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 = 0;
        _safeID = 0;
        _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。