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)

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