Java反射——获取运行时类的内容

1.获取运行时类的属性　　

 1  public static void test1() {
 2         Class clazz = Person.class;
 3         //getFields():获取当前运行时类及其父类中声明为public访问权限的属性
 4         Field[] fields = clazz.getFields();
 5         for(Field f : fields) {
 6             System.out.println(f);
 7         }
 8         Field[] declaredFields = clazz.getDeclaredFields();
 9         for (Field f : declaredFields) {
10             //1.权限修饰符
11             int modifier = f.getModifiers();
12             System.out.println(modifier + "--" + Modifier.toString(modifier));
13             //2.获取数据类型
14             Class type = f.getType();
15             System.out.println(type);
16             //3.获取变量名
17             String fName = f.getName();
18             System.out.println(fName);
19         }
20     }

 

2.获取运行时类的方法

 1 public static void test1() {
 2         Class clazz = Person.class;
 3         //获取当前运行时类及其父类声明为public权限的方法
 4         Method[] methods = clazz.getMethods();
 5         for(Method m : methods) {
 6             System.out.println(m);
 7         }
 8         System.out.println();
 9         //获取当前运行时类声明的所有方法
10         Method[] declaredMethods = clazz.getDeclaredMethods();
11         for (Method m : declaredMethods) {
12             System.out.println(m);
13         }
14     }

获取方法内的有关信息

 1 public static void test2() {
 2         Class clazz = Person.class;
 3         Method[] declaredMethods = clazz.getDeclaredMethods();
 4         for (Method m : declaredMethods) {
 5             //1.获取方法声明的注解
 6             Annotation[] annotation = m.getAnnotations();
 7             for (Annotation a : annotation) {
 8                 System.out.println(a);
 9             }
10             //2.权限修饰符
11             System.out.println("修饰符为:" + Modifier.toString(m.getModifiers()));
12             //3.获取方法的返回值类型
13             System.out.println("返回值类型为:" + m.getReturnType());
14             //4.获取方法的方法名
15             System.out.println("方法名为:" + m.getName());
16             //5.形参列表
17             Class[] parameterTypes = m.getParameterTypes();
18             System.out.print("形参为:");
19             if (parameterTypes != null && parameterTypes.length != 0) {
20                 for (Class par : parameterTypes) {
21                     System.out.print(par.getName() + " ");
22                 }
23             }
24             System.out.println();
25             //6.抛出的异常
26             Class[] exceptionTypes = m.getExceptionTypes();
27             System.out.print("抛出的异常为:");
28             if (exceptionTypes != null && exceptionTypes.length != 0) {
29                 for (Class exc : exceptionTypes) {
30                     System.out.print(exc.getName() + " ");
31                 }
32             }
33             System.out.println();
34         }
35     }

 

3.获取构造器

 1 /*
 2     获取构造器结构
 3      */
 4     public static void test1() {
 5         Class clazz = Person.class;
 6         Constructor[] constructors = clazz.getConstructors();
 7         for (Constructor c : constructors) {
 8             System.out.println(c);
 9         }
10         Constructor[] declaredConstructor = clazz.getDeclaredConstructors();
11         for (Constructor c : declaredConstructor) {
12             System.out.println(c);
13         }
14     }

 

4.获取运行时带泛型的父类

 1 public static void test2() {
 2         Class clazz = Person.class;
 3         //获取带泛型父类
 4         Type genericSuperclass = clazz.getGenericSuperclass();
 5         //转为参数化类型
 6         ParameterizedType paramType = (ParameterizedType) genericSuperclass;
 7         //获取所有的参数
 8         Type[] actualTypeArguments = paramType.getActualTypeArguments();
 9         System.out.println(genericSuperclass);
10         System.out.println(actualTypeArguments[0].getTypeName());
11     }

 

5.获取运行时类所在的接口

1 public static void test3() {
2         Class clazz = Person.class;
3         Class[] interfaces = clazz.getInterfaces();
4         for (Class c : interfaces) {
5             System.out.println(c);
6         }
7     }

 

6.获取运行时类所在的包

1  public static void test4() {
2         Class clazz = Person.class;
3         Package pack = clazz.getPackage();
4         System.out.println(pack);
5     }

 

7.获取运行时类所在的注解

1 public static void test5() {
2         Class clazz = Person.class;
3         Annotation[] annotation = clazz.getAnnotations();
4         for (Annotation anno : annotation) {
5             System.out.println(anno);
6         }
7     }

 

posted @ 2022-07-10 19:27  jue1e0  阅读(210)  评论(0)    收藏  举报