第73节：Java中的HTTPServletReauest和HTTPServletResponse
第73节：
Java中的HTTPServletReauest和HTTPServletResponse
HTTP协议
客户端与服务器端通讯的一种规则。
request:
请求行
请求头
请求体
response:
响应行
响应头
响应体
Get:
请求的时候带上的数据，在url上拼接，数据长度有限制
POST:
以流的方式写数据，数据没有限制
Content-Type: 数据类型
Content-Length: 多少长度的数据
Servlet入门：
写一个类，实现接口Servlet
注册 web.xml
<servlet>
servlet-name: 自定义
servlet-class: 全路径
<init-params> 不必要写 -servletconfig
</servlet>
<servlet-mapping>
<servlet-name>: 上面的servlet-name
<url-patter>: 以正斜杠开头
</servlet-mapping>
servlet的生命周期：
init: 默认情况下初次访问时就会执行，服务器启动时，只能执行一次
提前：
<servlet>
servlet-name:
servlet-class:
<load-on-startup>2</load-on-startup>
</servlet>
service: 可以执行多次，只要进行请求
destory：销毁的使用，销毁在从服务器中移除托管或shutdown.bat
// servlet
public class Demo implements Servlet {
@Override
void service(){
...
}
}
// 优化
继承接口已有的实现类
// 抽象类一定有抽象方法，不一定，有抽象方法的，一定是抽象类
class Demo2 extends HttpServlet {
void doGet();
void doPost();
}
// 源码
public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
HttpServletRequest request;
HttpServletResponse response;
try{
request = (HttpServletRequest) req;
response = (HttpServletResponse) res;
}catch(ClassCastException e){
throw new ServletException("non-HTTP request or response");
}
service(request,response);
}
HttpServletRequest和HttpServletResponse
package com.dashucoding.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Demo extends HttpServlet{
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("来了一个请求。。。");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req,resp);
}
}
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>ServletRegister</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>demo</servlet-name>
<servlet-class>com.dashucoding.servlet.Demo</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>demo</servlet-name>
<url-pattern>/demo</url-pattern>
</servlet-mapping>
</web-app>
创建Server
// 创建ServletRegister -> 选择Servlet
package com.dashucoding.servlet;
import java.io.IOException;
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 implementation class ServletRegister
*/
@WebServlet("/ServletRegister")
public class ServletRegister extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ServletRegister() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
package com.dashucoding.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class ServletRegister
*/
public class ServletRegister extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>TestRegister</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<description></description>
<display-name>ServletRegister</display-name>
<servlet-name>ServletRegister</servlet-name>
<servlet-class>com.dashucoding.servlet.ServletRegister</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ServletRegister</servlet-name>
<url-pattern>/ServletRegister</url-pattern>
</servlet-mapping>
</web-app>
Servlet配置路径方式：
* : 就是个通配符，匹配任意文字。
/a*
*.aa
ServletContext
// web.xml
// 用于配置全局的参数
<context-param>
<param-name>dashu</param-name>
<param-value>dashucoding</param-value>
</context-param>
// <init-param></init-param>
// 获取对象
ServletContext context = getServletContext();
// 获取参数值
String name = context.getInitParameter("dashu");
System.out.println("name=" + name);
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 获取对象
ServletContext context = getServletContext();
// 获取参数值
String name = context.getInitParameter("dashu");
System.out.println("name=" + name);
}
获取资源文件
package com.dashucoding.servlet;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Demo03
*/
public class Demo03 extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
// 获取ServletContext对象
ServletContext context = getServletContext();
// 获取给定的文件在服务器上面的绝对路径
String path = context.getRealPath("");
System.out.println("path=" + path);
/*// 创建属性对象
Properties properties = new Properties();
// 指定载入的数据源
InputStream is = new FileInputStream(path);
properties.load(is);
// 获取属性的值
String name = properties.getProperty("name");
System.out.println("name=" + name);*/
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
package com.dashucoding.servlet;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Demo03
*/
public class Demo03 extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// TODO Auto-generated method stub
// 获取ServletContext对象
ServletContext context = getServletContext();
// 获取给定的文件在服务器上面的绝对路径
String path = context.getRealPath("/file/config.properties");
System.out.println("path=" + path);
// 创建属性对象
Properties properties = new Properties();
// 指定载入的数据源
InputStream is = new FileInputStream(path);
properties.load(is);
// 获取属性的值
String name = properties.getProperty("name");
System.out.println("name=" + name);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
package com.dashucoding.servlet;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Demo03
*/
public class Demo03 extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// test01();
test02();
}
// alt + shift + z
private void test02() {
try {
// 获取ServletContext对象
ServletContext context = getServletContext();
// 创建属性对象
Properties properties = new Properties();
// 指定载入的数据源
InputStream is = context.getResourceAsStream("/file/config.properties");
properties.load(is);
// 获取属性的值
String name = properties.getProperty("name");
System.out.println("name02=" + name);
is.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
// alt + shift + m
private void test01() throws FileNotFoundException, IOException {
// 获取ServletContext对象
ServletContext context = getServletContext();
// 获取给定的文件在服务器上面的绝对路径
String path = context.getRealPath("/file/config.properties");
System.out.println("path=" + path);
// 创建属性对象
Properties properties = new Properties();
// 指定载入的数据源
InputStream is = new FileInputStream(path);
properties.load(is);
// 获取属性的值
String name = properties.getProperty("name");
System.out.println("name=" + name);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
package com.dashucoding.servlet;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Demo03
*/
public class Demo03 extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// test01();
// test02();
test03();
}
private void test03() {
// TODO Auto-generated method stub
try {
// 获取ServletContext对象
ServletContext context = getServletContext();
// 创建属性对象
Properties properties = new Properties();
// 指定载入的数据源
InputStream is = getClass().getClassLoader().getResourceAsStream("../../file/config.properties");
properties.load(is);
// 获取属性的值
String name = properties.getProperty("name");
System.out.println("name02=" + name);
is.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
// alt + shift + z
private void test02() {
try {
// 获取ServletContext对象
ServletContext context = getServletContext();
// 创建属性对象
Properties properties = new Properties();
// 指定载入的数据源
InputStream is = context.getResourceAsStream("/file/config.properties");
properties.load(is);
// 获取属性的值
String name = properties.getProperty("name");
System.out.println("name02=" + name);
is.close();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
// alt + shift + m
private void test01() throws FileNotFoundException, IOException {
// 获取ServletContext对象
ServletContext context = getServletContext();
// 获取给定的文件在服务器上面的绝对路径
String path = context.getRealPath("/file/config.properties");
System.out.println("path=" + path);
// 创建属性对象
Properties properties = new Properties();
// 指定载入的数据源
InputStream is = new FileInputStream(path);
properties.load(is);
// 获取属性的值
String name = properties.getProperty("name");
System.out.println("name=" + name);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
ServletContext可以获取全局配置参数，可以获取web工程中的资源，存储数据，servlet简共享数据。
使用ServletContext获取数据
package com.dashucoding.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class LoginServlet
*/
public class LoginServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 别人把数据给你了,你就要进行获取数据
String userName = request.getParameter("username");
String password = request.getParameter("password");
System.out.println("usrName=" + userName + "==password==" + password );
// 校验数据
if("dashu".equals(userName)&&"123".equals(password)) {
System.out.println("登录成功");
}else {
System.out.println("登录失败");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>登录</h2>
<form action="LoginServlet" method="get">
账号:<input type="text" name="username"/><br>
密码:<input type="text" name="password"/><br>
<input type="submit" value="登录"/>
</form>
</body>
</html>
登录
package com.dashucoding.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class LoginServlet
*/
public class LoginServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 别人把数据给你了,你就要进行获取数据
String userName = request.getParameter("username");
String password = request.getParameter("password");
System.out.println("usrName=" + userName + "==password==" + password );
// 校验数据
// response
PrintWriter pw = response.getWriter();
if("dashu".equals(userName)&&"123".equals(password)) {
// System.out.println("登录成功");
pw.write("login success");
}else {
// System.out.println("登录失败");
pw.write("login failed");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>登录成功</h2>
<a href="CountSrevlet">获取网站登录成功总数 </a>
</body>
</html>
package com.dashucoding.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class LoginServlet
*/
public class LoginServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 别人把数据给你了,你就要进行获取数据
String userName = request.getParameter("username");
String password = request.getParameter("password");
System.out.println("usrName=" + userName + "==password==" + password );
// 校验数据
// response
PrintWriter pw = response.getWriter();
if("dashu".equals(userName)&&"123".equals(password)) {
// System.out.println("登录成功");
// pw.write("login success");
// 成功跳转 login_success.html
// 设置状态码
response.setStatus(302);
response.setHeader("Location", "login_success.html");
}else {
// System.out.println("登录失败");
pw.write("login failed");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
登录次数
package com.dashucoding.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class CountServlet
*/
public class CountServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 取值
int count = (int)getServletContext().getAttribute("count");
// 输出界面
response.getWriter().write("login success count == "+count);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
package com.dashucoding.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class LoginServlet
*/
public class LoginServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 别人把数据给你了,你就要进行获取数据
String userName = request.getParameter("username");
String password = request.getParameter("password");
System.out.println("usrName=" + userName + "==password==" + password );
// 校验数据
// response
PrintWriter pw = response.getWriter();
if("dashu".equals(userName)&&"123".equals(password)) {
// System.out.println("登录成功");
// pw.write("login success");
// 成功跳转 login_success.html
// 成功次数累加 存东西
// 获取以前旧的值,然后给它赋新值
Object obj = getServletContext().getAttribute("count");
int totalCount = 0;
if(obj != null) {
totalCount = (int)obj;
}
System.out.println("登录成功的此时是" + totalCount);
// 给count赋新值 set add put
getServletContext().setAttribute("count",totalCount+1);
// 设置状态码
response.setStatus(302);
response.setHeader("Location", "login_success.html");
}else {
// System.out.println("登录失败");
pw.write("login failed");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>登录成功</h2>
<a href="CountServlet">获取网站登录成功总数 </a>
</body>
</html>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>登录</h2>
<form action="LoginServlet" method="get">
账号:<input type="text" name="username"/><br>
密码:<input type="text" name="password"/><br>
<input type="submit" value="登录"/>
</form>
</body>
</html>
路径：
<form action="login" method="get">
账号:<input type="text" name="username"/><br>
密码:<input type="text" name="password"/><br>
<input type="submit" value="登录"/>
</form>
<servlet-mapping>
<servlet-name>LoginServlet</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
// ServletContext 销毁，服务器移除，关闭服务器
只要同一个应用程序就行
作用：
- 获取全局配置
- 获取web工程中的资源
- 存储数据
- 共享数据
HttpServletRequest获取请求头
获取所有的头信息:
package com.dashucoding.servlet;
import java.io.IOException;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Demo01
*/
public class Demo01 extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
// request封装了客户端提交过来的一切数据
// 拿所有的头 得到一个枚举 List集合
Enumeration<String> headerNames = request.getHeaderNames();
while(headerNames.hasMoreElements()) {
String name = (String) headerNames.nextElement();
System.out.println("name=" + name);
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
得到所有
package com.dashucoding.servlet;
import java.io.IOException;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Demo01
*/
public class Demo01 extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
// request封装了客户端提交过来的一切数据
// 拿所有的头 得到一个枚举 List集合
Enumeration<String> headerNames = request.getHeaderNames();
while(headerNames.hasMoreElements()) {
String name = (String) headerNames.nextElement();
String value = request.getHeader(name);
System.out.println("name=" + name + ";value=" + value);
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
获取提交的信息
package com.dashucoding.servlet;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Demo01
*/
public class Demo01 extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
// request封装了客户端提交过来的一切数据
// 拿所有的头 得到一个枚举 List集合
Enumeration<String> headerNames = request.getHeaderNames();
while(headerNames.hasMoreElements()) {
String name = (String) headerNames.nextElement();
String value = request.getHeader(name);
System.out.println("name=" + name + ";value=" + value);
}
System.out.println("----------");
// 请求体，拼接过来的数据 获取客户端提交过来的数据
String name = request.getParameter("name");
System.out.println("name=" + name);
// http://localhost:8080/RequestDemo01/Demo01?name=dashucoding
// http://localhost:8080/RequestDemo01/Demo01?name=dashucoding&address=GD
System.out.println("----------");
// 获取所有参数
// Enumeration<String> parameterNames = request.getParameterNames();
Map<String, String[]> map = request.getParameterMap();
Set<String> keySet = map.keySet();
Iterator<String> iterator = keySet.iterator();
while(iterator.hasNext()) {
String key = (String) iterator.next();
System.out.println("key="+key+"，的值总数" + map.get(key).length);
String value = map.get(key)[0];
String value1 = map.get(key)[1];
String value2 = map.get(key)[2];
System.out.println(key+" == "+value + "=" + value1 + "=" + value2);
// http://localhost:8080/RequestDemo01/Demo01?name=dashucoding&address=GD
// name=zhangsan&name=lisi
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
get请求过来的数据已经在url地址栏上进行过编码了，所以取到的是乱码。
getParameter默认使用ISO-8859-1去解码
username = new String(username.getBytes("ISO-8859-1"), "UTF-8");
System.out.println("userName="+username+"==password="+password);
post
package com.dashucoding.servlet;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class LoginServlet
*/
public class LoginServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
// 设置请求体的文字编码
request.setCharacterEncoding("UTF-8");
String username = request.getParameter("username");
String password = request.getParameter("password");
// test01(username, password);
//post过来的数据乱码处理：
System.out.println("post:userName="+username+"==password="+password);
}
private void test01(String username, String password) throws UnsupportedEncodingException {
System.out.println("username" + username +"password" + password);
// 转成ISO-8859-1字节数组，再utf-8去拼接
username = new String(username.getBytes("ISO-8859-1"),"UTF-8");
System.out.println("userName="+username+"==password="+password);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
System.out.println("来了一个post请求");
doGet(request, response);
}
}
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<h2>登录</h2>
<form action="login" method="post">
账号:<input type="text" name="username"/><br>
密码:<input type="text" name="password"/><br>
<input type="submit" value="登录"/>
</form>
</body>
</html>
HttpServletResponse
package com.dashucoding.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Demo01
*/
public class Demo01 extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
// 字符流的方式
// response.getWriter().write("hello response");
response.getOutputStream().write("hello".getBytes());
// 设置当前请求的处理状态码
// response.setStatus("");
// 设置一个头
// response.setHeader(name, value);
// 设置响应内容的类型，以及编码
// response.setContentType(type);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
package com.dashucoding.servlet;
import java.io.IOException;
import java.nio.charset.Charset;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Demo01
*/
public class Demo01 extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
// test01(response);
// test02(response);
// 字节流 默认是使用utf-8
// response.getOutputStream().write("我是谁".getBytes());
// 参数可以指定编码方式
String csn = Charset.defaultCharset().name();
response.setHeader("Content-Type", "text/html; charset=UTF-8");
response.getOutputStream().write("我是谁".getBytes("UTF-8"));
}
void test02(HttpServletResponse response){
try {
// 中文乱码
// 默认编码ISO-8859-1
response.setCharacterEncoding("UTF-8");
// 规定浏览器用什么编码去看
response.setHeader("Content-Type", "text/html; charset=UTF-8");
response.getWriter().write("我是谁");
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
// Ctrl + shift + f
void test01(HttpServletResponse response) {
// 字符流的方式
// response.getWriter().write("hello response");
try {
response.getOutputStream().write("hello".getBytes());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// 设置当前请求的处理状态码
// response.setStatus("");
// 设置一个头
// response.setHeader(name, value);
// 设置响应内容的类型，以及编码
// response.setContentType(type);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
下载资源文件
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
默认servlet去下载<br>
<a href="download/aa.jpg">aa.jpg</a><br>
<a href="download/bb.txt">bb.txt</a><br>
<a href="download/cc.rar">cc.rar</a><br>
</body>
</html>
手动下载
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
默认servlet去下载<br>
<a href="download/aa.jpg">aa.jpg</a><br>
<a href="download/bb.txt">bb.txt</a><br>
<a href="download/cc.rar">cc.rar</a><br>
<br>手动下载<br>
<a href="Demo01?filename=aa.jpg">aa.jpg</a><br>
<a href="Demo01?filename=bb.txt">bb.txt</a><br>
<a href="Demo01?filename=cc.rar">cc.rar</a><br>
</body>
</html>
用于用户下载
package com.dashucoding.servlet;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Demo01
*/
public class Demo01 extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
// 获取要下载的文件名字
String fileName = request.getParameter("filename");
// 获取这个文件在tomcat里面的绝对路径地址
String path = getServletContext().getRealPath("download/"+fileName);
// 用于用户下载
response.setHeader("Content-Disposition", "attachment; filename="+fileName);
// 转化成输入流
InputStream is = new FileInputStream(path);
OutputStream os = response.getOutputStream();
int len = 0;
byte[] buffer = new byte[1024];
while( (len = is.read(buffer)) != -1) {
os.write(buffer, 0, len);
}
os.close();
is.close();
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
小结重点
HttpServletRequest：获取请求头
HttpServletResponse：对请求作出响应
如果看了觉得不错
点赞！转发！
达叔小生：往后余生，唯独有你
You and me, we are family !
90后帅气小伙，良好的开发习惯；独立思考的能力；主动并且善于沟通
简书博客： 达叔小生
https://www.jianshu.com/u/c785ece603d1
结语
- 下面我将继续对 其他知识 深入讲解 ，有兴趣可以继续关注
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