Servlet请求和响应参数获取_怎么获取响应体的内部参数

1.HttpServletRequest获取参数

String getParameter(String name):通过指定名称获取参数值
 
String[] getParameterValues(String name):通过指定名称获取参数值数组，有可能一个名字对应多个值，例如表单中的多个复选框使用相同的name时。
 
Enumeration getParameterNames(): 获取所有参数的名字
 
Map getParameterMap()：获取所有参数对应的Map，其中key为参数名，value为参数值。

2.传递及获取参数的方式

方式：GET和POST

GET:

（1）地址栏中直接给出参数：http://localhost/param/ParamServlet?a1=aa&a2=a2

（2）超链接中给出参数：

<h1>链接请求</h1>
<a href="/HelloWord_war_exploded/hello?name=张三">点击</a>

（3）表单中给出的参数：<form method="GET" acton="paramservelt">....</form>

POST:

（1）表单中给出的参数：<form method="GET" acton="paramservelt">....</form>

 <h1>表单提交</h1>
  <form action="/HelloWord_war_exploded/hello?" method="get">
    姓名：<input type="text" name="name"><br>
    年龄：<input type="text" name="age"><br>
    爱好：
      <input type="checkbox" value="1" name="favor">篮球
      <input type="checkbox" value="2" name="favor">足球
      <input type="checkbox" value="3" name="favor">游泳
    <br>
    <input type="submit" value="提交">
  </form>

• String getParameter(String name)单参数获取

 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
 
public class Test01 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        /*
        *单值接收
        * */
        // 根据请求中的key来获得值
        String name = req.getParameter("name");
        String age = req.getParameter("age");
        // 不适合接收多选，他只能接收到多选中的第一个
        // String favor = req.getParameter("favor");
        System.out.println(name);
        System.out.println(age);
 
    }
 
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

 

• HttpServletRequest多参获取

 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
 
public class Test01 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
 
        /*
         *多值接收
         * */
        // 接收多选
        String[] favors = req.getParameterValues("favor");
        for (String val : favors) {
            System.out.println(val);
        }
 
    }
 
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

• Enumeration getParameterNames()的使用

 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Enumeration;
 
public class Test02 extends HttpServlet {
    /*
    * getParameterNames用于获得表单中文本域的所有的name，适合动态表单
    * */
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 获得表单中所有文本域的name
        Enumeration<String> names = req.getParameterNames();
        while (names.hasMoreElements()) {
            // 获得每个文本域的name
            String s = names.nextElement();
            // 根据文本域的name来获得值
            String[] values = req.getParameterValues(s);
            for (String value : values) {
                System.out.println(value);
            }
        }
    }
 
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}

 

 

• Map getParameterMap()取值

 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Map;
import java.util.Set;
 
public class Test03 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 获得表单中所有文本域的name和值，以map方式存储
        Map<String, String[]> map = req.getParameterMap();
        // 获得map的key(就是表单中文本域的name集合)
        Set<String> set = map.keySet();
        for (String name : set) {
            // 获得每个文本域所对应的值
            String[] vals = map.get(name);
            System.out.println(name);
            for(String val : vals) {
                System.out.println(val);
            }
        }
    }
 
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doGet(req,resp);
    }
}