Decompile the jar package and recompile it into a jar package after modification

Using open source jar Package or supplier jar Packet time , Will find some bug Or the existing functions cannot meet our requirements , Need to be right jar Medium .class File modification . The processing steps are as follows ：

1. Use the decompile tool to jar Decompile package into source file

For decompilation tools, please refer to XJAD2.2 Version download address ：http://www.blogjava.net/Files/96sd2/XJad2.2.rar

If only a few class Need modification , It can be used directly IDEA perhaps jd-gui Tool open , take .class Directly copy the contents of the file and create a file with the same name .java file （ Need basis jar Set up all the upper directories in the package , such as com.athome.cas.Test.java, Need to create com.athome.cas Such as catalog , take Test.java Put it under the directory ）

2. modify java file

For source files .java Write and test functions

3. Compile the whole jar Packages or specific ones java file

use IDEA Open the entire source file , Use bulid Compile the file or the entire project （ You can select individual java The file is compiled as .class）

4. Processing when compiling an error

The following examples are the most common compilation errors ：

Util.java:9: error : Package javax.servlet non-existent
import javax.servlet.ServletException

You need to import the corresponding dependency , We can do it in pom.xml Add... To the document pom rely on , The required packages can be queried in the warehouse

  https://mvnrepository.com/

  If it is a few alone .class Files can be directly opened with compressed files jar package , Compile the generated after modification class The file can be directly dragged in .