Servlet的体系结构:
Servlet – 接口 GenericServlet – 抽象类 HttpServlet – 抽象类
GenericServlet:将Servlet接口中其他方法做了默认空实现,只将service()方法作为抽象,将来定义Servlet类时,可以继承GenericServlet,实现service()方法即可
HttpServlet:对http协议的一种封装,简化操作:
1,定义类继承HttpServlet
2,复写doGet/doPost方法
Servlet相关配置:
一个Servlet可以定义多个访问路径:@WebServlet({"/d4","/dd4","/ddd4"})
路径定义三种规范:
1,/xxx:路径匹配 2,/xxx/xxx:多层路径,目录结构 3,*.do:扩展名匹配
超文本传输协议:定义了客户端和服务器端通信时发送数据的格式
特点:
1,request和response对象是由服务器创建的。
2,request对象负责获取请求消息,response对象是来设置响应消息
request对象继承体系结构:
ServletRequest --接口 HttpServletRequest–接口org.apache.catalina.connector.RequestFacade – 类(tomcat)
获取请求行数据:
package com.wzc.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.IOException; /* 演示Request对象获取数据请求行数据 * */ @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 { // 获取请求方式:GET String method = request.getMethod(); System.out.println(method); // 获取虚拟路径 String contextPath = request.getContextPath(); System.out.println(contextPath); // 获取Servlet路径 String queryString = request.getQueryString(); System.out.println(queryString); // 获取请求URI String requestURI = request.getRequestURI(); System.out.println(requestURI); // 获取URL StringBuffer requestURL = request.getRequestURL(); System.out.println(requestURL); // 获取协议以及版本 String protocol = request.getProtocol(); System.out.println(protocol); // 获取客户机的IP地址 String remoteAddr = request.getRemoteAddr(); System.out.println(remoteAddr); } }
获取请求头数据:
package com.wzc.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.IOException; import java.util.Enumeration; @WebServlet("/RequestDemo2") public class RequestDemo2 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //获取请求头数据 // 获取所有请求头名称 Enumeration<String> headerNames = request.getHeaderNames(); // 遍历 while(headerNames.hasMoreElements()){ String name = headerNames.nextElement(); // 根据名称获取请求头的值 String value = request.getHeader(name); System.out.println(name+"------"+value); } } }
获取请求体数据:
package com.wzc.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; @WebServlet("/RequestDemo5") public class RequestDemo5 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 获取请求消息体--请求参数 // 获取字符流 BufferedReader br = request.getReader(); // 读取数据 String line = null; while ((line = br.readLine()) !=null){ System.out.println(line); } } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { } }
其他功能:
获取请求参数通用方式:不论get还是post请求方式都可以使用下列方法来获取请求参数
1. String getParameter(String name):根据参数名称获取参数值 username=zs&password=123
2. String[] getParameterValues(String name):根据参数名称获取参数值的数组 hobby=xx&hobby=game
3. Enumeration getParameterNames():获取所有请求的参数名称
4. Map<String,String[]> getParameterMap():获取所有参数的map集合
如何解决中文乱码问题:
get方式:tomcat8已经将get方式乱码问题解决了
post方式:会乱码,通过设置request的编码request.setCharacterEnconding(“utf-8”)
请求转发:一种在服务器内部的资源跳转方式
1,通过request对象获取请求转发器对象:RequestDispatcher getRequestDispatcher(String path)
2,使用RequestDispatcher对象来进行转发:forward(ServletRequest
request,ServletResponse response)
特点:
1,浏览器地址栏路径不发生变化
2,只能转发到当前服务器内部资源中
3,转发是一次请求
共享数据:
域对象:一个有作用范围的对象,可以在范围内共享数据
request域:代表一次请求范围,一般用于请求转发的多个资源中共享数据
package com.wzc.web.request; import javax.servlet.RequestDispatcher; 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.IOException; import java.util.Enumeration; import java.util.Map; import java.util.Set; @WebServlet("/RequestDemo7") public class RequestDemo7 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { System.out.println("demo7777被访问了"); // 转发到demo8资源 /* RequestDispatcher requestDispatcher = request.getRequestDispatcher("/RequestDemo8"); requestDispatcher.forward(request,response);*/ // 存储数据到request域中 request.setAttribute("msg","hello"); request.getRequestDispatcher("/RequestDemo8").forward(request,response); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } }
package com.wzc.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.IOException; import java.util.Enumeration; import java.util.Map; import java.util.Set; @WebServlet("/RequestDemo8") public class RequestDemo8 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 获取数据 Object msg = request.getAttribute("msg"); System.out.println(msg); System.out.println("demo8888被访问了"); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } }
获取ServletContext:
package com.wzc.web.request; import javax.servlet.ServletContext; 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.IOException; @WebServlet("/RequestDemo9") public class RequestDemo9 extends HttpServlet { protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { ServletContext servletContext = request.getServletContext(); System.out.println(servletContext); } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request,response); } }