反射的代码

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最新推荐文章于 2022-08-18 09:03:07 发布

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package com.oracle.reflection;<pre name="code" class="html">package com.oracle.reflection;
import java.util.LinkedList;
public class Test3 {
public static void main(String[] args) throws InstantiationException, IllegalAccessException {
// Class<?> c=LinkedList.class;
// Class<?>[]cc=c.getInterfaces();
// Class<?>ccc=c.getSuperclass();//获得父类
// for(Class c1:cc){
// System.out.println(c1.getName());
//
// }
Class<?> c=String[].class;
System.out.println(c.getName());
if(c.isArray()){
System.out.println("这是一个数组");
System.out.println("数组中的元素类型是");
Class ac= c.getComponentType();//获得中数组中元素的类型
System.out.println(ac.getName());
}
Class<?> c1=Person.class;
Object o=c1.newInstance();
System.out.println(o.toString());
}
}
</pre>
<pre name="code" class="html">package com.oracle.reflection;
import java.lang.reflect.Field;
public class Test4 {
public static void main(String[] args) throws SecurityException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException {
Class c=Person.class;
Person p=new Person(10,"张大妈","女");
Field f=c.getDeclaredField("name");
// f.setAccessible(true);//这样设置就能访问私有的变量
f.set(p, "小龙女");
System.out.println(f.get(p));
}
}</pre>
<pre name="code" class="html">package com.oracle.reflection;
import java.lang.reflect.Field;
public class TestStudent {
public static void main(String[] args) {
Class c=Student.class;
Field[]fs=c.getDeclaredFields();
for(Field f:fs){
System.out.println(f.getModifiers()+":"+f.getName());
//修饰符的编号，都是2的次方，两个修饰符的编号可以相加
}
}
}
</pre>
public class Person {int personno;String name;String sex;public void eat(){System.out.println(this.name+"正在吃");}public int getPersonno() {return personno;}public void setPersonno(int personno) {this.personno = personno;}public String getName() {return name;}public
void setName(String name) {this.name = name;}public String getSex() {return sex;}public void setSex(String sex) {this.sex = sex;}public Person(int personno, String name, String sex) {super();this.personno = personno;this.name = name;this.sex = sex;}public
Person() {super();}}
<pre></pre>
<pre name="code" class="html">package com.oracle.reflection;
public class Student extends Person {
int score;
public String school;
}
</pre>
<pre name="code" class="html">package com.oracle.reflection;
import java.lang.reflect.Field;
public class Test {
public static void main(String[] args) {
//1.先获得类实例，这是反射的起点
// Class c=Person.class;
// System.out.println(c.getName()) ;//包名和类名
// System.out.println(c.getSimpleName());//只是类名
//当前这个类有多少个属性，每个属性是什么
//Field []fs=c.getFields();//java.lang.reflect包
//System.out.println(fs.length);//只能获得共有的
// //方法2
Person p=new Person();
Class cc=p.getClass();
Field []fs=cc.getDeclaredFields();
for(Field f:fs){
System.out.println(f.getName()+","+f.getType());
}
}
}
</pre>
<pre name="code" class="html">package com.oracle.reflection;
import java.lang.reflect.Field;
import java.util.Scanner;
public class Test2 {
public static void main(String[] args) throws ClassNotFoundException {
// Scanner s=new Scanner(System.in);
// System.out.println("请输入一个类名");
// String name=s.nextLine();
//
// Class c=Class.forName(name) ;
//System.out.println("这个类是："+c.getSimpleName());
//Field []fs=c.getDeclaredFields();
//for(Field f:fs){
// System.out.println(f.getName()+","+f.getType());
// }
//
Person p=new Person();
insert(p);
}
//利用反射机制可以拼接出一个sql语句
public static void insert(Object obj){
Class c=obj.getClass();
String name=c.getSimpleName();//类名就是表名
String sql="insert into "+name+"(";
String value="values(";
Field[]fs=c.getDeclaredFields();
for(int i=0;i<fs.length;i++){
if(i==fs.length-1){
sql+=fs[i].getName()+")";
value+="?)";
}else{
sql+=fs[i].getName()+",";
value+="?,";
}
}
System.out.println(sql+value);
//ps=conn.prepareStatement(sql+value)
for(int i=0;i<fs.length;i++){
Field f=fs[i];
f.setAccessible(true);
//ps.setObject(i+1,f.get(obj))
}
//ps.execute();
}
}
</pre>
上面是类和属性的反射，下面是方法的反射<pre name="code" class="html">package fangfa;
public class Person {
String name;
String sex;
public void eat(){
System.out.println(this.name+"正在吃");
}
private void eat(String food){
System.out.println(this.name+"正在吃"+food);
}
protected void drink(){
System.out.println(this.name+"正在喝");
}
public Person(String name, String sex) {
super();
this.name = name;
this.sex = sex;
}
public Person() {
super();
}
private Person(String name) {
super();
this.name = name;
}
}</pre>
<pre name="code" class="html">package fangfa;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
public class TestConstructor {
/**
* 得到构造方法(用的少)
* @throws NoSuchMethodException
* @throws SecurityException
* @throws InvocationTargetException
* @throws IllegalAccessException
* @throws InstantiationException
* @throws IllegalArgumentException
*/
public static void main(String[] args) throws SecurityException, NoSuchMethodException, IllegalArgumentException, InstantiationException, IllegalAccessException, InvocationTargetException {
Class c=Person.class;
// Constructor[]cs=c.getDeclaredConstructors();
// for(Constructor cc:cs){
// System.out.println(cc.getName());
// Class[]pc=cc.getParameterTypes();
// if(pc.length==0){
// System.out.println("无参数");
// }else{
// for(Class pcc:pc){
// System.out.println(pcc.getName());
// }
// }
// }
Constructor cs=c.getDeclaredConstructor(String.class);
cs.setAccessible(true);
Object o=cs.newInstance("李四");
System.out.println(o);
Object o1= c.newInstance();
System.out.println(o1);
}
}</pre>
<pre name="code" class="html">package fangfa;
import java.lang.reflect.Method;
public class TestMethod {
/**
* @param args
* @throws NoSuchMethodException
* @throws SecurityException
*/
public static void main(String[] args) throws SecurityException, NoSuchMethodException {
Class c=Person.class;
//Method[]ms=c.getMethods();
// Method[]ms=c.getDeclaredMethods();
// for(Method m:ms){
// System.out.println(m.getName());
// }
// Method ms=c.getDeclaredMethod("eat",String.class);
//
// System.out.println(ms.getName());
//
// Class<?>[]ct=ms.getParameterTypes();
// for(Class c1:ct){
// System.out.println(c1.getName());
// }
//每个方法的名，参数，返回值
Method[]ms=c.getMethods();
for(Method m:ms){
System.out.println(m.getReturnType().getSimpleName()+","+m.getName());
//获得参数
Class<?>[]cp=m.getParameterTypes();
if(cp.length!=0){
for(Class<?> c1:cp){
System.out.println("\t"+ c1.getName());
}
}else{
System.out.println("\t 无参数");
}
}}
}
</pre>