IDEA后台与安卓数据交互

实现功能：Android app发ID数据给IDEA
后台，后台根据获取到的ID数据查询数据库并将对应的数据发回客户端显示在app界面

开发工具：IDEA，Android studio，MySQL

Android端：(以下为需要新建或者修改的文件，以便新手学习)
Java：MainActivity
GuestToServer
layout:activity_main
build.gradle(app)
AndoidManifest.xml
客户端运行示例：

代码展示：

import androidx.appcompat.app.AppCompatActivity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.View;import android.widget.Button;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;import org.json.JSONException;import org.json.JSONObject;import java.io.BufferedReader;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStreamReader;public class MainActivity extends AppCompatActivity {    //登录用户名输入框    private EditText et_username;    //登录密码输入框    private EditText et_password;    //登录按钮    private EditText id;    private Button bt_login;    private TextView tv;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        //获取组件        init();        //对登录按钮的点击监控        bt_login.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                // Toast.makeText(LoginActivity.this, "登录成功！", Toast.LENGTH_LONG).show();                final Handler myHandler = new Handler(){                    public void handleMessage(Message msg){                        String responseResult = (String)msg.obj;                        // Toast.makeText(LoginActivity.this, "登录成功！", Toast.LENGTH_LONG).show();                        //登录成功               System.out.println("response"+responseResult);                       try{                        JSONObject root = new JSONObject(responseResult);                           String userName = root.getString("userName");                           tv.append("userName"+"="+userName+"/n");                       }                       catch (JSONException e) {                           e.printStackTrace();                       }                        if(responseResult.equals("" +                                "true")){  Toast.makeText(com.example.myapplication.MainActivity.this, "登录成功！", Toast.LENGTH_LONG).show();                        }                        //登录失败                        else{                 Toast.makeText(com.example.myapplication.MainActivity.this, "登录失败！", Toast.LENGTH_LONG).show();                        }                    }                };                new Thread(new Runnable() {                    @Override                    public void run() {                        GuestToServer guestToServer = new GuestToServer();                        try {                            //如果是调用GuestToServer中验证用户名与密码的方法则使用下面句                           //String result = guestToServer.doPost(et_username.getText().toString().trim(), et_password.getText().toString().trim());                            String result = guestToServer.doPost(id.getText().toString().trim());                            Message msg = new Message();                         msg.obj = result;                            myHandler.sendMessage(msg);                        } catch (IOException e) {                            e.printStackTrace();                        }                    }                }).start();            }        });    }    /**     * 获取组件     */    private void init() {        et_username = (EditText)findViewById(R.id.et_username);        et_password = (EditText)findViewById(R.id.et_password);        id= (EditText)findViewById(R.id.id);        bt_login = (Button)findViewById(R.id.bt_login);        tv = (TextView) findViewById(R.id.tv);//获取到TextView组件    }}

 GuestToServer

import android.util.Log;import org.apache.http.HttpEntity;import org.apache.http.HttpResponse;import org.apache.http.HttpStatus;import org.apache.http.NameValuePair;import org.apache.http.client.HttpClient;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.client.methods.HttpPost;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.message.BasicNameValuePair;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.net.HttpURLConnection;import java.net.MalformedURLException;import java.net.URL;import java.util.ArrayList;import java.util.List;public class GuestToServer {    //localhost为本地主机IP地址/login为idea后台项目名    private String url = "http://localhost:8080/login";    //服务器返回的结果//    String result = "";    /**     * 使用Post方式向服务器发送请求并返回响应     *     * //如果使用验证用户名及密码的方法那么使用public String doPost(String username, String password) throws IOException {     * //且放出下面两句参数设置    // * @param username 传递给服务器的username   //  * @param password 传递给服务器的password     *  @param id 传递给服务器的id     * @return     */    public String doPost(String id) throws IOException {        HttpClient httpClient = new DefaultHttpClient();        HttpPost httpPost = new HttpPost(url);        NameValuePair param3 = new BasicNameValuePair("id", id);        List<NameValuePair> params = new ArrayList<NameValuePair>();        params.add(param3);        //将参数包装如HttpEntity中并放入HttpPost的请求体中        HttpEntity httpEntity = new UrlEncodedFormEntity(params, "GBK");        httpPost.setEntity(httpEntity);        HttpResponse httpResponse = httpClient.execute(httpPost);        //如果响应成功        if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {            //得到信息体            HttpEntity entity = httpResponse.getEntity();            InputStream inputStream = entity.getContent();            BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));            String readLine = null;            while ((readLine = br.readLine()) != null) {                result += readLine;            }            inputStream.close();            return result;        }        //响应失败        else {            return "false";        }    }    /*    public String doPost(String username, String password) throws IOException {        HttpClient httpClient = new DefaultHttpClient();        HttpPost httpPost = new HttpPost(url);        //将username与password参数装入List中        NameValuePair param1 = new BasicNameValuePair("username", username);        NameValuePair param2 = new BasicNameValuePair("password", password);        List params = new ArrayList();        params.add(param1);        params.add(param2);        //将参数包装如HttpEntity中并放入HttpPost的请求体中        HttpEntity httpEntity = new UrlEncodedFormEntity(params, "GBK");        httpPost.setEntity(httpEntity);        HttpResponse httpResponse = httpClient.execute(httpPost);        //如果响应成功        if (httpResponse.getStatusLine().getStatusCode() == HttpStatus.SC_OK) {            //得到信息体            HttpEntity entity = httpResponse.getEntity();            InputStream inputStream = entity.getContent();            BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));            String readLine = null;            while ((readLine = br.readLine()) != null) {                result += readLine;            }            inputStream.close();            return result;        }        //响应失败        else {            return "false";        }    }*/}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/activity_login"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical">    <TextView        android:text="登录界面"        android:textSize="10dp"        android:textColor="#003399"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/textView1"        android:gravity="center_horizontal"        android:layout_margin="10dp"/>    <TextView        android:text="用户名"        android:textSize="20dp"        android:textColor="#CC0000"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/textView2"        android:layout_margin="10dp"/>    <EditText        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:inputType="textPersonName"        android:ems="10"        android:id="@+id/et_username"        android:textSize="10dp"        android:textColor="#003399"        android:layout_margin="10dp"/>    <TextView        android:text="密码 "        android:textSize="20dp"        android:textColor="#CC0000"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/textView3"        android:layout_margin="10dp"/>    <EditText        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:inputType="textPersonName"        android:ems="10"        android:id="@+id/et_password"        android:textSize="10dp"        android:textColor="#003399"        android:layout_margin="10dp"/>    <TextView        android:text="ID "        android:textSize="20dp"        android:textColor="#CC0000"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/idtextview"        android:layout_margin="10dp"/>    <EditText        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:inputType="textPersonName"        android:ems="10"        android:id="@+id/id"        android:textSize="10dp"        android:textColor="#003399"        android:layout_margin="10dp"/>    <Button        android:text="登录"        android:textSize="20dp"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/bt_login"        android:layout_marginLeft="20dp"        android:layout_marginRight="20dp"        android:background="#0099FF"/>    <TextView        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/tv"/></LinearLayout>

如果项目出现报错，记得检查报错日志，一般是apache没有导入
在build.gradle里加入这行
useLibrary’org.apache.http.legacy’

由于版本不同，有些需要在manifest文件中的appication加入

<application        android:allowBackup="true"        android:icon="@mipmap/ic_launcher"        android:label="@string/app_name"        android:roundIcon="@mipmap/ic_launcher_round"        android:supportsRtl="true"        android:theme="@style/AppTheme"        android:usesCleartextTraffic="true">        <uses-library android:name="org.apache.http.legacy" android:required="false"/>

至此，Android app搭建完毕，可试运行
IDEA后台项目搭建：
可参考上一篇小程序后台，共用一个后台与数据库无需更改