安卓APP：利用AndroidStudio开发usb串口通信软件【第1步】

一、搭建开发环境

（1）安装JDK，配置环境变量；（详略）

（2）下载AndroidStudio并双击打开安装；

下载地址：https://developer.android.google.cn/studio/

其他教程：https://developer.android.google.cn/studio/intro/

二、具体开发过程

（第一步的效果图）

（1）查找参考资料

参考1：https://blog.csdn.net/weixin_37185329/article/details/80759555

参考2：https://blog.csdn.net/dyh0023/article/details/79041725

（2）编写初步代码（未实现usb串口功能时）

文件activity_main.xml：

文件MainActivity.java:

package com.example.usb_to_ttl;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.widget.Toast;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;


public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    //number 0-9
    private Button n_0;
    private Button n_1;
    private Button n_2;
    private Button n_3;
    private Button n_4;
    private Button n_5;
    private Button n_6;
    private Button n_7;
    private Button n_8;
    private Button n_9;

    //other symbol
    private Button clear_all;
    private Button equal;

    boolean clean;

    private EditText editText_table;
    private EditText editText_ele;

    private Context context;

    private String usbNumber;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //the instantiation of number 0-9
        n_0 = findViewById(R.id.button0);
        n_1 = findViewById(R.id.button1);
        n_2 = findViewById(R.id.button2);
        n_3 = findViewById(R.id.button3);
        n_4 = findViewById(R.id.button4);
        n_5 = findViewById(R.id.button5);
        n_6 = findViewById(R.id.button6);
        n_7 = findViewById(R.id.button7);
        n_8 = findViewById(R.id.button8);
        n_9 = findViewById(R.id.button9);
        //the instantiation of others
        clear_all = findViewById(R.id.button11);
        equal = findViewById(R.id.button12);

        editText_table = findViewById(R.id.editText);
        editText_ele = findViewById(R.id.editText2);

        //unable to edit
        editText_ele.setFocusable(false);
        editText_ele.setFocusableInTouchMode(false);
        editText_table.setFocusable(false);
        editText_table.setFocusableInTouchMode(false);

        //click
        n_0.setOnClickListener(this);
        n_1.setOnClickListener(this);
        n_2.setOnClickListener(this);
        n_3.setOnClickListener(this);
        n_4.setOnClickListener(this);
        n_5.setOnClickListener(this);
        n_6.setOnClickListener(this);
        n_7.setOnClickListener(this);
        n_8.setOnClickListener(this);
        n_9.setOnClickListener(this);

        clear_all.setOnClickListener(this);
        equal.setOnClickListener(this);

        context = this;
    }

    public void onClick(View view){
        //get the input
        String input = editText_table.getText().toString();
        //Determine which key is being pressed
        switch (view.getId()){
            case R.id.button0:
            case R.id.button1:
            case R.id.button2:
            case R.id.button3:
            case R.id.button4:
            case R.id.button5:
            case R.id.button6:
            case R.id.button7:
            case R.id.button8:
            case R.id.button9:
                if(clean){
                    clean = false;
                    editText_table.setText("");
                }
                editText_table.setText(input+((Button)view).getText()+"");
                break;
            //clean
            case R.id.button11:
                if(clean){
                    clean = false;
                    input = "";
                    editText_table.setText("");
                }
                if(!input.equals("")){
                    editText_table.setText(input.substring(0,input.length() - 1));
                    break;
                }
                break;
            case R.id.button12:
                sendToUSB();
                break;

        }
    }

    private void sendToUSB(){
        usbNumber = editText_table.getText().toString();
        Toast t = Toast.makeText(context,"Succeed to send "+usbNumber,Toast.LENGTH_LONG);
        t.show();
    }
}