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();
不能同时调用