Request request parameter acquisition + BeanUtils framework -- study notes

Get information about the request body

  a)request.getParameter(String):String
  b)request.getParameterValues(String):String[]
    注意：在GET请求方式下，如果参数不一致，返回null，可能出现空指针异常
  c)BeanUtils框架能够自动将String参数设置到JavaBean对象中（commons-beanutils-1.8.0.jar、commons-logging.jar）
    1)无需理会参数的类型，个数，但是参数名一定要和JavaBean中的字段一致
    2)String->8种基本类型自动转换，非8种基本类型可以注册转换器材
    3)String或String[]类型的参数自动感知装配 

java code:

import java.io.IOException;
import java.io.PrintWriter;
import java.lang.reflect.InvocationTargetException;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;

import cn.web.request.domain.User;

public class Rdome3 extends HttpServlet {

    //http://localhost:8080/day04/Rdome3?username=jack&age=30&salary=5000&likes=dance&likes=sing回车
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        //分别取得的客户端提交的信息
        String strUsername =request.getParameter("username");
        String strAge = request.getParameter("age");
        String strSalary = request.getParameter("salary");
        String[] strLikes = request.getParameterValues("likes"); //一对多；

        //判断
        BeanUtils bu = new BeanUtils();
        User user = new User();
        Enumeration<String> enums = request.getParameterNames();
        while(enums.hasMoreElements())
        {
            String keys = enums.nextElement();
            String[] values = request.getParameterValues(keys);
            try {
                bu.setProperty(user, keys, values);
            } catch (Exception e) {

                e.printStackTrace();
            }
        }

        //处理中文
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter pw = response.getWriter();
        pw.write("用户名：" + strUsername + "<br/>");
        pw.write("年龄：" + strAge + "<br/>");
        pw.write("期望薪水：" + strSalary + "<br/>");
        pw.write("爱好个数：" + strLikes + "<br/>");
        pw.flush();
        pw.close();

    }

}

user.java

public class User {

    private String username;
    private int age;
    private double salary;
    private String[] likes;

    public User() {
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }

    public String[] getLikes() {
        return likes;
    }

    public void setLikes(String[] likes) {
        this.likes = likes;
    }
}