public class Example_01 {
String s;
int i,i2,i3;
private Example_01(){}
protected Example_01(String s,int i){
this.s = s;
this.i = i;
}
public Example_01(String... strings) throws NumberFormatException{
if(0 < strings.length){
i = Integer.valueOf(strings[0]);
}
if(1 < strings.length){
i2 = Integer.valueOf(strings[1]);
}
if(2 < strings.length){
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);
}
}
import java.lang.reflect.Constructor;
public class Main_01 {
public static void main(String[] args) {
Example_01 example = new Example_01("10","20","30");
Class<? extends Example_01> exampleC = example.getClass();
Constructor[] declaredConstructors = exampleC.getDeclaredConstructors();
for(int i = 0; i < declaredConstructors.length; i++){
Constructor<?> constructor = declaredConstructors[i];
System.out.println("查看是否允许带有可变数量的参数："+constructor.isVarArgs());
System.out.println("该构造方法的入口参数类型依次为：");
Class[] parameterTypes = constructor.getParameterTypes();
for (int j = 0; j < parameterTypes.length; j++) {
System.out.println(""+parameterTypes[j]);
}
System.out.println("该构造方法可能抛出的异常类型为:");
Class[] exceptionTypes = constructor.getExceptionTypes();
for (int j = 0; j < exceptionTypes.length ; j++) {
System.out.println(""+exceptionTypes[j]);
}
Example_01 example2 = null;
while (example2 == null){
try{
if(i == 2){
example2 = (Example_01)constructor.newInstance();
}else if(i == 1){
example2 = (Example_01)constructor.newInstance("7",5);
}else {
Object[] parameters = new Object[]{new String[]{"100","200","300"}};
example2 = (Example_01)constructor.newInstance(parameters);
}
}catch (Exception e){
System.out.println("在创建对象时抛出的异常，下面执行setAccessible()方法");
constructor.setAccessible(true);
}
}
if(example2 != null){
example2.print();
System.out.println();
}
}
}
}
public class Example_02 {
int i;
public float f;
protected boolean b;
private String s;
}
import java.lang.reflect.Field;
public class Main_02 {
public static void main(String[] args) {
Example_02 example = new Example_02();
Class exampleC = example.getClass();
Field[] declaredFields = exampleC.getDeclaredFields();
for (int i = 0; i < declaredFields.length; i++) {
Field field = declaredFields[i];
System.out.println("名称为:"+field.getName());
Class fieldType = field.getType();
System.out.println("类型为："+field);
boolean isTurn = true;
while (isTurn){
try {
isTurn = false;
System.out.println("修改前的值为："+field.get(example));
if(fieldType.equals(int.class)){
System.out.println("利用方法setInt（）修改成员变量的值");
field.setInt(example,168);
}else if(fieldType.equals(float.class)){
System.out.println("利用方法setFloat（）修改成员变量的值");
field.setFloat(example,99.9F);
}else if(fieldType.equals(boolean.class)){
System.out.println("利用方法setBoolean()修改成员变量的值");
field.setBoolean(example,true);
}else {
System.out.println("利用方法set()方法修改成员变量的值");
field.set(example,"MWQ");
}
System.out.println("修改后的值为："+field.get(example));
}catch (Exception e){
System.out.println("在设置成员变量值时抛出的异常，下面执行setAccessible()方法");
field.setAccessible(true);
isTurn = true;
}
}
System.out.println();
}
}
}
public class Example_03 {
static void staticMethod(){
System.out.println("执行staticMethod()方法");
}
public int publicMethod(int i){
System.out.println("执行publicMethod()方法");
return i*100;
}
protected int protectedMethod(String s,int i) throws NumberFormatException{
System.out.println("执行protectedMethod（）方法");
return Integer.valueOf(s)+i;
}
private String privateMethod(String... strings){
System.out.println("执行privateMethod（）方法");
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i <strings.length ; i++) {
stringBuilder.append(strings[i]);
}
return stringBuilder.toString();
}
}
import java.lang.reflect.Method;
public class Main_03 {
public static void main(String[] args) {
Example_03 example = new Example_03();
Class exampleC = example.getClass();
Method[] declaredMethods = exampleC.getDeclaredMethods();
for (int i = 0; i <declaredMethods.length ; i++) {
Method method = declaredMethods[i];
System.out.println("名称为："+method.getName());
System.out.println("是否允许带有可变数量的参数："+method.isVarArgs());
System.out.println("入口参数类型依次为：");
Class[] parameterTypes = method.getParameterTypes();
for (int j = 0; j < parameterTypes.length; j++) {
System.out.println(parameterTypes[j]);
}
System.out.println("返回值类型为："+method.getReturnType());
System.out.println("可能抛出的异常类型有：");
Class[] exceptionTypes = method.getExceptionTypes();
for (int j = 0; j <exceptionTypes.length ; j++) {
System.out.println(exceptionTypes[j]);
}
boolean isTurm = true;
while (isTurm){
try {
isTurm = false;
if("staticMethod".equals(method.getName())){
method.invoke(example);
}
else if("publicMethod".equals(method.getName())){
System.out.println("返回值为"+method.invoke(example,168));
}
else if("protectedMethod".equals(method.getName())){
System.out.println("返回值为"+method.invoke(example,"7",5));
}
else if("privatedMethod".equals(method.getName())){
Object[] parameters = new Object[]{new String[]{"M","W","Q"}};
System.out.println("返回值为"+method.invoke(example,parameters));
}
}catch (Exception e){
System.out.println("在执行方法时抛出异常下面执行setAccessible()方法");
method.setAccessible(true);
isTurm = true;
}
}
System.out.println();
}
}
}
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target(ElementType.CONSTRUCTOR)
@Retention(RetentionPolicy.RUNTIME)
public @interface Constructor_Annotation {
String value() default "默认构造方法";
}
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Target({ElementType.FIELD,ElementType.METHOD,ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
public @interface Field_Method_Parameter_Annotation {
String describe();
Class type() default void.class;
}
public class Record {
@Field_Method_Parameter_Annotation(describe = "编号",type = int.class)
int id;
@Field_Method_Parameter_Annotation(describe = "姓名",type = String.class)
String name;
@Constructor_Annotation()
public Record(){}
@Constructor_Annotation("立即初始化构造方法")
public Record(@Field_Method_Parameter_Annotation(describe = "编号",type = int.class)
int id,
@Field_Method_Parameter_Annotation(describe = "姓名",type = String.class)
String name
){
this.id = id;
this.name = name;
}
@Field_Method_Parameter_Annotation(describe = "获取编号",type = int.class)
public int getId(){
return id;
}
@Field_Method_Parameter_Annotation(describe = "设置编号")
public void setId(
@Field_Method_Parameter_Annotation(describe = "编号",type = int.class)
int id
){
this.id = id;
}
@Field_Method_Parameter_Annotation(describe = "编号",type = String.class)
public String getName(){
return name;
}
@Field_Method_Parameter_Annotation(describe = "设置姓名")
public void setName(
@Field_Method_Parameter_Annotation(describe = "姓名",type = String.class)
String name
){
this.name = name;
}
}