从头开始一个 JSR269 工程

修改 pom.xml

添加依赖 sun.tools：

<dependency>
    <groupId>com.sun.tools</groupId>
    <artifactId>com.sun.tools</artifactId>
    <version>1.6</version>
</dependency>

处理资源文件，跳过执行自定义 processor ：

<build>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <excludes>
                <exclude>META-INF/**/*</exclude>
            </excludes>
        </resource>
    </resources>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-resources-plugin</artifactId>
            <version>2.6</version>
            <executions>
                <execution>
                    <id>process-META</id>
                    <phase>prepare-package</phase>
                    <goals>
                        <goal>copy-resources</goal>
                    </goals>
                    <configuration>
                        <outputDirectory>target/classes</outputDirectory>
                        <resources>
                            <resource>  <directory>${basedir}/src/main/resources/</directory>
                                <includes>
                                    <include>**/*</include>
                                </includes>
                            </resource>
                        </resources>
                    </configuration>
                </execution>
            </executions>
        </plugin>
        ... 省略其它插件
    </plugins>
</build>

新建一个编译时注解

这个注解就是对外的注解，后续引用该包的源码上带该注解的都会被处理：

package cn.lzxz1234.jsr269.core;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

Retention(RetentionPolicy.SOURCE)
@Target(ElementType.METHOD)
public @interface Api {

}

新建处理类

编译时的执行类，可以在这里对被编译的类进行方法、字段的增删修改，也可以另外添加新类等任意操作：

package cn.lzxz1234.jsr269.core;

import java.util.*;

import javax.annotation.processing.*;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.*;

import com.sun.source.tree.Tree.Kind;
import com.sun.tools.javac.api.JavacTrees;
import com.sun.tools.javac.code.Symbol.ClassSymbol;
import com.sun.tools.javac.processing.JavacProcessingEnvironment;
import com.sun.tools.javac.tree.*;
import com.sun.tools.javac.tree.JCTree.*;
import com.sun.tools.javac.util.*;

@SupportedAnnotationTypes("cn.lzxz1234.jsr269.core.Api")
public class ApiProcessor extends AbstractProcessor {

    private JavacTrees trees;
    private TreeMaker treeMaker;
    private Names names;

    @Override
    public SourceVersion getSupportedSourceVersion()
    {
      return SourceVersion.latest();
    }

    @Override
    public synchronized void init(ProcessingEnvironment processingEnv) {
        super.init(processingEnv);

        this.trees = JavacTrees.instance(processingEnv);
        Context context = ((JavacProcessingEnvironment)processingEnv).getContext();
        this.treeMaker = TreeMaker.instance(context);
        this.names = Names.instance(context);
    }

    /**
     * 处理注解
     *
     * @param annotations
     * @param env
     * @return
     */
    @Override
    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment env) {

        // 处理过程就略了
        return true;
    }

}

示例处理类没做任何处理，具体逻辑还是看业务要求，在这里推荐个工具类吧：JavaPoet

添加配置文件

在 src/main/resources/META-INF/services 目录里新建配置文件 javax.annotation.processing:

cn.lzxz1234.jsr269.core.ApiProcessor

All Done !

到这就结束了，打包引用就可以了，这算是最精简的起步指南了吧