Use Idea remote debugging Java code

purpose
- When an error occurs on the server code, the log to analyze too much trouble, may sometimes unable to locate the exact cause of the problem; it is the FBI by remote debug server code, accurately and efficiently.
Server configuration
- First of all, we want to let the remote server supports remote debugging feature, additional specific JVM arguments on the project can start, parameters are as follows:
  - Command line arguments for running remote JVM (later than JDK 1.4.X versions)
  - |
```
-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=9508
```
  - JDK 1.4.X versions
  - |
```
-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=9508
```
  - JDK 1.3.X or early release
  - |
```
-Xnoagent -Djava.compiler=NONE -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=9508
```
- The first: Spring boot -jar by Java -agentlib: Transport JDWP = = the dt_socket, Server Y =, = n-Suspend, address = 9508 xxx.jar &, configured to startup command line;
- Second: Set JAVA_OPTS nodes can now catalina.bat (linux environment settings catalina.sh) in. - Configure Tomcat server
  to the next $ TOMCAT_HOME / bin directory:
```
vi catalina.sh
#在# OS specific support.上面添加
export JAVA_OPTS='-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=9508'
```
Idea Configuration
- Click Edit Configurations, you can enter the Run / Debug Configurations interface, configure remote:
Start Debugging
- Click below identifies the debug start mark, will start a successful output on the console panel: Connected to at The target VM, address: '140.143.29.146:9508', Transport: 'socket'
Possible problems and solutions
- problem:
  - 第一个问题：Error running 'remote-ms-collection': Unable to open debugger port (XXXX:9508): java.net.ConnectException "Connection timed out: connect"
  - The second question: IP and port number no problem but "Connection refused"
- Solution:
  - Open the relevant ports:
  - ```
  vi /etc/sysconfig/iptables 
  
  #在-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT之后添加
  
  -A INPUT -m state --state NEW -m tcp -p tcp --dport 8080 -j ACCEPT
  
  -A INPUT -m state --state NEW -m tcp -p tcp --dport 9508 -j ACCEPT
```
- Restart the firewall:
```
  service iptables restart
```
- Also OK if troublesome, or to turn off the firewall security less demanding direct:
```
  service iptables stop
```
- Restart Service
Note: The remote debug while ensuring that a client can only connect