Java反射实例

public class ReflectDemo {

	public ReflectDemo() {
		// TODO Auto-generated constructor stub
	}

	public static void main(String[] args) {
		// 使用反射机制进行处理
		try {
			//================获取反射对象=============================================
			System.out.println("********************获取反射对象********************");
			// 获取消息处理方法
			Class clazz = AddressReflect.class;
//			forName中的参数一定是完整的类名（包名+类名），效果与AddressReflect.class一样
//			Class clazz = Class.forName("com.swh.xml.entity.AddressReflect");
			System.out.println("============clazz=" + clazz);
			
			//================获取构造方法=============================================
			System.out.println("********************获取构造方法 并执行********************");
			Constructor con = clazz
					.getDeclaredConstructor(new Class[] { String.class ,Integer.class});
			con.setAccessible(true); // 设置可访问的权限
			Object obj = con.newInstance(new Object[] { "samgwenhao",123456 });
			System.out.println(obj); // 打印一下这个对象的信息

			// 获取所有的构造方法集合
			Constructor con1[] = clazz.getDeclaredConstructors();
			con1[0].setAccessible(true);
			
			//=================获取方法 处理================================================
			System.out.println("*******************获取方法处理*******************");
			//反射机制 方法的处理
			//getMethod获取指定公有方法 参数1：方法名 参数2：参数类型集合
			//getDeclaredMethod获取任意指定方法(包括私有，这时要设置setAccessible(true) )
			Method method = clazz.getDeclaredMethod("getMsg", String.class);
			method.setAccessible(true);//获取权限
			System.out.println("============method方法="+method);
			System.out.println(" method.getName获取方法名："+method.getName());

			String returnMsg = (String) method.invoke(obj, "obj");
			System.out.println("处理结果返回内容："+returnMsg);
			
			Object obj2 = clazz
					.getConstructor(new Class[] { String.class ,String.class})
					.newInstance(new Object[] { "samgwenhao","zipcode" });
			String returnMsg2 = (String) method.invoke(obj2, "obj2");
			System.out.println("处理结果返回内容："+returnMsg2);
			
			  // 通过默认无参构造方法创建一个新的对象     
		    Constructor con3 = clazz.getDeclaredConstructor(new Class[] {});
	        con3.setAccessible(true); // 设置可访问的权限
	        Object obj3 = con3.newInstance(new Object[] {});  
			String returnMsg3 = (String) method.invoke(obj3, "obj3");
			System.out.println("处理结果返回内容："+returnMsg3);
			
			//获取方法集合，用法同上
			//getMethod获取指定公有方法集合;
			//getDeclaredMethods获取任意指定方法集合(包括私有，这时要设置setAccessible(true) )
			Method[] methods = clazz.getDeclaredMethods();
			for(int i=0;i<methods.length;i++){
				methods[i].setAccessible(true);
				System.out.println("============methods["+i+"]="+methods[i] //同 toGenericString 方法
						+"nt methods[i].getName():"+methods[i].getName()
						+"nt methods[i].getModifiers():"+Modifier.toString(methods[i].getModifiers())
//						+"nt methods[i].getAnnotation:"+methods[i].getAnnotation(Annotation.class)
						+"nt methods[i].toGenericString():"+methods[i].toGenericString()
						);
			}
//			System.out.println("============methods[0]=" + methods[0]
//					+ " methods[1]=" + methods[1]);
			
			Class<?>[] clazz2 = methods[0].getParameterTypes();
			System.out.println("============clazz2[0]=" + clazz2
					+ " methods[1].getName=" + methods[1].getName());
			
			//==============字段属性处理方法================================================
			System.out.println("*******************字段属性处理方法*******************");
			//public Field getDeclaredField(String name)获取任意指定名字的成员
			//public Field[] getDeclaredFields() 获取所有的成员变量
			//public Field getField(String name)获取任意public成员变量
			//public Field[] getFields() 获取所有的public成员变量
			
			Field field = clazz.getDeclaredField("add");
			field.setAccessible(true);
			System.out.println("============获取成员变量：field="+field+"; field.getName()="+field.getName());
			
			Field[] fields = clazz.getDeclaredFields();
			for(int i=0;i<fields.length;i++){
				fields[i].setAccessible(true);
				System.out.println("============获取成员变量："
						+"nt fields["+i+"]" +fields[i] //同toGenericString方法
						+"nt fields.getName()="+fields[i].getName() // 字段名 add
						+"nt fields[i].getType():"+fields[i].getType()//返回类型 class java.lang.String
						+"nt fields[i].toGenericString():"+fields[i].toGenericString() //字段的定义 private java.lang.String com.swh.xml.entity.AddressReflect.add
						+"nt fields[i].getModifiers():"+Modifier.toString(fields[i].getModifiers())//返回字段的修饰符
						);
			}
			
			//=================给成员变量赋值 ,注意：成员变量必须实现set方法==========================
			System.out.println("*******************给成员变量赋值*******************");
			Field[] _fields = clazz.getDeclaredFields();
			Constructor _con = clazz.getDeclaredConstructor(new Class[] {});
			_con.setAccessible(true); // 设置可访问的权限(因此样例的无参构造函数是私有的)
	        Object _obj = _con.newInstance(new Object[] {});  
			for(Field _field : _fields){
//				_fields[i].setAccessible(true);
//				System.out.println("============获取成员变量：fields.getName()="+fields[i].getName()+" ; fields[i].getType():"+fields[i].getType());
				//构建方法名 setXXX 
				String fieldName = _field.getName() ;
				String firstLetter = fieldName.substring(0, 1).toUpperCase();
				String setMethodName = "set" + firstLetter + fieldName.substring(1);
				String getMethodName = "get" + firstLetter + fieldName.substring(1);
				
				//获取指定方法名 setXXX 和 参数类型 的方法
				Method setMethod = clazz.getMethod(setMethodName, _field.getType());
				Method getMethod = clazz.getMethod(getMethodName);//或用下面的方法
//				Method getMethod = clazz.getMethod(getMethodName,new Class[] {});
				
				if(String.class.isAssignableFrom(_field.getType())){
					System.out.println("进入String.class  _field.getType():"+_field.getType());
					//调用setXXX方法
					setMethod.invoke(_obj, "asdfas");
//					String result = getMethod.invoke(_obj, new Object[]{});
				}else if(boolean.class.isAssignableFrom(_field.getType())){
					System.out.println("进入boolean.class  _field.getType():"+_field.getType());
					//调用setXXX方法
					setMethod.invoke(_obj, true);
//					String result = getMethod.invoke(_obj, new Object[]{});
				}else if(Boolean.class.isAssignableFrom(_field.getType())){
					System.out.println("进入Boolean.class  _field.getType():"+_field.getType());
					//调用setXXX方法
					setMethod.invoke(_obj, true);
//					String result = getMethod.invoke(_obj, new Object[]{});
				}else if(int.class.isAssignableFrom(_field.getType())){
					System.out.println("进入int.class  _field.getType():"+_field.getType());
					//调用setXXX方法
					setMethod.invoke(_obj, 123);
//					String result = getMethod.invoke(_obj, new Object[]{});
				}else if(Integer.class.isAssignableFrom(_field.getType())){
					System.out.println("进入Integer.class  _field.getType():"+_field.getType());
					//调用setXXX方法
					setMethod.invoke(_obj, 123);
//					String result = getMethod.invoke(_obj, new Object[]{});
				}else{
					System.out.println("解析 _field.getType() 类型出错了");
				}
			}
			String result = (String) clazz.getMethod("toString").invoke(_obj);
			System.out.println("返回结果 result:"+result);
			
			//=================给实现了set方法的成员变量赋值 ==========================
			System.out.println("*******************给实现了set方法的成员变量赋值*******************");
			Method[] methods_ = clazz.getDeclaredMethods();
			
			for(Method method_ : methods_){
//				method_.setAccessible(true);//为true则可以访问private方法,默认为false
				String methodName = method_.getName();
				if(methodName.startsWith("set")){
					Method setMethod = clazz.getMethod(methodName,method_.getParameterTypes()[0]);
//					Method setMethod = clazz.getMethod(methodName,(Class) method_.getGenericParameterTypes()[0]);
					if(String.class.isAssignableFrom(method_.getParameterTypes()[0])){
						System.out.println("进入String.class  _field.getType():"+method_.getParameterTypes()[0]);
						//调用setXXX方法
						setMethod.invoke(_obj, "asdfas");
					}else if(boolean.class.isAssignableFrom(method_.getParameterTypes()[0])){
						System.out.println("进入boolean.class  _field.getType():"+method_.getParameterTypes()[0]);
						//调用setXXX方法
						setMethod.invoke(_obj, true);
					}else if(Boolean.class.isAssignableFrom(method_.getParameterTypes()[0])){
						System.out.println("进入Boolean.class  _field.getType():"+method_.getParameterTypes()[0]);
						//调用setXXX方法
						setMethod.invoke(_obj, true);
					}else if(int.class.isAssignableFrom(method_.getParameterTypes()[0])){
						System.out.println("进入int.class  _field.getType():"+method_.getParameterTypes()[0]);
						//调用setXXX方法
						setMethod.invoke(_obj, 123);
					}else if(Integer.class.isAssignableFrom(method_.getParameterTypes()[0])){
						System.out.println("进入Integer.class  _field.getType():"+method_.getParameterTypes()[0]);
						//调用setXXX方法
						setMethod.invoke(_obj, 123);
					}else{
						System.out.println("解析 _field.getType() 类型出错了");
					}
				  }
				}
			    String result2 = (String) clazz.getMethod("toString").invoke(_obj);
				System.out.println("返回结果 result:"+result2);
			

		} catch (Exception e) {
			// TODO: handle exception
			e.printStackTrace();
		}
	}
}

public class AddressReflect { 
    private String add; 
    private String zipcode; 
    private Integer num ;
    private static boolean flag ;
    
    private AddressReflect(){
    	System.out.println("进入无参构造方法");
    }

    public AddressReflect(String add, String zipcode) { 
        this.add = add; 
        this.zipcode = zipcode;
        System.out.println(toString());
    } 
    @SuppressWarnings("unused")
	private AddressReflect(String add,Integer num) { 
        this.add = add; 
        this.num = num  ;
        System.out.println(toString());
    } 
    @Override
    public String toString() { 
        return "Address{" + 
                "add='" + add + ''' + 
                ", zipcode='" + zipcode + ''' + 
                ",num="+num+",flag="+flag+"}"; 
    }

    private String getMsg(String content){
    	return "getMsg = "+content ;
    }
    
	public String getAdd() {
		return add;
	}


	public void setAdd(String add) {
		this.add = add;
	}

	public String getZipcode() {
		return zipcode;
	}

	public void setZipcode(String zipcode) {
		this.zipcode = zipcode;
	}

	public Integer getNum() {
		return num;
	}
	
	public void setNum(Integer num) {
		this.num = num;
	}

	public boolean getFlag() {
		return flag;
	}

	@SuppressWarnings("static-access")
	public void setFlag(boolean flag) {
		this.flag = flag;
	}
}