更新
This commit is contained in:
tensorflow-jumao
113
Java/code/ClassEx.java
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113
Java/code/ClassEx.java
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package 类;
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import java.util.ArrayList;
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import java.util.Date;
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import java.util.List;
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enum E { A, B };//枚举类型E
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public class ClassEx {
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public static void main(String[] args) throws Exception {
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//第1种获取Class实例的方法 ：对象名.getClass()，原始类型、接口类型对应的Class实例不能用这种方法获取
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//类类型
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Class c = "foo".getClass();
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System.out.println(c);
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c = System.out.getClass();
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System.out.println(c);
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Date date=new Date();
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c=date.getClass();
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System.out.println(c);
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//接口类型
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List<Date> array=new ArrayList<Date>();
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c=array.getClass();
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System.out.println(c);
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//数组类型
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int[] a=new int[10];
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c=a.getClass();
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System.out.println(c+" "+c.getCanonicalName());
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char[] b=new char[10];
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c=b.getClass();
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System.out.println(c+" "+c.getName());
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double[] d=new double[10];
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c=d.getClass();
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System.out.println(c);
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long[] l=new long[10];
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c=l.getClass();
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System.out.println(c);
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Date[] f=new Date[10];
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c=f.getClass();
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System.out.println(c+" "+c.getCanonicalName());
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//枚举类型
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E e=E.A;
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c=e.getClass();
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System.out.println(c);
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System.out.println("*****************************");
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//基本类型，编译错误
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//int a=10;
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//c=a.getClass();
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//第2种获取Class实例的方法 ：类型名.class，所有类型对应的Class实例都可以用这种方法获取
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c=String.class;
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System.out.println(c);
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c=Date.class;
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System.out.println(c);
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c=List.class;
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System.out.println(c);
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c=int.class;
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System.out.println(c);
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c=int[][].class;
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System.out.println(c);
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c=Date[][].class;
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System.out.println(c);
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c=E.class;
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System.out.println(c);
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System.out.println("*****************************");
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//第3种获取Class实例的方法 ：Class.forName(类全名字符串)，原始类型对应的Class实例不可以用这种方法获取
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c=Class.forName("java.lang.String");
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System.out.println(c);
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c=Class.forName("java.util.List");
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System.out.println(c);
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c=Class.forName("[I");//int数组类型int[]
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System.out.println(c);
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c = Class.forName("[D");//double型数组double[]
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System.out.println(c);
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c = Class.forName("[[Ljava.lang.String;");//String二维数组String[][]
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System.out.println(c);
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c=Class.forName("类.E");
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System.out.println(c);
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System.out.println("*****************************");
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//基本类型包装类中的TYPE成员的值是基本类型对应的Class类实例
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c=Double.TYPE;
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System.out.println(c);
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c=Void.TYPE;
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System.out.println(c);
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}
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}
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54
Java/code/Deet.java
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54
Java/code/Deet.java
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package 方法;
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import static java.lang.System.out;
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import java.lang.reflect.InvocationTargetException;
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import java.lang.reflect.Method;
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import java.lang.reflect.Type;
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import java.util.Locale;
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public class Deet<T> {
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private boolean testDeet(Locale l) {
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out.format("Locale = %s, Language Code = %s%n", l.getDisplayName(), l.getLanguage());
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return true;
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}
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private boolean testFoo(Locale l) {
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return false;
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}
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private boolean testBar() {
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return true;
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}
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public static void main(String... args) {
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try {
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//获取Deet类的Class实例
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Class<?> c = Deet.class;
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//有Class实例创建一个类对象
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Object t = c.newInstance();
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//获取Class实例对应的类型声明的所有的方法
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Method[] allMethods = c.getDeclaredMethods();
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for (Method m : allMethods) {
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String mname = m.getName();//获取方法的名字
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//如果方法的名字不以test开头，或者返回类型不是boolean型
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if (!mname.startsWith("test") || (m.getReturnType() != boolean.class)) {
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continue;
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}
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//获取方法的所有参数类型
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Type[] pType = m.getGenericParameterTypes();
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//如果有参数，并且第一个参数是Locale类型
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if ((pType.length != 1) || Locale.class.isAssignableFrom(pType[0].getClass())) {
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continue;
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}
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out.format("调用 %s()%n", mname);
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try {
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//调用方法，o是方法返回值
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Object o = m.invoke(t, Locale.CHINA);
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out.format("%s() 返回 %b%n%n", mname, (Boolean) o);
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} catch (InvocationTargetException x) {
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x.printStackTrace();
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} }
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} catch (InstantiationException x) {
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x.printStackTrace();
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} catch (IllegalAccessException x) {
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x.printStackTrace();
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}
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}
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}
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78
Java/code/RefEx.java
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78
Java/code/RefEx.java
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package test;
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import static java.lang.System.out;
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import java.lang.annotation.Annotation;
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import java.lang.reflect.Constructor;
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import java.lang.reflect.Field;
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import java.lang.reflect.Method;
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import java.lang.reflect.Modifier;
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import java.lang.reflect.Type;
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import java.lang.reflect.TypeVariable;
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import java.util.ArrayList;
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public class RefEx {
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public static void main(String[] args) {
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// TODO Auto-generated method stub
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String s="hello";
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Class c=s.getClass();//获取类型
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System.out.println(c);
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String modifiers=Modifier.toString(c.getModifiers());//获取修饰符
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System.out.println(modifiers);
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TypeVariable<?>[] tv = c.getTypeParameters();//获取泛型类型参数
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if (tv.length != 0) {
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out.format(" ");
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for (TypeVariable<?> t : tv)
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out.format("%s ", t.getName());
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out.format("%n%n");
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} else {
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out.format(" -- No Type Parameters --%n%n");
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}
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Class superclass=c.getSuperclass();//获取类型的父类
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System.out.println(superclass);
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Type[] intfs = c.getGenericInterfaces();//获取类实现的接口
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if (intfs.length != 0) {
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for (Type intf : intfs)
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out.format(" %s%n", intf.toString());
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out.format("%n");
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} else {
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out.format(" -- No Implemented Interfaces --%n%n");
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}
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Annotation[] ann = c.getAnnotations();//获取类的注解
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if (ann.length != 0) {
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for (Annotation a : ann)
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out.format(" %s%n", a.toString());
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out.format("%n");
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} else {
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out.format(" -- No Annotations --%n%n");
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}
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Constructor[] cons=c.getDeclaredConstructors();//获取类的构造方法
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for(Constructor con:cons){
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System.out.println(con.toGenericString());
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}
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out.format("%n%n");
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Field[] fs=c.getDeclaredFields();//获取类的数据成员（成员变量）
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for(Field f:fs){
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System.out.println(f.toGenericString());
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}
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out.format("%n%n");
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Method[] ms=c.getMethods();//获取类的公有成员方法（包含从父类继承的）
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for(Method m:ms){
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System.out.println(m.toGenericString());
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}
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out.format("%n%n");
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}
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}
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87
Java/code/Test.java
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87
Java/code/Test.java
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package test;
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import java.lang.reflect.Constructor;
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import java.lang.reflect.Field;
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import java.lang.reflect.InvocationTargetException;
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import java.lang.reflect.Method;
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public class Test {
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public static String classname="类.Student";
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public static String fieldname="name";
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public static String methodname="setName";
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public static String[] mptypes= {"java.lang.String"};
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public static Object fvalue=new String("xiaolin");
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public static Object mp1=new String("xiaohong");
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public static void main(String[] args) {
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// TODO Auto-generated method stub
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try {
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Class c=Class.forName(classname);//根据类名字符串获得类对应的Class实例
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//第一种用反射创建类对象的方法，相当于调用类的无参数构造方法
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Object o=c.newInstance();//Student o=new Student();
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//使用反射访问类对象的属性（给属性设置值，获取属性的值）
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Field f=c.getDeclaredField(fieldname);//根据Field名，获得Field对象
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f.setAccessible(true);
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f.set(o,fvalue);//o.name="xiaolin";使用反射给o对象的f代表的属性设置值为发value的值
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System.out.println(f.get(o));//获取o对象的f属性对应的值，并输出
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@SuppressWarnings("unchecked")
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//使用反射调用对象的方法
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//使用反射根据方法名，和参数类型、参数数量来获取具体某个方法
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Method m=c.getDeclaredMethod(methodname, Class.forName(mptypes[0]));//String.class
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//方法的调用，调用o对象的m方法，方法的实际参数是mp1，mo是方法调用的返回值
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Object mo=m.invoke(o,mp1);//o.setName("xiaohong");
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System.out.println(mo);
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//调用了o对象名为setAge，参数有1个，类型是int型的方法，实际参数是21
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m=c.getDeclaredMethod("setAge", int.class);
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m.invoke(o, 21);
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System.out.println(o);
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/*Method m=c.getDeclaredMethod(methodname);
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Object mo=m.invoke(o);
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System.out.println(mo);
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System.out.println(f.get(o));*/
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@SuppressWarnings({ "unchecked", "rawtypes" })
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//第二种用反射创建类对象的方法，先获取具体的Constructor，再用Constructor去创建对象
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Constructor con=c.getDeclaredConstructor(String.class,int.class);//根据构造方法参数类型来获取某个构造方法
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Object o1=con.newInstance("Mary",20);
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//用Constructor创建类对象，相当于Student o1=new Student("Mary",20);
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System.out.println(o1);
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} catch (ClassNotFoundException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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} catch (NoSuchFieldException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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} catch (SecurityException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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} catch (InstantiationException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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} catch (IllegalAccessException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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} catch (NoSuchMethodException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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} catch (IllegalArgumentException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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} catch (InvocationTargetException e) {
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// TODO Auto-generated catch block
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e.printStackTrace();
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}
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}
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}
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