HttpServletRequest与HttpServletResponse概要

Tips：以下代码均在IE中通过测试，由于只有IE支持response字符流方法print()向客户端写入html代码，其它浏览器均需用write()方法。

HttpServletResponse

1.状态码
http协议中的常见状态码：
200：表示成功
302：表示重定向
404：表示客户端错误（访问资源不存在）
500：表示服务器端错误
更多：http://developer.qiniu.com/docs/v6/api/reference/codes.html
相关方法：
  response.setStatus(int sc)：设置成功状态码；
  response.setError(int sc)：设置错误状态码
  response.sendError(int sc,String msg)：设置错误状态码,显示错误信息。
2.响应头
详细：http://developer.qiniu.com/docs/v6/api/reference/codes.html
相关方法：
   response.setHeader(String name,String value)：设置单值响应头
   response.addHeader(String name,String value)：设置多值响应头
   response.setIntHeader(String name,int value)：设置单值int响应头
   response.addIntHeader(String name,int value)：设置多值int响应头
   response.setDateHeader(String name,long value)：设置单值毫秒型响应头
   response.addDateHeader(String name,long value)：设置多值毫秒型响应头
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重定向

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B->A

public class BServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setHeader("Location","/Response/AServlet" );response.setStatus(302);}}

***重定向sendRedirect(Sting url)方法

public class GServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.sendRedirect("/Response/AServlet");}}

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定时刷新

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public class CServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {PrintWriter writer = response.getWriter();writer.println("5秒跳转");response.setHeader("Refresh", "5;URL=/Response/AServlet");}}

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禁用缓存

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public class DServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setHeader("Cache-Control", "no-cache");response.setHeader("pragma", "no-cache");response.setDateHeader("expires", -1);response.getWriter().write("hhhhhh");}}

***meat标签可以代替响应头
3.响应体
    ServletOutputStream sout = response.getOutputStream();

    PritnWriter pout = response.gerWriter();

//字节流public class FServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {String s="FServlet";byte[] bytes = s.getBytes();response.getOutputStream().write(bytes);    //图片response.setContentType("image/jpeg");String path="F:/a.jpg";FileInputStream in = new FileInputStream(path);byte[] bytes1=IOUtils.toByteArray(in);response.getOutputStream().write(bytes1);}}

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HttpServletRequest

1.获取常用信息
——request.getRemoteAddr()：获取客户端IP
——request.getMethod()：获取请求方式post或get
2.获取请求头
——String getHeader(String name)：适用于单值请求头
——int getIntHeader(String name)：适用于单值int请求头
——long getDateHeader(String name)：适用于单值毫秒型请求头
——Enumeration<String> getHeaders(Sting name)：适用于多值请求头
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获取IP、请求方式、User-Agent

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public class AServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//获取客户端的IP地址String addr = request.getRemoteAddr();//获取请求方式String method=request.getMethod();//获取User-AgentString userAgent=request.getHeader("User-Agent");System.out.println("IP:"+addr);System.out.println("Method:"+method);System.out.println("User-Agent"+userAgent);}}

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利用Referer请求头防盗链

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public class BServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.getWriter().print(request.getScheme()+"://");response.getWriter().print(request.getServerName()+":");response.getWriter().print(request.getServerPort());response.getWriter().print(request.getContextPath());response.getWriter().print(request.getServletPath()+"?");response.getWriter().print(request.getQueryString()+"<br/>");response.getWriter().print(request.getRequestURI()+"<br/>");response.getWriter().print(request.getRequestURL());}}

3.获取请求URL
eg：http://localhost:8080/Request/AServlet?username=xxx&password=xxx
String getScheme():获取协议 http
String getServerName()：获取服务器名 localhost
String getServerPort()：获取服务器端口 8080
String getContextPath()：获取项目名称 /Request
String getServletPath()：获取Servlet路径 /AServlet
String getQueryString()：获取部分参数 username=xxx&password=xxx
String getRequestURI()：获取请求URI /Request/AServlet
String getRequestURL()：获取请求URL http://localhost:8080/Request/AServlet?username=xxx&password=xxx
4.获取请求参数
在请求体中（post）
在URL之后（get）
String getParameter(String name)：获取指定名称的请求参数值（单值）
String[] getParameter(String name)：获取获取指定名称的请求参数值（多值）
Enumeration<String> getParameterNames()：获取所有请求参数的名称
Map<String,String[]> getParameterMap()：获取所有请求参数
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超链接参数、表单数据

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public class AServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.getWriter().print(request.getParameter("nicknames")+",");response.getWriter().print(request.getParameter("age")+"<br/>");}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.getWriter().print(request.getParameter("<br/>"+"usenames")+"<br/>");response.getWriter().print(request.getParameter("password")+"<br/>");String[] hobby = request.getParameterValues("hobby");String s=Arrays.toString(hobby);response.getWriter().print(s);//获取所有参数Enumeration names = request.getParameterNames();while(names.hasMoreElements()){response.getWriter().print("<br/>"+names.nextElement());}//获取所有请求参数，封装到Map中Map<String,String[]>map=request.getParameterMap();for(String name:map.keySet()){String[] values = map.get(name);System.out.println(name+"="+Arrays.toString(values));}}}