java 反射小应用 <模范eclipse里面的ctrl+o快捷键>

eclipse里面有很多的地方都体现了反射的因素，现在模范这些做了一个小的应用虽然样子不是很好看，而且还点地方没处理好但是能带到体现其中效果。

先看看最终的界面效果。

这页面没有怎么仔细的去排版和处理，先将就看下

在代码方面我们需要建立三个类，一个显示页面<ReflectJFrame>，一个处理类<Reflect>，一个底层类<Student>

先看看我们的底层类Student，该类没有什么多的东西就随便的写了些，只是为了体现效果：

/** * @author YangJing * */public class Student {int a=0;String yangjing = null;public Student() {System.out.println( "Student构造方法!" );}public String SayHello(){String s = "SayHello";return s;}public String myName(){yangjing = "yangjing";return yangjing;}}

Student类里面只有两个公共的字段与三个方法。

处理类Reflect，他里面有三个方法，分别是得到字段，得到方法以及得到构造方法

import java.lang.reflect.Constructor;import java.lang.reflect.Field;import java.lang.reflect.Method;import java.util.ArrayList;import java.util.List;/** * @author YangJing * */public class Reflect {        //得到字段public List<String> getField(String className) throws Exception{Class c;try {c = Class.forName(className);} catch (ClassNotFoundException e) {throw new Exception("无法加载该类字段");}List<String> fields = new ArrayList<String>();Field[] f = c.getDeclaredFields();for (int i = 0; i < f.length; i++) {fields.add(f[i].getName());}return fields;}        //得到方法public List<String> getMethod(String className) throws Exception{Class c;try {c = Class.forName(className);} catch (ClassNotFoundException e) {throw new Exception("无法加载该类方法");}List<String> methods = new ArrayList<String>();Method[] f = c.getDeclaredMethods();for (int i = 0; i < f.length; i++) {methods.add(f[i].getName());}return methods;}       //得到构造方法public List<String> getConstr(String className) throws Exception{Class c;List<String> constructor = new ArrayList<String>();try {c = Class.forName(className);Constructor[] f = c.getConstructors();for (int i = 0; i < f.length; i++) {constructor.add(f[i].getName());}} catch (ClassNotFoundException e) {throw new Exception("无法加载该类方法");}return constructor;}}

页面显示类 ReflectJFrame  在这类里面只是用到了最基本的操作，如事件和面板这些东西

import java.awt.BorderLayout;import java.awt.FlowLayout;import java.awt.GridLayout;import java.awt.TextArea;import java.awt.TextField;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import java.awt.event.ItemEvent;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.List;import javax.swing.JButton;import javax.swing.JComboBox;import javax.swing.JFrame;import javax.swing.JOptionPane;import javax.swing.JPanel;/** * @author YangJing * */public class ReflectJFrame extends JFrame implements ActionListener{TextField txtClassName = new TextField(20);JButton jbuShow = new JButton("显示"),jbuexecute = new JButton("执行");JComboBox combobox = new JComboBox();TextArea txaMatter = new TextArea(20,30),  txtContent = new TextArea(15,30);JPanel p1 = new JPanel(new FlowLayout(FlowLayout.LEFT)),   p2 = new JPanel(new FlowLayout(FlowLayout.LEFT)),   p3 = new JPanel(new FlowLayout()),   p4 = new JPanel(new FlowLayout()),   p5 = new JPanel(new BorderLayout());String s = null;public ReflectJFrame() {this.setLayout(new BorderLayout());this.setTitle("Reflect 反射机制");this.setSize(500, 400);this.init();this.setResizable(false);this.setLocationRelativeTo(null);this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);this.setVisible(true);}public void init(){//顶部jbuShow.addActionListener(this);p1.add(txtClassName);p1.add(jbuShow);//右边p3.add(combobox);combobox.addActionListener(this);p3.add(jbuexecute);jbuexecute.addActionListener(this);p4.add(txtContent);p5.add(p3,BorderLayout.NORTH);p5.add(p4,BorderLayout.CENTER);//左边p2.add(txaMatter);this.add(p1,BorderLayout.NORTH);this.add(p2,BorderLayout.CENTER);this.add(p5,BorderLayout.EAST);}/** * @param args */public static void main(String[] args) {new ReflectJFrame();}Reflect reflect = new Reflect();@Overridepublic void actionPerformed(ActionEvent e) {if(e.getSource()==jbuShow){try {List<String> fields= reflect.getField(this.txtClassName.getText().trim());StringBuffer str = new StringBuffer("--Field--");str.append("\n");for (int i = 0; i < fields.size(); i++) {str.append(fields.get(i));str.append("\n");}this.txaMatter.setText(str.toString());List<String> methods = reflect.getMethod(this.txtClassName.getText().trim());str.append("--Methods--");str.append("\n");for (int i = 0; i < methods.size(); i++) {str.append(methods.get(i));str.append("\n");combobox.addItem(methods.get(i));}this.txaMatter.setText(str.toString());List<String> constructor = reflect.getConstr(this.txtClassName.getText().trim());str.append("--constructors--");str.append("\n");for (int i = 0; i < constructor.size(); i++) {str.append(constructor.get(i));str.append("\n");combobox.addItem(constructor.get(i));}this.txaMatter.setText(str.toString());} catch (Exception e1) {JOptionPane.showMessageDialog(this, e1.getMessage(),"Error",JOptionPane.ERROR_MESSAGE);}}if(e.getSource()==jbuexecute){s=(String)combobox.getSelectedItem();try {Class c = Class.forName(this.txtClassName.getText().trim());//获得指定的方法Method m = c.getMethod(s,null);StringBuffer sr = new StringBuffer();sr.append(m.invoke(c.newInstance(), null));this.txtContent.setText(sr.toString());} catch (IllegalArgumentException e1) {e1.printStackTrace();} catch (IllegalAccessException e1) {e1.printStackTrace();} catch (InvocationTargetException e1) {e1.printStackTrace();} catch (InstantiationException e1) {e1.printStackTrace();} catch (SecurityException e1) {e1.printStackTrace();}catch (NoSuchMethodException e1) {e1.printStackTrace();} catch (ClassNotFoundException e1) {e1.printStackTrace();}}}}

这只是一个简单的模型，也是为了学习的时候更好的体现出效果而做的一个demo，虽然还有些地方还没有完善！

作者：杨静（YangJing）
出处： [杨静の专栏]   (博文连接)