Request获取参数

Request获取参数

package com.itheima.request;

import java.beans.IntrospectionException;

import java.beans.PropertyDescriptor;

import java.io.IOException;

import java.io.PrintWriter;

import java.lang.reflect.Method;

import java.util.Enumeration;

import java.util.Map;

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 com.itheima.domain.User;

/*

GET方式： URI？username=abc&password=123 username和password就是请求参数

POST方式： 请求正文中 username=abc&password=123

*/

public class RequestDemo3 extends HttpServlet {

public response)

void doGet(HttpServletRequest request, HttpServletResponse

throws ServletException, IOException {

try {

test7(request, response);

} catch (Exception e) {

e.printStackTrace();

}

}

//实际开发中怎么玩：封装对象 借助第三方开发包 BeanUtils 终极版

private void test7(HttpServletRequest request, HttpServletResponse response)

throws IOException, Exception {

User user = new User();

System.out.println(\"封装前：\"+user);

//表单的字段名和User中的属性名一致

BeanUtils.populate(user, request.getParameterMap());

System.out.println(\"封装后：\"+user);

}

//实际开发中怎么玩：封装对象 借助第三方开发包 BeanUtils

private void test6(HttpServletRequest request, HttpServletResponse response)

throws IOException, Exception {

User user = new User();

System.out.println(\"封装前：\"+user);

//表单的字段名和User中的属性名一致

Map map = request.getParameterMap();//key：表单中input的name value：请求参数的值数组

for(Map.Entry me:map.entrySet()){

String paramName = me.getKey();

String paramValues[] = me.getValue();

BeanUtils.setProperty(user, paramName, paramValues);//调用对应的setter方法

}

System.out.println(\"封装后：\"+user);

}

//实际开发中怎么玩：封装对象(技术点：反射+内省) 参考：java基础加强

private void test5(HttpServletRequest request, HttpServletResponse response)

throws IOException, Exception {

User user = new User();

System.out.println(\"封装前：\"+user);

//表单的字段名和User中的属性名一致

Map map = request.getParameterMap();//key：表单中input的name value：请求参数的值数组

for(Map.Entry me:map.entrySet()){

String paramName = me.getKey();

String paramValues[] = me.getValue();

//调用User中对应的写属性：比如当前username，需要调用setUsername(paramValues);

PropertyDescriptor pd = new PropertyDescriptor(paramName, User.class);//属性描述器：就是得getter或setter方法的类

Method method = pd.getWriteMethod();// setter方法

if(paramValues!=null){

if(paramValues.length==1){

method.invoke(user, paramValues);//有一个数组（参考反射main方法）

}else{

method.invoke(user, (Object)paramValues);

}

}

}

System.out.println(\"封装后：\"+user);

}

//实际开发中怎么玩：封装对象(技术点：反射+内省) 参考：java基础加强

private void test4(HttpServletRequest request, HttpServletResponse response)

throws IOException, Exception {

User user = new User();

System.out.println(\"封装前：\"+user);

//表单的字段名和User中的属性名一致

Enumeration e = request.getParameterNames();

while(e.hasMoreElements()){

String paramName = (String) e.nextElement();//每一个form中的input域的name 和User中的属性一致

String paramValues[] = request.getParameterValues(paramName);

//调用User中对应的写属性：比如当前username，需要调用setUsername(paramValues);

PropertyDescriptor pd = new PropertyDescriptor(paramName, User.class);//属性描述器：就是得getter或setter方法的类

Method method = pd.getWriteMethod();// setter方法

if(paramValues!=null){

if(paramValues.length==1){

method.invoke(user, paramValues);//有一个数组（参考反射main方法）

}else{

method.invoke(user, (Object)paramValues);

}

}

}

System.out.println(\"封装后：\"+user);

}

//获取所有的请求参数

private void test3(HttpServletRequest request, HttpServletResponse response)

throws IOException {

response.setContentType(\"text/html;charset=UTF-8\");

PrintWriter out = response.getWriter();

Enumeration e = request.getParameterNames();//获取所有请求参数名

while(e.hasMoreElements()){

String paramName = (String)e.nextElement();//请求参数名

String values [] = request.getParameterValues(paramName);

out.write(paramName+\"=\");

for(String v:values){

out.write(v+\"，\");

}

out.write(\"
\");

}

}

//为什么返回的是String或String[]:用户的所有输出都是字符串

//获取重名的请求参数

private void test2(HttpServletRequest request, HttpServletResponse response)

throws IOException {

String passwords[] = request.getParameterValues(\"password\");

response.setContentType(\"text/html;charset=UTF-8\");

PrintWriter out = response.getWriter();

for(String p:passwords)

out.write(p+\"
\");

}

//获取单一的请求参数：重名的特例

private void test1(HttpServletRequest request, HttpServletResponse response)

throws IOException {

String username = request.getParameter(\"username\");

String password = request.getParameter(\"password\");

String code = request.getParameter(\"code\");

response.setContentType(\"text/html;charset=UTF-8\");

PrintWriter out = response.getWriter();

out.write(username+\":\"+password+\":\"+code);

}

public void doPost(HttpServletRequest request, response)

throws ServletException, IOException {

doGet(request, response);

}

}

HttpServletResponse