是否可以从罐子中编织一些类而排除其余的类？

Question

我正在尝试使用新功能扩展第三个库代码。

并且由于我只需要围绕一个方法从一个 class 注入一些代码，我想我可以：

分叉项目并应用我的更改 (seems sloppy, and will definitely require lots of work whenever I try to upgrade to a newer version of the lib, not to mention licensing nightmare)
使用 [AOP] 从一个巨大的 jar (seems cleaner) 中的那个 class 拦截那个方法并注入我的额外测试

万一你们想知道，那个 class 不是 spring bean 并且在代码深处使用，所以我不能简单地扩展它和 override/wrap 这种方法很容易，它至少需要额外的几层 extend&override/wrap。所以 AspectJ 和 AOP 似乎是更好的选择。

我设法用一些插件设置我的项目来调用 ajc 并在 -inpath 参数中用我想要的 jar 编织代码。唯一的问题是 ajc 似乎编织了一切（或者至少复制了它）；

所以我基本上需要的是让 AJC 简单地挥动那个罐子里的那个 class，而不是整个罐子！

Answer 1

如您所见，AspectJ 编译器总是输出在 weave 依赖项 (in-JARs) 中找到的所有文件，无论它们是否更改。无法通过命令行 AFAIK 更改此行为。所以你需要自己打包 JAR。

这是一个示例项目，包括。 Maven POM 向您展示了如何做到这一点。我选择了一个涉及 Apache Commons Codec 的相当愚蠢的例子：

示例应用程序：

应用程序对文本进行 base64 编码，再次解码并将两个文本打印到控制台。

package de.scrum_master.app;

import org.apache.commons.codec.binary.Base64;

public class Application {
    public static void main(String[] args) throws Exception {
        String originalText = "Hello world!";
        System.out.println(originalText);
        byte[] encodedBytes = Base64.encodeBase64(originalText.getBytes());
        String decodedText = new String(Base64.decodeBase64(encodedBytes));
        System.out.println(decodedText);
    }
}

通常输出如下所示：

Hello world!
Hello world!

这里没有惊喜。但是现在我们定义了一个方面来操纵从第三方库返回的结果，用'0'（零）替换每个字符'o'（哦）：

package de.scrum_master.aspect;

import org.apache.commons.codec.binary.Base64;

public aspect Base64Manipulator {
    byte[] around() : execution(byte[] Base64.decodeBase64(byte[])) {
        System.out.println(thisJoinPoint);
        byte[] result = proceed();
        for (int i = 0; i < result.length; i++) {
            if (result[i] == 'o')
                result[i] = '0';
        }
        return result;
    }
}

顺便说一句，如果您只是在这里使用 call() 而不是 execution()，则无需实际编入第三方代码。但无论如何，你要求它，所以我向你展示如何去做。

Maven POM:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>de.scrum-master.Whosebug</groupId>
  <artifactId>aspectj-weave-single-3rd-party-class</artifactId>
  <version>1.0-SNAPSHOT</version>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <java.source-target.version>1.8</java.source-target.version>
    <aspectj.version>1.8.10</aspectj.version>
    <main-class>de.scrum_master.app.Application</main-class>
  </properties>

  <build>

    <pluginManagement>
      <plugins>

        <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-compiler-plugin</artifactId>
          <version>3.6.0</version>
          <configuration>
            <source>${java.source-target.version}</source>
            <target>${java.source-target.version}</target>
            <!-- IMPORTANT -->
            <useIncrementalCompilation>false</useIncrementalCompilation>
          </configuration>
        </plugin>

        <plugin>
          <groupId>org.codehaus.mojo</groupId>
          <artifactId>aspectj-maven-plugin</artifactId>
          <version>1.9</version>
          <configuration>
            <!--<showWeaveInfo>true</showWeaveInfo>-->
            <source>${java.source-target.version}</source>
            <target>${java.source-target.version}</target>
            <Xlint>ignore</Xlint>
            <complianceLevel>${java.source-target.version}</complianceLevel>
            <encoding>${project.build.sourceEncoding}</encoding>
            <!--<verbose>true</verbose>-->
            <!--<warn>constructorName,packageDefaultMethod,deprecation,maskedCatchBlocks,unusedLocals,unusedArguments,unusedImport</warn>-->
            <weaveDependencies>
              <dependency>
                <groupId>commons-codec</groupId>
                <artifactId>commons-codec</artifactId>
              </dependency>
            </weaveDependencies>
          </configuration>
          <executions>
            <execution>
              <!-- IMPORTANT -->
              <phase>process-sources</phase>
              <goals>
                <goal>compile</goal>
                <goal>test-compile</goal>
              </goals>
            </execution>
          </executions>
          <dependencies>
            <dependency>
              <groupId>org.aspectj</groupId>
              <artifactId>aspectjtools</artifactId>
              <version>${aspectj.version}</version>
            </dependency>
            <dependency>
              <groupId>org.aspectj</groupId>
              <artifactId>aspectjweaver</artifactId>
              <version>${aspectj.version}</version>
            </dependency>
          </dependencies>
        </plugin>

        <plugin>
          <groupId>org.codehaus.mojo</groupId>
          <artifactId>exec-maven-plugin</artifactId>
          <version>1.5.0</version>
          <configuration>
            <mainClass>${main-class}</mainClass>
          </configuration>
        </plugin>

      </plugins>
    </pluginManagement>

    <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>aspectj-maven-plugin</artifactId>
      </plugin>
      <plugin>
        <artifactId>maven-clean-plugin</artifactId>
        <version>2.5</version>
        <executions>
          <execution>
            <id>remove-unwoven</id>
            <!-- Phase 'process-classes' is in between 'compile' and 'package' -->
            <phase>process-classes</phase>
            <goals>
              <goal>clean</goal>
            </goals>
            <configuration>
              <!-- No full clean, only what is specified in 'filesets' -->
              <excludeDefaultDirectories>true</excludeDefaultDirectories>
              <filesets>
                <fileset>
                  <directory>${project.build.outputDirectory}</directory>
                  <includes>
                    <include>org/apache/commons/codec/**</include>
                    <include>META-INF/**</include>
                  </includes>
                  <excludes>
                    <exclude>**/Base64.class</exclude>
                  </excludes>
                </fileset>
              </filesets>
              <!-- Set to true if you want to see what exactly gets deleted -->
              <verbose>false</verbose>
            </configuration>
          </execution>
        </executions>
      </plugin>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
      </plugin>
    </plugins>

  </build>

  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>org.aspectj</groupId>
        <artifactId>aspectjrt</artifactId>
        <version>${aspectj.version}</version>
        <scope>runtime</scope>
      </dependency>
      <dependency>
        <groupId>commons-codec</groupId>
        <artifactId>commons-codec</artifactId>
        <version>1.10</version>
      </dependency>
    </dependencies>
  </dependencyManagement>

  <dependencies>
    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjrt</artifactId>
    </dependency>
    <dependency>
      <groupId>commons-codec</groupId>
      <artifactId>commons-codec</artifactId>
    </dependency>
  </dependencies>

  <organization>
    <name>Scrum-Master.de - Agile Project Management</name>
    <url>http://scrum-master.de</url>
  </organization>
</project>

如您所见，我在 AspectJ Maven 插件中使用了 <weaveDependencies>（对于 AspectJ 编译器来说转换为 -inpath）并结合了 Maven Clean 插件的特殊执行，该插件删除了所有不需要的 classes 和原始 JAR 中的 META-INF 目录。

如果你运行 mvn clean package exec:java 你看到：

[INFO] ------------------------------------------------------------------------
[INFO] Building aspectj-weave-single-3rd-party-class 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
(...)
[INFO] --- aspectj-maven-plugin:1.9:compile (default) @ aspectj-weave-single-3rd-party-class ---
[INFO] Showing AJC message detail for messages of types: [error, warning, fail]
(...)
[INFO] --- maven-clean-plugin:2.5:clean (remove-unwoven) @ aspectj-weave-single-3rd-party-class ---
[INFO] Deleting C:\Users\Alexander\Documents\java-src\SO_AJ_MavenWeaveSingle3rdPartyClass\target\classes (includes = [org/apache/commons/codec/**, META-INF/**], excludes = [**/Base64.class])
(...)
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ aspectj-weave-single-3rd-party-class ---
[INFO] Building jar: C:\Users\Alexander\Documents\java-src\SO_AJ_MavenWeaveSingle3rdPartyClass\target\aspectj-weave-single-3rd-party-class-1.0-SNAPSHOT.jar
[INFO] 
[INFO] --- exec-maven-plugin:1.5.0:java (default-cli) @ aspectj-weave-single-3rd-party-class ---
Hello world!
execution(byte[] org.apache.commons.codec.binary.Base64.decodeBase64(byte[]))
Hell0 w0rld!
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------

这就是我的 target/classes 目录在构建后的样子：

如您所见，创建的 JAR 中只剩下一个 Apache Commons class 文件。

是否可以从罐子中编织一些类而排除其余的类？

Is it possible to weave some classes from a jar while excluding the rest of the classes?

java

aop

aspectj

bytecode

aspectj-maven-plugin

是否可以从罐子中编织一些 类 而排除其余的 类？

Is it possible to weave some classes from a jar while excluding the rest of the classes?

java

aop

aspectj

bytecode

aspectj-maven-plugin

是否可以从罐子中编织一些类而排除其余的类？