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
* BufferedReader getReader()：获取字符输入流，只能操作字符数据。
* ServletInputStream getInputStream()：获取字节输入流，可以操作所有类型数据
* 在文件上传知识点后讲解
2. 再从流对象中拿数据
举例：
login2.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="/servlet/ServletDemo06" method="post">
用户名：<input type="text" name="username" placeholder="请输入用户名"><br/>
密码：<input type="text" name="password" placeholder="请输入密码"><br/>
<input type="submit" value="提交">
</form>
</body>
</html>ServletDemo06.java
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.BufferedReader;
import java.io.IOException;
@WebServlet("/ServletDemo06")
public class ServletDemo06 extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//request.getInputStream()
BufferedReader reader = request.getReader();
String str = null;
while((str=reader.readLine()) !=null ){
System.out.println(str);
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
}
}
输出：username=sfd&password=sdf
