request对象_java学习之web基础（2）：Request
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request对象_java学习之web基础（2）：Request
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request
ServletRequest --(繼承)--> HttpServletRequest --(實(shí)現(xiàn))--> org.apache.catalina.connector.RequestFacade 類
通過request可以獲取請(qǐng)求消息數(shù)據(jù)
一：獲取請(qǐng)求行數(shù)據(jù):
對(duì)于請(qǐng)求行： GET /day14/demo1?name=zhangsan HTTP/1.1
1. 獲取請(qǐng)求方式 ：GET
String getMethod()2. (*)獲取虛擬目錄：/day14
String getContextPath()3. 獲取Servlet路徑: /demo1
String getServletPath()4. 獲取get方式請(qǐng)求參數(shù)：name=zhangsan
String getQueryString()5. (*)獲取請(qǐng)求URI：/day14/demo1
String getRequestURI(): /day14/demo1 StringBuffer getRequestURL() :http://localhost/day14/demo1 URL:統(tǒng)一資源定位符 ： http://localhost/day14/demo1 URI：統(tǒng)一資源標(biāo)識(shí)符 : /day14/demo16. 獲取協(xié)議及版本：HTTP/1.1
String getProtocol()7. 獲取客戶機(jī)的IP地址：
String getRemoteAddr()二：獲取請(qǐng)求頭數(shù)據(jù):
(*)String getHeader(String name):通過請(qǐng)求頭的名稱獲取請(qǐng)求頭的值 Enumeration<String> getHeaderNames():獲取所有的請(qǐng)求頭名稱三：獲取請(qǐng)求體數(shù)據(jù):
請(qǐng)求體：只有POST請(qǐng)求方式，才有請(qǐng)求體，在請(qǐng)求體中封裝了POST請(qǐng)求的請(qǐng)求參數(shù)
1. 獲取流對(duì)象
BufferedReader getReader()：獲取字符輸入流，只能操作字符數(shù)據(jù) ServletInputStream getInputStream()：獲取字節(jié)輸入流，可以操作所有類型數(shù)據(jù)2. 再?gòu)牧鲗?duì)象中拿數(shù)據(jù)
四：其他功能
獲取請(qǐng)求參數(shù)通用方式：不論get還是post請(qǐng)求方式都可以使用下列方法來(lái)獲取請(qǐng)求參數(shù)
1. String getParameter(String name):根據(jù)參數(shù)名稱獲取參數(shù)值 username=zs&password=123 2. String[] getParameterValues(String name):根據(jù)參數(shù)名稱獲取參數(shù)值的數(shù)組 hobby=xx&hobby=game 3. Enumeration<String> getParameterNames():獲取所有請(qǐng)求的參數(shù)名稱 4. Map<String,String[]> getParameterMap():獲取所有參數(shù)的map集合請(qǐng)求轉(zhuǎn)發(fā)：一種在服務(wù)器內(nèi)部的資源跳轉(zhuǎn)方式
特點(diǎn)：
瀏覽器地址欄路徑不發(fā)生變化
只能轉(zhuǎn)發(fā)到當(dāng)前服務(wù)器內(nèi)部資源中。
轉(zhuǎn)發(fā)是一次請(qǐng)求
步驟：
1. 通過request對(duì)象獲取請(qǐng)求轉(zhuǎn)發(fā)器對(duì)象：RequestDispatcher getRequestDispatcher(String path) 2. 使用RequestDispatcher對(duì)象來(lái)進(jìn)行轉(zhuǎn)發(fā)：forward(ServletRequest request, ServletResponse response)共享數(shù)據(jù)
域?qū)ο?#xff1a;一個(gè)有作用范圍的對(duì)象，可以在范圍內(nèi)共享數(shù)據(jù)
request域：代表一次請(qǐng)求的范圍，一般用于請(qǐng)求轉(zhuǎn)發(fā)的多個(gè)資源中共享數(shù)據(jù)
1. void setAttribute(String name,Object obj):存儲(chǔ)數(shù)據(jù) 2. Object getAttitude(String name):通過鍵獲取值 3. void removeAttribute(String name):通過鍵移除鍵值對(duì)獲取ServletContext：
ServletContext getServletContext()BeanUtils工具類，簡(jiǎn)化數(shù)據(jù)封裝，用于封裝JavaBean
JavaBean：標(biāo)準(zhǔn)的Java類
要求：
1. 類必須被public修飾
2. 必須提供空參的構(gòu)造器
3. 成員變量必須使用private修飾
4. 提供公共setter和getter方法
成員變量：類中定義的成員變量
屬性：setter和getter方法截取后的產(chǎn)物
例如：getUsername() --> Username--> username
工具類中的方法：（要求JavaBean中的get、set方法命名規(guī)范）
1. setProperty() 2. getProperty() 3. populate(Object obj , Map map):將map集合的鍵值對(duì)信息，封裝到對(duì)應(yīng)的JavaBean對(duì)象中 比如： Map<String,String[]> map = req.getParameterMap(); User loginUser = new User(); BeanUtils.populate(loginUser,map);例子：
頁(yè)面：http://localhost:8080/servlet_learn/form.html<!DOCTYPE html> <html lang="en"> <head><meta charset="UTF-8"><title>post</title> </head> <body><form action="/servlet_learn/requestDemo1" method="get"><input type="text" name="user"/><br><input type="checkbox" name="like" value="game">游戲<input type="checkbox" name="like" value="study">學(xué)習(xí)<br><input type="submit" value="提交"></form> </body> </html>// HttpServlet
package cn.figo.web.request;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 java.io.BufferedReader; import java.io.IOException; import java.util.Enumeration; import java.util.Map; import java.util.Set;@WebServlet("/requestDemo1") public class RequestDemo1 extends HttpServlet {protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// 請(qǐng)求體，只有post方式有//獲取字符輸入流，只能操作字符數(shù)據(jù)// user=lisi&btn=%E6%8F%90%E4%BA%A4BufferedReader br = request.getReader();String line = null;while ((line = br.readLine()) != null){System.out.println(line);}//獲取字節(jié)輸入流，可以操作所有類型數(shù)據(jù)// ServletInputStream getInputStream()}protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {// 請(qǐng)求行// GET /requestDemo1?user=shangsan&btn=%E6%8F%90%E4%BA%A4 HTTP/1.1// GET /servlet_learn/requestDemo1?user=lisi&btn=%E6%8F%90%E4%BA%A4 HTTP/1.1System.out.println(request.getMethod()); // GETSystem.out.println(request.getContextPath());// 第一次tomcat中配置為/因此為空；第二次配置為/servlet_learn，結(jié)果為 /servlet_learnSystem.out.println(request.getServletPath()); // /requestDemo1System.out.println(request.getQueryString()); // user=shangsan&btn=%E6%8F%90%E4%BA%A4System.out.println(request.getRequestURI()); // /requestDemo1System.out.println(request.getRequestURL()); // http://localhost:8080/requestDemo1System.out.println(request.getProtocol()); // HTTP/1.1System.out.println(request.getRemoteAddr()); // 0:0:0:0:0:0:0:1// 請(qǐng)求頭Enumeration<String> headerNames = request.getHeaderNames();System.out.println(headerNames);while (headerNames.hasMoreElements()){String headerName = headerNames.nextElement();String value = request.getHeader(headerName);System.out.println(headerName + ": " + value);}System.out.println("-----------------------------");String userValue = request.getParameter("user");System.out.println(userValue);System.out.println("-----------------------------");String[] likeValues = request.getParameterValues("like");for (String likeValue : likeValues) {System.out.println(likeValue);}System.out.println("-----------------------------");Enumeration<String> paraNames = request.getParameterNames();while (paraNames.hasMoreElements()){String paraName = paraNames.nextElement();String paraValue = request.getParameter(paraName);// String[] paraValue = request.getParameterValues(paraName);System.out.println(paraName + ": " + paraValue);}System.out.println("-------------------------------");Map<String,String[]> paraMap = request.getParameterMap();Set<String> keySet = paraMap.keySet();for (String name :keySet){System.out.println(name);String[] values = paraMap.get(name);System.out.println(values);for (String value : values){System.out.println(value);}System.out.println("============");}} }輸出：
GET /servlet_learn /requestDemo1 user=lisi&like=game&like=study /servlet_learn/requestDemo1 http://localhost:8080/servlet_learn/requestDemo1 HTTP/1.1 0:0:0:0:0:0:0:1 org.apache.tomcat.util.http.NamesEnumerator@57206aaf host: localhost:8080 connection: keep-alive upgrade-insecure-requests: 1 user-agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.132 Safari/537.36 sec-fetch-mode: navigate sec-fetch-user: ?1 accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3 sec-fetch-site: same-origin referer: http://localhost:8080/servlet_learn/form.html accept-encoding: gzip, deflate, br accept-language: zh-CN,zh;q=0.9 cookie: JSESSIONID=63D658A1F557F36FEA8C97A6D6AF6B8C; _ga=GA1.1.1778445080.1563089064; csrftoken=ZnWKg5ZuuSYd3dwts5iqnfjQvSnp21n9OiuFZAKz11WdGZuXENLhAxYckiLHFTsI ----------------------------- lisi ----------------------------- game study ----------------------------- user: lisi like: game ------------------------------- user [Ljava.lang.String;@25f76ac0 lisi ============ like [Ljava.lang.String;@12bedba3 game study ============總結(jié)
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