HttpServletResponse
1.簡單分類
1.1響應狀態碼
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負責向瀏覽器發送數據的方法
ServletOutputStream getOutputStream() throws IOException;
PrintWriter getWriter() throws IOException;
1.3負責向瀏覽器發送響應頭的方法
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.常見應用
2.1向瀏覽器傳遞信息
2.2下載文件
- 要獲取下載文件的路徑
- 下載的文件名是啥？
- 設置想辦法讓瀏覽器能夠支持下載我們需要的東西
- 獲取下載文件的輸入流
- 創建緩衝區
- 獲取OutputStream對象
- 將FileOutputStream流寫入到buffer緩衝區
- 使用OutputStream將緩衝區中的數據輸出到客戶端！
public class FileServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
// 1. 要獲取下載文件的路徑
String realPath = "D:\\IDEA\\jsp\\servlet-java\\disangechengxu\\src\\main\\resource\\1.png";
System.out.println("下載文件的路徑："+realPath);
// 2. 下載的文件名是啥？
String fileName = realPath.substring(realPath.lastIndexOf("\\") + 1);
// 3. 設置想辦法讓瀏覽器能夠支持(Content-Disposition)下載我們需要的東西,中文文件名URLEncoder.encode編碼，否則有可能亂碼
resp.setHeader("Content-Disposition","attachment;filename="+fileName);
// 4. 獲取下載文件的輸入流
FileInputStream in = new FileInputStream(realPath);
// 5. 創建緩衝區
int len=0;
byte[] bytes = new byte[1024];
// 6. 獲取OutputStream對象
ServletOutputStream out = resp.getOutputStream();
// 7. 將FileOutputStream流寫入到buffer緩衝區,使用OutputStream將緩衝區中的數據輸出到客戶端！
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驗證碼功能,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簡單實現登錄重定向
在Webapp–>編寫index.jsp
<html>
<body>
<h2>Hello World!</h2>
<form action="${pageContext.request.contextPath}/login"method="get">
用戶名：<input type="text"name="username"><br>
密碼：<input type="password"name="password"><br>
<input type="submit">
</form>
</body>
</html>
編寫測試代碼
public class RequestTest extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String username = req.getParameter("username");
String password = req.getParameter("password");
System.out.println(username+":"+password);
resp.sendRedirect("../success.jsp");
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}
在Webapp–>編寫success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>success</h1>
</body>
</html>HttpServletRequest
HttpServletRequest代表客戶端的請求，用戶通過Http協議訪問服務器，HTTP請求中的所有信息會被封裝到HttpServletRequest，通過這個HttpServletRequest的方法，獲得客戶端的所有信息；
應用場景:獲取參數，請求轉發
編寫 index.jsp
<%--
Created by IntelliJ IDEA.
User: 27170
Date: 2020/2/18
Time: 23:52
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>登錄</title>
</head>
<body>
<h1>登錄</h1>
<div style="text-aline:center">
<form action="${pageContext.request.contextPath}/login"method="post">
用戶名：<input type="text"name="username"><br>
密碼：<input type="password"name="password"><br>
愛好：
<input type="checkbox"name="hobbys"value="女孩">女孩
<input type="checkbox"name="hobbys"value="代碼">代碼
<input type="checkbox"name="hobbys"value="唱歌">唱歌
<input type="checkbox"name="hobbys"value="電影">電影
<br>
<input type="submit">
</form>
</div>
</body>
</html>
編寫success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h1>登陸成功</h1>
</body>
</html>
測試代碼
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);
}
}