1.1 Resquest的概述
Web服务器收到客户端的http请求，会针对每一次请求，分别创建一个用于代表请求的request对象和代表响应的response对象。
request和response对象既然代表请求和响应，那我们要获取客户机提交过来的数据，只需要找request对象就行了。要向客户机输出数据，只需要找response对象即可。
Request代表请求对象，其中封装了对请求中具有请求行、请求头、实体内容的操作的方法
1.1.1 Resquest的一些方法
| 方法 | 描述 |
|---|---|
| String getRequestURI() | Returns the part of this request's URL from the protocol name up to the query string in the first line of the HTTP request. |
| StringBuffer getRequestURL() | Reconstructs the URL the client used to make the request. |
| String getMethod() | Returns the name of the HTTP method with which this request was made, for example, GET, POST, or PUT. |
| String getQueryString() | Returns the query string that is contained in the request URL after the path. |
- 代码实例
public class RequestDemo extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
/*
* 获取请求行
StringBuffer getRequestURL()
String getRequestURI()
String getMethod()
String getContextPath()
String getQueryString()
*/
//http://localhost:8080/myRequest/RequestDemo
String url = request.getRequestURL().toString();//完整的URL
// /myRequest/RequestDemo
String uri = request.getRequestURI();//请求行中的资源路径
//GET
String method = request.getMethod();//请求方式
// /myRequest
String contextPath = request.getContextPath();//当前项目的路径
//username=zhangsan&password=123
String queryString = request.getQueryString();//请求行中资源路径后面的参数
System.out.println(url);
System.out.println(uri);
System.out.println(method);
System.out.println(contextPath);
System.out.println(queryString);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
1.2 Resquest应用于表单的提交
定义一个HTML
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>注册页面</title>
</head>
<body>
<form action="/myRequest/RequestDemo6" method="get">
用户名：<input type="text" name="username" />
<br />
密码：<input type="password" name="password"/>
<br />
兴趣爱好：
<input type="checkbox" name="hobbies" value="java"/>java
<input type="checkbox" name="hobbies" value="php"/>php
<input type="checkbox" name="hobbies" value="python"/>python
<input type="checkbox" name="hobbies" value="android"/>android
<br />
<input type="submit" name="submit" value="注册"/>
</form>
</body>
</html>
1.2.1 获取表单提交的数据
String getParameter(String name) :根据表单项的name来获取表单项的value
String username = request.getParameter("username");
System.out.println(username);
String password = request.getParameter("password");
System.out.println(password);
String gender = request.getParameter("gender");
System.out.println(gender);
- 注意:
- 有表单项提交过来,但是没有值, 打印的是空字符串
- 表单项根本没有提交过来,打印的就是null,就不能调用字符串的方法,否则会报空指针异常
1.2.2 获取表单提交的数据2
String[] getParameterValues(String name)
String hobbies = request.getParameter("hobbies");System.out.println(hobbies);
String[] hobbies = request.getParameterValues("hobbies");
for (String h : hobbies) {
System.out.println(h);
}
String[] username = request.getParameterValues("username");
for (String s : username) {
System.out.println(s);
}
1.2.3 获取表单提交的数据3
//Map getParameterMap()
Map<String,String[]> map = request.getParameterMap();
//遍历Map
//获取所有的key
Set<String> keys = map.keySet();
//获取每一个key
for (String key : keys) {
System.out.println(key);
//通过key来获取Map的value
String[] arr = map.get(key);
//遍历数组，获取每一个表单项的value
for (String value : arr) {
System.out.println(" " + value);
}
}
//Enumeration getParameterNames()
Enumeration<String> e = request.getParameterNames();
while(e.hasMoreElements()) {
String name = e.nextElement();
System.out.println(name);
}
1.3获取表单提交的数据乱码的处理
-
原因:
- 编码前后不一致
- 表单提交数据用的是UTF-8
- 请求对象接收数据转换成字符串 用的是默认的ISO-8859-1
-
对于post请求
- request.setCharacterEncoding("UTF-8");//只能处理请求体,这里设置请求对象创建字符串所使用的编码是UTF-8
默认也是ISO-8859-1
request.setCharacterEncoding("UTF-8");//只能处理请求体
String username = request.getParameter("username");
System.out.println(username);
- 对于get请求
- 浏览器
- 按照表单页面的编码(UTF-8)进行转码,转成字节数组,拼接在请求资源的后面
- 接下来把字节数组做一个转义(url编码)在发送
- 服务器
- 服务器首先拿到这个数据做一个url解码,(正确的)
- 然后把解码之后的数据按照ISO-8859-1拼成字符串(错误)
- 浏览器
//把字符串打回原形
byte[] bys = request.getParameter("username").getBytes("ISO-8859-1");
//把字节数组按照正确的编码转换字符串
String username = new String(bys,"UTF-8");
System.out.println(username);
