# AptDemo

**Repository Path**: bear_android/AptDemo

## Basic Information

- **Project Name**: AptDemo
- **Description**: No description available
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2019-12-10
- **Last Updated**: 2020-12-19

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# Apt + JavaPoet
## APT 步骤
1.  创建java lib annotation 和 compiler
2.  创建依赖关系
```java
    // ---- compiler ----
    // 谷歌的服务
    compileOnly 'com.google.auto.service:auto-service:1.0-rc6'
    annotationProcessor 'com.google.auto.service:auto-service:1.0-rc6'
    // 注解项目
    implementation project(':annotation')
    // 控制台中文乱码的问题
    tasks.withType(JavaCompile){
        options.encoding = "UTF-8"
    }
    // ---- app ----
    implementation project(':annotation')
    annotationProcessor project(':compiler')
```
3.  创建注解类
```java
    // ---- annotation ----
    @Target(ElementType.TYPE)
    @Retention(RetentionPolicy.CLASS)
    public @interface ARouter {
        String path();
    }
```
4.  创建注解执行类
```java
@AutoService(Processor.class)
// 接收的类型
@SupportedAnnotationTypes({Constants.AROUTER_ANNOTATION_TYPES})
// JDK的版本
@SupportedSourceVersion(SourceVersion.RELEASE_7)
public class ARouterProcessor extends AbstractProcessor {
    // 操作Element工具类
    private Elements elementsUtils;
    // 打印日志
    private Messager messager;
    // 文件生成器
    private Filer filer;

    @Override
    public synchronized void init(ProcessingEnvironment processingEnvironment) {
        super.init(processingEnvironment);
        // 初始化工作
        elementsUtils = processingEnvironment.getElementUtils();
        messager = processingEnvironment.getMessager();
        filer = processingEnvironment.getFiler();
    }

// 可以用注解来代替

//    @Override
//    public Set<String> getSupportedAnnotationTypes() {
//        return super.getSupportedAnnotationTypes();
//        // 支持的注解类型
//    }
//
//    @Override
//    public SourceVersion getSupportedSourceVersion() {
//        return super.getSupportedSourceVersion();
//        // 支持的JDK版本
//    }
//
//
//    @Override
//    public Set<String> getSupportedOptions() {
//        return super.getSupportedOptions();
//        // 接受参数
//    }

    @Override
    public boolean process(Set<? extends TypeElement> set, RoundEnvironment roundEnvironment) {
        if(set.isEmpty()) return false;
        // 获取所有带有ARouter注解的类节点
        Set<? extends Element> elements = roundEnvironment.getElementsAnnotatedWith(ARouter.class);
        for(Element element:elements){
            // 通过类节点，获取包节点全路径名
            String packageName = elementsUtils.getPackageOf(element).getQualifiedName().toString();
            // 获取简单类名
            String className = element.getSimpleName().toString();
            messager.printMessage(Diagnostic.Kind.NOTE,"备注解的类："+className);
            // 最终生成类的名称
            String finalClassName = className + "$$ARouter";
            try{
                JavaFileObject sourceFile = filer.createSourceFile(packageName+"."+finalClassName);
                Writer writer = sourceFile.openWriter();
                writer.write("package "+packageName+";\n");
                writer.write("import android.util.Log;\n");
                writer.write("public class "+finalClassName+" {\n");
                writer.write("public void hello (String path){\n");
                writer.write("Log.d(\"aaa\",\"path:\"+path);\n");
                writer.write("}\n");
                writer.write("}\n");
                writer.close();
            }catch (IOException e){
                e.printStackTrace();
            }
        }
        return true;
    }
}
```
## Java Poet
1.  第一二三步同上
2.  第四步
```java
    // 创建了一个main方法案例

    public void parseElements(Set<? extends Element> elements) throws IOException{
        // 方法
        MethodSpec mainMethod = MethodSpec.methodBuilder("main")
                .addModifiers(Modifier.PUBLIC,Modifier.STATIC)
                .returns(void.class)
                .addParameter(String[].class,"args")
                .addStatement("$T.out.println($S)",System.class,"Hello JavaPoet")
                .build();
        // 类
        TypeSpec helloWorld = TypeSpec.classBuilder("Hello$$world")
                .addModifiers(Modifier.PUBLIC,Modifier.FINAL)
                .addMethod(mainMethod)
                .build();
        // 文件生成器
        JavaFile javaFile = JavaFile.builder("com.chamei.builder",helloWorld)
                .build();
        javaFile.writeTo(filer);
        messager.printMessage(Diagnostic.Kind.NOTE,"文件生成结束>>>>>>>>>>>>>");
    }
```