《Android进阶之光》--注解与依赖注入框架

时间:2022-10-22 04:06:31

No1:

标准注解:

1)@Override:覆写

2)@Deprecated:过时

3)@SuppressWarnings:取消警告

4)@SafeVarargs:申明使用了可变长度参数的方法

No2:

元注解:用来注解其他注解,从而创建新的注解

1)@Targe:注解所修饰的对象范围

2)@Inherited:注解可以被继承

3)@Documented:应该被JavaDoc工具记录

4)@Retention:保留策略

5)@Repeatable:一个注解在同一声明类型上多次使用

No3:

定义注解:

1)基本定义

public @interface Swordsman{

}
//使用
@Swordsman
public class AnnotationTest{ }

2)定义成员变量

public @interface Swordsman{
String name();
int age();
}
//使用
public class AnnotationTest{
@Swordsman(name="张无忌",age=23)
public void fighting(){
...
}
}
public @interface Swordsman{
String name() default "张无忌";
int age() default 23;
}
//使用
public class AnnotationTest{
@Swordsman
public void fighting(){ }
}

3)定义运行时注解

@Retention设定注解的保留策略

RetentionPolicy.RUNTIME:运行时动态获取注解信息

RententionPolicy.CLASS:编译时进行一些预处理操作

RententionPolicy.SOURCE:做一些检查性的操作

@Rentation(RetentationPolicy.CLASS)
public @interface Swordsman{
String name() default "张无忌";
int age() default 23;
}

No4:

运行时注解处理器

public class AnnotationProcessor{
public static void main(String[] args){
Method[] methods = AnnotationTest.class.getDeclaredMethods();
for(Method m:methods){
GET get = m.getAnnotation(GET.class);
System.out.println(get.value());
}
}
}

No5:

编译时注解处理器:

public class ClassProcessor extends AbstractProcessor{
@Override
public synchronized void init(ProcessingEnvironment processingEnv){
super.init(processingEnv);
}
@Override
public boolean process(Set<? extends TypeElement> annotations,RoundEnvironment roundEnv){
Messager messager = processingEnv.getMessager();
for(Element element:roundEnv.getElementsAnnotatedWith(BindView.class)){
if(element.getKind()==ElementKind.FIELD){
messager.printMessage(Diagnostic.Kind.NOTE,"printMessage:"+element.toString());
}
}
return true;
}
@Override
public Set<String> getSupportedAnnotationTypes(){
Set<String> annotations = new LinkedHashSet<String>();
annotations.add(BindView.class.getCanonicalName());
return annotations;
}
@Override
public SourceVersion getSupportedSourceVersion(){
return SourceVersion.latestSupported();
}
}

No6:

依赖注入:IoC(控制反转)容器在运行期间,动态地将某种依赖关系注入到对象中

No7:

为了解耦

public class Car{
private Engine mEngine;
public Car(){
mEngine = new PetrolEngine();
}
}

1)构造方法注入

public class Car{
private Engine mEngine;
public Car(Engine mEngine){
this.mEngine = mEngine;
}
}

2)Setter方法注入

public class Car{
private Engine mEngine;
public void set(Engine mEngine){
this.mEngine = mEngine;
}
}

3)接口注入

public interface ICar{
public void setEngine(Engine engine);
} public class Car implements ICar{
private Engine mEngine;
@Override
public void setEngine(Engine engine){
this.mEngine = engine;
}
}

No8:

《Android进阶之光》--ButterKnife

No9:

《Android进阶之光》--Dagger2