@WebServlet("/hello.view")
public class HelloServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException {
// 设置响应内容类型器
response.setContentType("text/html;charset=UTF-8");
// 取得响应输出对象
PrintWriter out = response.getWriter();
// 取得 "请求参数"
String name = request.getParameter("name");
out.println("<html>");
out.println("<head>");
out.println("<title>HelloServlet</title>");
out.println("</head>");
out.println("<body>");
out.println("<p>hello, " + name + "! </p>");
out.println("</body>");
out.println("</html>");
out.close();
}
}<web-app>
<servlet>
<servlet-name>hello</servlet-name>
<servlet-class>org.example.java_web.servlet.hello.HelloServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>hello</servlet-name>
<url-pattern>/hello.view</url-pattern>
</servlet-mapping>
</web-app>
@WebServlet("/hello.view")/hello.view?name=zhangsan
- requestURI = contextURI + servletURI + pathInfo
out.println("<p>request.getRequestURI(): " + request.getRequestURI() + "</p>");
out.println("<p>request.getContextPath(): " + request.getContextPath() + "</p>");
out.println("<p>request.getServletPath(): " + request.getServletPath() + "</p>");
out.println("<p>request.getPathInfo(): " + request.getPathInfo() + "</p>");<p>request.getRequestURI(): /JavaWeb_Servlet_war/path.view</p>
<p>request.getContextPath(): /JavaWeb_Servlet_war</p>
<p>request.getServletPath(): /path.view</p>
<p>request.getPathInfo(): null</p>
Enumeration<String> names = request.getHeaderNames();
while (names.hasMoreElements()) {
String name = names.nextElement();
out.println("<p>" + name + ": " + request.getHeader(name) + "</p>");
}<p>host: localhost:8080</p>
<p>connection: keep-alive</p>
<p>cache-control: max-age=0</p>
<p>sec-ch-ua: " Not A;Brand";v="99", "Chromium";v="90", "Microsoft Edge";v="90"</p>
<p>sec-ch-ua-mobile: ?0</p>
<p>upgrade-insecure-requests: 1</p>
<p>user-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.85 Safari/537.36 Edg/90.0.818.46</p>
<p>accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9</p>
<p>sec-fetch-site: none</p>
<p>sec-fetch-mode: navigate</p>
<p>sec-fetch-user: ?1</p>
<p>sec-fetch-dest: document</p>
<p>accept-encoding: gzip, deflate, br</p>
<p>accept-language: zh-CN,zh;q=0.9,en;q=0.8,en-GB;q=0.7,en-US;q=0.6</p>
out.println("<p>host: " + request.getHeader("host") + "</p>");Enumeration<String> uas = request.getHeaders("user-agent");
while (uas.hasMoreElements()) {
String ua = uas.nextElement();
out.println("<p>user-agent: " + ua + "</p>");
}response.setContentType("text/html;charset=UTF-8");request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");private String readBody(HttpServletRequest request) throws IOException {
BufferedReader reader = request.getReader();
String input;
StringBuilder requestBody = new StringBuilder();
while ((input = reader.readLine()) != null) {
requestBody.append(input).append("<br>");
}
return requestBody.toString();
}<p>user=%E5%BC%A0%E4%B8%89&password=123456&btn=submit</p>
form 标签需要设置 enctype="multipart/form-data"
<form action="upload1.do" method="post" enctype="multipart/form-data">
<div class="form-group">
<input id="file" type="file" name="filename" value="" />
</div>
<button class="btn btn-primary" name="btn" value="upload">上传</button>
</form>
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException {
// 读取请求的 body
byte[] body = readBody(request);
// 取得所有 body 内容的字符串显示
String textBody = new String(body, StandardCharsets.ISO_8859_1);
// 取得上传的文件名称
String fileName = getFileName(textBody);
// 取得文件开始和结束位置
Position p = getFilePosition(request, textBody);
// 输出至文件
writeTo("d:/" + fileName, body, p);
}private byte[] readBody(HttpServletRequest request) throws IOException {
int formDataLength = request.getContentLength();
// 获取 ServletInputStream 对象
DataInputStream dataStream = new DataInputStream(request.getInputStream());
byte[] body = new byte[formDataLength];
int totalBytes = 0;
while (totalBytes < formDataLength) {
int bytes = dataStream.read(body, totalBytes, formDataLength);
totalBytes += bytes;
}
return body;
}private class Position {
int begin;
int end;
Position(int begin, int end) {
this.begin = begin;
this.end = end;
}
}private Position getFilePosition(HttpServletRequest request, String textBody) {
// 取得文件区段边界位置
String contentType = request.getContentType();
String boundaryText = contentType.substring(contentType.lastIndexOf("=") + 1);
// 取得实际上传文件的起始位置和结束位置
int pos = textBody.indexOf("filename\"");
pos = textBody.indexOf("\n", pos) + 1;
pos = textBody.indexOf("\n", pos) + 1;
pos = textBody.indexOf("\n", pos) + 1;
int boundaryLoc = textBody.indexOf(boundaryText, pos) - 4;
int begin = ((textBody.substring(0, pos).getBytes(StandardCharsets.ISO_8859_1)).length);
int end = ((textBody.substring(0, boundaryLoc).getBytes(StandardCharsets.ISO_8859_1)).length);
return new Position(begin, end);
}private String getFileName(String textBody) {
// 截掉filename前面
String fileName = textBody.substring(textBody.indexOf("filename=\"") + 10);
// 截掉 换行符后面的内容
fileName = fileName.substring(0, fileName.indexOf("\n"));
// 截掉文件所在目录 和最后一个 "
fileName = fileName.substring(fileName.lastIndexOf("\\") + 1, fileName.indexOf("\""));
return fileName;
}private void writeTo(String fileName, byte[] body, Position p) throws IOException {
FileOutputStream fos = new FileOutputStream(fileName);
fos.write(body, p.begin, (p.end - p.begin));
fos.flush();
fos.close();
}
- Tomcat 中必须设置
MultipartConfig 标注才能使用 getPart() 相关的 API
@MultipartConfig
@WebServlet("/upload2.do")
public class Upload2Servlet extends HttpServlet {
// ...
}@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
// 使用 getPart() 取得 Part 对象
Part part = request.getPart("filename");
String fileName = getFilename(part);
writeTo("d:/" + fileName, part);
}private String getFilename(Part part) { // 取得上传文件名
String header = part.getHeader("Content-Disposition");
return header.substring(header.indexOf("filename=\"") + 10, header.lastIndexOf("\""));
}private void writeTo(String fileName, Part part) throws IOException {
InputStream in = part.getInputStream();
OutputStream out = new FileOutputStream(fileName);
byte[] buffer = new byte[1024];
int length = -1;
while ((length = in.read(buffer)) != -1) {
out.write(buffer, 0, length);
}
in.close();
out.close();
}@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
Part part = request.getPart("filename");
String fileName = getFilename(part);
part.write("d:/" + fileName);
}private String getFilename(Part part) { // 取得上传文件名
String header = part.getHeader("Content-Disposition");
return header.substring(header.indexOf("filename=\"") + 10, header.lastIndexOf("\""));
}@MultipartConfig(location = "d:/")
@WebServlet("/upload4.do")
public class Upload4Servlet extends HttpServlet {
// ...
}@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
for (Part part : request.getParts()) {
if (part.getName().startsWith("file")) {
String fileName = getFilename(part);
part.write("d:/" + fileName);
}
}
}@WebServlet("/some.view")
public class SomeServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
out.println("Some do one ... ");
RequestDispatcher rd = request.getRequestDispatcher("other.view");
rd.include(request, response);
out.println("Some do two ... ");
out.close();
}
}@WebServlet("/other.view")
public class OtherServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
out.println("Other do one ... ");
// 这里不要关闭 out,否则页面将无法继续写入 some.view 后面的内容
}
}public class HelloModel {
private final Map<String, String> messages = new HashMap<>();
public HelloModel() {
messages.put("zhangsan", "hello");
messages.put("lisi", "welcome");
messages.put("wangwu", "hi");
}
public String doHello(String user) {
String massage = messages.get(user);
return massage + ", " + user + "!";
}
}@WebServlet("/request/hello.do")
public class HelloController extends HttpServlet {
private final HelloModel helloModel = new HelloModel();
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
String name = request.getParameter("user");
String message = helloModel.doHello(name);
request.setAttribute("message", message);
request.getRequestDispatcher("hello.view").forward(request, response);
}
}@WebServlet("/request/hello.view")
public class HelloView extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setCharacterEncoding("UTF-8");
String user = request.getParameter("user");
String message = (String) request.getAttribute("message");
String htmlTemplate = ""
+ "<html>"
+ "<head>"
+ "<title>%s</title>"
+ "</head>"
+ "<body>"
+ "<p>%s</p>"
+ "</body>"
+ "</html>";
String html = String.format(htmlTemplate, user, message);
response.getWriter().print(html);
}
}/request/hello.do?user=zhangsan
response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();
<?xml version="1.0" encoding="UTF-8"?>
<web-app>
<locale-encoding-mapping-list>
<locale-encoding-mapping>
<locale>zh_CN</locale>
<encoding>UTF-8</encoding>
</locale-encoding-mapping>
</locale-encoding-mapping-list>
<mime-mapping>
<extension>pdf</extension>
<mime-type>application/pdf</mime-type>
</mime-mapping>
</web-app>
@WebServlet("/download.do")
public class DownloadServlet extends HttpServlet {
// ...
}@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException {
doPost(request, response);
}@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setCharacterEncoding("UTF-8");
// 设置内容类型
response.setContentType("application/pdf");
// 输入串流
InputStream in = getServletContext().getResourceAsStream("WEB-INF/content.pdf");
// 输出串流
OutputStream out = response.getOutputStream();
// 读取文件并输出到浏览器
writeBytes(in, out);
}private void writeBytes(InputStream in, OutputStream out)
throws IOException {
byte[] buffer = new byte[1024];
int length;
while ((length = in.read(buffer)) != -1) {
out.write(buffer, 0, length);
}
in.close();
out.close();
}@WebServlet("/redirect.do")
public class RedirectServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
response.sendRedirect("https://www.baidu.com");
// String msg = "bad request";
// response.sendError(HttpServletResponse.SC_BAD_REQUEST, msg);
}
}protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>QuestionServlet</title>");
out.println("</head>");
out.println("<body>");
out.println("<form action='question.view' method='post'>");
String page = request.getParameter("page");
String nextPage = "下一页";
String finish = "完成";
if (page == null) {
out.println("问题一:<input type='text' name='p1q1'><br>");
out.println("问题一:<input type='text' name='p1q2'><br>");
out.println("<input type='submit' name='page' value='下一页'>");
} else if (nextPage.equals(page)) {
String plq1 = request.getParameter("p1q1");
String plq2 = request.getParameter("p1q2");
out.println("问题三:<input type='text' name='p2q1'><br>");
out.println("<input type='hidden' name='p1q1' value='" + plq1 + "'>");
out.println("<input type='hidden' name='p1q2' value='" + plq2 + "'>");
out.println("<input type='submit' name='page' value='完成'>");
} else if (finish.equals(page)) {
out.println(request.getParameter("p1q1") + "<br>");
out.println(request.getParameter("p1q2") + "<br>");
out.println(request.getParameter("p2q1") + "<br>");
}
out.println("</form>");
out.println("</body>");
out.println("</html>");
out.close();
}<form action="question.view" method="post">
问题三:<input type="text" name="p2q1" /><br />
<input type="hidden" name="p1q1" value="qqq" />
<input type="hidden" name="p1q2" value="kkk" />
<input type="submit" name="page" value="完成" />
</form>
<form action="cookie/login.do" method="post">
<div class="form-group">
<label for="username">用户名: </label>
<input id="username" class="form-control" type="text" name="username" value="" />
</div>
<div class="form-group">
<label for="password">密码: </label>
<input id="password" class="form-control" type="password" name="password" value="" />
</div>
<div class="form-group">
<label for="login">记住我: </label>
<input id="login" class="form-control" type="checkbox" name="login" value="auto" />
</div>
<button class="btn btn-primary" name="btn" value="submit">提交</button>
</form>
@WebServlet("/cookie/login.do")
public class LoginServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
String username = request.getParameter("username");
String password = request.getParameter("password");
String trueUsername = "zhangsan";
String truePassword = "123456";
String loginMode = "auto";
if (trueUsername.equals(username) && truePassword.equals(password)) {
String login = request.getParameter("login");
if (loginMode.equals(login)) {
Cookie cookie = new Cookie("user", username);
cookie.setMaxAge(60 * 60 * 24 * 7);
response.addCookie(cookie);
}
request.setAttribute("username", username);
request.getRequestDispatcher("user.view").forward(request, response);
} else {
response.sendRedirect("../cookie_login.html");
}
}
}@WebServlet("/cookie/user.view")
public class UserServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
String usernameKey = "username";
if (request.getAttribute(usernameKey) == null) {
response.sendRedirect("../cookie_login.html");
}
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>UserServlet</title>");
out.println("</head>");
out.println("<body>");
out.println("<p>" + request.getAttribute(usernameKey) + "</p>");
out.println("</body>");
out.println("</html>");
out.close();
}
}Set-Cookie: user=zhangsan; Max-Age=604800; Expires=date;
@WebServlet("/cookie/search.do")
public class SearchServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>SearchServlet</title>");
out.println("</head>");
out.println("<body>");
int perPage = 10;
int totalPages = 20;
String page = request.getParameter("page");
if (page == null) {
page = "1";
}
int count = Integer.parseInt(page);
int begin = 10 * count - 9;
int end = 10 * count;
out.println("<p>从 " + begin + " 到 " + end + " 的搜索结果</p>");
out.println("<ul>");
String line = "<li>搜索结果: %d</li>";
for (int i = 0; i < perPage; i++) {
out.println(String.format(line, begin + i));
}
out.println("</ul>");
for (int i = 1; i <= totalPages; i++) {
if (i == count) {
out.print(i);
continue;
}
out.println("<a href='search.do?page=" + i + "'>" + i + "</a>");
}
out.println("</body>");
out.println("</html>");
out.close();
}
}protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>QuestionServlet</title>");
out.println("</head>");
out.println("<body>");
out.println("<form action='question.view' method='post'>");
String page = request.getParameter("page");
String nextPage = "下一页";
String finish = "完成";
if (page == null) {
out.println("问题一:<input type='text' name='p1q1'><br>");
out.println("问题一:<input type='text' name='p1q2'><br>");
out.println("<input type='submit' name='page' value='下一页'>");
} else if (nextPage.equals(page)) {
String plq1 = request.getParameter("p1q1");
String plq2 = request.getParameter("p1q2");
HttpSession session = request.getSession();
session.setAttribute("p1q1", plq1);
session.setAttribute("p1q2", plq2);
out.println("问题三:<input type='text' name='p2q1'><br>");
out.println("<input type='hidden' name='p1q1' value='" + plq1 + "'>");
out.println("<input type='hidden' name='p1q2' value='" + plq2 + "'>");
out.println("<input type='submit' name='page' value='完成'>");
} else if (finish.equals(page)) {
HttpSession session = request.getSession();
out.println(session.getAttribute("p1q1") + "<br>");
out.println(session.getAttribute("p1q2") + "<br>");
out.println(request.getParameter("p2q1") + "<br>");
}
out.println("</form>");
out.println("</body>");
out.println("</html>");
out.close();
}@WebServlet("/session/login.do")
public class LoginServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
String username = request.getParameter("username");
String password = request.getParameter("password");
String trueUsername = "zhangsan";
String truePassword = "123456";
if (trueUsername.equals(username) && truePassword.equals(password)) {
request.getSession().setAttribute("username", username);
request.getRequestDispatcher("user.view").forward(request, response);
} else {
response.sendRedirect("../session_login.html");
}
}
}@WebServlet("/session/user.view")
public class UserServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
String usernameKey = "username";
if (request.getSession().getAttribute(usernameKey) == null) {
response.sendRedirect("../session_login.html");
}
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>UserServlet</title>");
out.println("</head>");
out.println("<body>");
out.println("<p>" + request.getSession().getAttribute(usernameKey) + "</p>");
out.println("<a href='logout.view'>注销</a>");
out.println("</body>");
out.println("</html>");
out.close();
}
}@WebServlet("/session/logout.view")
public class LogoutServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
HttpSession session = request.getSession();
String username = (String) session.getAttribute("username");
session.invalidate();
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>LogoutServlet</title>");
out.println("</head>");
out.println("<body>");
out.println("<p>" + username + " 已注销</p>");
out.println("</body>");
out.println("</html>");
out.close();
}
}<web-app>
<session-config>
<!-- minutes -->
<session-timeout>30</session-timeout>
<cookie-config>
<name>sid</name>
<http-only>true</http-only>
</cookie-config>
</session-config>
</web-app>
@WebServlet("/session/counter.do")
public class CounterServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("text/html;charset=UTF-8");
int count = 0;
String countStr = "count";
HttpSession session = request.getSession();
if (session.getAttribute(countStr) != null) {
Integer c = (Integer) session.getAttribute(countStr);
count = c + 1;
}
session.setAttribute(countStr, count);
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title>CounterServlet</title>");
out.println("</head>");
out.println("<body>");
out.println("<p>Servlet Count: " + count + " </p>");
out.println("<a href='" + response.encodeURL("counter") + ".do'>递增</a>");
out.println("</body>");
out.println("</html>");
out.close();
}
}