第73节：Java中的HTTPServletReauest和HTTPServletResponse

时间：2021-07-26 06:09:02

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

第73节：Java中的HTTPServletReauest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>

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

创建Server

第73节：Java中的HTTPServletReauest和HTTPServletResponse

// 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>

第73节：Java中的HTTPServletReauest和HTTPServletResponse

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

第73节：Java中的HTTPServletReauest和HTTPServletResponse

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);

	}

}

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

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);

	}

}

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

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);

	}

}

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

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);

	}

}

第73节：Java中的HTTPServletReauest和HTTPServletResponse

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

第73节：Java中的HTTPServletReauest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;

/**

 * 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>

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

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);

	}

}

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

<!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

第73节：Java中的HTTPServletReauest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;

/**

 * 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>

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

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：

  1. 获取全局配置
  2. 获取web工程中的资源
  3. 存储数据
  4. 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);

	}

}

第73节：Java中的HTTPServletReauest和HTTPServletResponse

第73节：Java中的HTTPServletReauest和HTTPServletResponse

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);

	}

}

第73节：Java中的HTTPServletReauest和HTTPServletResponse

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

第73节：Java中的HTTPServletReauest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;

/**

 * 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

第73节：Java中的HTTPServletReauest和HTTPServletResponse

<!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>

第73节：Java中的HTTPServletReauest和HTTPServletResponse

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
  • 小礼物走一走 or 点赞

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