request对象多种方法封装表单数据

public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
//        test1(request);
//        test2(request);
        test3(request);
    }
//获取单个控件的值
    public void test1(HttpServletRequest request){
        String name = request.getParameter("username");
        System.out.println("name=" + name);
    }
    //获取同名控件的值
    public void test2(HttpServletRequest request){
        String[] age = request.getParameterValues("age");
        for (String string : age) {
            System.out.println("string=" + string);
        }
    }
    //获取全部控件
    public void test3(HttpServletRequest request){
        //获取所有控件的名字
        System.out.println("--------request--------" + request.toString());
        Enumeration<String> enu = request.getParameterNames();
        while(enu.hasMoreElements()){
            String name = enu.nextElement();//控件的名字
            //可能有多个重复
            String[] values = request.getParameterValues(name);//控件的值
            for (String value : values) {
                System.out.println(name + "---" + value);
            }
        }
    }
//将表单中的所有值封装到JavaBean中

第四种方法：将表单中的所有值封装到JavaBean中：采用PropertyDesceipt方法

首先添加一个Javabean：实现序列化接口： implements Serializable  表示对象可以被序列化

public class User implements Serializable{

    private String username;
    private String[] password;
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String[] getPassword() {
        return password;
    }
    public void setPassword(String[] password) {
        this.password = password;
    }
    @Override
    public String toString() {
        return "User [username=" + username + ", password="
                + Arrays.toString(password) + "]";
    }
}

实现方法：

public void test4(HttpServletRequest request){
        User user = new User();
        Enumeration<String> enu = request.getParameterNames();
        while(enu.hasMoreElements()){
            //拿到控件的名字
            String name = enu.nextElement();
            //控件的值
            String[] values = request.getParameterValues(name);

            try {
                //拿到属性name的属性描述器
                PropertyDescriptor pd = new PropertyDescriptor(name, User.class);
                //将值注入到属性中
                //拿到写描述器
                Method md = pd.getWriteMethod();
                //为了兼容jdk1.4，invoke方法在执行时将参数拆开进行传递，所以导致IllegalArgumentException
                if(values.length == ){
                    md.invoke(user, values);
                }else{
　　　　　　　　　　　　//数组被拆开了
                    //解决办法1：
//                    md.invoke(user, (Object)values);
                    //解决办法2：
                    md.invoke(user, new Object[] {values});
                }
//                md.invoke(user, values);
            } catch (IntrospectionException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IllegalArgumentException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }
        System.out.println("封装后的值："+ user);
    }

第六种方法：BeanUtils类封装

//将表单中的所有值封装到JavaBean中，采用第三方jar进行：BeanUtils类
    //需要：commons-logging-1.1.1.jar    commons-beanutils-1.8.3.jar
    public void test5(HttpServletRequest request){
        User user = new User();
        System.out.println("封装前：" + user);

        Enumeration<String> enu = request.getParameterNames();
        while(enu.hasMoreElements()){
            String name = enu.nextElement();
            String[] values = request.getParameterValues(name);
            //采用BeanUtils类封装
            try {
                BeanUtils.setProperty(user, name, values);
            } catch (IllegalAccessException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        System.out.println("封装后" + user);
    }

第七种：request.getParameterMap(); BeanUtils

//页面所有的数据传递都是String类型
    public void test6(HttpServletRequest request){
        User user = new User();
        System.out.println("封装前：" + user);
        Map<String, String[]> map = request.getParameterMap();

        for (Map.Entry<String , String[]> entry : map.entrySet()) {
            //拿到控件的名字
            String name = entry.getKey();
            String[] values = entry.getValue();
            //封装数据
            try {
                BeanUtils.setProperty(user, name, values);
            } catch (IllegalAccessException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        System.out.println("封装后" + user);
    }
    

 推荐方法

    //推荐方法
    public void test7(HttpServletRequest request){
        User user  = new User();
        try {
            BeanUtils.populate(user, request.getParameterMap());
        } catch (IllegalAccessException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        System.out.println("封装后777" + user);
    }