JAVA之反射

import java.lang.reflect.Constructor;

public class test{
public int i;
protected boolean b;
private double dd;
}

import java.awt.print.Paper;
import java.lang.reflect.Field;;

public class  fun{
public static void main(String[] args){
Field[] ff = test.class.getDeclaredFields();
test t = new test();
for(int i = 0;i<ff.length;i++){
Field field = ff[i];
System.out.println("名称为：" + field.getName());
Class fieldType = field.getType();
System.out.println("类型为：" + fieldType);

boolean isTurn = true;
while(isTurn){
try {
isTurn = false;
System.out.println("修改之前的值:" + field.get(t));
if(fieldType.equals(int.class)){
field.setInt(t, 168);
}else{
if(fieldType.equals(boolean.class)){
field.setBoolean(t, true);
}else{
if(fieldType.equals(double.class)){
field.setDouble(t, 1.11);
}
}
}
System.out.println("修改之后的值为：" + field.get(t));
} catch (Exception e) {
System.out.println("异常出现...");
field.setAccessible(true);
isTurn = true;
}
}
}
}
}

import java.lang.reflect.Constructor;

public class test{
static void static_A(){
System.out.println("static_A");
}

public int public_B(int i){
System.out.println("public_B");
return i*100;
}

protected int protected_C(String s,int i){
System.out.println("protected_C");
return Integer.valueOf(s) + i;
}

private String private_D(String... strings){
System.out.println("private_D");
StringBuffer sb = new StringBuffer();
for(int i=0;i<strings.length;i++){
sb.append(strings[i]);
}

return sb.toString();
}
}

import java.lang.reflect.Method;

public class  fun{
public static void main(String[] args){
Method[] dm = test.class.getDeclaredMethods();
//System.out.println(dm.length);
test t = new test();
for(int i=0;i<dm.length;i++){
Method method = dm[i];
System.out.println("方法名称为:" + method.getName());

Class[] paramentsType = method.getParameterTypes();
System.out.println("参数类型分别为:");
for(int j =0;j<paramentsType.length;j++){
System.out.println(paramentsType[j]);
}

Class returnType = method.getReturnType();
System.out.println("返回值类型为：" + returnType);

//System.out.println(method.getModifiers());//static=8 public=1 protected=4 private=130
int modifiersNum = method.getModifiers();
boolean flag = true;

while(flag){
try {
flag = false;
if(modifiersNum == 8){
method.invoke(t);
}else{
if(modifiersNum == 1){
System.out.println("返回值为：" + method.invoke(t, 168));
}else{
if(modifiersNum == 4){
System.out.println("返回值为：" + method.invoke(t, "7",5));
}else{
if(modifiersNum == 130){
System.out.println("返回值为：" + method.invoke(t, new Object[] {new String[] {"M","W","Q"}}));
}
}
}
}
} catch (Exception e) {
// TODO: handle exception
System.out.println("有异常....");
flag = true;
method.setAccessible(true);
}
}
}
}
}
invoke会执行指定的方法,注意到多个可变参数那里要用到Object[]的二维数组

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

public class  fun{
public static void main(String[] args){
Method[] dm = test.class.getDeclaredMethods();
//System.out.println(dm.length);
test t = new test();
for(int i=0;i<dm.length;i++){
Method method = dm[i];
System.out.println("方法名称为:" + method.getName());

Class[] paramentsType = method.getParameterTypes();
System.out.println("参数类型分别为:");
for(int j =0;j<paramentsType.length;j++){
System.out.println(paramentsType[j]);
}

Class returnType = method.getReturnType();
System.out.println("返回值类型为：" + returnType);

//System.out.println(method.getModifiers());//static=8 public=1 protected=4 private=130
String modifiersNum = Modifier.toString(method.getModifiers());
System.out.println(modifiersNum);
boolean flag = true;

while(flag){
try {
flag = false;
if(modifiersNum.equals("static")){
method.invoke(t);
}else{
if(modifiersNum.equals("public")){
System.out.println("返回值为：" + method.invoke(t, 168));
}else{
if(modifiersNum.equals("protected")){
System.out.println("返回值为：" + method.invoke(t, "7",5));
}else{
if(modifiersNum.equals("private transient")){
System.out.println("返回值为：" + method.invoke(t, new Object[] {new String[] {"M","W","Q"}}));
}
}
}
}
} catch (Exception e) {
// TODO: handle exception
System.out.println("有异常....");
flag = true;
method.setAccessible(true);
}
}
}
}
}

方法名称为:static_A
参数类型分别为:
返回值类型为：void
static_A
方法名称为:public_B
参数类型分别为:
int
返回值类型为：int
public_B
返回值为：16800
方法名称为:protected_C
参数类型分别为:
class java.lang.String
int
返回值类型为：int
protected_C
返回值为：12
方法名称为:private_D
参数类型分别为:
class [Ljava.lang.String;
返回值类型为：class java.lang.String
有异常....
private_D
返回值为：MWQ

类的标准名称：java.util.ArrayList
类的修饰符 : public
类的泛型参数：
E
类的所有接口
java.util.List<E>
interface java.util.RandomAccess
interface java.lang.Cloneable
interface java.io.Serializable
类的直接继承类:
java.util.AbstractList<E>
类的注解:
空

import java.awt.Window.*;
import java.io.ObjectInputStream.GetField;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import java.lang.reflect.Modifier;
import java.lang.reflect.TypeVariable;

public class  fun{
public static void main(String[] args) throws ClassNotFoundException{
Class<?> clazz = Class.forName("java.util.ArrayList");
System.out.println("类的标准名称：" + clazz.getCanonicalName());
System.out.println("类的修饰符 : " + Modifier.toString(clazz.getModifiers()));

//输出类的泛型参数
TypeVariable<?>[] typeVariables = clazz.getTypeParameters();
System.out.println("类的泛型参数：");
if(typeVariables.length != 0){
for(TypeVariable<?> typeVariable : typeVariables){
System.out.println(typeVariable + "\t");
}
}else{
System.out.println("空");
}

//输出类的所有接口
Type[] interFaces = clazz.getGenericInterfaces();
System.out.println("类的所有接口");
if(interFaces.length != 0){
for(Type type : interFaces){
System.out.println("\t" + type);
}
}else{
System.out.println("空");
}

//输出类的直接继承类
Type superClass = clazz.getGenericSuperclass();
System.out.println("类的直接继承类:");
if(superClass != null){
System.out.println(superClass);
}else{
System.out.println("空");
}

//输出类的所有注释信息
Annotation[] annotations = clazz.getAnnotations();
System.out.println("类的注解:");
if(annotations.length != 0){
for(Annotation annotation : annotations){
System.out.println("\t" + annotation);
}
}else{
System.out.println("空");
}
}
}