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学习笔记

Servlet Web 浏览器应用服务器 HTML

代码部分

request请求参数的获取+BeanUtils框架

package cn.itcast.web.request;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Demo1 extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		/*
		 * http://localhost:8080/day07/Demo1?name=jack&password=123回车
		 */
		//StringBuffer sb = request.getRequestURL();
		//String s1 = request.getRequestURI();
		//String s2 = request.getQueryString();
		//System.out.println(sb);
		//System.out.println(s1);
		//System.out.println(s2);
		
		//String s1 = request.getPathInfo();
		//String s2 = request.getRemoteAddr();
		//String s3 = request.getRemoteHost();
		//int s4 = request.getRemotePort();//1158
		
		String s1 = request.getLocalAddr();
		String s2 = request.getLocalName();
		int s3 = request.getLocalPort();//8080
		
		System.out.println(s1);
		System.out.println(s2);
		System.out.println(s3);
		
		
		
	}
}
getRequestURL方法返回客户端发出请求时的完整URL。
getRequestURI方法返回请求行中的资源名部分。
getQueryString 方法返回请求行中的参数部分。
getPathInfo方法返回请求URL中的额外路径信息。额外路径信息是请求URL中的位于Servlet的路径之后和查询参数之前的内容，它以“/”开头。
getRemoteAddr方法返回发出请求的客户机的IP地址。
getRemoteHost方法返回发出请求的客户机的完整主机名。
getRemotePort方法返回客户机所使用的网络端口号。
getLocalAddr方法返回WEB服务器的IP地址。
getLocalName方法返回WEB服务器的主机名。

package cn.itcast.web.request;

import java.io.IOException;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Demo2 extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		/*
		String host = request.getHeader("host");
		System.out.println("host=" + host);
		Enumeration enums = request.getHeaders("accept");
		while(enums.hasMoreElements()){
			String value = (String) enums.nextElement();
			System.out.print(value+"|");
		}
		*/
		Enumeration enums1 = request.getHeaderNames();
		while(enums1.hasMoreElements()){
			String key = (String) enums1.nextElement();//host|accept
			Enumeration enum2 = request.getHeaders(key);
		}
	}
}

package cn.itcast.web.request;

import java.io.IOException;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Demo3 extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		
		/*
		String name = request.getParameter("name");
		String password = request.getParameter("password");
		String aihao = request.getParameter("aihao");
		String[] aihaos = request.getParameterValues("aihao");
		
		if(name!=null && password!=null && aihaos!=null){
			response.getWriter().write("name=" + name + "<br/>");
			response.getWriter().write("password=" + password + "<br/>");
			for(String s : aihaos){
				response.getWriter().write("aihao=" + s + "<br/>");
			}	
		}
		*/
		
		Enumeration enums = request.getParameterNames();
		while(enums.hasMoreElements()){
			String name = (String) enums.nextElement();//name/password/aihao
			String[] values = request.getParameterValues(name);//"jack","123","abc"
			System.out.print(name + "->");
			for(String s : values){
				System.out.print(s);
			}
			System.out.println();
		}
	}
}



package cn.itcast.web.request;

import java.io.IOException;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.beanutils.BeanUtils;

public class Demo4 extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		/*
		 * http://localhost:8080/day08/Demo4?username=jack&password=123
		 */
		BeanUtils bu = new BeanUtils();
		User user = new User();
		Enumeration enums = request.getParameterNames();
		while(enums.hasMoreElements()){
			String name = (String) enums.nextElement();
			try {
				bu.setProperty(user,name,request.getParameter(name));
			} catch (Exception e) {
				throw new RuntimeException("参数装配出错");
			}
		}
		System.out.println("用户名："  + user.getUsername());
		System.out.println("密码："  + user.getPassword());
	}
}



防盗链

package cn.itcast.web.request;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Demo5 extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		//取得客户端点击下载功能页面来自于哪里
		String referer = request.getHeader("referer");
		if(referer!=null && referer.equals("http://localhost:8080/day07/index.html")){
			response.setHeader("content-disposition","attachment;filename=aaa.jpg");
		}else{
			response.sendRedirect("/day07/fail.html");
		}
	}
}

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>index.html</title>
    <meta http-equiv="content-type" content="text/html; charset=GB2312">
  </head>
  
  <body>
  	<a href="/day07/Demo5">下载</a>
  </body>
</html>


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>index.html</title>
    <meta http-equiv="content-type" content="text/html; charset=GB2312">
  </head>
  
  <body>
  	<a href="/day07/Demo5">下载</a>
  </body>
</html>

表单输入项数据的获取

package cn.itcast.web.request;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Demo6 extends HttpServlet {
	public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		
		String username = request.getParameter("username");
		String password = request.getParameter("password");
		String gender = request.getParameter("gender");
		String[] aihao = request.getParameterValues("aihao");
		String city = request.getParameter("city");
		String upfile = request.getParameter("upfile");
		String msg = request.getParameter("msg");
		String id = request.getParameter("id");
		
		int index = upfile.lastIndexOf("\\");
		String filename = upfile.substring(index+1);
		
		System.out.println("username="  + username);
		System.out.println("password="  + password);
		System.out.println("gender="  + gender);
		for(String s : aihao){
			System.out.print(s + "|");
		}
		System.out.println("\ncity="  + city);
		System.out.println("upfile="  + filename);
		System.out.println("msg=" + msg);
		System.out.println("id=" + id);
	}
}


POST请求参数的中文乱码问题 

package cn.itcast.web.request;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Demo7 extends HttpServlet {
	public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		//修改[请求体]的中文编码
		request.setCharacterEncoding("UTF-8");
		//取得表单输入输
		String username = request.getParameter("username");
		//显示在浏览器
		response.setContentType("text/html;charset=UTF-8");
		response.getWriter().write("姓名：" + username);
	}
}


URL地址的编码(GET方式对中文数据而言)

package cn.itcast.web.request;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Demo8 extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		//request.setCharacterEncoding("UTF-8");
		String username = request.getParameter("username");
		
		/*
		 * 手工将ISO8859-1的编码以UTF-8的方式查询，从而还原中文
		 */
		byte[] buf = username.getBytes("ISO8859-1");
		username = new String(buf,"UTF-8");
		
		response.setContentType("text/html;charset=UTF-8");
		response.getWriter().write("姓名：" + username);
	}
}

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>新用户注册</title>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
  </head>
  
  <body>
	<a href="/day07/Demo8?username=小王">提交</a>	
  </body>
</html>


使用转发，模拟MVC设计模式

package cn.itcast.web.request;

import java.io.IOException;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

//控制器
public class Demo9 extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		/*
		 * http://localhost:8080/day07/Demo8回车
		 */
		System.out.println("Demo9::doGet()");
		
		//调用模型
		Model m = new Model();
		boolean flag = m.check();
		
		if(flag){
			//转发
			RequestDispatcher rd = request.getRequestDispatcher("/view.html");
			rd.forward(request, response);
			//response.sendRedirect("/day07/view.html");
		}
	}
}
	如果在调用forward方法之前，在Servlet程序中写入的部分内容已经被真正地传送到了客户端，forward方法将抛出IllegalStateException异常。
	如果在调用forward方法之前向Servlet引擎的缓冲区(response)中写入了内容，只要写入到缓冲区中的内容还没有被真正输出到客户端，forward方法就可以被正常执行，原来写入到输出缓冲区中的内容将被清空，但是，已写入到HttpServletResponse对象中的响应头字段信息保持有效。 
	

package cn.itcast.web.request;

//模型
public class Model {
	public boolean check(){
		System.out.println("Model::check()");
		return true;
	}
}

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>index.html</title>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
  </head>
  
  <body>
	视图显示正确
  </body>
</html>


使用包含，将网页信息分为头/体/尾三部份处理


package cn.itcast.web.request;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

//负责产生该网站中所有网页的页头
public class HeaderServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		out.write("<a href='#'>首页</a>&nbsp;&nbsp;&nbsp;");
		out.write("<a href='#'>购物车</a>&nbsp;&nbsp;&nbsp;");
		out.write("<a href='#'>用户注册</a>");
		out.write("<br/>");
	}
}


package cn.itcast.web.request;

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

//负责产生该网站中所有网页的页尾
public class FooterServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		PrintWriter out = response.getWriter();
		response.setContentType("text/html;charset=UTF-8");
		out.write("<a href='#'>关于我们</a>&nbsp;&nbsp;&nbsp;");
		out.write("<a href='#'>联系我们</a>&nbsp;&nbsp;&nbsp;");
		out.write("<a href='#'>法律声明</a>");
		out.write("<br/>");
	}
}


package cn.itcast.web.request;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		//包含网页头
		request.getRequestDispatcher("/HeaderServlet").include(request, response);
		
		response.setContentType("text/html;charset=UTF-8");
		response.getWriter().write("用户登录");
		response.getWriter().write("<br/>");
		
		//包含网页尾
		request.getRequestDispatcher("/FooterServlet").include(request, response);
	}
}

将信息存储到request容器对象中

package cn.itcast.web.request;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Demo101 extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		/*
		 * http://localhost:8080/day07/Demo101?name=jack回车
		 */
		String name = request.getParameter("name");
		
		//将信息存储到request容器对象中
		request.setAttribute("NAME",name);
		
		//向浏览器输出内容
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		out.write("中国");
		out.flush();
		//out.close();
		
		request.getRequestDispatcher("/Demo102").forward(request, response);
		//response.sendRedirect("/day07/Demo102");//客户端 
	}
}

package cn.itcast.web.request;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Demo102 extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		//从request容器对象中根据key取得信息
		String name = (String) request.getAttribute("NAME");
		response.getWriter().write("name=" + name);
	}
}

重定向

package cn.itcast.web.response;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet {
	public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		
		System.out.println(request.hashCode());
		
		//取得表单中填入的用户名和密码
		String username = request.getParameter("username");//浏览器->服务器的请求
		String password = request.getParameter("password");
		if("jack".equals(username) && "123".equals(password)){
			//重定向到ShowServlet
			response.sendRedirect("/day07/ShowServlet");
			
			//重定向到success.html
			//response.sendRedirect("/day07/success.html");
			//以下二句代码的组合，与response.sendRedirect()等价
			//response.setStatus(302);
			//response.setHeader("locotion","/day07/success.html");
			
		}else{
			response.sendRedirect("/day07/fail.html");
		}
	}
}

package cn.itcast.web.response;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ShowServlet extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		System.out.println(request.hashCode());
		response.setContentType("text/html;charset=UTF-8");//响应头
		response.getWriter().write("登录成功");//字符方式显示//响应体
		//response.getOutputStream().write("success".getBytes());//字节方式显示
	}
}


观察Cookie特证

package cn.itcast.web.cookie;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Demo1 extends HttpServlet {
	public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
		//产生Cookie
		Cookie cookie = new Cookie("name","jack");
		//以秒为单位，设置Cookie的存活时间
		cookie.setMaxAge(7*24*60*60);
		//写入浏览器的缓存
		response.addCookie(cookie);
	}
}


注册页面

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>新用户注册</title>
    <meta http-equiv="content-type" content="text/html; charset=GB2312">
  </head>
  
  <body>
	<form action="/day07/Demo6" method="post">
		<table border="1" align="center">
			<caption>新用户注册</caption>
			<tr>
				<th>用户名</th>
				<td><input type="text" name="username"/></td>
			</tr>
			<tr>
				<th>密码</th>
				<td><input type="password" name="password"/></td>
			</tr>
			<tr>
				<th>性别</th>
				<td>
					<input type="radio" name="gender" value="male" checked/>男
					<input type="radio" name="gender" value="female"/>女
				</td>
			<tr>
				<th>爱好</th>
				<td>
					<input type="checkbox" name="aihao" value="sing"/>唱歌
					<input type="checkbox" name="aihao" value="dance"/>跳舞
					<input type="checkbox" name="aihao" value="play"/>打球
					<input type="checkbox" name="aihao" value="run"/>跑步
				</td>
			</tr>
			<tr>
				<th>你所在的城市</th>
				<td>
					<select name="city">
						<option value="bj">北京</option>
						<option value="sh">上海</option>
						<option value="gz" selected>广州</option>
						<option value="cq">重庆</option>
					</select>
				</td>
			</tr>
			<tr>
				<th>选择需要上传的文件</th>
				<td><input type="file" name="upfile"></td>
			</tr>
			<tr>
				<th>你的留言</th>			
				<td>
					<textarea rows="4" cols="20" name="msg"></textarea>
				</td>
			</tr>
			<tr>
				<td>
					<input type="hidden" name="id" value="20110221"/>
				</td>
			</tr>
			<tr>
				<td>
				</td>
				<td>
					<input type="submit" value="提交"/>
						&nbsp;&nbsp;&nbsp;&nbsp;
					<input type="reset" value="重填"/>
				</td>
			</tr>
		</table>
	</form>	
  </body>
</html>

今日总结

*1 重定向
response.sendRedirect("/day07/需要重定向到的目标资源位置");
    例如：response.sendRedirect("/day07/success.html");
    例如：response.sendRedirect("/day07/ShowServlet");
浏览器发放二次请求
浏览器地址栏前后变化
web服务器先后产生不同的request对象

错误提示：
405：
请求类型与方法不配对
java.lang.IllegalStateException: getWriter() has already been called for this response
response.getWriter()和response.getOutputStream()只有选用其中一个，不能同时使用

2 response细节
1)正确选用字符输出和字节输出
2)不能同时使用字符输出和字节输出
3)输出时会将响应头和响应体一通输出给浏览器
4)response产生的流对象在web服务器销毁response对象前，后自行关闭

3 StringBuffer
线程安全，即多个线程并发访问该变量时，不会产生错误问题。
可变字符，即适合于大量的增，删，改，查操作，不会产生新的变量。
String(不可变，即适合于查询操作）
StringBuilder(课后自行完成)
一个可变的字符序列。此类提供一个与 StringBuffer 兼容的 API，但不保证同步。该类被设计用作 StringBuffer 的一个简易替换，用在字符串缓冲区被单个线程使用的时候（这种情况很普遍）。如果可能，建议优先采用该类，因为在大多数实现中，它比 StringBuffer 要快。

http://localhost:8080/day07/Demo1?name=jack&password=123
URL      :http://localhost:8080/day07/Demo1
URI      :/day07/Demo1
查询字符串：name=jack&password=123

4 request常用API
URL/URI/RemoteAddr/RemotePort/LocaleAddr/LocalePort/...

*5 取得客户端请求头内容和请求体内容
获得客户机请求头
   getHeader(string name)方法:String
   getHeaders(String name)方法:Enumeration
   getHeaderNames()方法：Enumeration
   获得客户机请求参数(即，客户端提交的数据)
   getParameter()方法：String
   getParameterValues（String name）方法：String[]
   getParameterNames方法+BeanUtils框架：Enumeration

*6 Request的应用
1)防盗链
2)各种表单输入项数据的获取

*7 POST和GET请求参数的中文处理
1)POST
    记住三点一致：
a)<meta http-equiv="content-type" content="text/html; charset=UTF-8">
b)request.setCharacterEncoding("UTF-8");修改[请求体]的中文编码，如果内容在请求头，该行代码不起住用
        c)response.setContentType("text/html;charset=UTF-8");

2)GET
/*
* 手工将ISO8859-1的编码以UTF-8的方式查询，从而还原中文
*/
byte[] buf = username.getBytes("ISO8859-1");
username = new String(buf,"UTF-8");
        <a href="/day07/Demo8?username=<%=URLEncoder.encode("小王","UTF-8")%>">提交</a>

8 request细节
0)请求对象
1)request容器对象/范围对象
    request对象的方式比较：
    getHeader(String)
     取得请求头
    getParameter(String)
     取得请求参数
    getAttribute(String)
     取得request容器对象的属性的值
2)在forward()方法不要有任何的输出代码

*9)转发与重定向的区别
1)转发在WEB网站内，重定向在WEB网站内外
2)对于重定向，/表示webapps；对于转发，/表示当前web应用名，即day07
3)重定向地址栏前后变化，转发地址栏前后不变
4)重定向知道web服务器内部变化，转发不知道web服务器内部变化
5)重定向request对象前后不一致，转发request对象前后一致，response也一样
6)代码
重定向：response.sendRedirect()
转发：request.getRequestDispatcher().forward()

10)包含
   类似于Java中的方法调用，最终流程还会回到Servlet中
   乱码原因：在GET方式下，中文出错，需要手工强制转换，参照7知识点

11)会话的定义
   在同一个浏览器的一次或多次向web服务器的请求的过程，叫会话
   ServletContext容器对象/范围对象
   HttpServletRequest容器对象/范围对象
   请求头：Cookie: name=jack
   响应头：Set-Cookie: name=jack; Expires=Fri, 11-Mar-2011 09:07:26 GMT
   其中path表示;localhost/day07：但凡访问/day07应用下的所有资源，都会带上cookie，如果访问不是/day07下的所有资源，
   则不会带cookie