示例：此程序例子告诉大家如何操作Class/Field/Constructor/Method等与Java反射相关的类
package com.reflection;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
public class TestReflection {
private String username;
private String password;
private int[] age;
public void setUserName(String username) {
this.username = username;
}
private void setPassWord(String password) {
this.password = password;
}
public static void test01() throws ClassNotFoundException {
Class c1 = TestReflection.class;
Class c2 = Class.forName("com.reflection.TestReflection");
//获取指定的包名
String package01 = c1.getPackage().getName();
String package02 = c2.getPackage().getName();
System.out.println("package01 = " + package01);
System.out.println("package02 = " + package02);
//获取类的修饰符
int mod = c1.getModifiers();
String modifier = Modifier.toString(mod);
System.out.println("modifier = " + modifier);
//获取指定类的完全限定名
String className = c1.getName();
System.out.println("className = " + className);
//获取指定类的父类
Class superClazz = c1.getSuperclass();
String superClazzName = superClazz.getName();
System.out.println("superClazzName = " + superClazzName);
//获取实现的接口
Class[] interfaces = c1.getInterfaces();
for (Class t : interfaces) {
System.out.println("interfacesName = " + t.getName());
}
//获取指定类的成员变量
Field[] fields = c1.getDeclaredFields();
for (Field field : fields) {
modifier = Modifier.toString(field.getModifiers()); //获取每个
字段的访问修饰符
Class type = field.getType(); //获取字段的数据类型所对应的
Class对象
String name = field.getName(); //获取字段名
if (type.isArray()) { //如果是数组类型则需要特别处理
String arrType = type.getComponentType().getName() +
"[]";
System.out.println("" + modifier + " " + arrType + " "
+ name + ";");
} else {
System.out.println("" + modifier + " " + type + " " +
name + ";");
}
}
//获取类的构造方法
Constructor[] constructors = c1.getDeclaredConstructors();
for (Constructor constructor : constructors) {
String name = constructor.getName(); //构造方法名
modifier = Modifier.toString(constructor.getModifiers()); //获取访问修饰符
System.out.println("" + modifier +" " + name + "(");
Class[] paramTypes = constructor.getParameterTypes(); //获取构造方法中的参数
for (int i = 0; i < paramTypes.length; i++) {
if (i > 0) {
System.out.print(",");
}
if (paramTypes.isArray()) {
System.out.println(paramTypes
.getComponentType().getName()+"[]");
} else {
System.out.print(paramTypes.getName());
}
}
System.out.println(");");
}
//获取成员方法
Method[] methods = c1.getDeclaredMethods();
for (Method method: methods) {
modifier = Modifier.toString(method.getModifiers());
Class returnType = method.getReturnType(); //获取方法的返回类型
if (returnType.isArray()) {
String arrType = returnType.getComponentType
().getName()+"[]";
System.out.print(""+modifier+" " + arrType + " " +
method.getName() + "(");
} else {
System.out.print("" + modifier + " " +
returnType.getName() + " " + method.getName() + "(");
}
Class[] paramTypes = method.getParameterTypes();
for (int i = 0; i < paramTypes.length; i++) {
if (i > 0) {
System.out.print(",");
}
if (paramTypes.isArray()) {
System.out.println(paramTypes
.getComponentType().getName()+"[]");
} else {
System.out.print(paramTypes.getName());
}
}
System.out.println(");");
}
}
public static void test02() throws InstantiationException,
IllegalAccessException, SecurityException, NoSuchMethodException,
IllegalArgumentException, InvocationTargetException {
//反射调用方法，可以通过Method类的invoke方法实现动态方法的调用
//public Object invoke(Object obj, Object... args)
//第一个参数代表对象
//第二个参数代表执行方法上的参数
//若反射要调用类的某个私有方法，可以在这个私有方法对应的Mehtod对象上先
调用setAccessible(true)
Class c1 = TestReflection.class;
TestReflection t1 = (TestReflection) c1.newInstance(); //利用反射来创
建类的对象
System.out.println("username == " + t1.username);
System.out.println("password == " + t1.password);
Method method = c1.getDeclaredMethod("setUserName", String.class);
method.invoke(t1, "Java反射的学习");
System.out.println("username == " + t1.username);
method = c1.getDeclaredMethod("setPassWord", String.class);
method.setAccessible(true);
method.invoke(t1, "反射执行某个Private修饰的方法");
System.out.println("password == " + t1.password);
}
public static void main(String[] args) throws ClassNotFoundException,
SecurityException, IllegalArgumentException, InstantiationException,
IllegalAccessException, NoSuchMethodException, InvocationTargetException {
// test01();
test02();
}
}
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