1, open the page www.oracle.com
Download the corresponding platform JDK
2. Double-click to download
Windows32-bit operating systems such as download-8u121-Windows-the JDK i586.exe
Windows64-bit operating system such as download jdk-8u121-windows-x64.exe
3, enter the installation wizard
4, next, change the installation path, select to install all the components 
(1) to cancel the installation of the JRE independent
since JDK JRE already included, for developers, may not need to install a separate JRE, if you want to cancel the installation JRE, 
(2) change the installation path of JDK 
Note: The installation directory here contains Java \ JDK1.8.0_51, so next time you can clearly more intuitive to install their own which version of JDK
5, the next step to begin the installation 
6, configuration, My Computer / Computer Right Properties, select Advanced System Settings
7, click [Environment Variables]
8, the new variable "JAVA_HOME", is JDK installation
Here Note:
If you are after all developed using JDK under that user, you can choose to create a new user variable;
if it is later hoped that the variables are visible in all users, then select New System Variable;
I am here only one user, clarity is good maintenance, I chose to create a new user variable
9, the JAVA_HOME variable value to the variable path
Note: If you are a new user variable JAVA_HOME, you can only add JAVA_HOME to the path user variables, otherwise the situation could not find JAVA_HOME may occur
if a user no path variable, you can then create a path variable (path variables are the windows system when the command to execute the search path), add JAVA_HOME value; value% JAVA_HOME% \ bin;
if it already exists path, then edit it, the added value of JAVA_HOME in the original value;
recommended to copy original value to Notepad , and then edit, add% JAVA_HOME% \ bin in front of the old value; then copy them back to avoid making mistakes
10, test javac command
11, test java command
12, complete
API Download
Ultimately, while learning Java API (Application Programming Interface) document. Download:
http://www.oracle.com/technetwork/java/javase/downloads/index.html
the scroll bar on the page scroll down to find "Additional Resources"
to download the html version is here, you can choose to make tools into chm version
