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hello2 source analysis
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hello2 source analysis
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Hello2 應(yīng)用程序是一個(gè) Web 模塊,它使用 Java Servlet 技術(shù)來(lái)顯示問(wèn)候語(yǔ)和響應(yīng),使用的是 Java Servlet 技術(shù)。
該應(yīng)用程序源代碼在 tutorial-examples\web\servlet\hello2\src\main\java\javaeetutorial\hello2 下,分別為:GreetingServlet.java和ResponseServlet.java
此 servlet 重寫(xiě)該 doGet 方法,實(shí)現(xiàn) GET HTTP 方法。servlet 顯示一個(gè)簡(jiǎn)單的HTML問(wèn)候表單,GreetingServlet.java:
@WebServlet("/greeting")????? //將 URL 指定為/greeting
public class GreetingServlet extends HttpServlet { @Override
??? public void doGet(HttpServletRequest request,? //重寫(xiě) httpservlet 的 doget 方法,實(shí)現(xiàn)覆蓋并用來(lái)處理 get 請(qǐng)求
??????????? HttpServletResponse response)
??????????? throws ServletException, IOException { response.setContentType("text/html");? // 設(shè)置響應(yīng)類型為 HTML
??????? response.setBufferSize(8192);?
??????? try (PrintWriter out = response.getWriter()) {
??????????? out.println("<html lang=\"en\">"?????? //設(shè)置 HTML 語(yǔ)言
??????????????????? + "<head><title>Servlet Hello</title></head>");?? // 網(wǎng)頁(yè)標(biāo)題
???????????
??????????? // then write the data of the response
??????????? out.println("<body? bgcolor=\"#ffffff\">"
??????????????????? + "<img src=\"resources/images/duke.waving.gif\" "
??????????????????? + "alt=\"Duke waving his hand\">"
??????????????????? + "<form method=\"get\">"
??????????????????? + "<h2>Hello, my name is Duke. What's yours?</h2>"
??????????????????? + "<input title=\"My name is: \" type=\"text\" "
??????????????????? + "name=\"username\" size=\"25\"/>"
??????????????????? + "<p></p>"
??????????????????? + "<input type=\"submit\" value=\"Submit\"/>"
??????????????????? + "<input type=\"reset\" value=\"Reset\"/>"
??????????????????? + "</form>");? // HTML 源代碼,以顯示頁(yè)面
???????????
??????????? String username = request.getParameter("username");
?????????? //獲取傳來(lái)的參數(shù)值。
?????????? //通過(guò)容器傳遞給當(dāng)前 httpservlet
??????????
??????????? if (username != null && username.length() > 0) { ?//判斷用戶輸入的值是否有效
??????????????? RequestDispatcher dispatcher =
??????????????????????? getServletContext().getRequestDispatcher("/response");??? //獲取url為/response的servlet作為一個(gè)dispatcher資源
???????????????
??????????????? if (dispatcher != null) {
??????????????????? dispatcher.include(request, response);
??????????????? }
??????????? }
??????????? out.println("</body></html>");
??????? }
??? }
??? //dispatcher 中通過(guò) request 獲得 username,在response中添加了hello這幾句話,dispatcher 就是開(kāi)始獲得的 /response 對(duì)應(yīng)的httpservlet。
12345678910111213141516171819202122232425262728293031323334353637383940414243
編輯器打開(kāi) ResponseServlet.java :
@WebServlet("/response")?? ?// 將 URL 配置為 /response
public class ResponseServlet extends HttpServlet { @Override
??? public void doGet(HttpServletRequest request,
??????????? HttpServletResponse response)
??????????? throws ServletException, IOException {
??????? try (PrintWriter out = response.getWriter()) {??? //獲取輸出對(duì)象,用于向頁(yè)面寫(xiě)數(shù)據(jù)。返回一個(gè) PrintWriter 對(duì)象
??????????? String username = request.getParameter("username"); //獲取用戶的字符串或字符
??????????? if (username != null && username.length() > 0) { ?//判斷輸入值是否有效,有效則執(zhí)行
??????????????? out.println("<h2>Hello, " + username + "!</h2>");? //在頁(yè)面輸出一句話。
??????????? }
??????? }
??? } @Override
??? public String getServletInfo() {
??????? return "The Response servlet says hello."; }
}
123456789101112131415161718192021
以上就是 Hello2 的基本代碼實(shí)現(xiàn),整體來(lái)講實(shí)現(xiàn)代碼不多,也有很高的可讀性,代碼清晰,學(xué)習(xí)起來(lái)也沒(méi)那么困難。
在本地部署servlet時(shí),可以使用以下URL訪問(wèn)它:
http://localhost:8080/hello2/greeting
該應(yīng)用程序源代碼在 tutorial-examples\web\servlet\hello2\src\main\java\javaeetutorial\hello2 下,分別為:GreetingServlet.java和ResponseServlet.java
此 servlet 重寫(xiě)該 doGet 方法,實(shí)現(xiàn) GET HTTP 方法。servlet 顯示一個(gè)簡(jiǎn)單的HTML問(wèn)候表單,GreetingServlet.java:
@WebServlet("/greeting")????? //將 URL 指定為/greeting
public class GreetingServlet extends HttpServlet { @Override
??? public void doGet(HttpServletRequest request,? //重寫(xiě) httpservlet 的 doget 方法,實(shí)現(xiàn)覆蓋并用來(lái)處理 get 請(qǐng)求
??????????? HttpServletResponse response)
??????????? throws ServletException, IOException { response.setContentType("text/html");? // 設(shè)置響應(yīng)類型為 HTML
??????? response.setBufferSize(8192);?
??????? try (PrintWriter out = response.getWriter()) {
??????????? out.println("<html lang=\"en\">"?????? //設(shè)置 HTML 語(yǔ)言
??????????????????? + "<head><title>Servlet Hello</title></head>");?? // 網(wǎng)頁(yè)標(biāo)題
???????????
??????????? // then write the data of the response
??????????? out.println("<body? bgcolor=\"#ffffff\">"
??????????????????? + "<img src=\"resources/images/duke.waving.gif\" "
??????????????????? + "alt=\"Duke waving his hand\">"
??????????????????? + "<form method=\"get\">"
??????????????????? + "<h2>Hello, my name is Duke. What's yours?</h2>"
??????????????????? + "<input title=\"My name is: \" type=\"text\" "
??????????????????? + "name=\"username\" size=\"25\"/>"
??????????????????? + "<p></p>"
??????????????????? + "<input type=\"submit\" value=\"Submit\"/>"
??????????????????? + "<input type=\"reset\" value=\"Reset\"/>"
??????????????????? + "</form>");? // HTML 源代碼,以顯示頁(yè)面
???????????
??????????? String username = request.getParameter("username");
?????????? //獲取傳來(lái)的參數(shù)值。
?????????? //通過(guò)容器傳遞給當(dāng)前 httpservlet
??????????
??????????? if (username != null && username.length() > 0) { ?//判斷用戶輸入的值是否有效
??????????????? RequestDispatcher dispatcher =
??????????????????????? getServletContext().getRequestDispatcher("/response");??? //獲取url為/response的servlet作為一個(gè)dispatcher資源
???????????????
??????????????? if (dispatcher != null) {
??????????????????? dispatcher.include(request, response);
??????????????? }
??????????? }
??????????? out.println("</body></html>");
??????? }
??? }
??? //dispatcher 中通過(guò) request 獲得 username,在response中添加了hello這幾句話,dispatcher 就是開(kāi)始獲得的 /response 對(duì)應(yīng)的httpservlet。
12345678910111213141516171819202122232425262728293031323334353637383940414243
編輯器打開(kāi) ResponseServlet.java :
@WebServlet("/response")?? ?// 將 URL 配置為 /response
public class ResponseServlet extends HttpServlet { @Override
??? public void doGet(HttpServletRequest request,
??????????? HttpServletResponse response)
??????????? throws ServletException, IOException {
??????? try (PrintWriter out = response.getWriter()) {??? //獲取輸出對(duì)象,用于向頁(yè)面寫(xiě)數(shù)據(jù)。返回一個(gè) PrintWriter 對(duì)象
??????????? String username = request.getParameter("username"); //獲取用戶的字符串或字符
??????????? if (username != null && username.length() > 0) { ?//判斷輸入值是否有效,有效則執(zhí)行
??????????????? out.println("<h2>Hello, " + username + "!</h2>");? //在頁(yè)面輸出一句話。
??????????? }
??????? }
??? } @Override
??? public String getServletInfo() {
??????? return "The Response servlet says hello."; }
}
123456789101112131415161718192021
以上就是 Hello2 的基本代碼實(shí)現(xiàn),整體來(lái)講實(shí)現(xiàn)代碼不多,也有很高的可讀性,代碼清晰,學(xué)習(xí)起來(lái)也沒(méi)那么困難。
在本地部署servlet時(shí),可以使用以下URL訪問(wèn)它:
http://localhost:8080/hello2/greeting
轉(zhuǎn)載于:https://www.cnblogs.com/sclerx/p/10624723.html
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