangxiang/
本章正文通过Attribute指导Builder构造过程的完整示例
1、采用BuildStep定义装配过程的测试类型
#region 采用BuildStep定义装配过程的测试类型
/// <summary>
/// 用于显示测试结果的委托
/// </summary>
/// <remarks>
/// Action<string>是实际处理Build Step操作内容的委托
/// </remarks>
static Action<string, Action<string>> buildStepHandler = (x, y) =>
{
Trace.WriteLine("add " + x);
y(x);
};
class Car
{
public IList<string> Parts { get; private set; }
public Car(){Parts = new List<string>();}
/// <summary>
/// 为汽车添加轮胎
/// </summary>
/// <remarks>
/// Attributed Builder第二个执行的Setp
/// 执行4次,即为每辆汽车装配增加4个轮胎
/// </remarks>
[BuildStep(2, 4)]
public void AddWheel() { buildStepHandler("wheel", Parts.Add); }
/// <summary>
/// 为汽车装配引擎
/// </summary>
/// <remarks>
/// 没有通过Attribute标注的内容,因此不会被Attributed Builder执行
/// </remarks>
public void AddEngine() { buildStepHandler("engine", Parts.Add); }
/// <summary>
/// 为汽车装配车身
/// </summary>
/// <remarks>
/// Attributed Builder第一个执行的Setp
/// 执行1次,即为每辆汽车装配增加1个车身
/// </remarks>
[BuildStep(1)]
public void AddBody() { buildStepHandler("body", Parts.Add); }
}
class Computer
{
public string Bus { get; private set; }
public string Monitor { get; private set; }
public string Disk { get; private set; }
public string Memory { get; private set; }
public string Keyboard { get; private set; }
public string Mouse { get; private set; }
/// <summary>
/// 缓存Computer类型的所有Property
/// </summary>
static PropertyInfo[] properties = typeof (Computer).GetProperties();
/// <summary>
/// 获得Computer类型指定名称Property的Setter方法委托
/// </summary>
/// <param name="target">Computer类型实例</param>
/// <param name="name">Property名称</param>
/// <returns>指定名称Property的Setter方法委托</returns>
static Action<string> GetSetter(Computer target, string name)
{
var property = properties.Where(x => string.Equals(x.Name, name)).FirstOrDefault();
return x => property.SetValue(target, x, null);
}
[BuildStep(1)]
public void LayoutBus()
{
buildStepHandler("bus", GetSetter(this, "Bus"));
}
[BuildStep(2)]
public void AddDiskAndMemory()
{
buildStepHandler("disk", GetSetter(this, "Disk"));
buildStepHandler("16G memory", GetSetter(this, "Memory"));
}
[BuildStep(3)]
public void AddUserInputDevice()
{
buildStepHandler("USB mouse", GetSetter(this, "Mouse"));
buildStepHandler("keyboard", GetSetter(this, "Keyboard"));
}
[BuildStep(4)]
public void ConnectMonitor()
{
buildStepHandler("monitor", GetSetter(this, "Monitor"));
}
}
#endregion
/// <summary>
/// 用于显示测试结果的委托
/// </summary>
/// <remarks>
/// Action<string>是实际处理Build Step操作内容的委托
/// </remarks>
static Action<string, Action<string>> buildStepHandler = (x, y) =>
{
Trace.WriteLine("add " + x);
y(x);
};
class Car
{
public IList<string> Parts { get; private set; }
public Car(){Parts = new List<string>();}
/// <summary>
/// 为汽车添加轮胎
/// </summary>
/// <remarks>
/// Attributed Builder第二个执行的Setp
/// 执行4次,即为每辆汽车装配增加4个轮胎
/// </remarks>
[BuildStep(2, 4)]
public void AddWheel() { buildStepHandler("wheel", Parts.Add); }
/// <summary>
/// 为汽车装配引擎
/// </summary>
/// <remarks>
/// 没有通过Attribute标注的内容,因此不会被Attributed Builder执行
/// </remarks>
public void AddEngine() { buildStepHandler("engine", Parts.Add); }
/// <summary>
/// 为汽车装配车身
/// </summary>
/// <remarks>
/// Attributed Builder第一个执行的Setp
/// 执行1次,即为每辆汽车装配增加1个车身
/// </remarks>
[BuildStep(1)]
public void AddBody() { buildStepHandler("body", Parts.Add); }
}
class Computer
{
public string Bus { get; private set; }
public string Monitor { get; private set; }
public string Disk { get; private set; }
public string Memory { get; private set; }
public string Keyboard { get; private set; }
public string Mouse { get; private set; }
/// <summary>
/// 缓存Computer类型的所有Property
/// </summary>
static PropertyInfo[] properties = typeof (Computer).GetProperties();
/// <summary>
/// 获得Computer类型指定名称Property的Setter方法委托
/// </summary>
/// <param name="target">Computer类型实例</param>
/// <param name="name">Property名称</param>
/// <returns>指定名称Property的Setter方法委托</returns>
static Action<string> GetSetter(Computer target, string name)
{
var property = properties.Where(x => string.Equals(x.Name, name)).FirstOrDefault();
return x => property.SetValue(target, x, null);
}
[BuildStep(1)]
public void LayoutBus()
{
buildStepHandler("bus", GetSetter(this, "Bus"));
}
[BuildStep(2)]
public void AddDiskAndMemory()
{
buildStepHandler("disk", GetSetter(this, "Disk"));
buildStepHandler("16G memory", GetSetter(this, "Memory"));
}
[BuildStep(3)]
public void AddUserInputDevice()
{
buildStepHandler("USB mouse", GetSetter(this, "Mouse"));
buildStepHandler("keyboard", GetSetter(this, "Keyboard"));
}
[BuildStep(4)]
public void ConnectMonitor()
{
buildStepHandler("monitor", GetSetter(this, "Monitor"));
}
}
#endregion
2、执行单元测试
[TestMethod]
public void BuildComputerByAttributeDirection()
{
Trace.WriteLine("\nassembly computer");
var computer = new Computer();
Assert.IsNull(computer.Keyboard);
Assert.IsNull(computer.Memory);
computer = new Builder<Computer>().BuildUp();
Assert.IsNotNull(computer.Bus);
Assert.IsNotNull(computer.Monitor);
Assert.IsNotNull(computer.Disk);
Assert.IsNotNull(computer.Memory);
Assert.IsNotNull(computer.Keyboard);
Assert.IsNotNull(computer.Mouse);
}
[TestMethod]
public void BuildCarByAttributeDirection()
{
Trace.WriteLine("build car");
var car = new Builder<Car>().BuildUp();
Assert.IsNotNull(car);
Assert.IsFalse(car.Parts.Contains("engine")); // 不会被执行的内容
Assert.AreEqual<string>("body", car.Parts.ElementAt(0));
for (var i = 1; i <= 4; i++)
Assert.AreEqual<string>("wheel", car.Parts.ElementAt(i));
}
public void BuildComputerByAttributeDirection()
{
Trace.WriteLine("\nassembly computer");
var computer = new Computer();
Assert.IsNull(computer.Keyboard);
Assert.IsNull(computer.Memory);
computer = new Builder<Computer>().BuildUp();
Assert.IsNotNull(computer.Bus);
Assert.IsNotNull(computer.Monitor);
Assert.IsNotNull(computer.Disk);
Assert.IsNotNull(computer.Memory);
Assert.IsNotNull(computer.Keyboard);
Assert.IsNotNull(computer.Mouse);
}
[TestMethod]
public void BuildCarByAttributeDirection()
{
Trace.WriteLine("build car");
var car = new Builder<Car>().BuildUp();
Assert.IsNotNull(car);
Assert.IsFalse(car.Parts.Contains("engine")); // 不会被执行的内容
Assert.AreEqual<string>("body", car.Parts.ElementAt(0));
for (var i = 1; i <= 4; i++)
Assert.AreEqual<string>("wheel", car.Parts.ElementAt(i));
}
3、Output窗口输出内容
------ Test started: Assembly: Builder.Tests.dll ------
assembly computer
add bus
add disk
add 16G memory
add USB mouse
add keyboard
add monitor
build car
add body
add wheel
add wheel
add wheel
add wheel
2 passed, 0 failed, 0 skipped, took 0.70 seconds (MSTest 10.0).
assembly computer
add bus
add disk
add 16G memory
add USB mouse
add keyboard
add monitor
build car
add body
add wheel
add wheel
add wheel
add wheel
2 passed, 0 failed, 0 skipped, took 0.70 seconds (MSTest 10.0).
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