目录
从web.xml文件中获取默认参数
从浏览器的网址界面获取界面参数
继承servlet接口的方法从浏览器的网址界面获取界面参数
继承HttpServlet接口的方法从浏览器的网址界面获取界面参数
从网页表单中获取表单参数
继承Httpservlet中的doPost和doGet各自的作用
从web.xml文件中获取默认参数
首先需要在xml文件中定义和声明，在servlet下的init-parm下的parm-name写入参数名字，parm-value写入参数的值
<!DOCTYPE web-app PUBLIC
"-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
"http://java.sun.com/dtd/web-app_2_3.dtd" >
<web-app>
<display-name>Archetype Created Web Application</display-name>
<!-- 创建一个servlet实例，类似java中的new-->
<servlet>
<servlet-name>MyServlet01</servlet-name>
<servlet-class>com.zpark.servlet.MyServlet01</servlet-class>
<init-param>
<param-name>name</param-name>
<param-value>Lungcen</param-value>
</init-param>
<init-param>
<param-name>password</param-name>
<param-value>110120130</param-value>
</init-param>
</servlet>
<!-- 配置访问的规则-->
<servlet-mapping>
<servlet-name>MyServlet01</servlet-name>
<url-pattern>/Lun.do</url-pattern>
<!-- .do是针对jsp来的，以.do来访问servlet-->
</servlet-mapping>
</web-app>除了web.xml内声明了参数，还要在servlet中利用变量接收参数，再发送到浏览器中显示出来。
package com.zpark.servlet;
import javax.servlet.*;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
public class MyServlet01 implements Servlet {
private String name;
private String password;
@Override
public void init(ServletConfig servletConfig) throws ServletException {
//获得配置文件中的参数,用一个枚举结构来接收
Enumeration<String> initParameterNames = servletConfig.getInitParameterNames();
while(initParameterNames.hasMoreElements())
{
String tump = initParameterNames.nextElement();
if ("name".equals(tump))
name = servletConfig.getInitParameter(tump);
if ("password".equals(tump))
password = servletConfig.getInitParameter(tump);
}
}
@Override
public void service(ServletRequest servletRequest, ServletResponse servletResponse)
throws ServletException, IOException {
//每次请求，都会调用一次 service() 方法,设置字符集
servletResponse.setContentType("text/html;charset=UTF-8");
//使用PrintWriter.write()方法向前台页面输出内容
PrintWriter writer = servletResponse.getWriter();
writer.write("学习servlet，开启新征程 <br />");
writer.write("name ->" + name + "<br />");
writer.write("password ->" + password);
writer.close();
}
@Override
public ServletConfig getServletConfig() {
return null;
}
@Override
public String getServletInfo() {
return null;
}
@Override
public void destroy() {
}
}
从浏览器的网址界面获取界面参数
继承servlet接口的方法从浏览器的网址界面获取界面参数
package com.zpark.servlet;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
public class MyServlet01 implements Servlet {
// 继承servlet的方法不是很常用
private String IU_name;
private String IU_password;
@Override
public void init(ServletConfig servletConfig) throws ServletException {
//获得配置文件中的参数,用一个枚举结构来接收
Enumeration<String> initParameterNames = servletConfig.getInitParameterNames();
while(initParameterNames.hasMoreElements())
{
String tump = initParameterNames.nextElement();
if ("name".equals(tump))
IU_name = servletConfig.getInitParameter(tump);
if ("password".equals(tump))
IU_password = servletConfig.getInitParameter(tump);
}
}
@Override
public void service(ServletRequest servletRequest, ServletResponse servletResponse)
throws ServletException, IOException {
//向下转型
HttpServletRequest httpServletRequest = (HttpServletRequest) servletRequest;
//设置请求编码
httpServletRequest.setCharacterEncoding("utf-8");
String name;
String password;
String name_hsr = httpServletRequest.getParameter("name");
if(name_hsr != null && !"".equals(name_hsr) && !"null".equals(name_hsr) )
name = httpServletRequest.getParameter("name");
else
name = IU_name;
String password_hsr = httpServletRequest.getParameter("password");
if(password_hsr != null && !"".equals(password_hsr) && !"null".equals(password_hsr) )
password = httpServletRequest.getParameter("password");
else
password = IU_password;
//设置下响应字符集编码
servletResponse.setContentType("text/html;charset=UTF-8");
//使用PrintWriter.write()方法向前台页面输出内容
PrintWriter writer = servletResponse.getWriter();
writer.write("学习servlet，开启新征程 <br />");
writer.write("name ->" + name + "<br />");
writer.write("password ->" + password);
writer.close();
}
@Override
public ServletConfig getServletConfig() {
return null;
}
@Override
public String getServletInfo() {
return null;
}
@Override
public void destroy() {
}
}继承HttpServlet接口的方法从浏览器的网址界面获取界面参数
package com.zpark.servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebInitParam;
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.io.PrintWriter;
import java.util.Enumeration;
//这个类似于再web.xml文件的配置的访问路径和参数的对象和值
@WebServlet(value = {"/ms4.do", "/ms5.do"},
initParams = {@WebInitParam(name = "name", value = "默认姓名（赵三）"),
@WebInitParam(name = "password", value = "默认密码（110120130）")}
)
public class MyServlet4 extends HttpServlet {
private String IU_name = "";
private String IU_password = "";
@Override
public void init(ServletConfig config) throws ServletException {
Enumeration<String> ParameterNames = config.getInitParameterNames();
while (ParameterNames.hasMoreElements())
{
//如果还存在元素，就拿出元素
String temp = ParameterNames.nextElement();
if ("name".equals(temp))
IU_name = config.getInitParameter(temp);
if ("password".equals(temp))
IU_password = config.getInitParameter(temp);
}
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String name;
String password;
//设置响应对象的编码字符集
resp.setContentType("text/html;charset=utf-8");
//设置请求对象的编码字符集
resp.setCharacterEncoding("UTF-8");
//输出信息
PrintWriter writer = resp.getWriter();
String um = req.getParameter("name");
String hsr = req.getParameter("password");
if ( um != null && !"".equals(um) && !"null".equals(um) )
name = um;
else
name = IU_name;
if ( hsr != null && !"".equals(hsr) && !"null".equals(hsr) )
password = hsr;
else
password = IU_password;
writer.write("username:" + name);
writer.write("<br/>");
writer.write("password:" + password);
writer.close();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
//设置请求编码
req.setCharacterEncoding("utf-8");
this.doGet(req, resp);
}
}
从网页表单中获取表单参数
继承Httpservlet中的doPost和doGet各自的作用
doPost是接收请求，请求是由<form>表单标签来发送请求。
doGet是接收响应，响应给浏览器，所以再浏览器网址回车的时候，会调用diGet然后响应给浏览器。
<%-- method可以选择是post还是get，但是我们一般是post请求--%>
<form action="/uned_war/ms3.do" method="post">
用户:<input type="text" name="username" />
密码:<input type="password" name="password" />
<input type="submit" value="提交">
</form>在jsp文件中写入表单，然后再浏览器的表单输入参数
在servlet中接收参数然后再响应到浏览器
<%@page language="java" pageEncoding="UTF-8" %>
<html>
<head>
<title>ti mu</title>
</head>
<body>
<form action="/unwar/ms3.do" method="post">
用户:<input type="text" name="username" />
密码:<input type="password" name="password" />
<input type="submit" value="提交">
</form>
</body>
</html>package com.zpark.servlet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
public class MyServlet3 extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
//获取界面的内容
String username = req.getParameter("username");
String password = req.getParameter("password");
//设置响应对象的编码字符集
resp.setContentType("text/html;charset=utf-8");
//输出信息
PrintWriter writer = resp.getWriter();
writer.write("Hello world" + "<br/>");
writer.write("username ->" + username + "<br/>");
writer.write("password ->" + password + "<br/>");
writer.close();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
//设置请求编码
req.setCharacterEncoding("UTF-8");
doGet(req, resp);
}
}
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