The best way for using JDB is create a configuration file named jdb.ini in a specified folder.
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Local debug support:
Create a command line(ex. jdb_load.bat) and input the following commands set:
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SET CLAsspATH=D:/work/ReverseTest/TestClass/bin
jdb -J-Duser.home=.
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At the same folder of this command line,please create a jdb.ini and fill the following settings:
stop in TestClass.main
use D:/work/ReverseTest/TestClass/bin;D:/work/ReverseTest/TestClass/src
run TestClass
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Finally by clicking "jdb_load.bat" and then you can debug the application -- TestClass.
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Remote debug support:
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First create a command line set for loading the application like the following(Let's call this file load_app.bat)
SET CP=D:/work/ReverseTest/TestClass/bin
java -cp %CP% -agentlib:jdwp=transport=dt_socket,address=localhost:8888,server=y,suspend=y TestClass
For a tomcat or Jboss,weblogic server,please set the following options in its loading shell script.
JBOSS:
Change run.bat/run.sh under JBOSS_HOME/bin(add the red line as following):
JBOSS_HOME: /var/jboss4
JAVA: /usr/java/j2sdk1.4.2_06/bin/java
JAVA_OPTS: -server -xms128m -Xmx128m -Dprogram.name=run.sh
DEBUG_OPTS = -Xdebug -Xrunjdwp:transport= dt_socket,suspend=n
CLAsspATH: /var/jboss4/bin/run.jar:/usr/java/j2sdk1.4.2_06/lib/tools.jar
TOMCAT:
Change catalina.bat/catalina.sh under TOMCAT_HOME/bin.(add the red line as following)
DEBUG_OPTS = -Xdebug -Xrunjdwp:transport= dt_socket,suspend=n
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Second create a command line named jdb_load.bat.
jdb -J-Duser.home=. -connect com.sun.jdi.socketAttach:hostname=localhost,port=8888
Thirdly create a jdb.ini under the same folder of jdb_load.bat.
stop in TestClass.main
use D:/work/ReverseTest/TestClass/bin;D:/work/ReverseTest/TestClass/src
run TestClass
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Finally by first clicking "load_app.bat",then clicking "jdb_load.bat" and then we can debug this application remotely.
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Sample for debugging:
Jdb set breakpoint skill:
The best way for using JDB debug is by using the ini configuration file,this is the highly-efficient way for setting debug environment:
stop in org.apache.commons.dbcp.PoolingConnection.<init>(java.sql.Connection)
stop in org.apache.commons.dbcp.PoolingConnection.<init>(java.sql.Connection,org.apache.commons.pool.KeyedobjectPool)
use D:/swap/commons-dbcp.jar;D:/swap/jar-src list
Attention: when we set the break point for a specified class,we should set their whole name (including its class path,package name etc.)
otherwise it won't make any effect on the specified execution routine,if there are multiple entries for a specified name, we should take the whole funciton's prototype into this call.
Using the remote debug configuration for a specified class will be the best choice.
Debug experience for using JDB: (Without source code to debug)
Firstly using the decompile tool to get the basic source code for a specified source package.
Secondly we'll start the program and then the jdb debugger by using command line(see configdebugsupport).
Thirdly when we get the break from the command line debug tool,we'll use the following commands:
Where -- Shows current break position and source code list.
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http-01%2F192.168.1.133-8080-1[1] where
[1] org.apache.commons.dbcp.DriverConnectionFactory.createConnection (DriverConnectionFactory.java：38)
[2] org.apache.commons.dbcp.PoolableConnectionFactory.makeObject (PoolableConnectionFactory.java：294)
[3] org.apache.commons.dbcp.BasicDataSource.validateConnectionFactory (BasicDataSource.java：1,247)
[4] org.apache.commons.dbcp.BasicDataSource.createDataSource (BasicDataSource.java：1,221)
[5] org.apache.commons.dbcp.BasicDataSource.getConnection (BasicDataSource.java：880)
[6] org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection (DataSourceUtils.java：113)
[7] org.springframework.jdbc.datasource.DataSourceUtils.getConnection (DataSourceUtils.java：79)
Then find your fields list (private fields) in the specified class.
fields classid --- Shows all fields of the specified class.
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http-01%2F192.168.1.133-8080-1[1] fields org.apache.commons.dbcp.DriverConnectionFactory
** fields list **
java.sql.Driver _driver
java.lang.String _connectUri
java.util.Properties _props
print/dump variables in current context
http-01%2F192.168.1.133-8080-1[1] print _driver
_driver = "jtds 1.2"
http-01%2F192.168.1.133-8080-1[1] print _connectUri
_connectUri = "jdbc:jtds:sqlserver://sql01:1433/Router_PROD;user=sa;password=sql01;"
http-01%2F192.168.1.133-8080-1[1] print _props
_props = "{user=sa,password=sql01}"
step up -- run until the return of current frame or function call
We can read the decompiled source code and then use this step up to trace its logic and get the specified breakpoint for us,watch the specified/key variables in this process,then debug or remove the bug at last.
