Java反射的基本操作

野性酷女 2022-06-16 05:56 231阅读 0赞

最近重新复习了Java反射，记录如下。  
通过反射获取类的基本信息：  
获取类的构造函数：

public static void getConstructors(Object obj) {
            Class class1 = obj.getClass();
            //get class1's constructors
            Constructor[] constructors = class1.getDeclaredConstructors();
            for (Constructor constructor : constructors) {
                String cName = constructor.getName();
                System.out.print(cName+"(");
                Class[] parameterTypes = constructor.getParameterTypes();
                for (Class type : parameterTypes) {
                    System.out.print(type.getName()+",");
                }
                System.out.println(")");
            }
        }
            //测试代码：
            ReflactDemo.getConstructors(new Integer(1));
            System.out.println("-----");
            ReflactDemo.getConstructors("test");

测试结果：

![这里写图片描述][SouthEast]

获取类的属性

public static void getFields(Object obj) {
            Class class1 = obj.getClass();
            //get class1's members
            Field[] fields = class1.getDeclaredFields();
            for (Field field : fields) {
                String fieldName = field.getName();
                String fieldType = field.getType().getSimpleName();
                System.out.println(fieldType + " " + fieldName);
            }
        }
    //测试代码
    class TestClass1{
        public String name = "bear";
        public int age = 18;
        public float power = (float) 10.6;
    
        public TestClass1() {
            this.name = "bear2";
        }
    
        public void print()
        {
            System.out.println(name+" "+age+" "+power);
        }
    }
    
    
    ReflactDemo.getFields(new TestClass1());

![这里写图片描述][SouthEast 1]  
获取类的方法：

public static void getMethods(Object object) {
            Class class1 = object.getClass();
            //get class1's methods;
            Method[] methods = class1.getDeclaredMethods();
            for (Method method : methods) {
                Type returnType = method.getGenericReturnType();
                System.out.print(returnType+" ");
                System.out.print(method.getName()+"(");
                Class[] types = method.getParameterTypes();
                for (Class type : types) {
                    System.out.print(type.getName()+",");
                }
                System.out.println(")");
            }
        }
        //测试代码：
        ReflactDemo.getMethods("klajs");

![这里写图片描述][SouthEast 2]

调用类的方法：

try { Class class1 = Class.forName("com.bear.TestClass1"); Method method = class1.getMethod("print", new Class[]{});
                method.invoke(class1.newInstance());
    
            } catch (ClassNotFoundException | NoSuchMethodException | SecurityException | IllegalAccessException | IllegalArgumentException | InvocationTargetException | InstantiationException e) { e.printStackTrace(); }

[SouthEast]: /images/20220616/8b6006c3f5d240768c13bb2046bd872d.png
[SouthEast 1]: /images/20220616/4aeabd6108ef495b8102c3c6b036eefe.png
[SouthEast 2]: /images/20220616/be2d68596712421f9dbe1e6c5bb24b25.png