Java 学习 注解

@TestAnnotation
public class Test {
}

@Retention(RetentionPolicy.RUNTIME)
public @interface TestAnnotation {
}

@Inherited
@Retention(RetentionPolicy.RUNTIME)
@interface Test {}@Test
public class A {}public class B extends A {}

@interface Persons {
Person[] value();
}@Repeatable(Persons.class)
@interface Person{
String role default "";
}@Person(role="artist")
@Person(role="coder")
@Person(role="PM")
public class SuperMan{}

@interface Persons {
Person[] value();
}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface TestAnnotation { int id(); String msg();}

@TestAnnotation(id=3,msg="hello annotation")
public class Test {}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface TestAnnotation { public int id() default -1; public String msg() default "Hi";}

@TestAnnotation()
public class Test {}

public @interface Check {
String value();
}

@Check("hi")
int a;

@Check(value="hi")
int a;

public @interface Perform {}

@Perform
public void testMethod(){}

public class Hero { @Deprecated
public void say(){
System.out.println("Noting has to say!");
} public void speak(){
System.out.println("I have a dream!");
}}

@SuppressWarnings("deprecation")
public void test1(){
Hero hero = new Hero();
hero.say();
hero.speak();
}

@SafeVarargs // Not actually safe!
static void m(List<String>... stringLists) {
Object[] array = stringLists;
List<Integer> tmpList = Arrays.asList(42);
array[0] = tmpList; // Semantically invalid, but compiles without warnings
String s = stringLists[0].get(0); // Oh no, ClassCastException at runtime!
}

@FunctionalInterface
public interface Runnable {
/**
* When an object implementing interface <code>Runnable</code> is used
* to create a thread, starting the thread causes the object's
* <code>run</code> method to be called in that separately executing
* thread.
* <p>
* The general contract of the method <code>run</code> is that it may
* take any action whatsoever.
*
* @see java.lang.Thread#run()
*/
public abstract void run();
}

public boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) {}

public <A extends Annotation> A getAnnotation(Class<A> annotationClass) {}

public Annotation[] getAnnotations() {}

@TestAnnotation()
public class Test { public static void main(String[] args) { boolean hasAnnotation = Test.class.isAnnotationPresent(TestAnnotation.class); if ( hasAnnotation ) {
TestAnnotation testAnnotation = Test.class.getAnnotation(TestAnnotation.class); System.out.println("id:"+testAnnotation.id());
System.out.println("msg:"+testAnnotation.msg());
} }}

@TestAnnotation(msg="hello")
public class Test { @Check(value="hi")
int a; @Perform
public void testMethod(){} @SuppressWarnings("deprecation")
public void test1(){
Hero hero = new Hero();
hero.say();
hero.speak();
} public static void main(String[] args) { boolean hasAnnotation = Test.class.isAnnotationPresent(TestAnnotation.class); if ( hasAnnotation ) {
TestAnnotation testAnnotation = Test.class.getAnnotation(TestAnnotation.class);
//获取类的注解
System.out.println("id:"+testAnnotation.id());
System.out.println("msg:"+testAnnotation.msg());
} try {
Field a = Test.class.getDeclaredField("a");
a.setAccessible(true);
//获取一个成员变量上的注解
Check check = a.getAnnotation(Check.class); if ( check != null ) {
System.out.println("check value:"+check.value());
} Method testMethod = Test.class.getDeclaredMethod("testMethod"); if ( testMethod != null ) {
// 获取方法中的注解
Annotation[] ans = testMethod.getAnnotations();
for( int i = 0;i < ans.length;i++) {
System.out.println("method testMethod annotation:"+ans[i].annotationType().getSimpleName());
}
}
} catch (NoSuchFieldException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println(e.getMessage());
} catch (SecurityException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println(e.getMessage());
} catch (NoSuchMethodException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.out.println(e.getMessage());
}
}}

package ceshi;
import ceshi.Jiecha;public class NoBug { @Jiecha
public void suanShu(){
System.out.println("1234567890");
}
@Jiecha
public void jiafa(){
System.out.println("1+1="+1+1);
}
@Jiecha
public void jiefa(){
System.out.println("1-1="+(1-1));
}
@Jiecha
public void chengfa(){
System.out.println("3 x 5="+ 3*5);
}
@Jiecha
public void chufa(){
System.out.println("6 / 0="+ 6 / 0);
} public void ziwojieshao(){
System.out.println("我写的程序没有 bug!");
}}

package ceshi;import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;@Retention(RetentionPolicy.RUNTIME)
public @interface Jiecha {}

package ceshi;import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;public class TestTool { public static void main(String[] args) {
// TODO Auto-generated method stub NoBug testobj = new NoBug(); Class clazz = testobj.getClass(); Method[] method = clazz.getDeclaredMethods();
//用来记录测试产生的 log 信息
StringBuilder log = new StringBuilder();
// 记录异常的次数
int errornum = 0; for ( Method m: method ) {
// 只有被 @Jiecha 标注过的方法才进行测试
if ( m.isAnnotationPresent( Jiecha.class )) {
try {
m.setAccessible(true);
m.invoke(testobj, null); } catch (Exception e) {
// TODO Auto-generated catch block
//e.printStackTrace();
errornum++;
log.append(m.getName());
log.append(" ");
log.append("has error:");
log.append("\n\r caused by ");
//记录测试过程中，发生的异常的名称
log.append(e.getCause().getClass().getSimpleName());
log.append("\n\r");
//记录测试过程中，发生的异常的具体信息
log.append(e.getCause().getMessage());
log.append("\n\r");
}
}
} log.append(clazz.getSimpleName());
log.append(" has ");
log.append(errornum);
log.append(" error."); // 生成测试报告
System.out.println(log.toString()); }}

public class ExampleUnitTest {
@Test
public void addition_isCorrect() throws Exception {
assertEquals(4, 2 + 2);
}
}

public class MainActivity extends AppCompatActivity { @BindView(R.id.tv_test)
TextView mTv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); ButterKnife.bind(this);
}
}

public interface GitHubService {
@GET("users/{user}/repos")
Call<List<Repo>> listRepos(@Path("user") String user);
}Retrofit retrofit = new Retrofit.Builder()
.baseUrl("https://api.github.com/")
.build();GitHubService service = retrofit.create(GitHubService.class);