一篇博客上手request和response
概念
request：获取请求数据
response：设置响应数据
Request
request继承体系
ServletRequest——Java提供的请求对象根接口
HttpServletRequest——Java提供的对http协议封装的请求对象接口
RequestFacade——tomcat实现定义类
request获取数据
package com.itheijma.web;
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.BufferedReader;
import java.io.IOException;
@WebServlet("/req1")
public class RequestDemo1 extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//String method() 获取请求方式
String method = req.getMethod();
System.out.println(method);
//String getContextPath() 获取虚拟目录（项目访问路径）
String contextPath = req.getContextPath();
System.out.println(contextPath);
//StringBuffer getRequestURL() 获取URL（统一资源定位符）
StringBuffer url = req.getRequestURL();
System.out.println(url.toString());
//String getRequestURI() 获取URI（统一资源标识符）
String uri = req.getRequestURI();
System.out.println(uri);
//String getQueryString() 获取请求参数（get方式）
String queryString = req.getQueryString();
System.out.println(queryString);
//------------
//获取请求头
String agent = req.getHeader("user-agent");
System.out.println(agent);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//获取post请求体：请求参数
// 1. 获取字符输入流
BufferedReader br = req.getReader();
// 2. 读取数据
String line = br.readLine();
System.out.println(line);
}
}
request通用的方式获取数据
package com.itheijma.web;
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("/req2")
public class RequestDemo2 extends HttpServlet{
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//get请求逻辑
// System.out.println("get...");
// 1.获取所有参数的map集合
Map<String, String[]> map = req.getParameterMap();
for (String key : map.keySet()) {
//username:zhangsan
System.out.print(key+":");
//获取值
String[] values = map.get(key);
for (String value : values) {
System.out.print(value + " ");
}
System.out.println();
}
System.out.println("----------");
// 2.根据key获取参数值，数组
String[] hobbies = req.getParameterValues("hobby");
for (String hobby : hobbies) {
System.out.println(hobby);
}
// 3. 根据key获取单个参数值
String username = req.getParameter("username");
String password = req.getParameter("password");
System.out.println(username);
System.out.println(password);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//post请求逻辑
this.doGet(req,resp);
// System.out.println("post...");
// // 1.获取所有参数的map集合
// Map<String, String[]> map = req.getParameterMap();
// for (String key : map.keySet()) {
// //username:zhangsan
// System.out.print(key+":");
//
// //获取值
// String[] values = map.get(key);
// for (String value : values) {
// System.out.print(value + " ");
// }
//
// System.out.println();
// }
//
// System.out.println("----------");
//
// // 2.根据key获取参数值，数组
// String[] hobbies = req.getParameterValues("hobby");
// for (String hobby : hobbies) {
//
// System.out.println(hobby);
// }
//
// // 3. 根据key获取单个参数值
// String username = req.getParameter("username");
// String password = req.getParameter("password");
// System.out.println(username);
// System.out.println(password);
}
}
request请求参数中文乱码解决方法
package com.itheijma.web;
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.nio.charset.StandardCharsets;
/**
* 中文乱码问题解决方案
*/
@WebServlet("/req3")
public class RequestDemo3 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 1. 解决乱码 POST 获取参数方式:getReader()读取数据流
request.setCharacterEncoding("utf-8"); //设置字符输入流的编码
// 2. 获取username
String username = request.getParameter("username");
System.out.println("解决乱码前："+username);
// 3. 解决乱码 GET 获取参数方式:getQueryString
// 乱码原因：tomcat进行url解码，默认的字符集ISO-8859-1
// // 3.1 先对乱码数据进行编码：转为字节数组
// byte[] bytes = username.getBytes(StandardCharsets.ISO_8859_1);
// // 3.2 字节数组解码
// username = new String(bytes, StandardCharsets.UTF_8);
username = new String(username.getBytes(StandardCharsets.ISO_8859_1),StandardCharsets.UTF_8);
System.out.println("解决乱码后"+username);
}
}
request请求转发
请求转发（forward）：一种在服务器内部的资源跳转方式。
请求转发特点：
- 浏览器地址栏路径不发生变化
- 只能转发到当前服务器的内部资源
- 一次请求，可以在转发的资源间使用request共享数据
req4
package com.itheijma.web;
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.nio.charset.StandardCharsets;
/**
* 请求转发
*/
@WebServlet("/req4")
public class RequestDemo4 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("demo4");
//存储数据
request.setAttribute("msg","hello");
//请求转发
request.getRequestDispatcher("/req5").forward(request,response);
}
}
req5
package com.itheijma.web;
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;
@WebServlet("/req5")
public class RequestDemo5 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("demo5");
//获取数据
Object msg = request.getAttribute("msg");
System.out.println(msg);
}
}
response
Response完成重定向
重定向：一种资源跳转的方式
resp1
package com.itheima.web.response;
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;
@WebServlet("/resp1")
public class ResponseDemo1 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("resp1...");
// // 重定向
// // 1. 设置状态码 302
// response.setStatus(302);
// // 2. 设置响应头 Location
// response.setHeader("Location","/tomcat-demo2/resp2");
// 简化方式完成重定向
response.sendRedirect("/tomcat-demo2/resp2");
}
}
resp2
package com.itheima.web.response;
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;
@WebServlet("/resp2")
public class ResponseDemo2 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("resp2...");
}
}
重定向特点：
- 浏览器地址栏路径发生变化
- 可以重定向到任意位置的资源（服务器内、外部均可）
- 两次请求，不能在多个资源使用request共享数据
资源路径问题（什么时候加虚拟目录）
浏览器使用：需要加虚拟目录
服务端使用：不需要加虚拟目录
动态获取虚拟目录
//动态获取虚拟目录
String contextPath = request.getContextPath();
response.sendRedirect(contextPath + "/resp2");
Response响应字符数据
package com.itheima.web.response;
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.io.PrintWriter;
/**
* 响应字符数据：设置字符数据的响应体
*/
@WebServlet("/resp3")
public class ResponseDemo3 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html;charset=utf-8");
//获取字符输出流
PrintWriter writer = response.getWriter();
//content-type
//response.setHeader("content-type","text/html");
writer.write("你好");
writer.write("<h1>aaa</h1>");
//细节：流不需要关闭
}
}
Response响应字节数据
package com.itheima.web.response;
import org.apache.commons.io.IOUtils;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.PrintWriter;
/**
* 响应字节数据：设置字节数据的响应体
*/
@WebServlet("/resp4")
public class ResponseDemo4 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
this.doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 1. 读取文件
FileInputStream fis = new FileInputStream("e://a.jpg");
// 2. 获取response字节输出流
ServletOutputStream os = response.getOutputStream();
// 3. 完成流的copy
// byte[] buff = new byte[1024];
// int len = 0;
// while ((len = fis.read(buff)) != -1){
// os.write(buff,0,len);
// }
IOUtils.copy(fis,os);//使用工具类
fis.close();
}
}
pom文件导入工具类
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.6</version>
</dependency>
