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发表于 2009-06-15 09:55 |只看该作者 |倒序浏览

Reflection 是Java被视为动态（或准动态）语言的一个关键性质。这个机制允许程序在运行时透过Reflection APIs取得任何一个已知名称的class的内部信息，包括其modifiers（诸如public, static 等等）、superclass（例如Object）、实现之interfaces（例如Cloneable），也包括fields和methods的所有信息，并可于运行时改变fields内容或唤起methods。
个人理解就是在运行时可以得到某个对象的所有信息，包括方法，类型，属性，方法参数，方法返回值以及可以调用该类的所有方法。
下面是两个例子：
Java代码
[/url]

package cn.test;

import java.lang.reflect.Array;

import java.lang.reflect.Constructor;

import java.lang.reflect.Field;

import java.lang.reflect.Method;

/**

* Java Reflection Cookbook

*

* @author Michael Lee

* @since 2006-8-23

* @version 0.1a

*/

public class TestReflection {

/**

* 得到某个对象的公共属性

*

* @param owner, fieldName

public Object getProperty(Object owner, String fieldName) throws Exception {

Class ownerClass = owner.getClass();

Field field = ownerClass.getField(fieldName);

Object property = field.get(owner);

* @param className 类名

* @param fieldName 属性名

* @return 该属性对象

* @throws Exception

*/

public Object getStaticProperty(String className, String fieldName)

throws Exception {

Class ownerClass = Class.forName(className);

Field field = ownerClass.getField(fieldName);

Object property = field.get(ownerClass);

public Object invokeMethod(Object owner, String methodName, Object[] args)

throws Exception {

Class ownerClass = owner.getClass();

Class[] argsClass = new Class[args.length];

for (int i = 0, j = args.length; i

argsClass = args.getClass();

}

Method method = ownerClass.getMethod(methodName, argsClass);

return method.invoke(owner, args);

public Object invokeStaticMethod(String className, String methodName,

Object[] args) throws Exception {

Class ownerClass = Class.forName(className);

Class[] argsClass = new Class[args.length];

for (int i = 0, j = args.length; i

argsClass = args.getClass();

}

Method method = ownerClass.getMethod(methodName, argsClass);

return method.invoke(null, args);

public Object newInstance(String className, Object[] args) throws Exception {

Class newoneClass = Class.forName(className);

Class[] argsClass = new Class[args.length];

for (int i = 0, j = args.length; i

argsClass = args.getClass();

}

Constructor cons = newoneClass.getConstructor(argsClass);

return cons.newInstance(args);

* @return 如果 obj 是此类的实例，则返回 true

*/

public boolean isInstance(Object obj, Class cls) {

return cls.isInstance(obj);

* @return 返回指定数组对象中索引组件的值

*/

public Object getByArray(Object array, int index) {

return Array.get(array,index);

}

}  package cn.test;
import java.lang.reflect.Array;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
/**
* Java Reflection Cookbook
*
* @author Michael Lee
* @since 2006-8-23
* @version 0.1a
*/
public class TestReflection {
/**
   * 得到某个对象的公共属性
   *
   * @param owner, fieldName
   * @return 该属性对象
   * @throws Exception
   *
   */
public Object getProperty(Object owner, String fieldName) throws Exception {
      Class ownerClass = owner.getClass();
      Field field = ownerClass.getField(fieldName);
      Object property = field.get(owner);
      return property;
}
/**
   * 得到某类的静态公共属性
   *
   * @param className 类名
   * @param fieldName 属性名
   * @return 该属性对象
   * @throws Exception
   */
public Object getStaticProperty(String className, String fieldName)
         throws Exception {
      Class ownerClass = Class.forName(className);
      Field field = ownerClass.getField(fieldName);
      Object property = field.get(ownerClass);
      return property;
}
/**
   * 执行某对象方法
   *
   * @param owner
   *          对象
   * @param methodName
   *          方法名
   * @param args
   *          参数
   * @return 方法返回值
   * @throws Exception
   */
public Object invokeMethod(Object owner, String methodName, Object[] args)
         throws Exception {
      Class ownerClass = owner.getClass();
      Class[] argsClass = new Class[args.length];
      for (int i = 0, j = args.length; i
Java代码
[url=http://canofy.javaeye.com/blog/359565#]

package cn.test;

import java.lang.reflect.Field;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.util.ArrayList;

import cn.IpUtils.IpBean;

public class TestObject {

/**

* 设置属性值

* @param list

* @param cla

* @return

*/

public ArrayList array2bean(ArrayList list, Class cla) {

ArrayList result = new ArrayList();

int filed_len = cla.getDeclaredFields().length;

System.out.println(":"+cla.getDeclaredFields().length);

for (int i = 0; i

Object[] o = (Object[]) list.get(i);

int length = filed_len

try {

result.add(cla.newInstance());

for (int j = 0; j

Method m = null;

String mName =cla.getDeclaredFields()[j].getName();

mName = mName.substring(0, 1).toUpperCase()+ mName.substring(1);

mName = "set" + mName;

m = cla.getMethod(mName, new Class[] { String.class });

//调用设置的方法，给属性赋值

m.invoke(result.get(i), new Object[] { o[j] == null ? "": o[j].toString() });

}

} catch (Exception e) {

e.printStackTrace();

}

return result;

}

/**

* 获取get的取值

* @param obj

* @return

* @throws Exception

*/

public String getObjectToString(Object obj) throws Exception{

Class cla=obj.getClass();

Method[] ma=cla.getDeclaredMethods();//获取所有声明的方法数组

Method method=null;

String methodName=null;

Object returnValue=null;

for(int i=0;i

method=ma;

methodName=method.getName();//方法名

if(methodName.indexOf("get")==0){//以get开始的方法，排除set方法

returnValue=method.invoke(obj, null);//调用方法，相当于执行get方法得到的结果，这里返回的是一个对象

System.out.print(methodName+"::");

System.out.println(returnValue==null?"":returnValue.toString());

}

return "";

}

/**

* 获取对象的属性值，含有get方法的

* @param obj

* @return

* @throws NoSuchMethodException

* @throws SecurityException

* @throws InvocationTargetException

* @throws IllegalAccessException

* @throws IllegalArgumentException

*/

public String getAttributeValue(Object obj) throws SecurityException, NoSuchMethodException, IllegalArgumentException, IllegalAccessException, InvocationTargetException{

Class cla=obj.getClass();

Field[] fds=cla.getDeclaredFields();

Field field=null;

String fieldName=null;

String methodName=null;

Method method=null;

Object returnValue=null;

for(int i=0;i

field=fds;

fieldName=field.getName();

methodName="get"+fieldName.substring(0, 1).toUpperCase()+fieldName.substring(1);

method=cla.getDeclaredMethod(methodName, null);

returnValue=method.invoke(obj, null);//调用方法，相当于执行get方法得到的结果，这里返回的是一个对象

System.out.print(methodName+"::");

System.out.println(returnValue==null?"":returnValue.toString());

}

return "";

}

/**

* @param args

* @throws Exception

*/

public static void main(String[] args) throws Exception {

// IpBean.class

TestObject to=new TestObject();

IpBean ib=new IpBean();

ib.setFrom("from1");

ib.setPosition("position1");

ib.setTo("to1");

ib.setId(10);

to.getObjectToString(ib);

// to.getAttributeValue(ib);

}

}  package cn.test;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import cn.IpUtils.IpBean;
public class TestObject {

/**
   * 设置属性值
   * @param list
   * @param cla
   * @return
   */
public ArrayList array2bean(ArrayList list, Class cla) {
ArrayList result = new ArrayList();
int filed_len = cla.getDeclaredFields().length;
System.out.println(":"+cla.getDeclaredFields().length);
for (int i = 0; i
Java代码
[/url]

package cn.IpUtils;

public class IpBean {

private String from; // IP段起始

private String to; // IP结束

private String position; // 地理名称

private int id = 0;

public String getFrom() {

return from;

}

public void setFrom(String from) {

this.from = from;

}

public String getTo() {

return to;

}

public void setTo(String to) {

this.to = to;

}

public String getPosition() {

return position;

}

public void setPosition(String position) {

this.position = position;

}

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

} package cn.IpUtils;
public class IpBean {
private String from; // IP段起始
private String to; // IP结束
private String position; // 地理名称
private int id = 0;
public String getFrom() {
return from;
}
public void setFrom(String from) {
this.from = from;
}
public String getTo() {
return to;
}
public void setTo(String to) {
this.to = to;
}
public String getPosition() {
return position;
}
public void setPosition(String position) {
this.position = position;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}

}

本文来自ChinaUnix博客，如果查看原文请点：[url]http://blog.chinaunix.net/u1/57965/showart_1964357.html

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