Request随笔

GET

/RequestDemo1

null

http://localhost/RequestDemo1

/RequestDemo1

HTTP/1.1

0:0:0:0:0:0:0:1

2. 获取请求头数据

方法：（重点记住打*号即可）

//1.通过请求头的名称获取请求头的值（*）

String getHeader(String name)

//2.获取所有的请求头名称

Enumeration getHeaderNames()

代码：

@WebServlet(“/RequestDemo1”)

public class RequestDemo extends HttpServlet {

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

//获取请求头数据：user-agent

String agent = request.getHeader(“user-agent”);

if (agent.contains(“Chrome”)) {

System.out.println(“谷歌来了…”);

} else if (agent.contains(“Firefox”)) {

System.out.println(“火狐来了…”);

}

//获取请求头数据：referer

String referer = request.getHeader(“referer”);

if (referer.contains(“/xpp”)) {

System.out.println(“牛!!!”);

} else {

System.out.println(“欢迎去优酷！”);

}

}

@Override

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

}

}

3. 获取请求体数据

请求体：只有POST请求方式，才有请求体，在请求体中封装了POST请求的请求参数。

步骤：

1. 获取流对象

2. 在从流对象中拿数据

//1.获取字符输入流，只能操作字符数据

BufferedReader getReader()

//2.获取字节输入流，可以操作所有类型数据

ServletInputStream getInputStream()

@WebServlet(“/RequestDemo1”)

public class RequestDemo extends HttpServlet {

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

}

@Override

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

//获取请求消息体-请求参数

//1.获取字符流

BufferedReader br = request.getReader();

//2.读取数据

String line=null;

while((line=br.readLine())!=null){

System.out.println(line);

}

}

}

输出：

username=zhangsan&password=124

2. 其他功能

3. 获取请求参数通用方式：不论get还是post请求方式都可以使用下列方法来获取请求参数。

//1. 根据参数名称获取参数值 username=zs&password=123

String getParameter(String name):

//2.根据参数名称获取参数值的数组 hobby=xx&hobby=game

String[] getParameterValues(String name)

//3.获取所有请求的参数名称

Enumeration getParameterNames()

//4.:获取所有参数的map集合

Map<String,String[]> getParameterMap()

样例：

@WebServlet(“/RequestDemo1”)

public class RequestDemo extends HttpServlet {

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

String username = request.getParameter(“username”);

System.out.println(username);

Enumeration parameterNames = request.getParameterNames();

while (parameterNames.hasMoreElements()) {

String name = parameterNames.nextElement();

String value = request.getParameter(name);

System.out.println(name + “------” + value);

}

System.out.println(“___________________”);

Map<String, String[]> parameterMap = request.getParameterMap();

parameterMap.forEach((a, b) -> System.out.println(a + “-------” + b[0]));

}

@Override

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

request.setCharacterEncoding(“utf-8”);

this.doGet(request, response);

}

}

输出：

小皮皮mzz

username------小皮皮mzz

password------232323

---

username-------小皮皮mzz

password-------232323

第二种方法演示：

游戏

学习

@WebServlet(“/RequestDemo1”)

public class RequestDemo extends HttpServlet {

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

String[] hobbies = request.getParameterValues(“hobby”);

for (String hobby : hobbies) {

System.out.println(hobby);

}

}

@Override

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

request.setCharacterEncoding(“utf-8”);

this.doGet(request, response);

}

}

输出：

game

study

中文乱码问题

• get方式：tomcat 8 已经将get方式乱码问题解决了

• post方式：会乱码

解决：在获取参数前，设置request的编码request.setCharacterEncoding("utf-8");

2. 请求转发：一种在服务器内部的资源跳转方式。

步骤：

//1. 通过request对象获取请求转发器对象：

RequestDispatcher getRequestDispatcher(String path)

//2. 使用RequestDispatcher对象来进行转发：

forward(ServletRequest request, ServletResponse response)

特点：

1. 浏览器地址栏路径不发生变化。

2. 只能转发到当前服务器内部资源中。

3. 转发是一次请求。

@WebServlet(“/RequestDemo2”)

public class RequestDemo2 extends HttpServlet {

@Override

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

this.doPost(request, response);

}