Java 反射 調用 demo

標籤：返回   pac   cto   targe   泛型   this   setname   method   override   

基礎類.供demo反射練習

 1 package fanshe; 2  3 public class Person { 4     public String name; 5     private String age; 6     private int p; 7     public Person() {}; 8     public Person(String name, String age) { 9         super();10         this.name = name;11         this.age = age;12     }13     private Person(String name, String age,int p) {14         super();15         this.name = name;16         this.age = age;17         this.p = p;18     }19     public String getName() {20         return name;21     }22     @Override23     public String toString() {24         return "Person [name=" + name + ", age=" + age + "]" + "p -"+ p;25     }26     public void setName(String name) {27         this.name = name;28     }29     public String getAge() {30         return age;31     }32     public void setAge(String age) {33         this.age = age;34     }35 }

反射demo類

 1 package fanshe; 2  3 import java.lang.reflect.Constructor; 4 import java.lang.reflect.Field; 5 import java.lang.reflect.InvocationTargetException; 6 import java.lang.reflect.Method; 7  8 public class demo1 { 9 10     public static void main(String[] args) {11         // TODO Auto-generated method stub12         try {13             d_3();14         } catch (Exception e) {15             // TODO: handle exception16             e.printStackTrace();17         }18     }19     20     private static void d_1() {21         Person p = new Person();22         Class  c = p.getClass();23     24     }25     26     private static void d_2() {27         Class  c =  Person.class;28           System.out.println(c);29     }30     private static void d_3() throws ClassNotFoundException, NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, NoSuchFieldException {31         Class  c = Class.forName("fanshe.Person");32         33         //--------------------------//34         Constructor con = c.getConstructor(); //獲得 空參數的構造器 public35         Object o= con.newInstance(); //運行擷取到的構造方法36         System.out.println(o.toString());37         38         //--------------------------//39         Constructor con2 = c.getConstructor(String.class,String.class); //獲得帶有參數的構造方法 public40         Object o2 = (Person)con2.newInstance("a","22");41         System.out.println(o2.toString());42         43         //--------------------------//44         45         Constructor con3 = c.getDeclaredConstructor(String.class,String.class,int.class); //獲得帶有參數的構造方法 private46         con3.setAccessible(true);47         Object o3 = (Person)con3.newInstance("a","22",14);48         System.out.println(o3.toString());49         50         //--------------------------//51         Object tmp_obj = c.newInstance();52         Field f_name = c.getField("name");//獲得成員變數 public53         f_name.set(tmp_obj, "abc"); //設定變數54         System.out.println(tmp_obj);55         56         //--------------------------//57         Field f_age = c.getDeclaredField("age");//獲得成員變數 public58         System.out.println(f_age);59         60         //--------------------------//61         Method m_getName = c.getMethod("getName"); //獲得類函數無參數 public62         Object o1 = m_getName.invoke(tmp_obj); //運行getName方法.傳回值 反給obj63         System.out.println(o1);64         65         //--------------------------//66         Method m_setName = c.getMethod("setName",String.class);67         m_setName.invoke(tmp_obj,"abcdqweqwe");68         System.out.println(tmp_obj.toString());69     }70 }

通過反射.繞開泛型

1 ArrayList<String> arr = new ArrayList<String>();2 arr.add("a");3 Class carr = arr.getClass();4 Method arr_add = carr.getMethod("add",Object.class);5 arr_add.invoke(arr, 1);6 arr_add.invoke(arr, 2);7 arr_add.invoke(arr, 3);8 arr_add.invoke(arr, 4);9 System.out.println(arr);

 

Java 反射 調用 demo