| 方法名 | 描述 |
|---|---|
| getName() | 获取全类名 |
| getSimpleName() | 获取简单类名 |
| getFields() | 获取所有public修饰的属性，包含本类以及父类的 |
| getDeclaredFields() | 获取本类中所有的属性 |
| getMethods() | 获取所有public修饰的方法，包含本类以及父类的，包括Object类中的 |
| getDeclaredMethods() | 获取本类所有的方法 |
| getConstructors() | 获取本类中所有的public修饰的构造器 |
| getDeclaredConstructors() | 获取本类中所有的构造器 |
| getPackage() | 返回包的信息 |
| getSuperClass() | 以Class形式返回父类信息 |
| getInterfaces() | 以Class[]形式返回接口信息 |
| getAnnotations() | 以Annotation[]形式返回注解信息 |
2.案例代码 2.1 准备一个父类 Pat注 ： 本文是 对上述的API 进行使用的案例，故会涉及到 类的继承、类的接口实现、注解相关的内容。
代码可能会比较长，但按照API 分开来看会比较明确。
package com.northcastle.groupclass;
public class Pat {
public String patField1; // public 修饰的可以被子类的反射拿到
private String patField2;
protected String patField3;
String patField4;
public Pat() {
}
public void patMethod1(){} // public 修饰的可以被子类的反射拿到
private void patMehod2(){}
protected void patMethod3(){}
void patMethod4(){}
}
2.2 准备两个接口
package com.northcastle.groupclass;
public interface Sleep {
void sleep();
}
package com.northcastle.groupclass;
public interface CatchMouse {
}
2.3 准备两个注解
package com.northcastle.groupclass;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Retention(RetentionPolicy.RUNTIME) // 必须是RUNTIME才可以被反射获取到
@Target(ElementType.TYPE)//可以修饰类的注解
public @interface ForReflection1 {
}
package com.northcastle.groupclass;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
public @interface ForReflection2 {
String value() default "hello";
String value2();
}
2.4 要进行反射的类
package com.northcastle.groupclass;
@ForReflection1
@ForReflection2(value = "World",value2 = "哈哈")
public class Cat extends Pat implements Sleep,CatchMouse{
//1.属性
public String catField1;
private String catField2;
protected String catField3;
String catFiled4;
//3.构造器
public Cat() {
}
public Cat(String catField1) {
this.catField1 = catField1;
}
public Cat(String catField1, String catField2) {
this.catField1 = catField1;
this.catField2 = catField2;
}
private Cat(String catField1, String catField2, String catField3) {
this.catField1 = catField1;
this.catField2 = catField2;
this.catField3 = catField3;
}
public Cat(String catField1, String catField2, String catField3, String catFiled4) {
this.catField1 = catField1;
this.catField2 = catField2;
this.catField3 = catField3;
this.catFiled4 = catFiled4;
}
//2.方法
public void catMethod1(){}
private void catMethod2(){}
protected void catMethod3(){}
void catMethod4(){}
//4.实现接口中的方法:会被反射getMethods() 和 getDeclaredMethods()获取到
@Override
public void sleep() {
System.out.println("cat sleep...");
}
}
2.5 测试类代码
package com.northcastle.groupclass;
import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Arrays;
public class Application {
public static void main(String[] args) throws ClassNotFoundException {
//0.获取Class类的对象
String classPath = "com.northcastle.groupclass.Cat";
Class clazz = Class.forName(classPath);
//1.getName():获取全类名
String name = clazz.getName();
System.out.println("getName() : "+name);
//2.getSimpleName():获取简单类名
String simpleName = clazz.getSimpleName();
System.out.println("getSimpleName() : "+simpleName);
//3.getFields():获取所有public修饰的属性，包含本类以及父类的
System.out.println("=========getFields() begin================");
Field[] fieldList1 = clazz.getFields();
for (Field field : fieldList1) {
System.out.println(field.getName()+"-"+field.toString());
}
System.out.println("=========getFields() end================");
//4.getDeclaredFields():获取本类中所有的属性
System.out.println("=========getDeclaredFields() begin================");
Field[] declaredFieldList = clazz.getDeclaredFields();
for (Field field : declaredFieldList) {
System.out.println(field.getName()+"-"+field.toString());
}
System.out.println("=========getDeclaredFields() end================");
//5.getMethods():获取所有public修饰的方法，包含本类以及父类的,包括Object类中的
System.out.println("=========getMethods() begin================");
Method[] methodList = clazz.getMethods();
for (Method method : methodList) {
System.out.println(method.getName()+"-"+method.toString());
}
System.out.println("=========getMethods() end================");
//6.getDeclaredMethods():获取本类所有的方法
System.out.println("=========getDeclaredMethods() begin================");
Method[] declaredMethodsList = clazz.getDeclaredMethods();
for (Method method : declaredMethodsList) {
System.out.println(method.getName()+"-"+method.toString());
}
System.out.println("=========getDeclaredMethods() end================");
//7.getConstructors():获取本类中所有的public修饰的构造器 : 1=public;2=private
System.out.println("=========getConstructors() begin================");
Constructor[] constructorList = clazz.getConstructors();
for (Constructor constructor : constructorList) {
System.out.println(constructor.getModifiers()+ "-"+constructor.getName()+"-"+ Arrays.toString( constructor.getParameters()));
}
System.out.println("=========getConstructors() end================");
//8.getDeclaredConstructors():获取本类中所有的构造器
System.out.println("=========getDeclaredConstructors() end================");
Constructor[] declaredConstructorsList = clazz.getDeclaredConstructors();
for (Constructor constructor : declaredConstructorsList) {
System.out.println(constructor.getModifiers()+ "-"+constructor.getName()+"-"+Arrays.toString(constructor.getParameters()));
}
System.out.println("=========getDeclaredConstructors() end================");
//9.getPackage():返回包的信息
Package aPackage = clazz.getPackage();
System.out.println("getPackage() : "+aPackage);
//10.getSuperClass():以Class形式返回父类信息
Class superclass = clazz.getSuperclass();
System.out.println("getSuperClass() : "+superclass);
//11.getInterfaces():以Class[]形式返回接口信息
System.out.println("=========getInterfaces() begin================");
Class[] interfaceList = clazz.getInterfaces();
for (Class interfaceClass : interfaceList) {
System.out.println(interfaceClass.getName());
}
System.out.println("=========getInterfaces() end================");
//12.getAnnotations():以Annotation[]形式返回注解信息
System.out.println("=========getAnnotations() begin================");
Annotation[] annotationList = clazz.getAnnotations();
for (Annotation annotation : annotationList) {
System.out.println(annotation+"-"+annotation.getClass()+"-"+annotation.annotationType()+"-");
}
// 获取注解的值
ForReflection2 annotation = clazz.getAnnotation(ForReflection2.class);
String value = annotation.value();
String value2 = annotation.value2();
System.out.println(value+"-"+value2);
System.out.println("=========getAnnotations() end ================");
}
}
2.6 运行结果
D:BDevToolsJavajdk1.8binjava.exe "-javaagent:D:BDevToolsBIDEAIntelliJ IDEA 2019.1libidea_rt.jar=52203:D:BDevToolsBIDEAIntelliJ IDEA 2019.1bin" -Dfile.encoding=UTF-8 -classpath D:BDevToolsJavajdk1.8jrelibcharsets.jar;D:BDevToolsJavajdk1.8jrelibdeploy.jar;D:BDevToolsJavajdk1.8jrelibextaccess-bridge-64.jar;D:BDevToolsJavajdk1.8jrelibextcldrdata.jar;D:BDevToolsJavajdk1.8jrelibextdnsns.jar;D:BDevToolsJavajdk1.8jrelibextjaccess.jar;D:BDevToolsJavajdk1.8jrelibextjfxrt.jar;D:BDevToolsJavajdk1.8jrelibextlocaledata.jar;D:BDevToolsJavajdk1.8jrelibextnashorn.jar;D:BDevToolsJavajdk1.8jrelibextsunec.jar;D:BDevToolsJavajdk1.8jrelibextsunjce_provider.jar;D:BDevToolsJavajdk1.8jrelibextsunmscapi.jar;D:BDevToolsJavajdk1.8jrelibextsunpkcs11.jar;D:BDevToolsJavajdk1.8jrelibextzipfs.jar;D:BDevToolsJavajdk1.8jrelibjavaws.jar;D:BDevToolsJavajdk1.8jrelibjce.jar;D:BDevToolsJavajdk1.8jrelibjfr.jar;D:BDevToolsJavajdk1.8jrelibjfxswt.jar;D:BDevToolsJavajdk1.8jrelibjsse.jar;D:BDevToolsJavajdk1.8jrelibmanagement-agent.jar;D:BDevToolsJavajdk1.8jrelibplugin.jar;D:BDevToolsJavajdk1.8jrelibresources.jar;D:BDevToolsJavajdk1.8jrelibrt.jar;D:DDevWorkspaceworkspaceJavajavaReflectionStudyoutproductionjavaReflectionStudy com.northcastle.groupclass.Application getName() : com.northcastle.groupclass.Cat getSimpleName() : Cat =========getFields() begin================ catField1-public java.lang.String com.northcastle.groupclass.Cat.catField1 patField1-public java.lang.String com.northcastle.groupclass.Pat.patField1 =========getFields() end================ =========getDeclaredFields() begin================ catField1-public java.lang.String com.northcastle.groupclass.Cat.catField1 catField2-private java.lang.String com.northcastle.groupclass.Cat.catField2 catField3-protected java.lang.String com.northcastle.groupclass.Cat.catField3 catFiled4-java.lang.String com.northcastle.groupclass.Cat.catFiled4 =========getDeclaredFields() end================ =========getMethods() begin================ sleep-public void com.northcastle.groupclass.Cat.sleep() catMethod1-public void com.northcastle.groupclass.Cat.catMethod1() patMethod1-public void com.northcastle.groupclass.Pat.patMethod1() wait-public final void java.lang.Object.wait() throws java.lang.InterruptedException wait-public final void java.lang.Object.wait(long,int) throws java.lang.InterruptedException wait-public final native void java.lang.Object.wait(long) throws java.lang.InterruptedException equals-public boolean java.lang.Object.equals(java.lang.Object) toString-public java.lang.String java.lang.Object.toString() hashCode-public native int java.lang.Object.hashCode() getClass-public final native java.lang.Class java.lang.Object.getClass() notify-public final native void java.lang.Object.notify() notifyAll-public final native void java.lang.Object.notifyAll() =========getMethods() end================ =========getDeclaredMethods() begin================ sleep-public void com.northcastle.groupclass.Cat.sleep() catMethod2-private void com.northcastle.groupclass.Cat.catMethod2() catMethod4-void com.northcastle.groupclass.Cat.catMethod4() catMethod3-protected void com.northcastle.groupclass.Cat.catMethod3() catMethod1-public void com.northcastle.groupclass.Cat.catMethod1() =========getDeclaredMethods() end================ =========getConstructors() begin================ 1-com.northcastle.groupclass.Cat-[java.lang.String arg0, java.lang.String arg1, java.lang.String arg2, java.lang.String arg3] 1-com.northcastle.groupclass.Cat-[java.lang.String arg0, java.lang.String arg1] 1-com.northcastle.groupclass.Cat-[java.lang.String arg0] 1-com.northcastle.groupclass.Cat-[] =========getConstructors() end================ =========getDeclaredConstructors() end================ 1-com.northcastle.groupclass.Cat-[java.lang.String arg0, java.lang.String arg1, java.lang.String arg2, java.lang.String arg3] 2-com.northcastle.groupclass.Cat-[java.lang.String arg0, java.lang.String arg1, java.lang.String arg2] 1-com.northcastle.groupclass.Cat-[java.lang.String arg0, java.lang.String arg1] 1-com.northcastle.groupclass.Cat-[java.lang.String arg0] 1-com.northcastle.groupclass.Cat-[] =========getDeclaredConstructors() end================ getPackage() : package com.northcastle.groupclass getSuperClass() : class com.northcastle.groupclass.Pat =========getInterfaces() begin================ com.northcastle.groupclass.Sleep com.northcastle.groupclass.CatchMouse =========getInterfaces() end================ =========getAnnotations() begin================ @com.northcastle.groupclass.ForReflection1()-class com.sun.proxy.$Proxy1-interface com.northcastle.groupclass.ForReflection1 @com.northcastle.groupclass.ForReflection2(value=World, value2=哈哈)-class com.sun.proxy.$Proxy2-interface com.northcastle.groupclass.ForReflection2 World-哈哈 =========getAnnotations() end ================ Process finished with exit code 03.完成
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