Servlet的5种方式实现表单提交（注册小功能），后台获取表单数据

用servlet实现一个注册的小功能 ，后台获取数据。

注册页面：

　　

注册页面代码 ：

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
    <form action="/RequestDemo/RequestDemo3" method="post">
        用户名：<input type="text" name="userName"><br/>
        密码：<input type="text" name="pwd"><br/>
        性别：<input type="radio" name="sex" value="男" checked="checked">男
            <input type="radio" name="sex" value="女">女<br/>
        爱好：<input type="checkbox" name="hobby" value="足球">足球
            <input type="checkbox" name="hobby" value="篮球">篮球
            <input type="checkbox" name="hobby" value="排球">排球
            <input type="checkbox" name="hobby" value="羽毛球">羽毛球<br/>
        所在城市：<select name="city">
                 <option>---请选择---</option>
                 <option value="bj">北京</option>
                 <option value="sh">上海</option>
                 <option value="sy">沈阳</option>
               </select>        
               <br/>
        <input type="submit" value="点击注册">
    </form>
</body>
</html>

人员实体类： 注意：人员实体类要与表单中的name一致，约定要优于编码

package com.chensi.bean;

//实体类中的字段要与表单中的字段一致，约定优于编码
public class User {

    private String userName;
    private String pwd;
    private String sex;
    private String[] hobby;
    private String city;
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getPwd() {
        return pwd;
    }
    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public String[] getHobby() {
        return hobby;
    }
    public void setHobby(String[] hobby) {
        this.hobby = hobby;
    }
    public String getCity() {
        return city;
    }
    public void setCity(String city) {
        this.city = city;
    }
    
}

接收方法一：         Servlet页面(后台接收数据方法一)

package com.chensi;

import java.io.IOException;
import java.util.Iterator;

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

/**
 * Servlet 获得填写的表单数据
 */
@WebServlet("/RequestDemo3")
public class RequestDemo3 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        //获取传过来的表单数据,根据表单中的name获取所填写的值
        String userName = request.getParameter("userName");
        String pwd = request.getParameter("pwd");
        String sex = request.getParameter("sex");
        String[] hobbys = request.getParameterValues("hobby");
        
        System.out.println(userName);
        System.out.println(pwd);
        System.out.println(sex);
        for (int i = 0; hobbys!=null&&i < hobbys.length; i++) {
            System.out.println(hobbys[i]+"	");
        }
    }

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

}

得到的数据：

　　　　

接收方法二：

package com.chensi;

import java.io.IOException;
import java.util.Enumeration;
import java.util.Iterator;

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

/**
 * Servlet 获得填写的表单数据
 */
@WebServlet("/RequestDemo3")
public class RequestDemo3 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        //获取传过来的表单数据,根据表单中的name获取所填写的值
        Enumeration<String> names = request.getParameterNames();
        while (names.hasMoreElements()) {
            String strings = (String) names.nextElement();
            String[] parameterValues = request.getParameterValues(strings);
            for (int i = 0;parameterValues!=null&&i < parameterValues.length; i++) {
                System.out.println(strings+":"+parameterValues[i]+"	");
            }
        }
    }

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

}

得到的数据：

　　　　

接收方法三： 利用反射赋值给User

package com.chensi;

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;

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 com.chensi.bean.User;

/**
 * Servlet 获得填写的表单数据
 */
@WebServlet("/RequestDemo3")
public class RequestDemo3 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        //获取传过来的表单数据,根据表单中的name获取所填写的值
        
            
            try {
                User u = new User();
                System.out.println("数据封装之前: "+u);
                //获取到表单数据
                Map<String, String[]> map = request.getParameterMap();
                for(Map.Entry<String,String[]> m:map.entrySet()){
                    String name = m.getKey();
                    String[] value = m.getValue();
                    //创建一个属性描述器
                    PropertyDescriptor pd = new PropertyDescriptor(name, User.class);
                    //得到setter属性
                    Method setter = pd.getWriteMethod();
                    if(value.length==1){
                        setter.invoke(u, value[0]);
                    }else{
                        setter.invoke(u, (Object)value);
                    }
                }
                System.out.println("封装数据之后: "+u);
            } catch (IntrospectionException | IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
                e.printStackTrace();
            }
            
        }
        
    

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

}

得到的结果：

　　

接收方法四：使用apache 的 BeanUtils 工具来进行封装数据（ps：这个Benautils工具，Struts框架就是使用这个来获取表单数据的哦！）

package com.chensi;

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;

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 org.apache.commons.beanutils.BeanUtils;

import com.chensi.bean.User;

/**
 * Servlet 获得填写的表单数据
 */
@WebServlet("/RequestDemo3")
public class RequestDemo3 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        //获取传过来的表单数据,根据表单中的name获取所填写的值
    
        //方法四：使用beanUtil来封装User类
        User u = new User();
        System.out.println("没有使用BeanUtil封装之前：  "+u);
        try {
            BeanUtils.populate(u, request.getParameterMap());
            System.out.println("使用BeanUtils封装之后：  "+u);
        } catch (IllegalAccessException | InvocationTargetException e) {
            e.printStackTrace();
        }
            
        }
        
    

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

得到的结果：

　　　

接收方法 方式五： 使用inputStream流来进行接收（一般字符串啥的不用这个方法，一般是文件上传下载时候才会使用这种方法）因为接收到的字符串各种乱码，编码问题解决不好

package com.chensi;

import java.beans.IntrospectionException;
import java.beans.PropertyDescriptor;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;

import com.chensi.bean.User;

/**
 * Servlet 获得填写的表单数据
 */
@WebServlet("/RequestDemo3")
public class RequestDemo3 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        //获取传过来的表单数据,根据表单中的name获取所填写的值
        response.setContentType("text/html;charset=UTF-8");
        //获取表单数据
        ServletInputStream sis = request.getInputStream();
        int len = 0;
        byte[] b = new byte[1024];
        while((len=sis.read(b))!=-1){
            System.out.println(new String(b, 0, len, "UTF-8"));
        }
        
        sis.close();
        
    }

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

得到的结果：（各种乱码 。。。。）

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原文地址：https://www.cnblogs.com/zhanghaoliang/p/5622900.html