Android+Struts2实现简单的前后台交互--Android网络编程

1、下面测试截图，基本过程就是：点击按钮向服务器端发送请求，后台收到请求后给出返回的数据，前台只需要显示服务端数据就可以了。例子很简单能但引发很多思考，博主学了杂七杂八的，这又在来想杂学Android了？……其实是想多了解一下其他东西，毕竟博主还在上大学呀！多学点没什么不好……

2、客户端(Android)关键代码

MainActivity.java：

 package thonlon.example.cn.sendgetdemo;

 import android.inputmethodservice.KeyboardView;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
 import android.view.View;
 import android.widget.Button;
 import android.widget.ScrollView;
 import android.widget.TextView;

 import java.io.IOException;

 import okhttp3.Call;
 import okhttp3.Callback;
 import okhttp3.OkHttpClient;
 import okhttp3.Request;
 import okhttp3.Response;

 public class MainActivity extends AppCompatActivity {

     private TextView tv;
     private String mBaseUrl = "http://192.168.43.218:8080/OkHttpGetServer/";
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
     }

     public void doGet(View view) {
         //拿到okHttpClient对象
         OkHttpClient okHttpClient = new OkHttpClient();
         //构造Request
         Request request = new Request.Builder().get()
                 .url(mBaseUrl+"login?username=Thanlon&password=123").build();
 //        将Request封装成Call
 //        执行Call
         okHttpClient.newCall(request).enqueue(new Callback() {
             @Override
             public void onFailure(Call call, IOException e) {
                 e.printStackTrace();
             }

             @Override
             public void onResponse(Call call, Response response) throws IOException {
                 String res = response.body().string();
                 showResultInfo(res);
             }
         });
     }

     private void showResultInfo(final String resultInfo) {
         tv = (TextView) findViewById(R.id.tv);
         runOnUiThread(new Runnable() {
             @Override
             public void run() {
                 tv.setText(resultInfo);
             }
         });
     }
 }

activity_main.xml：(布局也发了，做个参考)

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="thonlon.example.cn.sendgetdemo.MainActivity">

    <Button
        android:id="@+id/btn_send"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:onClick="doGet"
        android:text="向服务器端发送请求（这里以Get请求作为示例)"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.0" />

    <TextView
        android:id="@+id/tv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintVertical_bias="0.097" />

</android.support.constraint.ConstraintLayout>

3、服务器端主要代码

UserLoginAction.java：（Servlet自然也可以，这里借助了strut2框架）

 package com.okhttp;

 import java.io.IOException;
 import java.io.PrintWriter;

 import javax.security.auth.message.callback.PrivateKeyCallback.Request;
 import javax.servlet.http.HttpServletResponse;

 import org.apache.struts2.ServletActionContext;

 import com.opensymphony.xwork2.ActionSupport;

 public class UserLoginAction extends ActionSupport {

     private String username;
     private String password;

     public String login() throws IOException {
 //        System.out.println(username+ "," + password);
         HttpServletResponse response = ServletActionContext.getResponse();
         response.setCharacterEncoding("utf-8");  //防止服务端发送到到客户端的数据出现中文乱码
         PrintWriter pw = response.getWriter();
         pw.write("下面是服务器端返回的数据:\n\n");
         pw.write("您提交的用户名是："+username);
         pw.flush();
         return null;
     }

     public String getUsername() {
         return username;
     }

     public void setUsername(String username) {
         this.username = username;
     }

     public String getPassword() {
         return password;
     }

     public void setPassword(String password) {
         this.password = password;
     }
 }

struts.xml：

 <?xml version="1.0" encoding="UTF-8" ?>
 <!DOCTYPE struts PUBLIC
     "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
     "http://struts.apache.org/dtds/struts-2.0.dtd">
 <struts>
     <package name="default" namespace="/" extends="struts-default">
         <action name="login" class="com.okhttp.UserLoginAction" method="login">
         </action>
     </package>
 </struts>

附：个人网站www.nxl123.cn(后台采用Python Flask框架搭建，2019年1月1日将升级完成并正式启用。哎，本人还是学生狗呢！网站做的不好多多提点意见和建议吧，别骂我就好！嘿嘿……以后SEO什么的还得多向大家学习……)