Request和Response分别用来处理客户端发送的数据和服务器应该作出的响应，使用较为简单，主要都是api。读者可使用以下代码自行练习
/**
* HttpServletRequest用来存放客户端请求的参数
* 请求行
* 请求头
* 请求数据
*
* @author Song X.
* @date 2020/02/11
*/
public class RequestServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("It is from POST Request/n");
showRequestInfo(request);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("It is from GET Request/n");
showRequestInfo(request);
}
private void showRequestInfo(HttpServletRequest request) {
/*以下都是请求行里的内容*/
System.out.println("-----------Request Line-----------");
//获取请求中的请求方式
String method = request.getMethod();
System.out.println("Request Method: " + method);
//获取请求的完整地址
StringBuffer requestURL = request.getRequestURL();
System.out.println("Entire Request Address: " + requestURL);
//获取请求中的资源路径
String requestURI = request.getRequestURI();
System.out.println("Entire Request Path: " + requestURI);
//获取请求中的协议与版本号
String protocol = request.getProtocol();
System.out.println("Protocol: " + protocol);
//获取请求中的协议
String scheme = request.getScheme();
System.out.println("Schema: " + scheme);
System.out.println("----------------------------------/n");
/*以下都是请求头里的内容*/
//根据Key获取对应Value的值
System.out.println("-----------Request Header-----------");
//比如获取User-Agent
String userAgent = request.getHeader("User-Agent");
System.out.println("User-Agent" + userAgent);
//header中有很多的Key，可通过以下方式获取请求头信息中的所有key的枚举对象，并获取到所有的Value
Enumeration<String> headerNames = request.getHeaderNames();
while (headerNames.hasMoreElements()) {
//headerNames.nextElement()是所有的Key
String key = headerNames.nextElement();
String value = request.getHeader(key);
System.out.println(key + " : " + value);
}
System.out.println("------------------------------------/n");
/*以下都是请求数据里的内容*/
System.out.println("-----------Request Data-----------");
//这里的参数是method.jsp里配置的，如果不一致，这里只会获取到null
String name = request.getParameter("name");
String pwd = request.getParameter("pwd");
System.out.println(name + " : " + pwd);
//如果不知道都有什么配置参数，可以通过如下方式获得
Enumeration<String> parameterNames = request.getParameterNames();
while(parameterNames.hasMoreElements()) {
System.out.println(parameterNames.nextElement());
}
System.out.println("----------------------------------/n");
}
}
/**
* HttpServletResponse用来存放服务器端响应的参数
* 响应行
* 响应头
* 响应体
*
* @author frank
* @date 2020/02/11
*/
public class ResponseServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("It is from POST Request/n");
showResponseInfo(response);
}
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("It is from GET Request/n");
showResponseInfo(response);
}
private void showResponseInfo(HttpServletResponse response) throws IOException {
/*以下都是响应行里的内容*/
//设置响应码和响应状态
///response.sendError(404,"The Page is lost");
/*以下都是响应头里的内容*/
/* 按照Key-Value键值对的方式设置响应头，下面两种方式都可以设置响应头
区别在于在key相同的情况下，set的方式，新的会覆盖旧的，add的方式则不会 */
response.setHeader("beijing","gugong");
response.setHeader("beijing", "yiheyuan");
response.addHeader("shanghai","dongfangmingzhu");
response.addHeader("shanghai","waitan");
/*以下都是响应体里的内容*/
//服务端给客户端回消息，并且会解析其中的html标签
//如果不想解析其中的html标签，或者想自定义解析方式，只要设置ContentType即可(text/xxx)，默认就是text/html
//可以有比如text/palin纯文本，text/json用json解析
response.getWriter().write("<b>Hello world</b>");
response.setContentType("text/html");
}
}
<%--method.jsp--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<%--这里action的值配置的是对应跳转的Servlet的url-pattern--%>
<form action="response" method="post">
用户名: <input type="text" name="name" value="" /><br>
密码: <input type="text" name="pwd" value="" /><br>
<input type="submit" value="登陆">
</form>
</body>
</html>
<!--web.xml-->
<servlet>
<servlet-name>RequestServlet</servlet-name>
<servlet-class>home.frank.RequestServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>RequestServlet</servlet-name>
<url-pattern>/request</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>ResponseServlet</servlet-name>
<servlet-class>home.frank.ResponseServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ResponseServlet</servlet-name>
<url-pattern>/response</url-pattern>
</servlet-mapping>
页面输入localhost:8080/method.jsp即可测试运行
原创文章，作者：ItWorker，如若转载，请注明出处：https://blog.ytso.com/20602.html