Android APT 实现控件注入框架SqInject的示例

public class MainActivity extends AppCompatActivity {
	
 //绑定ID
 @BindView(SqR.id.tv)
 TextView hello;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 SqInject.bind(this);
 Log.e("SqInject", hello.getText().toString());
 }

 //绑定点击事件
 @OnClick(SqR.id.tv)
 public void click(View view) {
 Intent intent = new Intent(MainActivity.this, TestActivity.class);
 startActivity(intent);
 }
}

@AutoService(Processor.class)
@SupportedSourceVersion(SourceVersion.RELEASE_7)
public class SqInjectProcessor extends AbstractProcessor {

 ...
	
 //核心方法
 @Override
 public boolean process(Set<? extends TypeElement> set, RoundEnvironment roundEnvironment) {
 //控件类注解解析,ResChecker检查资源id合法性，合法则生成"类名+$ViewBinder类,否则编译失败
 BindViewBuilder bindViewBuilder = new BindViewBuilder(roundEnvironment, mResChecker, mElementUtils, mTypeUtils, mFiler, mMessager);
 bindViewBuilder.build();
 //id类注解解析，ResChecker检查资源id合法性，合法则生成"类名+$IdBinder类",否则编译失败
 BindIdsBuilder bindIdsBuilder = new BindIdsBuilder(roundEnvironment, mResChecker, mElementUtils, mTypeUtils, mFiler, mMessager);
 bindIdsBuilder.build();
 return false;
 }
 
}

/**
 * 检测资源id在R文件中是否存在
 * @param name
 * @param type
 * @return
 */
 public boolean isIdValid(String name, String type) {
 String RClassName = mPackageNeme + ".R." + type;
 TypeElement RClassType = mElementUtils.getTypeElement(RClassName);
 if (RClassType == null) {
  mMessager.printMessage(Diagnostic.Kind.ERROR, RClassName + "不存在，请检查是否包名有误，或者类型错误");
 } else {
  //遍历属性
  for (Element element : RClassType.getEnclosedElements()) {
  String fieldName = element.getSimpleName().toString();
  if (name.equals(fieldName)) {
   return true;
  }
  }
 }
 return false;
 }

/**
 * 解析BindView注解
 * @return
 */
 private Map<TypeElement, List<VariableElement>> parseBindView(){
 Set<Element> elements = (Set<Element>) mRoundEnvironment.getElementsAnnotatedWith(BindView.class);
 if (!Utils.isEmpty(elements)) {
  Map<TypeElement, List<VariableElement>> map = new HashMap<>();
  for (Element element : elements) {
  if (element instanceof VariableElement) {
   //获取该属性所在类
   TypeElement targetElement = (TypeElement) element.getEnclosingElement();
   mTargetSet.add(targetElement);
   if (map.get(targetElement) == null) {
   List<VariableElement> targetStringLists = new ArrayList<>();
   targetStringLists.add((VariableElement) element);
   map.put(targetElement, targetStringLists);
   } else {
   map.get(targetElement).add((VariableElement) element);
   }
  }
  }
  return map;
 }
 return null;
 }

if (mBindViewIdTargetMap != null && mBindViewIdTargetMap.get(targetElement) != null) {
  List<VariableElement> viewElements = mBindViewIdTargetMap.get(targetElement);
  //方法体
  for (VariableElement viewElement : viewElements) {
   //获取属性名
   String fieldName = viewElement.getSimpleName().toString();
   //获取类型
   TypeMirror typeMirror = viewElement.asType();
   TypeElement fieldClassElement = (TypeElement) mTypeUtils.asElement(typeMirror);
   mMessager.printMessage(Diagnostic.Kind.NOTE, "注解的字段类型为: " + fieldClassElement.getQualifiedName().toString());
   TypeElement fieldType = mElementUtils.getTypeElement(fieldClassElement.getQualifiedName());
   ClassName fieldClassName = ClassName.get(fieldType);
   //获取@BindView注解的值,即名称
   String name = viewElement.getAnnotation(BindView.class).value();
   //检测名称是否合法
   if(!mResChecker.isIdValid(name, "id")){
   mMessager.printMessage(Diagnostic.Kind.ERROR, "R文件中不存在id为" + name + "的值");
   }
   methodBuilder.addStatement("target.$N = $T.findRequiredViewAsType(source, $S, $S, $T.class)", fieldName, JptConstants.UTILS, name, "field " + fieldName,fieldClassName);
  }
  }

public class MainActivity$ViewBinder implements ViewBinder<MainActivity> {
 @Override
 public void bindView(final MainActivity target, final View source) {
 //这里就是上面的代码生成的
 target.hello = ViewUtils.findRequiredViewAsType(source, "tv", "field hello", TextView.class);
 IdUtils.findViewByName("tv", source).setOnClickListener(new DebouncingOnClickListener() {
 public void doClick(View v) {
 target.click(v);
 }
 } );
 }
}