Java基礎-常用API(上)

為什麼要寫這篇呢?因為吃飽太閒嗎，當然不是=_=，因為人的記憶力是有限的，好啦，其實是我的記憶力是有限的 冏，有些東西真的是每天用，很自然就會記得了，比如if和for，但，有些大概一個星期用到一次，或是一陣子沒用…就很自然的忘記了，不過，有些人記憶力是真的蠻好的就是了，但，我不行，所以整理了一下，我覺得常用的Java API。

不過呢，Java是物件導向的程式語言，何謂物件導向呢…其實，這個問題可以說三天三夜，但，不是這裏的重點，重點是，相同類別的function，很可能會被記到同一個類別上，所以，常常會利用IDE的auto instance功能，來協助查詢可用的api，不過，基本上這樣也就夠了嘛，要用再查嘛，但，其實另一個重點就是速度，天下武功，唯快不破(根本在亂用XD)，要當一個產值高的Progamer還是記一下常用的API吧 冏

大概列一下我覺得常用的API類型好了
型別轉換-
在強型別的世界，應該是幾乎每天都在使用吧，但，我也常常一沒寫就忘光光了 冏

日期運算-
沒那麼常用，但我敢保證，如果你有在寫程式，你這輩子一定會用到

正規化-
就我個人的經驗，不常用，有的人可能不會用到，但，我每次用都要重查，也蠻麻煩的=_=

IO處理-
這個嘛，常用到，但通常的情況是，用過一次之後，就掛在那邊了XD

TDD for Java (1)

之前去上了TDD的課，覺得收獲蠻多的
不過行銷文還是少講一點好了XD
因為課程還是以C#為主，但工作上還是以Java為主就是了
不過，基本上概念還是相通的就是了
基本上，講了很多很實用的觀念
不過，最後還是要靠自已慢慢吸收、消化和實踐就是了

基本上，我覺得會寫測試，是一個工程師的一個重要指標
代表你所產出來的程式碼的品質，是否正確和可靠
也可代表具有可維護性
當然還有其它面向的東西，可讀性、clean、彈性、效能等等
彈性和可維護性，可以從Design Pattern上學習
可靠性也和Exception Hangle相關
至於可讀性和Clean，個人覺得可以看看Clean Code...或是Effective Java之類的
至於，效能又只另外一個議題了，程式碼的寫法、系統面、設計面等等，甚至到資料結構和演算法面…

不過，第一步還是先從測試開始吧…
畢竟，在商業軟體的世界，先把東西對才是重點
先求有再求好XD
但，如果客戶要求說，我這個功能需要每秒可以處理百萬筆資料
那又是另一個議題了
畢竟，就像某些人常講的，技術不是問題
當然不是問題，問題在於口袋夠不夠深XD

至於上課說了什麼，老實說
年紀大了沒辦法記那麼多了 冏

只記得第一天是講了Unit Test
如何做到Isolate的測試，如果使用Mock和stub做到這點
和一些測試的準則
第二天，主要講了整合測試的部分，再利用整合測試做重構
然後，再進一步做Unit Test
第三天，主要講了TDD和BDD的部分
如何簡單的根據需求，轉換成test case和進行開發

So, anyway, Let's start practice in Java.
I show some resources below.

Resource:
http://www.ithome.com.tw/news/87245
http://ithelp.ithome.com.tw/question/10109845
http://blog.littlelin.info/posts/2014/04/26/tdd-is-dead-long-live-testing
http://openhome.cc/Gossip/JUnit/
http://www.vogella.com/tutorials/JUnit/article.html
http://www.dotspace.idv.tw/ArecaChen/Test/JUnit_Primer.htm
http://blog.iamzsx.me/show.html?id=118001
http://blog.csdn.net/yasi_xi/article/details/24642517
http://billben.iteye.com/blog/1872196
http://obullxl.iteye.com/blog/727304
http://www.codedata.com.tw/java/unit-test-the-way-changes-my-programming
https://blog.alphacamp.co/2015/03/02/tdd-kata/

Insert Sequence Column - Oracle

基本上在Oracle上，不像SQL Server或DB 2有Identity的功能
沒有支援Auto Increment的功能，不過，這個功能真的還蠻常用的

不過其實還有有其它的技巧可以達成這件事的，比如使用下面參考資料的Trigger，不過，我個人比較喜歡單純一點的做法，在建立Table後，再建立Sequence，而在Insert的時候再使用Sequence.NEXTVAL取值的方式

CREATE TABLE TableName  
(  
  Column1 NUMBER NOT NULL,
  Column2  VARCHAR2(11) NOT NULL,
  CONSTRAINT TableName_PKEY PRIMARY KEY(Column1)
);

CREATE SEQUENCE TableName_SEQ;

INSERT INTO TableName (Column1, Column2)
VALUES(TableName_SEQ.NEXTVAL, 'Column2Value');

參考資料：
https://oracle-base.com/articles/misc/autonumber-and-identity

Tomcat JNDI設定

之前工作主要是用Spring的方式來設定資料庫，將連線的相關資訊另外寫到參數檔中，現在因為工作需要，所以需要設定一下JNDI，之前在用JBoss的時候，大概就有用過了，只是換到Tomcat上，還是要找一下資料來設定，其實細節大概看一下，下面的參考資料就知道怎麼用了，至於要怎麼做，就看環境和需求來取捨吧。

只是想說，不管是用Spring設定，或是AP Server設定，各有優缺點，畢竟Spring的設定方式也是蠻簡單的就是了，但設定在AP Server上，可以將資料庫連線的細節交給DB，實務上也不需要分成開發環境或是線上環境的連線設定檔了，當然，其實也可以說只是把設定檔移至AP Server上就是了 冏。

 其實還有不少東西可以丟給AP Server來處理，比如log或是MQ，不過就我個人觀點，不管是用Spring或是AP Server的方式，工作loading都不會減輕丫！只是單純的將業務邏輯無關的部分從程式中抽離就是了。


參考資料：
http://fanli7.net/a/fuwuqiruanjian/Tomcat/20120701/179189.html
https://tomcat.apache.org/tomcat-7.0-doc/jndi-datasource-examples-howto.html

Package naming

package主要的目的是避免相同名稱的Class發生衝突，因此可以避免開發上麻煩

不過，基本上大部分的人都是重視類別、方法、變數上的命名，不過也是因為套件的命名

其實也蠻少會做什麼特別的變動 

基本上，我以前也是亂命名套件的名稱，比如tw.bill.xxx

但，現在覺得tw的意思不大，如果是公司的話應該用com，組織的話就org，個人的話…

有想到pri，但如果是要推個人做的產品的話，目前還沒有想到好的單字，可能就還是先用pri吧，而第二個單字，一般就是公司名，或是省略，直接接產品名

再來呢，就會區分功能區塊了，而功能區塊下，

又會根據其特性，再進行細分，基本上就是這樣啦

另外，至於interface和實作是否要分開，個人會比較覺得分開會比較好，而實作再跟據其對應的對像進行package的分類，不過，這也只是我比較常遇到的清況，

也可以根據功能進行package區分就好，然後Interface和實作可以放在一起，看那種方式最適合實際情況吧

另一個情況要思考的是，關於繼承關系的package分類，這個可以參考一下java api的分類方式，可以看以我個人最常用的ArrayList和其父介面Collection，

http://docs.oracle.com/javase/7/docs/api/java/util/Collection.html

http://docs.oracle.com/javase/7/docs/api/java/util/ArrayList.html

嗯…都放在同一個package中，或許這是一個最簡單的作法

思考過多，反而會造成使用上的困難，但這是對外公開的介面，實際上或許package內部，也隱藏著不為人知的祕密吧XD

關於溝通

其實，這篇沒什麼內容，可能比較適合po在plurk之類的
主要是想說關於溝通的一些想法
之前聽過一個說法是說，人其實對於對方說的不能百分之百完全了解
忘記是50%還是多少百分比了
只是，對某些人聽了某些問題，說我懂了
但問他，他也說不出個什麼毛來
也有的人，可以馬上嘴出一個長篇大論，但狗屁不通
有的人，明明聽的時候，明明就在睡覺，
但問他，又可以說的頭頭是道，可能比較講者說的還好…
或許，在底層有些共同的道理存在吧…
只是想說，一知半解是很可怕的一件事情
但對某些人愛面子的人來說，說不知道可能是很難的一件事吧
不過，學著試著去表達自已的想法，就算錯了，也沒關係
也比裝著自已很懂的樣子，但說不出個毛來的好…

[Mac]如何讓popup視窗的button能夠使用鍵盤操作

在mack notebook上，預設popup視窗是不能使用鍵盤做選擇
使用鍵盤可以加速操作

系統設定->鍵盤->快速鍵->啟用 全部控制選項
tab選擇 space使用

圖一、設定畫面

Maven study

Gossip

I don't like Maven indeed. Xml configuration method is more complex for now. But, my most work still need Maven. The principle is same as other dependency tools. So, let us still work on it for now.  If you don't have any constrain, you can learn Gradle which is a modern dependency tool. Otherwise, I also don't like Eclipse, but I still work on it. Intellij IDEA is also good choice, but it is not free. You think you need to improve your production of coding, then buy it. However, I still need Eclipse for my working tool, so it is not necessary to learn two IDA as same time.

The reason why I return to study Maven is Spring 4. Spring 4 use Maven to set up Spring Boot or other Spring stuff. So, I need to understand Maven in some kind of level.

Resoure

Official Maven web site on Apache

https://maven.apache.org/index.html

Tutorial

http://www.tutorialspoint.com/maven/

http://www.mkyong.com/tutorials/maven-tutorials/

Create a sample project(3) - WebService Choice

The interesting thing is when I have finished studying AngularJ S, using server-client method is a good way to develop outside website. Because that we can reduce the network flow and more efficiency web app. But, SpringMVC is still a good way to develop some types website, because it can handle Session, redirect URL, and so on more easier.

So, should I choice a more efficient web service framework to handle backend server? I think the answer is YES!  Jersey is most popular Restful web service framework, and has high performance.  I have thought about using SpringMVC, but when I see this experiment. I decide change to Jersey.
https://github.com/jhipster/generator-jhipster/issues/814

The performance is bothered me for a long time. There is a solution appear called Netty. Netty is a network communication framework. It supports event-driven, asynchronise , non-blocking IO feathers.

Netty article
http://ifeve.com/netty1/

But, do we need to give up SpringMVC? Maybe yes or not, because SpringMVC is more suitable for small scale or inside website. Anyway, the last example project have add and query function. You can implement delete and update functions by your own.

Next, we should change our webservice framework to Jersey.

Front End Resorces

Angular.js And React.js are the two popular front end framework recently.

I choice the Angular be my front end backbone, may use some react components do some special job. 

This is an angular tutorial vedio

http://campus.codeschool.com/courses/shaping-up-with-angular-js/intro

Another tutorial from W3CSchool

http://www.w3schools.com/angular/angular_application.asp

Angular API

http://www.w3schools.com/angular/

EggHead. An expert do some examples on Angular( and also react).

https://egghead.io/

Some Chinese resources

http://blog.miniasp.com/archive.aspx#cat-AngularJS

React, not a good tutorial, but a good sample code library

http://leoyeh.me:8080/tags/React/

The CSS is also be my weakness, so I don't want to spend time for creating CSS template.

You can use bootstrap CSS or Wix web site template

http://getbootstrap.com/

http://www.wix.com/

Create a sample project(2) - Setup PostgreSQL on JBoss

After finishing the Maven hell, we can finally start the fun part. I choice the PostgerSQL be our database. There are some reasons. First, it's free. Then, it is more like Oracle, such SQL syntax, design model. So, this is why I don't choice MySQL. Moreover, why  not choice RMDB instead of NoSQL. There some pros and cons. RMDB is more convenient by using SQL. But , NoSQL is more powerful on big data. Anyway, I just choice a simple for starting. After then, I will also study MongoDB.

Actually, this is a simple one to install PostgreSQL on your computer, you can choice raphic installation which conclude pgAdmin. So, you can build db and execute SQL command on pgAdmin.
http://www.postgresql.org/download/
Otherwise, I not sure homebrew wheather contain pgAdmin.

All right, after we install PostgreSQL, we should build an example database on it. So, we create a new database called TEST. Note that using capital is prefer for naming rule, it will effect the SQL command after. Then, we use JPA tool to create the schema of example table.

We use previous project for our practice,

First, setup the connection of DB.
On project -> property -> Hibernate, setup up the Postgre Driver

Second, use JPA Tool to generate
Project -> JPA Tool -> Generate xxx
In here, we change Entity to Table

Next, we should setup the JBoss db connection, or used db configuration on JBoss.
Actually, this is hard part. If I don't see the document, I will never figure it out.
Anyway, we change the DB configuration on this step. Maybe we try not to config JBoss server config file.

I have use maven to import Postgre driver, but the result is fail. I don't know why

You can see this blog to config the database connection
http://wei-meilin.blogspot.tw/2012/07/jeap-6-datasource.html

I choice the module method to setup up. Note that please use the JDBC4(not JDBC41) for setup.

There are some tips you need to know on our prototype project.

1. Remove spring-quickstart-ds.xml
2. Change the value of hibernate.hbm2dll.auto on persistence.xml
3. Setup up datasource and driver on standalone.xml(or domain.xml) which is in JBoss folder(...this depend on that which you need is standalone or domain).
4. If you change the datasource JNDI name, you should change the JNDI value of dataSource on infrastructure.xml.
5. You also need to add dependence of PostgreSQL.

standalone.xml

<datasources>

    <datasource jndi-name="java:jboss/datasources/SpringQuickstartDS" pool-name="PostgresDS" enabled="true" use-java-context="true">

        <connection-url>jdbc:postgresql://172.0.0.1:5432/Test</connection-url>

        <driver>postgres</driver>

        <security>

            <user-name>postgres</user-name>

            <password>xxxx</password>

        </security>

    </datasource>

    <drivers>

        <driver name="postgres" module="com.postgresql">

            <xa-datasource-class>org.postgresql.Driver</xa-datasource-class>

        </driver>

    </drivers>

</datasources>

pom.xml

<dependency>

 <groupId>postgresql</groupId>

 <artifactId>postgresql</artifactId>

 <version>9.1-901.jdbc4</version>

</dependency>

Pardon me for such mess article. I avoided to write  to much detail for some reasons. Maybe I will reorganize this article one day. Finally, we create the Database connection. JPA and its annotation are such great tools to create relation with the database. But, we should not focus on that, because it so easy to use. Next time, we we will write the our backend code by using SpringMVC and its unit test. See you~

Maven Note - Basic

I have study this project manage tool, Maven, for a while. But, I still feel confused for this tool. I used Ant for my previous job. This is an easy tool to manage project. But, it does not have the dependency management. So, we still need to learn it. Actually, if you are java coder, you should learn it for its basic mech anism. Other program languages also have their own project manage tool, but this is not our main goal. So, I make a list which your should learn.

Installation
The Concept of Maven
Create a project
Know about pom.xml

---

Installation

How to install maven, you can google. If you use mac, you can used Homebrew is a very great package manage tool.

brew install maven

---

The Concept of Maven

There are some good tutorials of Maven
Chinese-
http://www.codedata.com.tw/java/understanding-gradle-2-maven/
http://juvenshun.iteye.com/blog/213959
http://takeshi-experience.blogspot.tw/2011/12/java-mvc-sample-2-with-maven.html
English-
http://www.javacodegeeks.com/?s=maven

Using a simply way to explain, there are three life cycle clean, default, site.
clean life cycle - you should clean your previous building content, before you build new one.
build life cycle - build your project, and deploy it.
site life cycle - Analyze the project data.

There are many phases defined for each life cycle. You can read this
http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html#Lifecycle_Reference 

Each phase define its workflow and goal to execute.
goal is a maven plugin to execute the command, like compiler:compile.
compiler is the plugin name, and compile is the goal name.

You can also combine these three lifecycle, like mvn clean compile site. compile is a phase of default lifecycle.

---

Create a project

You can use command line to build a simple project, like

mvn archetype:generate -DgroupId=com.di.maven -DartifactId=hello-world -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false

Actually, you can also use Eclipse( or other IDE which support Maven) to build Maven Project.
There pictures are how to create a Maven project in Eclipse.

---

Know about pom.xml

This is a simple pom.xml file

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.di.maven</groupId>
  <artifactId>hello-world</artifactId>
  <packaging>jar</packaging>
  <version>1.0-SNAPSHOT</version>
  <name>hello-world</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>

Maven is a convention over configuration software design pattern.  This is why pom.xml file is so sample. We have a super pom.xml which config a lot of detail. So, we can start a sample project faster. But, it still confused for me. Actually, when you need to setup other configuration, you still need to figure out the correct way to config. This topic is still a problem for me. Anyway, let start it easier. In this pom.xml file, we only need to understand how to add the jar files which is needed for our project. You only add the dependency config to <dependencies>. It will auto download the jar files we need. This is also why we need to use Maven. Maven can solve the dependency hell in some situations. Otherwise, <scope> is mean the dependency will effect which s cenario will be used.

You also can search the dependency you need in
http://mvnrepository.com/

Further, there is an example which we had built before.
https://github.com/bpmabpma/JBossExmple/blob/master/springMvc/pom.xml

We can see a lot new Xml elements show up, such as <properties>, <dependencyManagement>,  <<build>, <plugin>, <profiles>. I think they are very important. But, in my present situation, I should build my project be my primary job. So, when I finish build the major part of coding. I should return Maven, and build the CI system based on Maven.

Moreover, if you really need to an expert of Maven. You should read this
http://maven.apache.org/guides/index.html

Create sample project(1) - Spring MVC + JBoss

Actually, this pototype is stole from somewhere...
Anyway, I think this a good way to start my work.
So, let start...

Later, maybe I will research why JBoss is a good AP Server Choice, and compare with other ap server(or http server). But, this is a huge work. I desire to build something first. Otherwise, the reasons why I prefer Spring MVC be my MVC framework. Maybe it is not the best choice, but on least it work perfect on Spring framework. Maybe I will also research MVC framework later.

Prepare

There are some stuffs, we need to download before starting development.
Eclipse Luna
JBoss EAP 6.4
Maven 3.3.3

Extra Config and Plugin

If we don't find the Maven Central,  we will need to setup the Maven repository url.
Preference->Maven->Archetypes->Add Remote Catalog...
Catalog File = http://repo.maven.apache.org/maven2/archetype-catalog.xml
Description = Maven Central

And, we can install the JBoss plugin on Eclipse(many feathers which we can use).

Import Maven Project

We can quickly import the sample project from the remote Maven repository.
This is one is our need.

Setup Server and Run

Use startup or Server Perspective

See the Result

Conclusion

I cut out a lot of details, just show the key point for my note. JBoss has its own default H2 database, so we can see some database applications. Next step, we will create our own database and JPA(implemented by Hibernate) config.

Github link

https://github.com/bpmabpma/JBossExmple

Build my own project - Blueprint

Strugling a long time, I have choose some frameworks and tools to build my own project. The majority reasons I choice are free and based on Java.

AP server - JBoss, the reason which I choice is it can easily be a distributed system. There are more advantages, but I am still learning. It is new for me.  It also have support JEE standard. Its main target is EJB support, but it also support web operation now. Otherwise, it can handle other JEE standard(I am still figuring it out now)

MVC - Spring MVC, there are the plenty of options on MVC framework to choice, such as Struct 2, Wicket, Tapestry, Play, etc.  So, why I take this one.

Front End - AngularJs or React, they are two frameworks which are very popular now. They can easy develop the code of front end. I am not farmiliar with them. But, I trust them can more efficiently develop on the front end.

ORM - Hibernate, because it is very suitable with JBoss. Mybatis is another option, but it is suitable for the old database scheme or more efficient requirement.

DB - Postgre and Mongo DB, one is RMDB, one is no-sql for the different purposes. Postgre is more like Oracle, so I chose. Mongo is more popular, so... . It has its own advantage, such as easy to use, flexible, etc. But, I have really do research on other options.

IDE - Eclipse

Project Management - Maven and Ant(if it is more convenient).

Monitor - Not know yet.

Testing Tool - Maybe TestNG or just Junit, not decide yet.

CI - Jenkins

SCM - git and github...

Hey, just a list, let start building.

The todo list of second half of 2015

I have a long time to write the my blog.
I want to change this blog target.
This blog still records my research of IT technology.
But, I will write the content by English.

I have found the new job on my career.
But, I still think the goal of my career.
Oversea, remote, contractual, and consultant are all acceptable.
Architect, free System Design, Startup are all the paths of future.
Anyway, I will take some time to think about it.
The new goal in my new company also must be thought.

The goal of my career is not an emergency issue.
Even it is changeable, but I still need to find it ASAP.
Then, I will work on it.

In the short term, I will take my time to study the architect.
Then, I will create a project on the AWS.
Practice is an easy way to implement dream.

I have some skills and tools on Backend(Java).
I not very good on the front end, but still have a certain knowledge and experience.
So, I will work on some old skill, like Java, and old tool, like Eclipse.
But, I will study the new tools which I am not familiar with.

Following are the list of my study list.
Maven - This is a project manage tool.
JBoss - This is a middleware application server. Its main target is manage EJB. It is                         work on my new job.
Angular or React - There are two modern JS framework. I will choice one( or both) to               implement the front end.
MCV - Choice a Java MVC framework? I still not sure to use java be my backend
              language. There are  some frameworks, such as Spring MVC, Jersey(Restful).
MEAN - This is new architecture for web site design. Mongo, Express, Augular,
              Node.js.
 Memcached or Redis - There are two memory cach tool.
AP Server - Tomcat, JBoss, Webphere, Nginix
DB - Mongo DB
MQ - Ative MQ
Spring 4 & Java 8 - Java new tech.
Design Pattern
Refactoring
SA - Diagram

I have some skills and tools, bellowing
Eclipse, ant, Java7, JQury(not very good), html, javascript(not good), Tomcat, Wicket, Camel, linux(basic)...

Somehow I think I do not have so much time to learn or review all stuff...
Anyway, create a easy sample project first...

[Maven]基本概念

2014一下子就過去了

轉眼間就2015了…

也一陣子沒有寫Blog了

一直想整理一下常用的framework和開發工具

不過大部分的時間都在混水摸魚

希望2015能完成這個目標丫

2015的首po

就從一個很基礎的開發工具開始

Maven