获取request中的参数

下面的例子是获取request中的参数，一个简单的servlet

package com.yydone.web;

import java.io.IOException;
import java.util.Map;
import java.util.Map.Entry;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/TestServlet")
public class TestServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    public TestServlet() {
        super();
    }

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

	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		
		Map<String,String[]> parameterMap = request.getParameterMap();
		if(parameterMap!=null) {
			for(Entry<String, String[]> entry:parameterMap.entrySet()) {
				String [] values = entry.getValue();
				String value = "";
				if(values!=null){
					for(String s:values){
						value += s+ ","; 
					}
					if(!"".equals(value)){
						value = value.substring(0, value.length()-1);
					}
				}
				System.out.println(entry.getKey().toString()+":"+value);
			}
		}
	}

}

 request.getParameterMap()返回的是Map<String,String[]>，而不是Map<String,String>。

为什么要String[]呢，经过测试，当参数名同名时，String[]就会用到了。

如name=n1&name=n2&name=n3时，String[0]=n1,String[1]=n2,String[2]=n3。