2014.08.25 周一-查询数据没导入成功-http响应头

今天一天都在做查询页面的数据导入部分，本来打算今天能够弄出来的，不过最后还是有点小问题，没有把表格中的数据导进去。

一、eclipse快捷键

1、alt + shift + M：重构（提取代码）

二、HTTP响应头

1、常用响应头

1. Content-Encoding：服务器通过这个头，告诉浏览器，数据的压缩格式
   Content-Length: 服务器通过这个头，告诉浏览器回送数据的长度

   <pre class="java" name="code">package com.day04;
   
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
   import java.util.zip.GZIPOutputStream;
   
   import javax.servlet.ServletException;
   import javax.servlet.annotation.WebServlet;
   import javax.servlet.http.HttpServlet;
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   
   @WebServlet("/ServletDemo1")
   public class ServletDemo1 extends HttpServlet {
   	private static final long serialVersionUID = 1L;
   
   	protected void doGet(HttpServletRequest request,
   			HttpServletResponse response) throws ServletException, IOException {
   		
   		test2(request, response);
   	}
   
   	//数据压缩
   	public void test2(HttpServletRequest request, HttpServletResponse response) throws IOException {
   		String data = "abcdddddddddddddddddddddddddddddddddddddddddddd";
   		System.out.println("原始数据的大小为：" + data.getBytes().length);
   		
   		ByteArrayOutputStream bout = new ByteArrayOutputStream();
   		
   		GZIPOutputStream gout = new GZIPOutputStream(bout);  //buffer。自带有缓冲的
   		gout.write(data.getBytes());		
   		gout.close();
   		
   		//得到压缩后的数据
   		byte g[] = bout.toByteArray();
   		
   		response.setHeader("Content-Encoding", "gzip");
   		response.setHeader("Content-Length", g.length + "");
   		
   		response.getOutputStream().write(g);
   	}
   }

   显示结果如下： 
   
   
2. Content-Type：服务器通过这个头，告诉浏览器回送数据的类型（content中的c有区分大小写吗？）

   package com.day04;
   
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
   import java.io.InputStream;
   import java.io.OutputStream;
   import java.util.zip.GZIPOutputStream;
   
   import javax.servlet.ServletException;
   import javax.servlet.annotation.WebServlet;
   import javax.servlet.http.HttpServlet;
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   
   @WebServlet("/ServletDemo1")
   public class ServletDemo1 extends HttpServlet {
   	private static final long serialVersionUID = 1L;
   
   	protected void doGet(HttpServletRequest request,
   			HttpServletResponse response) throws ServletException, IOException {
   		
   		test3(request, response);
   	}
   	
   	//指定回送数据类型
   	public void test3(HttpServletRequest request, HttpServletResponse response) throws IOException {
   		
   		response.setHeader("content-type", "image/jpg");  //在D:\apache-tomcat-7.0.54\conf\web.xml中搜索>jpg就能找到image/jpg
   		
   		InputStream in = this.getServletContext().getResourceAsStream("/1.jpg");  
   		byte buffer[] = new byte[1024];
   		int len = 0;
   		OutputStream out = response.getOutputStream();
   		while((len = in.read(buffer)) > 0) {
   			out.write(buffer, 0, len);
   		}
   	}	
   }

   图片放置位置：
    
3. Refresh：服务器通过这个头，告诉浏览器定时刷新

   package com.day04;
   
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
   import java.io.InputStream;
   import java.io.OutputStream;
   import java.util.zip.GZIPOutputStream;
   
   import javax.servlet.ServletException;
   import javax.servlet.annotation.WebServlet;
   import javax.servlet.http.HttpServlet;
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   
   @WebServlet("/ServletDemo1")
   public class ServletDemo1 extends HttpServlet {
   	private static final long serialVersionUID = 1L;
   
   	protected void doGet(HttpServletRequest request,
   			HttpServletResponse response) throws ServletException, IOException {
   		
   		test4(request, response);
   	}
   	
   	//指定浏览器定时刷新
   	public void test4(HttpServletRequest request, HttpServletResponse response) throws IOException {
   		
   //		response.setHeader("refresh", "3");  //每3秒刷新一次
   		response.setHeader("refresh", "3; url = 'http://www.sina.com'");  //3秒之后调到新浪主页
   		response.getWriter().write("abcd");
   
   	}	
   }

4. Content-Disposition:服务器通过这个头，告诉浏览器以下载方式打数据

   package com.day04;
   
   import java.io.ByteArrayOutputStream;
   import java.io.IOException;
   import java.io.InputStream;
   import java.io.OutputStream;
   import java.util.zip.GZIPOutputStream;
   
   import javax.servlet.ServletException;
   import javax.servlet.annotation.WebServlet;
   import javax.servlet.http.HttpServlet;
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   
   @WebServlet("/ServletDemo1")
   public class ServletDemo1 extends HttpServlet {
   	private static final long serialVersionUID = 1L;
   
   	protected void doGet(HttpServletRequest request,
   			HttpServletResponse response) throws ServletException, IOException {
   		
   		test5(request, response);
   	}
   	
   	//指定浏览器下载
   	public void test5(HttpServletRequest request, HttpServletResponse response) throws IOException {
   		
   		response.setHeader("content-disposition", "attachment;filename=xxx.jpg");  //要下载文件(1.jpg)显示的名称
   		
   		InputStream in = this.getServletContext().getResourceAsStream("/1.jpg");
   		byte buffer[] = new byte[1024];
   		int len = 0;
   		OutputStream out = response.getOutputStream();
   		while((len = in.read(buffer)) > 0) {
   			out.write(buffer, 0, len);
   		}
   	}
   	
   	public void test3(HttpServletRequest request, HttpServletResponse response) throws IOException {
   		
   		response.setHeader("content-type", "image/jpg");  //在D:\apache-tomcat-7.0.54\conf\web.xml中搜索>jpg就能找到image/jpg
   		
   		InputStream in = this.getServletContext().getResourceAsStream("/1.jpg");  
   		byte buffer[] = new byte[1024];
   		int len = 0;
   		OutputStream out = response.getOutputStream();
   		while((len = in.read(buffer)) > 0) {
   			out.write(buffer, 0, len);
   		}
   	}
   }

5. 控制浏览器不要缓存：
   Expires: -1 
   Cache-Control: no-cache 
   Pragma: no-cache