request请求转换成对象。

1）前端post数据过来，key和val键值对会有很多，这个时候往后端进行插值的时候，最好将这些键值对转换成对象进行处理。

使用common-beanutils 来将前端传递过来的map直接转换成对象。

依赖jar包：

前端代码的name属性要和后端bean对象属性一致！

  <h1>测试POST</h1>
  <form action="/bean" method="post">
    <input type="text" name="username">用户名字
    <input type="password" name="passowrd">用户密码
    <button type="submit">提交</button>
  </form>
  </body>
</html>

后端代码：

package jd.com.bean_test;

import org.apache.commons.beanutils.BeanUtils;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Map;

@WebServlet(name = "Servlet_Bean")
public class Servlet_Bean extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws  ServletException, IOException {
        //只能针对post请求 不乱码。
        request.setCharacterEncoding("utf-8");
        Map<String,String[]> data=request.getParameterMap();
        User user_obj=new User();
        try {
            BeanUtils.populate(user_obj,data);
        }catch (Exception ex){
            ex.printStackTrace();
            throw  new RuntimeException("转换出问题！");
        }
        System.out.println(user_obj);


    }

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

    }
}

package jd.com.bean_test;

public class User {
    private String username;
    private String passowrd;
    public  User(){}

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

    public void setPassowrd(String passowrd) {
        this.passowrd = passowrd;
    }

    public String getUsername() {
        return username;
    }

    public String getPassowrd() {
        return passowrd;
    }

    @Override
    public String toString() {
        return username+" "+passowrd;
    }
}