利用Volley框架实现简单的Android与servlet信息交互

写这篇文章之前，我参考了这篇帖子内容https://blog.csdn.net/Mr_Megamind/article/details/74048891

先来进行servlet服务器的搭建

这里我就实现简单的获取来自客户端的信息，并返回一些信息

直接上代码：

package serverlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Map;

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 net.sf.json.JSONObject;

/**
 * Servlet implementation class net
 */
@WebServlet("/net")
public class net extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public net() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.setCharacterEncoding("utf-8");    //设置 HttpServletResponse使用utf-8编码
		response.setHeader("Content-Type", "text/html;charset=utf-8");    //通知浏览器使用utf-8解码
		
		response.getWriter().append("Served at: ").append(request.getContextPath());
		
		
	        request.setCharacterEncoding("utf-8");
	       
	
	        try (PrintWriter out = response.getWriter()) {

	            //获得请求中传来的用户名和密码
	            String accountNumber = request.getParameter("AccountNumber");
	            String password = request.getParameter("Password");

	          
	           String s=accountNumber+password;
	           System.out.println(s);
	            Map<String, String> params = new HashMap<>();
	            JSONObject jsonObject = new JSONObject();
	            params.put("Result",s);
	         

	           
	            jsonObject.put("params",params);
	            System.out.println(jsonObject.toString());
	            response.resetBuffer();//清空原有的输出流，方便客户端获取到json字符串

	            out.write(jsonObject.toString());//将json字符串写入输出流
	        }

		
		
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

　　

接下来是客户端的代码

使用Volley首先要在项目中添加Volley.jar包

接下来是使用步骤

1.创建RequestQuene对象,定义网络请求队列;

2.创建**Request对象，**代表String、JSON、Image用于定义网络请求的接收，这里我使用的是StringRequest；

3.把**Request请求对象添加到RequestQuene对象中，开始执行网络请求；

4.在AndroidManifest中注册,添加网络权限；

这里先附上添加网络权限的语句：

<uses-permission android:name="android.permission.INTERNET" />

然后是app内进行网络请求的函数体的代码

public  void LoginRequest(final String accountNumber, final String password) {
        //请求地址
        String url = "http://域名:端口号/MyFirstWebApp/LoginServlet";    
        String tag = "Login";   

        //取得请求队列
        RequestQueue requestQueue = Volley.newRequestQueue(getApplicationContext());

        //防止重复请求，先取消tag标识的请求队列
        requestQueue.cancelAll(tag);
        
        //创建StringRequest，定义字符串请求的请求方式为POST(省略第一个参数会默认为GET方式)
        final StringRequest request = new StringRequest(Request.Method.POST, url,
                new Response.Listener<String>() {
                    @Override

                    public void onResponse(String response) {


                        try {


//将传回的字符串转化为JSONObject
                            JSONObject jsonObject = (JSONObject) new         JSONObject(response).get("params");

                           String result = jsonObject.getString("Result"); 

//result的值就是servlet传回的result的值，对应的就是servlet中s的值
                            text.setText(result);//这部分内容是对返回信息的使用，text是一个Textview

                        } catch (JSONException e) {
                            //请求异常操作                 
                       Toast.makeText(MainActivity.this.getApplicationContext(),"无网络",Toast.LENGTH_SHORT).show();
                        }


                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {
                //响应错误操作
             
                Toast.makeText(MainActivity.this.getApplicationContext(),"响应错误",Toast.LENGTH_SHORT).show();
            }
        }) {
            @Override
            protected Map<String, String> getParams() throws AuthFailureError {
                Map<String, String> params = new HashMap<>();
                params.put("AccountNumber", accountNumber);  //注⑥
                params.put("Password", password);
                return params;
            }
        };

        //设置Tag标签
        request.setTag(tag);

        //将请求添加到队列中
        requestQueue.add(request);
    }





        @Override
        protected Response<String> parseNetworkResponse(NetworkResponse response) {
            String str = null;

            try {
                str = new String(response.data, "utf-8");
            }
            catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }

            return Response.success(str, HttpHeaderParser.parseCacheHeaders(response));
        }
    }