程序猿的開心一刻###
藺相如，司馬相如；魏無忌，長孫無忌。下列哪一組對應關系與此類似？
a，PHP，Python；b，JSP，servlet；c，java，java script ；d，C，C++
請在評論區輸入答案，接下來進入正題
Java接口#
參考文章：Java回調機制趣解
接口是什么：#####
- Java不支持多重繼承，但可以實現多個接口。
- 接口定義了某一批類所要遵守的規范，只規定這些類里必須提供某些方法。
- 接口并不是類，編寫接口的方式和類很相似，但是它們屬于不同的概念。
- 類描述對象的屬性和方法，接口則包含類要實現的方法。
- 接口可以多繼承
接口的作用：#####
- 擴展性： 如果業務邏輯發生變化需要新增類的方法，就可以在不改變原來已經寫好的代碼基礎上新增一個類來實現接口中定義的函數來實現。
- 規范性：告訴開發人員你需要實現哪些業務，并可以將命名規范限制住。
- 安全性：接口是實現軟件松耦合的重要手段，它描敘了系統對外的所有服務，而不涉及任何具體的實現細節。
接口實例一：回調傳值
接口文件代碼：
public interface Listener {
void send(String s);
}
Info.java文件代碼
public class Info {
public Listener mListener;
public Info(Listener mListener){
this.mListener = mListener;
}
public void sends(){
mListener.send("haha");
}
}
要實現接口里的方法的MainActivity.java文件代碼
public class MainActivity extends AppCompatActivity implements Listener{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Info info = new Info(this);
info.sends();
}
@Override
public void send(String s) {
System.out.println(s);
}
}
輸出結果####
1.png
思考：Java中接口和抽象類的區別？
Objective-C協議#
協議就是定義一套方法，遵守協議的類要去實現協議里的方法。
iOS實例一 ：控制器之間逆向傳值###
控制器一.m文件代碼：
#import "ViewController.h"
#import "SecondViewController.h"
@interface ViewController ()<MyProtocol>
@property(nonatomic,strong)UITextView* textView1;
@end
@implementation ViewController
//此方法只加載一次，類中成員對象和變量的初始化都會放在這個方法中
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor blueColor];
_textView1 = [[UITextView alloc] initWithFrame:CGRectMake(0, 100, 320, 30)];
_textView1.font = [UIFont systemFontOfSize:15];
_textView1.textColor = [UIColor whiteColor];
_textView1.backgroundColor = [UIColor blackColor];
[self.view addSubview:_textView1];
UIButton *button1 = [UIButton buttonWithType:UIButtonTypeCustom];
button1.frame = CGRectMake(0, 50, 320, 30);
button1.titleLabel.font = [UIFont systemFontOfSize:17];
[button1 setTitle:@"點擊按鈕，去顯示控制器二" forState:UIControlStateNormal];
button1.backgroundColor = [UIColor blackColor];
[button1 addTarget:self action:@selector(click) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:button1];
}
-(void)showMessage:(NSString *)str{
_textView1.text = str;
}
-(void)click{
SecondViewController *vc = [[SecondViewController alloc] init];
vc.delegate = self;
[self presentViewController:vc animated:YES completion:nil];
}
@end
控制器二.h文件代碼
#import <UIKit/UIKit.h>
//定義協議
@protocol MyProtocol <NSObject>
//必須實現
@required
-(void)showMessage:(NSString*)str;
//可選擇實現
@optional
-(void)showtext:(NSString*)str;
@end
@interface SecondViewController : UIViewController
@property(nonatomic,weak) id<MyProtocol> delegate;
@end
控制器二.m文件代碼
#import "SecondViewController.h"
@interface SecondViewController ()
@property(nonatomic,strong)UITextField *textField1;
@end
@implementation SecondViewController
//此方法只加載一次，類中成員對象和變量的初始化都會放在這個方法中
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor greenColor];
_textField1 = [[UITextField alloc] initWithFrame:CGRectMake(0, 100, 320, 30)];
_textField1.font = [UIFont systemFontOfSize:15];
_textField1.textColor = [UIColor whiteColor];
_textField1.backgroundColor = [UIColor blackColor];
[self.view addSubview:_textField1];
UIButton *button1 = [UIButton buttonWithType:UIButtonTypeCustom];
button1.frame = CGRectMake(0, 50, 320, 30);
button1.titleLabel.font = [UIFont systemFontOfSize:17];
[button1 setTitle:@"點擊按鈕，去顯示控制器一" forState:UIControlStateNormal];
button1.backgroundColor = [UIColor blackColor];
[button1 addTarget:self action:@selector(click) forControlEvents:UIControlEventTouchUpInside];
[self.view addSubview:button1];
}
-(void)click{
[_delegate showMessage:_textField1.text];
[self dismissViewControllerAnimated:YES completion:nil];
}
@end
效果演示###
未命名.gif
iOS實例二 ：View讓Controller幫它實現跳轉###
FirstView.h文件代碼
#import <UIKit/UIKit.h>
//定義協議
@protocol FirstViewDelegate <NSObject>
//必須實現
@required
-(void)jumpViewController;
//可選擇實現
@optional
-(void)showtext:(NSString*)str;
@end
@interface FirstView : UIView
@property(nonatomic,weak) id<FirstViewDelegate> delegate;
@end
FirstView.m文件代碼
#import "FirstView.h"
@implementation FirstView
-(id)initWithFrame:(CGRect)frame{
if(self = [super initWithFrame:frame]){
UIButton *button1 = [UIButton buttonWithType:UIButtonTypeCustom];
button1.frame = CGRectMake(0, 50, 320, 30);
button1.titleLabel.font = [UIFont systemFontOfSize:17];
[button1 setTitle:@"點擊按鈕，去顯示控制器二" forState:UIControlStateNormal];
button1.backgroundColor = [UIColor blackColor];
[button1 addTarget:self action:@selector(click) forControlEvents:UIControlEventTouchUpInside];
[self addSubview:button1];
}
return self;
}
-(void)click{
[_delegate jumpViewController];
}
@end
ViewController.m文件代碼
#import "ViewController.h"
#import "FirstView.h"
#import "SecondViewController.h"
@interface ViewController ()<FirstViewDelegate>
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor blueColor];
FirstView *firstView = [[FirstView alloc] initWithFrame:CGRectMake(0, 0, 320, 568)];
firstView.delegate = self;
[self.view addSubview:firstView];
}
-(void)jumpViewController{
SecondViewController *vc = [[SecondViewController alloc] init];
[self presentViewController:vc animated:YES completion:nil];
}
@end
效果演示###
未命名.gif
