index.jsp
<body>
<!--
如果用表单发送post请求给Servlet，则路径上面不能带"/",原因：
点击“提交”按钮发送的请求是客户端的请求，此时"/"参照服务器根路径，会丢失"web应用的根路径",
解决方案：1).把"/"去掉，此时servlet和页面都是参照web应用的根路径
2).保留"/"，在前面加上EL表达式${pageContext.request.contextPath }，得到web应用的根路径
-->
<form action="${pageContext.request.contextPath }/life.action" method="post">
<input type="submit" value="post提交">
</form>
</body>
HellowServlet.java
public class HelloServlet extends HttpServlet {
// 处理get请求的方法
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
System.out.println("处理Get请求");
}
// 处理post请求的方法
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
System.out.println("处理Post请求");
}
}
LifeServlet.java
public class LifeServlet extends HttpServlet {
private String str;
public LifeServlet() {
System.out.println("web服务器创建了Servlet实例！");
}
@Override
public void init() throws ServletException {
str = "aaa";
System.out.println("Servlet正在初始化");
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
System.out.println("doGet()被调用");
}
//销毁
@Override
public void destroy() {
// TODO Auto-generated method stub
System.out.println("servlet正在销毁");
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print(" This is ");
out.print(this.getClass());
out.println(", using the POST method");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}
request
index.jsp
<body>
<jsp:forward page="show.jsp"></jsp:forward>
</body>
show.jsp
<body>
<h2>我是show.jsp</h2>
获取request域中的数据:${msg }
</body>
t.jsp
<body>
<a href="${pageContext.request.contextPath}/req.action">请求servlet</a>
</body>
ForwardServlet.java
public class ForwardServlet extends HttpServlet {
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 转发前将数据存到request域对象中
request.setAttribute("msg", "我是request域中的数据");
// 请求转发:在服务器内发生跳转，跳转到新的资源上(jsp页面或servlet)
// 第1：得到请求转发器
// RequestDispatcher dispatcher =
// request.getRequestDispatcher("show.jsp");
// 第2：调用forward方法，实现转发动作
// dispatcher.forward(request, response);
// 以上2句合写成一句
request.getRequestDispatcher("/page/my.jsp").forward(request, response);
//request.getRequestDispatcher("http://www.baidu.com").forward(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print(" This is ");
out.print(this.getClass());
out.println(", using the POST method");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}
RedirectServlet.java
public class RedirectServlet extends HttpServlet {
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setAttribute("msg", "我是request域中的数据");
//重定向：跳转到新的资源上,request.getContextPath()代表获取web应用的根路径
// response.sendRedirect(request.getContextPath()+"/show.jsp");
response.sendRedirect("show.jsp");
// response.sendRedirect("http://www.baidu.com");
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print(" This is ");
out.print(this.getClass());
out.println(", using the POST method");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}
RequestServlet.java
public class RequestServlet extends HttpServlet {
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//this.getRequestLine(request);
this.getRequestHeader(request);
}
// 获取请求行
public void getRequestLine(HttpServletRequest req
) throws ServletException, IOException {
// 获取请求方法
String method = req.getMethod();
// 获取请求的路径
String url = req.getRequestURI();
// 获取请求协议及版本号
String protocol = req.getProtocol();
System.out.println("请求方法：" + method);
System.out.println("请求路径：" + url);
System.out.println("请求协议及版本号：" + protocol);
}
// 获取请求头
public void getRequestHeader(HttpServletRequest req
) throws ServletException, IOException {
String host= req.getHeader("Host");
String connection=req.getHeader("Connection");
System.out.println(host);
System.out.println(connection);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print(" This is ");
out.print(this.getClass());
out.println(", using the POST method");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}
ResponseServlet.java
public class ResponseServlet extends HttpServlet {
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 添加响应头addHeader()
response.addHeader("company", "whsxt");
// 设置响应头setHeader(name,value),可以修改已存在的响应头
// response.setHeader("Content-Type", "text/json;charset=UTF-8");
// 获取响应头的值getHeader
String value = response.getHeader("company");
System.out.println(value);// whsxt
// 设置响应的MiME类型(内容类型),text/html表示服务器响应给浏览器一个html文档
// response.setContentType("text/html");
// 设置响应的编码
// response.setCharacterEncoding("UTF-8");
// 以上两句代码可以简写成一句
//response.setContentType("text/html;charset=UTF-8");
response.setHeader("Content-Type", "text/html;charset=UTF-8");
// 获取打印流
PrintWriter out = response.getWriter();
// 向浏览器输出中文内容
out.print("欢迎学习servlet");
// 刷新缓冲区
out.flush();
// 关闭流
out.close();
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to
* post.
*
* @param request
* the request send by the client to the server
* @param response
* the response send by the server to the client
* @throws ServletException
* if an error occurred
* @throws IOException
* if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print(" This is ");
out.print(this.getClass());
out.println(", using the POST method");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}
TestServlet.java
public class TestServlet extends HttpServlet {
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// response.sendRedirect(request.getContextPath()+ "/show.jsp");
response.sendRedirect(request.getContextPath()+ "/req.action");
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.print(" This is ");
out.print(this.getClass());
out.println(", using the POST method");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}