Java之Builder模式（并用OC实现了这种模式）

本人在学习Java，直接先学习Netty框架，因为Netty框架是业界最流行的NIO框架之一，在学习的过程中，了解到Netty服务端启动需要先创建服务器启动辅助类ServerBootstrap，它提供了一系列的方法用于设置服务器端启动相关的参数。然而在创建ServerBootstrap实例时，发现ServerBootstrap只有一个无参的构造函数，事实上它需要与多个其它组件或者类交互。ServerBootstrap构造函数没有参数的原因是因为它的参数太多了，而且未来也可能会发生变化。Netty创造者为了解决这个问题，就引入了Builder模式。

学习到这里，在IOS开发中，我虽然也研习过23中常用的设计模式，但是我却从没听过的Builder模式，于是就开始了探索Builder模式，并尝试用OC语言去模仿实现这种模式。说不定以后在iOS开发中会用到呢。

Java的实例源码：

 public class DoDoContact {

     private final int    age;
     private final int    safeID;
     private final String name;
     private final String address;

     public int getAge() {
         return age;
     }

     public int getSafeID() {
         return safeID;
     }

     public String getName() {
         return name;
     }

     public String getAddress() {
         return address;
     }

     public static class Builder {
         private int    age     = 0;
         private int    safeID  = 0;
         private String name    = null;
         private String address = null;

         public Builder(String name) {
             this.name = name;
         }

         public Builder age(int val) {
             age = val;
             return this;
         }

         public Builder safeID(int val) {
             safeID = val;
             return this;
         }

         public Builder address(String val) {
             address = val;
             return this;
         }

         public DoDoContact build() {
             return new DoDoContact(this);
         }
     }

     private DoDoContact(Builder b) {
         age = b.age;
         safeID = b.safeID;
         name = b.name;
         address = b.address;

     }
 }

java的main函数

 public class Test2{
     public static void main(String[] args) {
         DoDoContact ddc = new DoDoContact.Builder("Ace").age(10)
                 .address("beijing").build();
         System.out.println("name=" + ddc.getName() + "age =" + ddc.getAge()
                 + "address" + ddc.getAddress());
     }
 }

有木有发现在main函数中，创建一个对象，却可以动态的传入参数。

下面使用OC来实现：

DoDoContact.h

 #import <Foundation/Foundation.h>

 @class Builder;

 @interface DoDoContact : NSObject

 @property (nonatomic,assign) NSInteger age;
 @property (nonatomic,assign) NSInteger safeID;
 @property (nonatomic,strong) NSString *name;
 @property (nonatomic,strong) NSString *address;

 + (Builder*)getBulder;

 @end

DoDoContact.m

 #import "DoDoContact.h"

 @interface Builder ()

 @property (nonatomic,assign) NSInteger age;
 @property (nonatomic,assign) NSInteger safeID;
 @property (nonatomic,strong) NSString *name;
 @property (nonatomic,strong) NSString *address;

 @end

 @interface DoDoContact ()

 @end

 @implementation DoDoContact

 - (instancetype)initWith:(Builder*)builder
 {
     self = [super init];
     if (self) {
         self.age = builder.age;
         self.safeID = builder.safeID;
         self.name = builder.name;
         self.address = builder.address;
     }
     return self;
 }

 + (instancetype)getDoDoContactWith:(Builder*)builder{
     DoDoContact *doDoContact = [[DoDoContact alloc] initWith:builder];
     return doDoContact;
 }

 + (Builder*)getBulder{
     return [Builder new];
 }

 @end

 @implementation Builder

 - (instancetype)init
 {
     self = [super init];
     if (self) {
         _age = ;
         _safeID = ;
         _name = NULL;
         _address = NULL;
     }
     return self;
 }

 - (Builder*)age:(NSInteger)age{
     self.age = age;
     return self;
 }

 - (Builder*)safeID:(NSInteger)safeID{
     self.safeID = safeID;
     return self;
 }

 - (Builder*)name:(NSString*)name{
     self.name = name;
     return self;
 }
 - (Builder*)address:(NSString*)address{
     self.address = address;
     return self;
 }

 - (DoDoContact*)getDoDoContact{
     return [DoDoContact getDoDoContactWith:self];
 }

 @end

再来看创建DoDoContact对象的方式，本人这里无意中用的是IOS工程所以直接在ViewController类中创建了。

虽然也是可以动态传入参数，但是OC的语言风格却不好看。但是用Swift可以，毕竟Swift也模仿了java的class类。