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手动去设置HTTP响应行、响应头、响应体

分类: 文章 • 2023-03-21 14:56:56

①手动去设置HTTP响应行中的状态码，这里用到了response的setStatus(int sc);这个方法

package com.itheima.line;

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 StatusServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		//手动去设置HTTP响应行中的状态码
		response.setStatus(1014);//这里的状态码设置为1014
		
	}

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

建立的工程如下：

手动去设置HTTP响应行、响应头、响应体

最后的结果如下：

手动去设置HTTP响应行、响应头、响应体

②通过response设置响应头

addHeader(String name, String value)
addIntHeader(String name, int value)
addDateHeader(String name, long date)

setHeader(String name, String value) 重点
setIntHeader(String name, int value)
setDateHeader(String name, long date)

其中，add表示添加，而set表示设置

为编辑之前的手动去设置HTTP响应行、响应头、响应体

手动去设置HTTP响应行、响应头、响应体

package com.itheima.header;

import java.io.IOException;
import java.util.Date;

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

public class HeaderServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		Date date = new Date();
		
		//设置响应头
		response.addHeader("name", "beyondyy");//若重复，则接着添加
		response.addHeader("name", "beyondwsq");
		response.addIntHeader("age", 19);
		response.addDateHeader("birthday", date.getTime());
	}

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

编辑之后的结果：

手动去设置HTTP响应行、响应头、响应体

同样的道理，add表示有相同的往后接着添加，set只保留一个，前面的会被后面的给取代。

③重定向（302）

老版

重定向：说白了就是，当你访问servlet1时，它没有资源，它给你说servlet2有，然后你就会再访问servlet2。

重定向 状态码 302
响应头 Location （代表重定向地址）
//servlet1
package com.itheima.header;

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 Servlet1 extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//没有响应资源 告知客户端去重定向到servlet2
		
		//1.设置状态码为302
		response.setStatus(302);
		//2.设置一个响应头Location
		response.setHeader("Location", "/WEB14/servlet2");
	}

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


//servl2
package com.itheima.header;

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 Servlet2 extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		response.getWriter().write("hello beyondsq...");
	}

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

手动去设置HTTP响应行、响应头、响应体

由于重定向的方法每次都那么写麻烦，javaEE进行封装成一个叫重定向的方法sendRedirect（url）；

封装之后的servlet1

新版 

//servlet1
package com.itheima.header;

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 Servlet1 extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//没有响应资源 告知客户端去重定向到servlet2
		//封装成一个重定向的方法sendRedirect(url);
		response.sendRedirect("/WEB14/servlet2");
	}

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

④定时刷新（跟重定向一样，就是多了一个时间延迟而已）

//refresh
package com.itheima.header;

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 RefreshServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//设置定时刷新的头
		response.setHeader("refresh", "5;url=//www.baidu.com");
		//5s之后再跳转到url为百度的地址
	}

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

⑤js完成页面的定时跳转

案例：5秒后自动跳转到百度
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript">
		window.onload = function(){
			var time = 5;
			var secondEle = document.getElementById("second");
			var timer = setInterval(function(){
				secondEle.innerHTML = time;
				time--;
				if(time==0){
					clearInterval(timer);	
					location.href="http://www.baidu.com";
				}
			},1000);//1000ms表示1s变一次
		}
</script>
</head>
<body>
		恭喜你，注册成功，<span style="color:red" id="second">5</span>秒后跳转。如不跳转，请点击<a href="http://www.baidu.com">这里</a>
</body>
</html>

⑥通过response设置响应体

旧

//text
package com.itheima.content;

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;

public class TextServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		//设置response查询的码表
		response.setCharacterEncoding("UTF-8");
		
		//通过一个头Content-Type告知客户端使用何种码表进行解码
		response.setHeader("Context-Type", "text/html;charset=UTF-8");//文本为HTML类型，编码为UTF-8 
		
		
		PrintWriter writer = response.getWriter();
		writer.write("原谅我这一生不羁放纵爱自由wsq");
	}

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

手动去设置HTTP响应行、响应头、响应体

工程创建手动去设置HTTP响应行、响应头、响应体

新（进行代码封装之后）

package com.itheima.content;

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;

public class TextServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		//进行方法封装之后	
		response.setContentType("text/html;charset=UTF-8");
		
		PrintWriter writer = response.getWriter();
		writer.write("原谅我这一生不羁放纵爱自由wsq");
	}

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

牢记这行代码即可：

response.setContentType(“text/html;charset=UTF-8”);

⑦response的outputstream来获得服务器上的图片

响应头设置字节

ServletOutputStream getOutputStream()
获得字节流，通过该字节流的write(byte[] bytes)可以向response缓冲区中写入字 节，在由Tomcat服务器将字节内容组成Http响应返回给浏览器。

//byte
package com.itheima.content;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ByteServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		//使用response获得字节输出流
		ServletOutputStream out = response.getOutputStream();
		
		//获得服务器上的图片
		String realPath = this.getServletContext().getRealPath("a.jpg");//相对地址，相对web应用的
		InputStream in = new FileInputStream(realPath);

		int len = 0;
		byte[] buffer = new byte[1024];
		while((len = in.read(buffer))>0){
			out.write(buffer,0,len);
		}
		
		in.close();
		out.close();	
	}

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

手动去设置HTTP响应行、响应头、响应体

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