HttpServletResponse
1.简单分类
1.1响应状态码
int SC_CONTINUE = 100;
int SC_SWITCHING_PROTOCOLS = 101;
int SC_OK = 200;
int SC_CREATED = 201;
int SC_ACCEPTED = 202;
int SC_NON_AUTHORITATIVE_INFORMATION = 203;
int SC_NO_CONTENT = 204;
int SC_RESET_CONTENT = 205;
int SC_PARTIAL_CONTENT = 206;
int SC_MULTIPLE_CHOICES = 300;
int SC_MOVED_PERMANENTLY = 301;
int SC_MOVED_TEMPORARILY = 302;
int SC_FOUND = 302;
int SC_SEE_OTHER = 303;
int SC_NOT_MODIFIED = 304;
int SC_USE_PROXY = 305;
int SC_TEMPORARY_REDIRECT = 307;
int SC_BAD_REQUEST = 400;
int SC_UNAUTHORIZED = 401;
int SC_PAYMENT_REQUIRED = 402;
int SC_FORBIDDEN = 403;
int SC_NOT_FOUND = 404;
int SC_METHOD_NOT_ALLOWED = 405;
int SC_NOT_ACCEPTABLE = 406;
int SC_PROXY_AUTHENTICATION_REQUIRED = 407;
int SC_REQUEST_TIMEOUT = 408;
int SC_CONFLICT = 409;
int SC_GONE = 410;
int SC_LENGTH_REQUIRED = 411;
int SC_PRECONDITION_FAILED = 412;
int SC_REQUEST_ENTITY_TOO_LARGE = 413;
int SC_REQUEST_URI_TOO_LONG = 414;
int SC_UNSUPPORTED_MEDIA_TYPE = 415;
int SC_REQUESTED_RANGE_NOT_SATISFIABLE = 416;
int SC_EXPECTATION_FAILED = 417;
int SC_INTERNAL_SERVER_ERROR = 500;
int SC_NOT_IMPLEMENTED = 501;
int SC_BAD_GATEWAY = 502;
int SC_SERVICE_UNAVAILABLE = 503;
int SC_GATEWAY_TIMEOUT = 504;
int SC_HTTP_VERSION_NOT_SUPPORTED = 505;
1.2负责向浏览器发送数据的方法
ServletOutputStream getOutputStream() throws IOException;
PrintWriter getWriter() throws IOException;
1.3负责向浏览器发送响应头的方法
void sendError(int var1, String var2) throws IOException;
void sendError(int var1) throws IOException;
void sendRedirect(String var1) throws IOException;
void setDateHeader(String var1, long var2);
void addDateHeader(String var1, long var2);
void setHeader(String var1, String var2);
void addHeader(String var1, String var2);
void setIntHeader(String var1, int var2);
void addIntHeader(String var1, int var2);
void setStatus(int var1);
2.常见应用
2.1向浏览器传递信息
2.2下载文件
- 要获取下载文件的路径
- 下载的文件名是啥？
- 设置想办法让浏览器能够支持下载我们需要的东西
- 获取下载文件的输入流
- 创建缓冲区
- 获取OutputStream对象
- 将FileOutputStream流写入到buffer缓冲区
- 使用OutputStream将缓冲区中的数据输出到客户端！
public class FileServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 1. 要获取下载文件的路径
String realPath = "D:\\IDEA\\jsp\\servlet-java\\disangechengxu\\src\\main\\resource\\1.png";
System.out.println("下载文件的路径："+realPath);
// 2. 下载的文件名是啥？
String fileName = realPath.substring(realPath.lastIndexOf("\\") + 1);
// 3. 设置想办法让浏览器能够支持(Content-Disposition)下载我们需要的东西,中文文件名URLEncoder.encode编码，否则有可能乱码
resp.setHeader("Content-Disposition","attachment;filename="+fileName);
// 4. 获取下载文件的输入流
FileInputStream in = new FileInputStream(realPath);
// 5. 创建缓冲区
int len=0;
byte[] bytes = new byte[1024];
// 6. 获取OutputStream对象
ServletOutputStream out = resp.getOutputStream();
// 7. 将FileOutputStream流写入到buffer缓冲区,使用OutputStream将缓冲区中的数据输出到客户端！
while((len=in.read(bytes))!=-1){
out.write(bytes,0,len);
}
in.close();
out.close();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}2.3验证码功能,五秒刷新一次
public class ImageServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setHeader("refresh","3");
BufferedImage image = new BufferedImage(80,20,BufferedImage.TYPE_INT_RGB);
Graphics2D g = (Graphics2D) image.getGraphics();
g.setColor(Color.white);
g.fillRect(0,0,80,20);
g.setColor(Color.BLUE);
g.setFont(new Font(null, Font.BOLD,20));
g.drawString(makeNum(),0,20);
resp.setContentType("image/jpeg");
resp.setDateHeader("expires",-1);
resp.setHeader("Cache-Control","no-cache");
resp.setHeader("Pragme","no-cache");
ImageIO.write(image,"jpg",resp.getOutputStream());
}
public String makeNum(){
Random random = new Random();
String num = random.nextInt(9999999) + "";
StringBuffer sb = new StringBuffer();
for (int i = 0; i < 7 - num.length(); i++) {
sb.append("0");
}
num=sb.toString()+num;
return num;
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
2.4简单实现登录重定向
在Webapp–>编写index.jsp
<html>
<body>
<h2>Hello World!</h2>
<form action="${pageContext.request.contextPath}/login"method="get">
用户名：<input type="text"name="username"><br>
密码：<input type="password"name="password"><br>
<input type="submit">
</form>
</body>
</html>
编写测试代码
public class RequestTest extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String username = req.getParameter("username");
String password = req.getParameter("password");
System.out.println(username+":"+password);
resp.sendRedirect("../success.jsp");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
在Webapp–>编写success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>success</h1>
</body>
</html>HttpServletRequest
HttpServletRequest代表客户端的请求，用户通过Http协议访问服务器，HTTP请求中的所有信息会被封装到HttpServletRequest，通过这个HttpServletRequest的方法，获得客户端的所有信息；
应用场景:获取参数，请求转发
编写 index.jsp
<%--
Created by IntelliJ IDEA.
User: 27170
Date: 2020/2/18
Time: 23:52
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>登录</title>
</head>
<body>
<h1>登录</h1>
<div style="text-aline:center">
<form action="${pageContext.request.contextPath}/login"method="post">
用户名：<input type="text"name="username"><br>
密码：<input type="password"name="password"><br>
爱好：
<input type="checkbox"name="hobbys"value="女孩">女孩
<input type="checkbox"name="hobbys"value="代码">代码
<input type="checkbox"name="hobbys"value="唱歌">唱歌
<input type="checkbox"name="hobbys"value="电影">电影
<br>
<input type="submit">
</form>
</div>
</body>
</html>
编写success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>登陆成功</h1>
</body>
</html>
测试代码
public class LoginServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
req.setCharacterEncoding("utf8");
resp.setCharacterEncoding("utf8");
String username = req.getParameter("username");
String password = req.getParameter("password");
String[] hobbys = req.getParameterValues("hobbys");
System.out.println("===============");
System.out.println(username);
System.out.println(password);
System.out.println(Arrays.toString(hobbys));
System.out.println("===============");
req.getRequestDispatcher("/r/success.jsp").forward(req,resp);
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
