前言
最近在项目中碰到个一个场景，我们需要把自己的java项目jar包部署到一个第三方的服务器上，虽然双方互相信任，但是综合考虑，避免别人拿到jar包后可以很快的编译出源码，我们决定给代码加一层混淆，虽然此方法不能从根源上解决问题，但是做了一层混淆，也可以增加阅读源码的难度，总结了一下，写下这篇文章。
如何反编译java代码
我用的是mac电脑，从官网:java-decompiler.github.io/#jd-gui-dow…下载JD-GUI，官网有很多版本，下载后安装打开即可，导入你想反编译的jar，我这里随便找了个jar包做演示
何为java混淆
细心的小伙伴肯定发现了，上面的截图有的包名是a，b，c这样命名的，但凡有点节操的程序员都不会这样命名的，这就是被混淆后的代码，让人不会一眼看出来代码里面的逻辑，效果会像下面这样
进行java混淆
我们以之前springboot项目为例，进行service层的代码的混淆，呼啸前效果如下：
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<groupId>com.github.wvengen</groupId>
<artifactId>proguard-maven-plugin</artifactId>
<version>2.0.14</version>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>proguard</goal>
</goals>
</execution>
</executions>
<configuration>
<proguardVersion>6.1.0beta2</proguardVersion>
<injar>${project.build.finalName}.jar</injar>
<outjar>${project.build.finalName}.jar</outjar>
<obfuscate>true</obfuscate>
<options>
<option>-dontshrink</option>
<option>-dontoptimize</option>
<!-- This option will replace all strings in reflections method invocations with new class names.
For example, invokes Class.forName('className')-->
<option>-adaptclassstrings</option>
<option>-keepdirectories</option>
<!-- This option will save all original annotations and etc. Otherwise all we be removed from files.-->
<option>-keepattributes
Exceptions,
InnerClasses,
Signature,
Deprecated,
SourceFile,
LineNumberTable,
*Annotation*,
EnclosingMethod
</option>
<!-- This option will save all original names in interfaces (without obfuscate).-->
<option>-keepnames interface **</option>
<!-- This option will save all original methods parameters in files defined in -keep sections,
otherwise all parameter names will be obfuscate.-->
<option>-keepparameternames</option>
<!--不使用大小写字母进行混淆，保持类唯一性-->
<option>-dontusemixedcaseclassnames</option>
<!-- This option will save all original class files (without obfuscate) but obfuscate all
in domain and service packages.-->
<option>-keep
class com.stone.zplxjj.Application {
public static void main(java.lang.String[]);
}
</option>
<!-- 指明哪些类可以不被混淆-->
<option>-keep class com.stone.zplxjj.autoconfiguration.** { *; }</option>
<option>-keep class com.stone.zplxjj.config.** { *; }</option>
<option>-keep class com.stone.zplxjj.controller.** { *; }</option>
<option>-keep class com.stone.zplxjj.dao.** { *; }</option>
<option>-keep class com.stone.zplxjj.entity.** { *; }</option>
<option>-keep class com.stone.zplxjj.event.** { *; }</option>
<option>-keep class com.stone.zplxjj.interceptor.** { *; }</option>
<option>-keep class com.stone.zplxjj.listener.** { *; }</option>
<option>-keep class com.stone.zplxjj.properties.** { *; }</option>
<option>-keep class com.stone.zplxjj.filter.** { *; }</option>
<!-- This option ignore warnings such as duplicate class definitions and classes in incorrectly
named files-->
<option>-ignorewarnings</option>
<!-- This option will save all original class files (without obfuscate) in service package-->
<!--<option>-keep class com.slm.proguard.example.spring.boot.service { *; }</option>-->
<!-- This option will save all original interfaces files (without obfuscate) in all packages.-->
<option>-keep interface * extends * { *; }</option>
<!-- This option will save all original defined annotations in all class in all packages.-->
<option>-keepclassmembers class * {
@org.springframework.beans.factory.annotation.Autowired *;
@org.springframework.beans.factory.annotation.Value *;
}
</option>
</options>
<injarNotExistsSkip>true</injarNotExistsSkip>
<libs>
<!--Put here your libraries if required-->
<lib>${java.home}/lib/rt.jar</lib>
</libs>
</configuration>
<dependencies>
<dependency>
<groupId>net.sf.proguard</groupId>
<artifactId>proguard-base</artifactId>
<version>6.1.0beta2</version>
</dependency>
</dependencies>
</plugin>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
复制代码执行打包命令：mvn package，会看到生成如下
注意点
- zplxjj_proguard_base.jar是没有经过混淆的jar
- 两个.txt文件说明了混淆前和混淆后的对应关系
- 如果项目中引入了spring框架，类的注入id要保持唯一性，否则就要重写生成bean的id规则的方法
- 更多pom文件细节可以参考：www.guardsquare.com/en/products…
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