目錄
Request
request對象和response對象的原理
- request和response對象是由服務器創建的。我們來使用它們
- request對象是來獲取請求消息,response對象是來設置響應消息
request對象繼承體系結構:
ServletRequest -- 接口
| 繼承
HttpServletRequest -- 接口
| 實現
org.apache.catalina.connector.RequestFacade 類(tomcat)
request對象功能
1. 獲取請求消息數據
1.獲取請求行數據
GET /day14/demo1?name=zhangsan HTTP/1.1
方法:
1. 獲取請求方式 :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方式請求參數:name=zhangsan
String getQueryString()
5. 獲取請求URI:/day14/demo1
String getRequestURI(): /day14/demo1
StringBuffer getRequestURL() :http://localhost/day14/demo1
URL:統一資源定位符 : http://localhost/day14/demo1 中華人民共和國
URI:統一資源標識符 : /day14/demo1 共和國 ,所以URI的範圍更大
6. 獲取協議及版本:HTTP/1.1
String getProtocol()
7. 獲取客戶機的IP地址:
String getRemoteAddr()
demo
@WebServlet("/requestDemo1")
public class RequestDemo1 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//1. 獲取請求方式 :GET
String method = request.getMethod();
System.out.println(method);
//2.(*)獲取虛擬目錄:/day14
String contextPath = request.getContextPath();
System.out.println(contextPath);
//3. 獲取Servlet路徑: /demo1
String servletPath = request.getServletPath();
System.out.println(servletPath);
//4. 獲取get方式請求參數:name=zhangsan
String queryString = request.getQueryString();
System.out.println(queryString);
//5.(*)獲取請求URI:/day14/demo1
String requestURI = request.getRequestURI();
StringBuffer requestURL = request.getRequestURL();
System.out.println(requestURI);
System.out.println(requestURL);
//6. 獲取協議及版本:HTTP/1.1
String protocol = request.getProtocol();
System.out.println(protocol);
//7. 獲取客戶機的IP地址:
String remoteAddr = request.getRemoteAddr();
System.out.println(remoteAddr);
}
}
2. 獲取請求頭數據
方法:
String getHeader(String name):通過請求頭的名稱獲取請求頭的值
Enumeration<String> getHeaderNames():獲取所有的請求頭名稱
demo
//演示獲取請求頭數據
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//-----獲取所有請求頭名稱
Enumeration<String> headerNames = request.getHeaderNames();
while(headerNames.hasMoreElements()){
String name = headerNames.nextElement();
//根據名稱獲取請求頭的值
String value = request.getHeader(name);
System.out.println(name+"---"+value);
}
//-----獲取是什麼瀏覽器訪問的
String agent = request.getHeader("user-agent");
if(agent.contains("Chrome")){
//谷歌
System.out.println("谷歌來了...");
}else if(agent.contains("Firefox")){
//火狐
System.out.println("火狐來了...");
}
String referer = request.getHeader("referer");
System.out.println(referer);//http://localhost/day14/login.html
//-----referer防盜鏈演示
if(referer != null ){
if(referer.contains("/day14")){
//正常訪問
// System.out.println("播放電影....");
response.setContentType("text/html;charset=utf-8");
response.getWriter().write("播放電影....");
}else{
//盜鏈
//System.out.println("想看電影嗎?來優酷吧...");
response.setContentType("text/html;charset=utf-8");
response.getWriter().write("想看電影嗎?來優酷吧...");
}
}
}
3. 獲取請求體數據:
請求體:只有POST請求方式,纔有請求體,在請求體中封裝了POST請求的請求參數
步驟:
1. 獲取流對象
BufferedReader getReader():獲取字符輸入流,只能操作字符數據
ServletInputStream getInputStream():獲取字節輸入流,可以操作所有類型數據
2. 再從流對象中拿數據
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//獲取請求消息體--請求參數
//1.獲取字符流
BufferedReader br = request.getReader();
//2.讀取數據
String line = null;
while((line = br.readLine()) != null){
System.out.println(line);
}
}
2. 其他功能
1. 獲取請求參數通用方式:
不論get還是post請求方式都可以使用下列方法來獲取請求參數
1. String getParameter(String name):根據參數名稱獲取參數值 username=zs&password=123
2. String[] getParameterValues(String name):根據參數名稱獲取參數值的數組 hobby=xx&hobby=game
3. Enumeration<String> getParameterNames():獲取所有請求的參數名稱
4. Map<String,String[]> getParameterMap():獲取所有參數的map集合
中文亂碼問題:
get方式:tomcat 8 已經將get方式亂碼問題解決了
post方式:會亂碼 ,解決:在獲取參數前,設置request的編碼request.setCharacterEncoding("utf-8");
2. 請求轉發:一種在服務器內部的資源跳轉方式
1. 步驟:
1. 通過request對象獲取請求轉發器對象:RequestDispatcher getRequestDispatcher(String path)
2. 使用RequestDispatcher對象來進行轉發:forward(ServletRequest request, ServletResponse response)
2. 特點:
1. 瀏覽器地址欄路徑不發生變化;
2. 只能轉發到當前服務器內部資源中;
3. 轉發是一次請求,由服務器自動完成,瀏覽器本身還是隻有一次請求;
3. 共享數據
域對象:一個有作用範圍的對象,可以在範圍內共享數據
request域:代表一次請求的範圍,一般用於請求轉發的多個資源中共享數據
方法:
1. void setAttribute(String name,Object obj):存儲數據
2. Object getAttitude(String name):通過鍵獲取值
3. void removeAttribute(String name):通過鍵移除鍵值對
@WebServlet("/requestDemo8")
public class RequestDemo8 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("demo8888被訪問了。。。");
//存儲數據到request域中
request.setAttribute("msg","hello");
//轉發到demo9資源
RequestDispatcher requestDispatcher = request.getRequestDispatcher("/requestDemo9");
requestDispatcher.forward(request,response);
}
}
@WebServlet("/requestDemo9")
public class RequestDemo9 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//獲取數據
Object msg = request.getAttribute("msg");
System.out.println(msg);
System.out.println("demo9999被訪問了。。。");
}
}
訪問requestDemo8後,服務器對請求進行轉發到requestDemo9 ,並傳遞參數過去, 在requestDemo9中可以獲取到該參數。
4. 獲取ServletContext
ServletContext getServletContext()
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletContext servletContext = request.getServletContext();
}