ARouter使用自定义注解处理器，自动生成跳转Activity的代码，避免手动填写和管理path

Posted 2022-11-11 guangdeshishe

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大家都知道ARouter要跳转目标Activity需要两步：

1.在Activity上添加Route注解

// Add annotations on pages that support routing (required)
// The path here needs to pay attention to need at least two levels : /xx/xx
@Route(path = "/test/activity")
public class YourActivity extend Activity 
    ...

2.执行ARouter.getInstance().build("/test/activity").navigation()方法即可实现跳转

// 1. Simple jump within application (Jump via URL in 'Advanced usage')
ARouter.getInstance().build("/test/activity").navigation();

// 2. Jump with param bundle
ARouter.getInstance().build("/test/1")
            .withBundle("key1", bundle)
            .navigation();

这就导致了我们需要去管理大量的path字符串，为什么ARouter不能在编译时期帮我们生成一个中间类去管理这些path字符串呢？

既然官方不支持那就自己来做一个吧，整体思路如下：

1.定义两个Activity并添加Route注解

@Route(path = "/login/LoginActivity")
class LoginActivity : AppCompatActivity()

@Route(path = "/login/RegisterActivity")
class RegisterActivity :BaseActivity()

2.通过自定义注解处理器，处理所有带Route注解的类，并取出注解里的path变量值，生成一个中间类用于管理所有的path，并封装跳转的方法，生成的中间类如下：

package com.agilezhu.processor.generate;

import android.os.Bundle;
import java.lang.String;

public final class ARouterPage 
  LoginActivity LoginActivity;

  RegisterActivity RegisterActivity;

  public ARouterPage() 
    LoginActivity.path = "/login/LoginActivity";
    RegisterActivity.path = "/login/RegisterActivity";
  

  public static class LoginActivity 
    public static String path;

    static 
      path= "/login/LoginActivity";
    

    public static void navigation(String key, Bundle params) 
      com.alibaba.android.arouter.launcher.ARouter.getInstance().build(path).withBundle(key,params).navigation();
    

    public static void navigation() 
      com.alibaba.android.arouter.launcher.ARouter.getInstance().build(path).navigation();
    
  

  public static class RegisterActivity 
    public static String path;

    static 
      path= "/login/RegisterActivity";
    

    public static void navigation(String key, Bundle params) 
      com.alibaba.android.arouter.launcher.ARouter.getInstance().build(path).withBundle(key,params).navigation();
    

    public static void navigation() 
      com.alibaba.android.arouter.launcher.ARouter.getInstance().build(path).navigation();

3.使用方法

//不带参数
ARouterPage.LoginActivity.navigation()
//带Bundle类型参数
ARouterPage.RegisterActivity.navigation("params",Bundle())
//也可以使用原有ARouter跳转方式携带各种参数
ARouter.getInstance().build(ARouterPage.LoginActivity.path).withBoolean("key",true).navigation();

有了注解处理器相当于自动帮我们生成了一个管理所有path的类：

可以通过类似调用目标Activity的方式进行跳转；
简化了ARouter跳转Acticity的代码；
每次添加、修改、删除对应的类，都不需要手动修改管理类代码；

注解处理器开发过程

添加一个java 类型Module

build.gradle 内容如下：

plugins 
    id 'java-library'

dependencies 
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    annotationProcessor 'com.google.auto.service:auto-service:1.0-rc7'//auto-service本身也是个注解处理器
    implementation 'com.google.auto.service:auto-service:1.0-rc7'//注解 processor 类，并对其生成 META-INF 的配置信息
    implementation 'com.squareup:javapoet:1.13.0' //通过类调用的形式来生成java代码，避免手动拼接字符串
    implementation "com.alibaba:arouter-annotation:1.0.6"



java 
    sourceCompatibility = JavaVersion.VERSION_1_7
    targetCompatibility = JavaVersion.VERSION_1_7

注解处理器核心类：

package com.agilezhu.processor;

import com.alibaba.android.arouter.facade.annotation.Route;
import com.google.auto.service.AutoService;
import com.squareup.javapoet.ClassName;
import com.squareup.javapoet.CodeBlock;
import com.squareup.javapoet.JavaFile;
import com.squareup.javapoet.MethodSpec;
import com.squareup.javapoet.TypeSpec;

import java.util.LinkedHashSet;
import java.util.Set;

import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.Filer;
import javax.annotation.processing.Messager;
import javax.annotation.processing.ProcessingEnvironment;
import javax.annotation.processing.Processor;
import javax.annotation.processing.RoundEnvironment;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.Element;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.TypeElement;
import javax.lang.model.util.Elements;
import javax.tools.Diagnostic;

/**
 * Generate ARouterPage.java for ARouter
 */
@AutoService(Processor.class)
public class ARouterProcessor extends AbstractProcessor 
    private Filer mFiler; //文件相关工具类：用于保存生成的java类文件
    private Elements mElementUtils; //元素相关工具类：用于获取java类文件
    private Messager mMessager;//用于打印日志

    @Override
    public synchronized void init(ProcessingEnvironment processingEnvironment) 
        super.init(processingEnvironment);
        mFiler = processingEnv.getFiler();
        mElementUtils = processingEnv.getElementUtils();
        mMessager = processingEnv.getMessager();
    

    @Override
    public Set<String> getSupportedAnnotationTypes() 
        //返回该注解处理器能够处理哪些注解
        Set<String> types = new LinkedHashSet<>();
        types.add(Route.class.getName());
        return types;
    

    @Override
    public SourceVersion getSupportedSourceVersion() 
        //返回当前注解处理器支持的java版本号
        return SourceVersion.latest();
    

    @Override
    public boolean process(Set<? extends TypeElement> set, RoundEnvironment roundEnvironment) 
        if (set == null || set.size() == 0) 
            return false;
        
        //将要生成的java完整类名
        String targetClassName = "ARouterPage";
        String packageName = "com.agilezhu.processor.generate";

        //创建方法(构造方法)
        MethodSpec.Builder bindMethodBuilder = MethodSpec.methodBuilder("<init>")
                .addModifiers(Modifier.PUBLIC);

        //创建类
        TypeSpec.Builder aRouterPageClassBuilder = TypeSpec.classBuilder(targetClassName)
                .addModifiers(Modifier.PUBLIC, Modifier.FINAL);

        //获取所有的源码文件
        Set<? extends Element> elements = roundEnvironment.getRootElements();
        for (Element element : elements) 
            if (!(element instanceof TypeElement)) //判断是否class类
                continue;
            
            //转换成class类型
            TypeElement typeElement = (TypeElement) element;
            //当前文件的类名
            String classSimpleName = element.getSimpleName().toString();
            Route routeAnnotation = element.getAnnotation(Route.class);
            if (routeAnnotation == null) 
                continue;
            
            mMessager.printMessage(Diagnostic.Kind.WARNING, "myProcess=====>>>>>" + classSimpleName);

            ClassName innerClassName = ClassName.get(packageName, targetClassName, classSimpleName);

            try 
                aRouterPageClassBuilder.addField(innerClassName, classSimpleName)
                        .addType(TypeSpec.classBuilder(innerClassName.simpleName())
                                .addModifiers(Modifier.STATIC, Modifier.PUBLIC)
                                .addField(String.class, "path", Modifier.PUBLIC, Modifier.STATIC)
                                .addStaticBlock(CodeBlock.builder().addStatement("path= \\"" + routeAnnotation.path() + "\\"").build())
                                .addMethod(MethodSpec
                                        .methodBuilder("navigation")
                                        .addParameter(String.class,"key")
                                        .addParameter(ClassName.get("android.os","Bundle"), "params")
                                        .addStatement("com.alibaba.android.arouter.launcher.ARouter.getInstance().build(path).withBundle(key,params).navigation()")
                                        .addModifiers(Modifier.PUBLIC, Modifier.STATIC)
                                        .build())
                                .addMethod(MethodSpec
                                        .methodBuilder("navigation")
                                        .addStatement("com.alibaba.android.arouter.launcher.ARouter.getInstance().build(path).navigation()")
                                        .addModifiers(Modifier.PUBLIC, Modifier.STATIC)
                                        .build())
                                .build());
             catch (Exception e) 
                e.printStackTrace();
            

            //构造方法中添加初始化代码
            bindMethodBuilder.addStatement(classSimpleName + ".path = \\"" + routeAnnotation.path() + "\\"");
        
        aRouterPageClassBuilder.addMethod(bindMethodBuilder.build());
        //创建java文件
        JavaFile bindProxyFile = JavaFile
                .builder(packageName, aRouterPageClassBuilder.build())
                .build();
        try 
            //保存java类文件
            bindProxyFile.writeTo(mFiler);
         catch (Throwable e) 
            e.printStackTrace();
        
        return false;

业务模块中引用：

kapt project(path: ':lib:processor') //这里用的kapt处理Kotlin代码

重新编译后，在当前模块build/generated/source/kapt/debug/com/agilezhu/processor/generate/ARouterPage.java路径下就能看到生成的类

模块代码下载

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