Learning Record V

One 、 Punch in

When I first saw this topic , I think everyone should have an idea , That is violent solution ！

But in addition to violent solutions , We have other ways ： Double finger needling

  How does double finger needling work ？

First , We put a pointer at the end , At this time, the maximum capacity is min(x,y)∗t=x∗t（t Represents the distance ）

Then ask for one , We can move the smaller of the two pointers

Why the small one ？

Because if you move the big one , There can be no bigger situation than before ！

So finally, we can get the code as follows ：

public class Solution {
    public int maxArea(int[] height) {
        int l = 0, r = height.length - 1;
        int ans = 0;
        while (l < r) {
            int area = Math.min(height[l], height[r]) * (r - l);
            ans = Math.max(ans, area);
            if (height[l] <= height[r]) {
                ++l;
            }
            else {
                --r;
            }
        }
        return ans;
    }
}

Two 、Spring Of Aop Learning from

1. Aop The advantages and functions of

AOP（ Section oriented programming ）

effect ： During program operation , Enhance the function of the method without modifying the source code

advantage ： Reduce duplicate code , Improve development efficiency , Easy to maintain

2. AOP The underlying implementation of

AOP The bottom layer is through Spring Provided by the dynamic proxy technology . During operation ,Spring Dynamically generated proxy objects through dynamic proxy technology , When the proxy object method is executed, enhance the function , Then adjust the method of the target object , In order to complete the function enhancement .

3. AOP Dynamic proxy technique

JDK agent ： Dynamic proxy technology based on interface

cglib agent ： Dynamic proxy technology based on parent class

4. JDK Dynamic proxy technique

The two problems to be solved in implementing dynamic proxy are ：

① How to dynamically create proxy objects and classes according to the proxy objects loaded into memory

② How to call the method with the same name of the proxied class when calling the method through the object of the proxy class

 5. cglib Dynamic proxy for

Import cglib Of jar package

6.AOP Related concepts of

Taget（ Target audience ）： The target object of the proxy

Proxy（ agent ）： A class is AOP After weaving in reinforcement , To produce a result proxy class

Joinpoint（ Connection point ）： The so-called connection points refer to the points that are intercepted . stay spring in , These points refer to methods , because spring Only method type connection points are supported .

Pointcut（ The breakthrough point ）： The so-called entry point refers to what we want to do Joinpoint Definition of interception

【 The connection point is the method that can be enhanced , The entry point is the enhanced method 】

Advice（ notice / enhance ）： The so-called notification refers to intercepting Joinpoint The next thing to do is to inform

Accept（ section ）： It is the combination of entry point and notification

Weaving （ Weaving ）： The process of applying enhancements to a target object to create a new proxy object .spring Weaving with dynamic agent , and AspectJ Compiler weaving and class loading weaving

7.AOP Develop clear objects

① What needs to be written

Business core code （ The target method of the target class ）

Write cut class , There are notifications in the aspect class （ Enhancement methods ）

In the configuration file , Configure weaving relationships , Which notifications will be combined with which connection points

②AOP Content of technical implementation

Spring The framework monitors the execution of pointcut methods . One - Once the pointcut method is monitored to be run , Use the proxy mechanism , Create the proxy object of the target object dynamically , According to notification category , In the corresponding position of the proxy object , Weave the function corresponding to the notification into , Complete the logic operation of the code .

③AOP Which proxy method is used at the bottom

It will decide which dynamic proxy method to use according to whether there is an interface

 8. be based on XML Of AOP Development

① Fast import AOP coordinate

② Create target interfaces and target classes （ There's a tangent point inside ）

③ Create the section class （ There are enhancement methods inside ）

④ Give the object creation right of target class and section class to spring

⑤ stay applicationContext.xml In the configuration weaving relationship

⑥ Test code

  3. Extraction of pointcut expressions

9. Annotation based AOP Development

  

  Daily picture sharing , I didn't have time to study yesterday's school year design defense ！