request請求參數的獲取+BeanUtils框架--學習筆記

取得請求體相關的信息

a)request.getParameter(String):String
  b)request.getParameterValues(String):String[]
    注意：在GET請求方式下，若是參數不一致，返回null，可能出現空指針異常
  c)BeanUtils框架可以自動將String參數設置到JavaBean對象中（commons-beanutils-1.8.0.jar、commons-logging.jar）
    1)無需理會參數的類型，個數，可是參數名必定要和JavaBean中的字段一致
    2)String->8種基本類型自動轉換，非8種基本類型能夠註冊轉換器材
    3)String或String[]類型的參數自動感知裝配

java代碼：

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回車
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        //分別取得的客戶端提交的信息
        String strUsername =request.getParameter("username");
        String strAge = request.getParameter("age");
        String strSalary = request.getParameter("salary");
        String[] strLikes = request.getParameterValues("likes"); //一對多；

        //判斷
        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();
            }
        }

        //處理中文
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter pw = response.getWriter();
        pw.write("用戶名：" + strUsername + "<br/>");
        pw.write("年齡：" + strAge + "<br/>");
        pw.write("指望薪水：" + strSalary + "<br/>");
        pw.write("愛好個數：" + 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;
    }
}