Java反射的使用-蒲公英云

主类：
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
/**
 * Created by cuboo on 2016/10/11.
 */
public class Main01 {
    public static void main(String agrs[]){
        Main01 mains = new Main01();
        exam01 exam = new exam01();
        //获得exam01的对象 方法1  方法2 examC = Class.forName(类路径) 方法3 examC = exam01.class
        Class examC = exam.getClass();
//        mains.constructor(examC);
//        mains.field(examC,exam);
        mains.method(examC,exam);
    }
    private void constructor(Class examC){
        //获得所有构造器方法
        Constructor[] constructors= examC.getDeclaredConstructors();
        //遍历构造方法
        for (int i = 0; i < constructors.length ; i++) {
            Constructor constrctor = constructors[i];
            System.out.println("是否带有可变数量的参数："+constrctor.isVarArgs());
            System.out.println("入口参数类型依次是：");
            Class[] parameter = constrctor.getParameterTypes();
            for (int j = 0; j < parameter.length; j++) {
                System.out.println(" "+parameter[j]);
            }
            System.out.println("可能抛出的异常值：");
            Class[] exception = constrctor.getExceptionTypes();
            for (int j = 0; j < exception.length; j++) {
                System.out.println(" "+exception[j]);
            }
            exam01 exam0 = null;
            while (exam0 == null){
                //如果为privatex对象则抛出异常
                try {
                    if (i == 2){
                        exam0 = (exam01) constrctor.newInstance();
                    }else if (i == 1){
                        exam0 = (exam01) constrctor.newInstance("2个参数的构造方法",2);
                    }else {
                        Object[] parameters = new Object[]{new String[]{"1","2","3"}};
                        exam0 = (exam01) constrctor.newInstance(parameters);
                    }
                }catch (Exception e){
                    System.out.println("创建对象时抛出异常，下面执行setAccessible()方法");
                    //设置允许访问
                    constrctor.setAccessible(true);
                }
            }
            exam0.print();
        }
    }
    private void field(Class examC,exam01 exam){
        //获得所有成员变量
        Field[] fields = examC.getDeclaredFields();
        for (int i = 0; i < fields.length; i++) {
            Field field = fields[i];
            //获得成员变量名称
            System.out.println("名称："+field.getName());
            System.out.println("类型："+field.getType());
            boolean isTurn = true;
            while(isTurn){
                //如果为private则抛出异常
                try{
                    isTurn = false;
                    System.out.println("修改前的值："+field.get(exam));
                    if (field.getType().equals(int.class)){
                       field.setInt(exam,100);
                    }else if (field.getType().equals(float.class)){
                        field.setFloat(exam,99.99f);
                    }else {
                        //设置各种类型的成员变量的值
                        field.set(exam,"成员变量"+field.getName());
                    }
                    System.out.println("修改后的值："+field.get(exam));
                }catch (Exception e){
                    System.out.println("设置成员变量是出现异常，执行setAccessible方法");
                    field.setAccessible(true);
                    isTurn = true;
                }
            }
        }
    }
    private  void method(Class examC,exam01 exam){
        //获得所有方法
        Method[] methods = examC.getDeclaredMethods();
        for (int i = 0; i < methods.length; i++) {
            Method method = methods[i];
            System.out.println("\n方法名称："+method.getName());
            System.out.println("是否可变参数："+method.isVarArgs());
            System.out.println("入口参数依次为：");
            Class[] parameters = method.getParameterTypes();
            if (parameters.length == 0){
                System.out.println("null");
            }
            for (int j = 0; j < parameters.length; j++) {
                System.out.println(parameters[j]);
            }
            //获得方法返回值的类型
            System.out.println("返回值类型："+method.getReturnType());
            boolean isTurn = true;
            while(isTurn){
                //如果为private则抛出异常
                try{
                    isTurn = false;
                    if ("staticMethod".equals(method.getName())){
                        System.out.println(method.invoke(exam));
                    }else if ("privateMethod".equals(method.getName())){
                        System.out.println(method.invoke(exam,100));
                    }else if ("protectedMethod".equals(method.getName())){
                        System.out.println(method.invoke(exam,"string",100));
                    }else if ("publicMethod".equals(method.getName())){
                        Object[] paras = new Object[]{new String[]{"a","b","c"}};
                       System.out.println(method.invoke(exam,paras));
                    }
                }catch (Exception e){
                    System.out.println("设置成员方法是出现异常，执行setAccessible方法");
                    method.setAccessible(true);
                    isTurn = true;
                }
            }
        }
    }
}
 调用类： /**
 * Created by cuboo on 2016/10/10.
 */
public class exam01 {
    String s;
    int i,i2,i3;
    private String str;
    protected int num;
    public float nums;
    private exam01(){
    }
    protected exam01(String s,int i){
        this.s = s;
        this.i = i;
    }
    public exam01(String... strings) throws NumberFormatException{
        if (strings.length > 0){
            i = Integer.valueOf(strings[0]);
        }
        if (strings.length > 1){
            i2 = Integer.valueOf(strings[1]);
        }
        if (strings.length > 2){
            i3 = Integer.valueOf(strings[2]);
        }
    }
    public void print(){
        System.out.println("s="+s);
        System.out.println("i="+i);
        System.out.println("i2="+i2);
        System.out.println("i3="+i3);
    }
    static void staticMethod(){
        System.out.println("执行staticMethod方法");
    }
    private void privateMethod(int i){
        System.out.println("执行privateMethod方法"+i);
    }
    protected void protectedMethod(String s,int i){
        System.out.println("执行protectedMethod方法"+s+" "+i);
    }
    public String publicMethod(String... strings){
        System.out.println("执行publicMethod方法");
        for (int j = 0; j < strings.length; j++) {
            System.out.print(strings[j]+" ");
        }
        System.out.println();
        return null;
    }
}