Java connection to Ethereum node

1. curl方法，file_get_contents,

2. My computer - & gt; Attribute - & gt; Advanced - & gt; Environment variables - & gt; Add the following environment variables to the system variables:
java_ The home value is: the directory where JDK is installed, and mine is C: &# 92; Program Files\ Java\ jdk1.6.0_ 34
the classpath value is:;% JAVA_ HOME%\ lib\ tools.jar;% JAVA_ HOME%\ lib\ dt.jar;% JAVA_ HOME%\ bin;( Pay attention to the & quot& quot; To add)
Path: append at the beginning.;% JAVA_ HOME%\ bin;% JAVA_ HOME%\ jre\ bin;( Pay attention to the & quot& quot; To add)

after the installation, you can check whether the JDK is installed successfully. Open the CMD window and enter Java – version to view the version information of JDK.

3. Yes, but it is better to use overseas servers. In addition, the server configuration should be medium or above.

4. Generally speaking, undefined index is the exact writing problem in the process of writing. Notice generally prompts for errors that are not directly related to the execution of code, but don't forget that notice sometimes returns some rendant error information

5. How many account addresses can an Ethereum node have at most
A: generally, there is only one account address, otherwise there will be an error! blockchain itself is unique. If there are multiple account addresses on one node, it violates the fundamental principle of blockchain!

6.

Ethereum specifies the JSON RPC API application development interface that each node needs to implement. This interface is transport independent. Applications can use this interface protocol to operate Ethereum nodes through HTTP, websocket or IPC and other communication mechanisms:

7. There is no inevitable relationship between whether the virtual currency will disappear or not and whether it can not be used on the third-party platform. Online third-party trading platform can only say that this kind of currency has another platform for trading, which shows that this kind of currency is more reliable
Ruitai coin has not been launched on the third-party platform, but it is rumored that it will also be launched on the third-party platform.

8. There is no problem at all, but relatively speaking, we must buy some reliable ones, because we must pay attention to them.