request代表了请求

response代表响应

HttpServletResponse

setStatus();----->发送状态码

setHeader();---->发送响应头

getWriter();和getOutputStream();------>发送数据

addHeader();---->添加一个头

containsHeader();--->包含几个头

HttpServletResponse细节一-------》码表的对应设置charset=UTF-8

ResponseDemo1



如果不加：




response.setHeader("Content-type","text/html;charset=UTF-8");






浏览器读出涓球，默认国标读，不是utf-8




package cn.itcaste.web.servlet;

import java.io.IOException;

import java.io.OutputStream;

import java.io.UnsupportedEncodingException;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet("/ResponseDemo1")

public class ResponseDemo1 extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // test2(response);

        //test1(response);

    }

    private void test2(HttpServletResponse response) throws IOException, UnsupportedEncodingException {

        //用html技术中的meta标签模拟http响应头,来控制浏览器的行为

        String data="中国";

        OutputStream out=response.getOutputStream();

        out.write("<meta http-equiv='content-type' content='text/html;charset=UTF-8'>".getBytes());

        out.write(data.getBytes("UTF-8"));

    }

    private void test1(HttpServletResponse response) throws IOException, UnsupportedEncodingException {

        //以什么编码发就用什么编码读

        response.setHeader("Content-type","text/html;charset=UTF-8");

        String data="中国";

        OutputStream out=response.getOutputStream();

        out.write(data.getBytes("UTF-8"));

    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // TODO Auto-generated method stub

        doGet(request, response);

    }

}




如下demo字符流输出：浏览器显示？？---------理由在下张图




	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		String data="中国";

		PrintWriter out=response.getWriter();

		out.write(data);

	}






先把中国写入respone，因为respone是外国人发明的，查找的是iso8859这个码表，查找不到所以显示？？




如下代码可以改变所查码表和浏览器所读取时查询码表：




    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

//        response.setCharacterEncoding("UTF-8");//控制写入response时所查询的码表

//        response.setHeader("content-type", "text/html;charset=UTF-8");//控制浏览器输出时时所查询的码表

        response.setContentType("text/html;charset=UTF-8");//这句话可以代替上两句话

        String data="中国";

        PrintWriter out=response.getWriter();

        out.write(data);//writer流只能写字符串！

    }






HttpServletResponse细节二-------》response实现（中文）文件下载


ResponseDemo3：




package cn.itcaste.web.servlet;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import javax.imageio.stream.FileCacheImageInputStream;

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 org.apache.taglibs.standard.tag.common.core.OutSupport;

/**

 * 文件下载案例

 */

@WebServlet("/ResponseDemo3")

public class ResponseDemo3 extends HttpServlet {

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		String path=this.getServletContext().getRealPath("/download/1.jpg");//获取绝对路径

		String filename=path.substring(path.lastIndexOf("\\")+1);//获取文件名称

		response.setHeader("content-disposition", "attachment;filename="+filename );//设置成按下载方式读取的响应头

		InputStream in=null;

		OutputStream out=null;

		try {

			in=new FileInputStream(path);

			int len=0;

			byte buffer[]=new byte[1024];

			out=response.getOutputStream();

			while((len=in.read(buffer))>0){//读取到缓冲区的总字节数，如果没有更多的数据，因为文件的结尾已经到达，则为-1

				out.write(buffer,0,len);//将该输入流中的len个字节数据读入一个字节数组

			}

		}

		finally {

			if (in!=null) {

				try {

					in.close();

				} catch (Exception e) {

					// TODO Auto-generated catch block

					e.printStackTrace();

				}

			}

		}

	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		doGet(request, response);

	}

}





发布服务后浏览器显示：


下面我们来尝试中文：美女.jpg


demo




package cn.itcaste.web.servlet;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.net.URLDecoder;

import java.net.URLEncoder;

import javax.imageio.stream.FileCacheImageInputStream;

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 org.apache.taglibs.standard.tag.common.core.OutSupport;

/**

 * 文件下载案例

 */

@WebServlet("/ResponseDemo3")

public class ResponseDemo3 extends HttpServlet {

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		//如果下载名是中文，要经过url编码

		String path=this.getServletContext().getRealPath("/download/美女.jpg");//获取绝对路径

		String filename=path.substring(path.lastIndexOf("/")+1);//获取文件名称

		filename=URLEncoder.encode(filename, "UTF-8");//按理说这样就不会中文乱码，但是只有谷歌生效了，safari不行，我还在寻找办法

		System.out.println(filename);

		System.out.println(URLDecoder.decode(filename, "UTF-8"));

	//	response.setHeader("content-type", "charset=UTF-8");//控制浏览器输出时时所查询的码表

		response.setHeader("content-disposition", "attachment;filename="  +filename );  //设置成按下载方式读取的响应头

		InputStream in=null;

		OutputStream out=null;

		try {

			in=new FileInputStream(path);

			int len=0;

			byte buffer[]=new byte[1024];

			out=response.getOutputStream();

			while((len=in.read(buffer))>0){//读取到缓冲区的总字节数，如果没有更多的数据，因为文件的结尾已经到达，则为-1

				out.write(buffer,0,len);//将该输入流中的len个字节数据读入一个字节数组

			}

		}

		finally {

			if (in!=null) {

				try {

					in.close();

				} catch (Exception e) {

					// TODO Auto-generated catch block

					e.printStackTrace();

				}

			}

		}

	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		doGet(request, response);

	}

}





浏览器显示：




HttpServletResponse细节三-------》response实现输出随机图片


先来看效果：------》目的在于防止恶意注册




demo：




package cn.itcaste.web.servlet;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.Graphics2D;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.util.Random;

import javax.imageio.ImageIO;

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 ResponseDemo4

 */

@WebServlet("/ResponseDemo4")

public class ResponseDemo4 extends HttpServlet {

   public static final int WIDTH=120;

   public static final int HEIGHT=35;

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //BufferedImage.TYPE_INT_RGB图像类型

		BufferedImage image=new BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB);//在内存中构建出一幅图像

		Graphics g=image.getGraphics();//得到图形！Graphics类是所有图形上下文的抽象基类，允许应用程序绘制在各种设备上实现的组件以及屏幕外图像。

		//1.设置背景色

		setBackGround(g);

		//2.设置边框

		setBorder(g);

		//3.画干扰线

		drawRandomLine(g);

		//4.画随机数

		drawRandomNum((Graphics2D)g);

		//5.图形写给随机数

		response.setContentType("image/jpeg");

		//发头控制浏览器不要缓存

		response.setDateHeader("expries", -1);

		response.setHeader("Cache-Control", "no-cache");

		response.setHeader("Pragma ","no-cache" );

		ImageIO.write(image, "jpg",  response.getOutputStream());

	}

	/**

	 * @param g

	 * 设置背景色

	 */

	private void setBackGround(Graphics g) {

		g.setColor(Color.WHITE);

		g.fillRect(0, 0, WIDTH, HEIGHT);

	}

	/**

	 * @param g

	 * 设置边框

	 */

	private void setBorder(Graphics g) {

		g.setColor(Color.RED);

		g.drawRect(0, 0, WIDTH-2, HEIGHT-2);

	}

	/**

	 * @param g

	 * 画干扰线

	 */

	private void drawRandomLine(Graphics g) {

		g.setColor(Color.GREEN);

		for(int i=0;i<5;i++){

			int x1=new Random().nextInt(WIDTH);

			int y1=new Random().nextInt(HEIGHT);

			int x2=new Random().nextInt(WIDTH);

			int y2=new Random().nextInt(HEIGHT);

			g.drawLine(x1, y1, x2, y2);

		}

	}

	/**

	 * @param g

	 * 画随机数

	 */

	private void drawRandomNum(Graphics2D g) {

		g.setColor(Color.BLACK);

		String c1 = null;

		g.setFont(new Font("宋体", Font.BOLD, 18));

		for(int i=0;i<4;i++){

			int d=new Random().nextInt()%30;

			char c=(char) (0x4e00+(int)(Math.random()*(0x9fa5-0x4e00+1)));

			c1 = String.valueOf(c);

			g.rotate((d*3.14)/180,( WIDTH-(30*i)-30),(HEIGHT-20));

			g.drawString(c1,( WIDTH-(30*i)-30), (HEIGHT-15));

			g.rotate((-1*d*3.14)/180,( WIDTH-(30*i)-30),(HEIGHT-20));

		}

	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		// TODO Auto-generated method stub

		doGet(request, response);

	}

}





点击图片换一张js：




HttpServletResponse细节二-------》response实现 refresh定时刷新页面以及特定情景




/**

 * Servlet implementation class ResponseDemo5

 */

@WebServlet("/ResponseDemo5")

public class ResponseDemo5 extends HttpServlet {

	//控制浏览器定时刷新

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		//假设这是一个用于处理登录的servlet

		//假设程序运行到此，用户等录成功

		//test1(response);

		response.setCharacterEncoding("UTF-8");

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

		response.getWriter().write("登录成功，三秒后将跳转到首页，如果没有，请点击<a href='/day04/ResponseDemo4'>超链接</a>");

		response.setHeader("refresh", "3;url='/day04/ResponseDemo4'");//每隔三秒拿一次数据

	}

	private void test1(HttpServletResponse response) throws IOException {

		response.setHeader("refresh", "3");//每隔三秒拿一次数据

		String data=new Random().nextInt(10000)+"";

		response.getWriter().write(data);

	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		// TODO Auto-generated method stub

		doGet(request, response);

	}

}





浏览器先看到如下，不点击超链接则3秒后自动跳转，点击则立刻跳转：




HttpServletResponse细节三-------》控制浏览器要缓存




/**

 * 控制浏览器要缓存

 */

@WebServlet("/ResponsDemo6")

public class ResponseDemo6 extends HttpServlet {

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		response.setDateHeader("expires", System.currentTimeMillis()+1000*3600);//设置缓存时间，当前时间加一秒乘3600=一天

		String data="aaaaaaaaa";

		response.getWriter().write(data);

	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		// TODO Auto-generated method stub

		doGet(request, response);

	}

}





HttpServletResponse细节四-------》重定向




/**

 * 实现请求重定向

 * 地址栏会发生变化：适用于登录跳转首页，购物

 */

@WebServlet("/ResponseDemo7")

public class ResponseDemo7 extends HttpServlet {

	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

//	 response.setStatus(302);

//	 response.setHeader("location", "/day04/1.jsp");

		response.sendRedirect("/day04/1.jsp");//这句可以代替上面两句，重定向等于发送两次请求

	}

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		// TODO Auto-generated method stub

		doGet(request, response);

	}

}





HttpServletResponse细节五-------》


response.getOutputStream();
        response.getWriter();


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