反射示例

 很熟悉的示例吧！熟悉一下反射机制以及reflect的SDK

public class ViewClassInfoFrame extends JFrame implements ActionListener{
    JTextField classnameField = new JTextField();
    JButton  viewinfoButton = new JButton();
    JLabel hintLabel = new JLabel();
    JTextArea infoTextArea  = new JTextArea();
    JScrollPane infoScrollPane = new JScrollPane();
    TitledBorder titledBorder;
    
    JPanel  upPanel = new JPanel();
    JPanel  centerPanel  = new JPanel();
    
    BorderLayout mainFrameBorderLayout = new BorderLayout();
    BorderLayout centerPanelBorderLayout = new BorderLayout();
    BorderLayout upPanelBorderLayout = new BorderLayout();
   
    /** 构造函数 */
    public ViewClassInfoFrame() {
        enableEvents(AWTEvent.WINDOW_EVENT_MASK);
        init();
        validate();
    }
    /**初始化窗口*/
    private void init(){
        
        classnameField.setFont(new Font("Dialog",0,15));
        classnameField.setSelectedTextColor(Color.white);
        classnameField.setText("");
        
        viewinfoButton.setFont(new Font("Dialog",0,13));
        viewinfoButton.setText("查看类详细信息");
        viewinfoButton.addActionListener(this);
        hintLabel.setFont(new Font("Dialog",0,13));
        hintLabel.setText("类路径");
        
        infoTextArea.setFont(new Font("Dialog",0,14));
        infoTextArea.setEditable(false);
        infoTextArea.setText("");
        
        titledBorder = new TitledBorder(BorderFactory.createEtchedBorder(Color.white,new Color(134,134,134)),"结果信息");
        infoScrollPane.setBorder(titledBorder);
        infoScrollPane.getViewport().add(infoTextArea,null);
        
        upPanel.setLayout(upPanelBorderLayout);
        centerPanel.setLayout(centerPanelBorderLayout);
        upPanel.add(hintLabel,BorderLayout.NORTH);
        upPanel.add(classnameField,BorderLayout.CENTER);
        upPanel.add(viewinfoButton,BorderLayout.SOUTH);
        
        centerPanel.add(infoScrollPane);
        
        this.getContentPane().setLayout(mainFrameBorderLayout);
        this.setSize(new Dimension(450,360));
        this.setTitle("使用反射机制查看类信息");
        
        this.getContentPane().add(upPanel,BorderLayout.NORTH);
        this.getContentPane().add(centerPanel,BorderLayout.CENTER);
        
        this.getRootPane().setDefaultButton(viewinfoButton);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
    public void actionPerformed(ActionEvent e) {
        String classname = classnameField.getText();
        StringBuffer  buffer  =  new StringBuffer();
        try {
            //动态加载类  获取类对象
            Class c = Class.forName(classname);
            buffer.append("/**类声明**/ \n");
            buffer.append(getClassStatement(c));
            buffer.append("\n");
            
            buffer.append("/**字段**/");
            buffer.append(getFields(c));
            
            buffer.append("/**构造函数**/");
            buffer.append(getConstructors(c));
            buffer.append("/**方法**/");
            buffer.append(getMethods(c));
            buffer.append("} \n");
        } catch (Exception e1) {
            JOptionPane.showMessageDialog(this, "没有找到类：" + e1.getMessage());
        }
        infoTextArea.setText(buffer.toString());
    }
    public String getClassStatement(Class c){
        StringBuffer buffer = new StringBuffer();
        if(c.getName().equals("java.lang.object")){
            buffer.append("public class Ojbect{");
            return buffer.toString();
        }else {
            String supername = c.getSuperclass().getName();
            buffer.append("public class").append(c.getName());
            buffer.append("extends").append(supername).append(";");
        }
        return buffer.toString();
    }
    /**
     * 获取类的属性
     * @param c
     * @return
     */
    public String getFields(Class c){
        StringBuffer  buffer = new StringBuffer();
        Field field = null;
        Field [] fields = c.getFields(); 
        for (int i = 0; i < fields.length; i++) {
            field = fields[i];
            buffer.append(Modifier.toString(field.getModifiers())).append(" ");
            Class type = field.getType();
            buffer.append(type.getName()).append(" ");
            buffer.append(field.getName()).append(";\n");//获取属性名
        }
        return buffer.toString();
    }
    /**
     * 获取类的构造方法
     * @param c
     * @return String
     */
    public String getConstructors(Class c){
        StringBuffer buffer = new StringBuffer();
        Constructor [] constructors = c.getDeclaredConstructors();
        Constructor constructor = null;
        for (int i = 0; i < constructors.length; i++) {
            constructor = constructors[i];
            buffer.append(Modifier.toString(constructor.getModifiers())).append(" ");
            buffer.append(constructor.getName()).append("(");
            //获取参数类型
            Class[] paramsTypes= constructor.getParameterTypes();
            Class class1= null;
            for (int j = 0; j < paramsTypes.length; j++) {
                class1 = paramsTypes[j];
                if (j==(paramsTypes.length-1)) {
                    buffer.append(class1.getName());
                }else {
                    buffer.append(class1.getName()).append(",");
                }
            }
            buffer.append(")");
            //获取方法声明的异常
            Class[] exceTypes = constructor.getExceptionTypes();
            for (int j = 0; j < exceTypes.length; j++) {
                class1 = exceTypes[j];
                if (j==0) {
                    buffer.append("throws");
                } 
                if(j==(exceTypes.length-1)){
                    buffer.append(class1.getName());
                } else {
                    buffer.append(class1.getName()).append(", ");
                }
            }
            buffer.append("\n");
            
        }
        
        
        return buffer.toString();
    }
    /**
     * 获取类的方法
     * @param c
     * @return String
     */
    public String getMethods(Class c){
        StringBuffer buffer = new StringBuffer();
        Method[] methods= c.getMethods();
        Method method = null;
        for (int i = 0; i < methods.length; i++) {
            method = methods[i];
            buffer.append(Modifier.toString(method.getModifiers())).append(" ");
            Class returnType = method.getReturnType();
            buffer.append(returnType.getName()).append(" ");
            buffer.append(method.getName()).append("(");
            //获取方法参数
            Class[] paramTypes =method.getParameterTypes();
            Class class1 = null;
            for (int j = 0; j < paramTypes.length; j++) {
                class1 = paramTypes[j];
                if (j==(paramTypes.length-1)) {
                    buffer.append(class1.getName());
                } else {
                    buffer.append(class1.getName()).append(", ");
                }
            }
            buffer.append(")");
          //获取方法声明的异常
            Class[] exceTypes = method.getExceptionTypes();
            for (int j = 0; j < exceTypes.length; j++) {
                class1 = exceTypes[j];
                if (j==0) {
                    buffer.append("throws");
                } 
                if(j==(exceTypes.length-1)){
                    buffer.append(class1.getName());
                } else {
                    buffer.append(class1.getName()).append(", ");
                }
            }
            buffer.append("\n");
        }
        return buffer.toString();
    }
    
    
    /**
     * @param args
     */
    public static void main(String[] args) {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception e) {
            e.printStackTrace();
        }
        ViewClassInfoFrame frame = new ViewClassInfoFrame();
        
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        Dimension frameSize = frame.getSize();
        if (frameSize.height>screenSize.height) {
            frameSize.height= screenSize.height;
        }
        if (frameSize.width>screenSize.width) {
            frameSize.width= screenSize.width;
        }
        frame.setLocation((screenSize.width-frameSize.width)/2, (screenSize.height-frameSize.height)/2);
        frame.setVisible(true);
    }

}