Java项目开启远程调试的方法步骤（tomcat、springboot）

当我们运行一个项目的时候，一般都是在本地进行debug。但是如果是一个分布式的微服务，这时候我们选择远程debug是我们开发的利器。

环境

apache-tomcat-8.5.16

Linux

如何启用远程调试

tomcat开启远程调试

方法

切换到你的tomcat的bin目录/apache-tomcat-8.5.16/bin下，执行:

./catalina.sh jpda start

执行上面的命令就可以开启远程debug了，如果想配置一些信息，比如端口号什么的，请参考下面的说明。

参数说明

#  JPDA_TRANSPORT (Optional) JPDA transport used when the "jpda start"
#          command is executed. The default is "dt_socket".
#
#  JPDA_ADDRESS  (Optional) Java runtime options used when the "jpda start"
#          command is executed. The default is localhost:8000.
#
#  JPDA_SUSPEND  (Optional) Java runtime options used when the "jpda start"
#          command is executed. Specifies whether JVM should suspend
#          execution immediately after startup. Default is "n".
#
#  JPDA_OPTS    (Optional) Java runtime options used when the "jpda start"
#          command is executed. If used, JPDA_TRANSPORT, JPDA_ADDRESS,
#          and JPDA_SUSPEND are ignored. Thus, all required jpda
#          options MUST be specified. The default is:
#
#          -agentlib:jdwp=transport=$JPDA_TRANSPORT,
#            address=$JPDA_ADDRESS,server=y,suspend=$JPDA_SUSPEND

操作说明

所以如果想修改配置，则如下操作：

在catalina.sh中进行配置：

JPDA_TRANSPORT=dt_socket 
JPDA_ADDRESS=5005 
JPAD_SUSPEND=n

或者通过JPDA_OPTS进行配置：

JPDA_OPTS='-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5005'

springboot开启远程调试

远程调试maven设置

The run goal forks a process for the boot application. It is possible to specify jvm arguments to that forked process. The following configuration suspend the process until a debugger has joined on port 5005

<project>
 ...
 <build>
  ...
  <plugins>
   ...
   <plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <version>1.1.12.RELEASE</version>
    <configuration>
     <jvmArguments>
      -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=5005
     </jvmArguments>
    </configuration>
    ...
   </plugin>
   ...
  </plugins>
  ...
 </build>
 ...
</project>

These arguments can be specified on the command line as well, make sure to wrap that properly, that is:

mvn spring-boot:run -Drun.jvmArguments="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=5005"

jar 命令开启远程调试

在执行jar的时候，添加上参数。如下：

java -Xdebug -Xrunjdwp:server=y,transport=dt_socket,address=8000,suspend=n -jar demo.jar

如果想深入了解Java调试，那么去看一下这个吧。深入Java调试体系

问题

如果出现Connection refused。

首先检查一下端口8000的使用情况:

use:~/tomcat/logs # netstat -an|grep 8000
cp    0   0 127.0.0.1:8000     0.0.0.0:*        LISTEN

可见当前16808端口服务被绑定了回环地址，外部无法访问。即本地调试。

办法：

修改catalina.sh中一个参数。

if [ -z "$JPDA_TRANSPORT" ]; then
  JPDA_TRANSPORT="dt_socket"
 fi
 if [ -z "$JPDA_ADDRESS" ]; then
  JPDA_ADDRESS="0.0.0.0:8000"
 fi
 if [ -z "$JPDA_SUSPEND" ]; then
  JPDA_SUSPEND="n"
 fi

对JPDA_ADDRESS="localhost:8000" 把默认值（localhost:8000）改成0.0.0.0:8000。默认是本地ip调试也就是无法远程调试，0.0.0.0表示所有ip地址都能调试。

远程连上后再看端口情况：

root@VM-198-217-ubuntu:/opt/apache-tomcat-8.5.16/bin# netstat -an | grep 8000
tcp    0   0 10.133.198.217:8000   60.177.99.27:49998   ESTABLISHED

断开后是这样的：

root@VM-198-217-ubuntu:/opt/apache-tomcat-8.5.16/bin# netstat -an | grep 8000
tcp    0   0 0.0.0.0:8000      0.0.0.0:*        LISTEN
tcp    0   0 10.133.198.217:8000   60.177.99.27:49998   TIME_WAIT

idea连接远程端口进行远程debug

我已经在服务器上开启了远程调试，idea连接的步骤，直接上图。

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