Big Data First day

The big data is based on Java's knowledge of Java before it learns big data, and Java is running on the computer, so you have to understand the knowledge of the computer.

The first is to be familiar with the computer's operating system: Mainstream for Windows:d esktop system

Linux: Stability + security (on behalf of Chentos,ubant,redhat,suse) Mac : Closed source

Directory

----------------

for the location of folder .

DOS commands (case insensitive in Windows):

-----------------

Common commands:

1.dir:diretoty Displays the disk directory.           

2.D:

Toggle Drive Letter

3.tab: Full button

Shift+tab: Reverse operation.

4.cd: Enter directory   

5.mkdir:mkd/make Directory

Create a Directory

6. Directory-related

.. : Return to Parent directory

. : Current directory

7. Copying

Copy CP

8.del: Delete file

Parameter:-S recursion

-Q Quiet Quiet

-F Force Mandatory

Typically combined use that is del/s/q/f * (* indicates the file to be deleted)

9.MV: Mobile

10.rmdir: Delete directory (directory must be empty) parameter/s/q

11.ipconfig: View the IP address of the MAC address and other parameters, parameter/all

12.ping: Check the connectivity of the network (with IP address or domain name)

Ping www.baidu.com

13.set: List all environment variables

14.cls:clear Screen Cleaning

Common sense:

Configure the host file to bypass DNS resolution

C:\windows\system32\drivers\etc\hosts Open the Host file

Modify the appropriate parameters to

2.win7 's precautions;

For system selection, use the Win7 X64 flagship operating system to log in with the Administrator account

3. Turn off the firewall that comes with your system

Control Panel--firewall--Turn off firewall

CPU Affinity

----------------------

CPU affinity can be used in very resource-eating applications to ensure the normal use of the computer

Command: Start affinity * (* indicated as 16 binary digits)

Extensions: The binary of the computer is binary, which is used to express the numbers, so the weight of the binary number is 2.

The counterpart of the CPU and the binary number is the opposite, and the binary number corresponding to the CPU0 and CPU1 is the number one and the penultimate.

650) this.width=650; "src=" Http://s1.51cto.com/wyfs02/M02/7F/AD/wKioL1co0gXyqEn3AACvUVxCbjE560.jpg "title=" Qq20160504002554.jpg "alt=" Wkiol1co0gxyqen3aacvuvxcbje560.jpg "/>

As shown, the preceding CPU permutations correspond to several numbers at the end.

So if the computer is 8 cores written bits 00001111-->16 when the first 4 CPUs are required. So the command is

Start Affinity F * (* Indicates the process of the software)

Binary: 0|1

8 binary: 0-7

10 mechanism: 0-9

16 binary: 0-9 A B C D E F

Binary conversion: You can say that all the binary is converted to binary and then converted to another binary. Other binary binaries only need to be replaced by two.

Myth: Error Prone in conversion, example 1232 binary number to decimal number 3*2^0+2*2^1+1*2^2=7 I'm right about that, but the problem is wrong at the beginning. 123 cannot be a binary number, so the problem is wrong.

Shortcut keys

---------------

[Text Edit]

CTRL + C copy

Ctrl + V Paste

Ctrl+x Cut

CTRL + A Select all

CTRL + Z Undo

Ctrl+y undo Undo (Return to previous step)

Ctrl+s Save

' Reference designator

tab//Tab

Shift+tab//Reverse operation

Ctrl+shift//Toggle Input Method

Shift+tab+alt//

Ctrl+alt+del//Open Task Manager

Windows+d//Open Desktop

Windows+r//Run

Services.msc//Services

Regedit//Open Registry

Netepad//Open Notepad

MSPaint//Open Paint

Calc//Computer

End//Position cursor to end of line

Home//Position cursor to beginning of line

Shift +end Select the current position to the end of the line

CTRL +//follow the word progression

EditPlus

-------------

Main advantages: Can be displayed by line

Support for text typesetting

Related commands can be highlighted when programming

ALT + Mouse: Select by column

Java Basics

-----------

Sun: Profile (now acquired by Oracle)

b/S: Brower (browser)/server (Web server),

C/S: Client/server (DB Server),

Ria:rich Internet Application Rich Network

Integration of data communication between Ws:web service heterogeneous systems

JAVA compiles once and executes everywhere.

The JVM that enables Java programs to execute everywhere

Sandbox: Sandbox, JVM

Jvm:java vitrual Machine, Java virtual machines

Jre:java Runtime Environment Java Runtime Environment

That is jvm+ Core class library

Jdk:java Develoment Kit Java Development Kit

jre+ Tool Software

Java operating mechanism

------------------

1. Writing Source code: Xxx.java

2. Compile the source code: *. Java--*.class//javac

3. Run: *.class//java

Programs: Executable files.

Process: a running program.

JDK Installation

----------------

1. Now the JDK file address

Http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html

Download the latest version of the JDK installation package

2. Run the Setup program

3. Select path: (Custom path-do not take Chinese path.) Be sure to remember it. The JRE is installed by default when installing the JDK so you can cancel when the installation prompts require the JRE to be installed. No duplicate installation required

4. After the installation is complete, check whether it can be used properly

5. Run the Javac command under the bin directory of the installation directory or run Java-vertion (view version number)

Configuring Environment variables

---------------

1. Computer--Properties--Advanced system settings

2. Advanced tab-Environment variables

3. New environment variable Java_home= * (* is the root directory of the installation directory)

4. Then locate the path variable to add the environment variable%java_home%\bin at the beginning of the line; Be sure to end with ";"

In Windows to; split

In Linux: Split

Extension: Displays the file name extension of the OS

------------------------

1. In any window

2. Press the ALT key

3. Display Menu

4. Tools--Folder Options--View

5. Deselect << Hide extensions for known files .>>

6. Click Apply to all folders

7. Determine.

*******************************

Writing the first Java program

*******************************

1. Writing a text file

New Demo.java File

Class demo{

Class for classes

public static Viod Main (String [] args) {

Public: Common

Static: Statically

void: Empty

Main: Name of the principal function

String: Parameter type, String type

Args: Formal parameters

The sentence is a fixed sentence, the only variable is the parameter args

System.out.println ("HelloWorld");

Enter and print the content

The quotation marks must be in the English state of note the end of the statement should have ";"

}

}

Curly braces indicate range

2. Compile the Java source file and generate the bytecode file (class file)

Javac Demo.java (Be sure to write the full file name here cannot be omitted. java)

3. Run the compiled class file

Java Demo is not required here. java

Path

----------------

The path order of the OS search file.

Classpath class Path

-------------------

1. In-Memory settings

The J-Ava program searches the order of Java classes.

Set Classpath= search in order from front to back

2. Add CLASSPATH Environment variables

Classpath=%java_home%\lib\tools.jar;%java_home%\lib\dt.jar;.

The last. Cannot omit

The classpath path can be specified directly when the 3.java instruction executes

JAVA-CP Demo

Java-classpath Demo

4. Class Search Order

1.-CP | The-classpath parameter specifies the path

Environment variables for 2.classpath systems.

3. Current directory.

-cp-classpath-->classpath System Environment variables--current directory

Big Data First day