类别 | API |
---|---|
请求行 |
request.getMethod(); 请求方式 request.getRequetURI() / request.getRequetURL() 请求资源 request.getProtocol() 请求http协议版本 |
请求头 |
request.getHeader("名称") 根据请求头获取请求值 request.getHeaderNames() 获取所有的请求头名称 |
实体内容 |
request.getInputStream() 获取实体内容数据 |
GET方式获取请求参数 |
request.getQueryString(); |
POST方式获取请求参数 |
request.getInputStream(); |
GET和POST获取 参数的方法(通用) |
request.getParameter("参数名"); 根据参数名获取参数值(注意,只能获取一个值的参数) request.getParameterValue("参数名“);根据参数名获取参数值(可以获取多个值的参数) request.getParameterNames(); 获取所有参数名称列表 |
1、获取请求行、请求头、实体内部的信息
package com.rk.http.a_request; import java.io.IOException; import java.io.PrintWriter; import java.util.Enumeration; import javax.servlet.ServletException; import javax.servlet.ServletInputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 请求数据的请求行、请求头、实体内容 */ public class Demo01 extends HttpServlet { /* * 1)tomcat服务器接收到浏览器发送的请求数据,然后封装到HttpServetRequest对象中 * 2)tomcat服务器调用doGet方法,然后把request对象传入到servlet中。 * 3)从request对象取出请求数据。 */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doPost(request, response); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); printRequestLine(request, response); printRequestHeaders(request, response); printRequestBody(request, response);//这里只有通过post方式提交的表单数据才能被打印出来 } /** * 请求行 */ private void printRequestLine(HttpServletRequest request, HttpServletResponse response) throws IOException { PrintWriter out = response.getWriter(); String strMethod = request.getMethod();//请求方式 StringBuffer strURL = request.getRequestURL();//请求资源 String strURI = request.getRequestURI(); String strProtocol = request.getProtocol();//http协议 out.write("<h1>请求行(Request Line)</h1>"); out.write("<strong>Request Method</strong>: " + strMethod + "<br/>"); out.write("<strong>Request URI</strong>: " + strURI + "<br/>"); out.write("<strong>Request URL</strong>: " + strURL + "<br/>"); out.write("<strong>Request Protocol</strong>: " + strProtocol + "<br/>"); out.write("<hr/>"); } /** * 请求头 */ private void printRequestHeaders(HttpServletRequest request, HttpServletResponse response) throws IOException { PrintWriter out = response.getWriter(); out.write("<h1>请求头(Request Headers)</h1>"); //遍历所有请求头 Enumeration<String> requestHeaders = request.getHeaderNames();//得到所有的请求头名称列表 while(requestHeaders.hasMoreElements())//判断是否有下一个元素 { String headerName = requestHeaders.nextElement();//取出下一个元素 String headerValue = request.getHeader(headerName);//根据头名称的到头的内容 out.write("<strong>" + headerName + "</strong>: " + headerValue + "<br/>"); } out.write("<hr/>"); } /** * 请求的实体内容 */ private void printRequestBody(HttpServletRequest request, HttpServletResponse response) throws IOException { PrintWriter out = response.getWriter(); out.write("<h1>实体内容(Request Body)</h1>"); ServletInputStream inStream = request.getInputStream();//得到实体内容 byte[] buf = new byte[1024]; int len = 0; while((len=inStream.readLine(buf, 0, buf.length)) != -1) { String strValue = new String(buf, 0, len); out.print(strValue); } out.write("<hr/>"); } }
2、获取浏览器的类型
获取浏览器的类型主要是依据HTTP请求头中的user-agent。
package com.rk.http.a_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; /** * 案例:获取浏览器的类型 */ public class Demo02 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=utf-8");//ContentType可以参照%tomcat%/conf/web.xml文件中的内容 PrintWriter out = response.getWriter(); StringBuilder sb = new StringBuilder(); sb.append("你正在使用的是"); String userAgent = request.getHeader("user-agent");//获取请求头: user-agent //判断用户使用的浏览器类型 if(userAgent.contains("Chrome")) { sb.append("Chrome"); } else if(userAgent.contains("Firefox")) { sb.append("Firefox"); } else if(userAgent.contains("Trident")) { sb.append("IE"); } else { sb.append("未知的"); } sb.append("浏览器"); out.write(sb.toString()); } }
3、防止非法链接
防止非法链接主要是依据HTTP请求头中的referer。
package com.rk.http.a_request; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 案例:防止非法链接 * 这是需要下载的资源 */ public class Demo03 extends HttpServlet { protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException ,IOException { response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=utf-8"); String referer = request.getHeader("referer");//得到referer头 System.out.println("referer: " + referer); /** * 判断非法链接: * 1)直接访问的话referer==null * 2)如果当前请求不是来自广告 */ if((referer == null) || !(referer.contains("/RK007HTTP/ad.html"))) { response.getWriter().write("当前是非法链接,请回到首页。<a href=‘/RK007HTTP/ad.html‘>首页</a>"); } else { response.getWriter().write("资源正在下载..."); } } }
4、获取GET方式和Post方式提交的参数
package com.rk.http.a_request; import java.io.IOException; import java.io.InputStream; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 获取GET方式和Post方式提交的参数 */ public class Demo04 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=utf-8"); String queryString = request.getQueryString();//获取到QueryString response.getWriter().write("<h1>通过GET方式获取提交的表单参数</h1>"); response.getWriter().write(queryString); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=utf-8"); response.getWriter().write("<h1>通过POST方式获取提交的表单参数</h1>"); InputStream inStream = request.getInputStream();//获取到InputStream byte[] buf = new byte[1024]; int len = 0; while((len = inStream.read(buf, 0, buf.length)) != -1) { String postData = new String(buf,0,len); response.getWriter().write(postData); } } }
5、请求参数编码问题
参数编码问题的原因:
a)浏览器默认情况下以UTF-8编码向Tomcat服务器发送HTTP请求。
同样,Tomcat在接收到HTTP请求时,默认以iso-8859-1进行解码。
b)如果HTTP请求中的数据是英文字符,由于UTF-8对iso-8859-1字符集的兼容性,因此不会出现乱码的问题。
c)如果HTTP请求中的数据是中文字符,由于字符编码和解码的不同,就会出乱码的情况。
要解决乱码的问题,就需要进行编码的转换,思路如下:
String str --> byte[] bytes --> String newString
首先,得到到Tomcat接收到的字符串str;
其次,用iso-8859-1编码方式获取到字符串str的字节数组bytes;
最后,用utf-8编码的方式将字节数组bytes转换为新的字符串newString。
GET方式和POST方式解决乱码问题的一些差异
通过GET方式传递的参数,只能通过对每一个传递的参数进行编码转换。
而通过POST方式传递的参数,除了对每个传递的参数进行编码转换之外,
还有一种简单的方式,就是使用request.setCharacterEncoding("UTF-8");这样后续获取参数时就不需要再进行编码转换了。
package com.rk.http.a_request; import java.io.IOException; import java.io.PrintWriter; import java.io.UnsupportedEncodingException; import java.util.Arrays; 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 Demo05 extends HttpServlet { @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=utf-8"); PrintWriter out = response.getWriter(); out.write("<h1>"+request.getMethod()+"方式</h1>"); Enumeration<String> paramEnum = request.getParameterNames(); while(paramEnum.hasMoreElements()) { String paramName = paramEnum.nextElement(); if(paramName.equals("hobby"))//如果参数名是hobby,则调用getParameterValues { String[] hobbies_iso_8859_1 = request.getParameterValues("hobby");//根据参数名获取参数值(可以获取多个值的同名参数) String[] hobbies = new String[hobbies_iso_8859_1.length]; for(int i=0;i<hobbies_iso_8859_1.length;i++) { hobbies[i] = convertToUTF8Encoding(hobbies_iso_8859_1[i]); } out.write(paramName + ": " + Arrays.toString(hobbies) + "<br/>"); } else { String paramValue_iso_8859_1 = request.getParameter(paramName);// 根据参数名得到参数值(只能获取一个值的参数) String paramValue = convertToUTF8Encoding(paramValue_iso_8859_1); out.write(paramName + ": " + paramValue + "<br/>"); } } } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { /** * 设置参数查询的编码request.setCharacterEncoding("UTF-8"); * 该方法只能对请求实体内容的数据编码起作用。POST提交的数据在实体内容中,所以该方法对POST方法有效! * GET方法的参数放在URI后面,所以对GET方式无效!!! * Overrides the name of the character encoding used in the body of this request. * This method must be called prior to reading request parameters or reading input using getReader(). */ request.setCharacterEncoding("UTF-8"); response.setCharacterEncoding("UTF-8"); response.setContentType("text/html;charset=utf-8"); PrintWriter out = response.getWriter(); out.write("<h1>"+request.getMethod()+"方式</h1>"); Enumeration<String> paramEnum = request.getParameterNames(); while(paramEnum.hasMoreElements()) { String paramName = paramEnum.nextElement(); if(paramName.equals("hobby"))//如果参数名是hobby,则调用getParameterValues { String[] hobbies = request.getParameterValues("hobby");//根据参数名获取参数值(可以获取多个值的同名参数) out.write(paramName + ": " + Arrays.toString(hobbies) + "<br/>"); } else { String paramValue = request.getParameter(paramName);// 根据参数名得到参数值(只能获取一个值的参数) out.write(paramName + ": " + paramValue + "<br/>"); } } } /** * 手动重新解码(iso-8859-1 字符串-> utf-8 字符串) */ private String convertToUTF8Encoding(String orginalString) throws IOException { return new String(orginalString.getBytes("iso-8859-1"),"UTF-8"); } }