今天完成了程序，源代码做备份在这里，以备以后使用

今天完成了，可以扫描条码后显示出设备信息

两个主程序，一个是MainActivity.java，还有一个Device.java

MainActivity.java如下

package com.strongdady.qrscan;

import java.util.Arrays;
import java.util.List;
import java.io.File;
import java.io.InputStream;
import java.io.FileOutputStream;
import android.database.sqlite.SQLiteDatabase;
import android.database.Cursor;
import com.google.zxing.integration.android.IntentIntegrator;
import com.google.zxing.integration.android.IntentResult;
import android.widget.Toast;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;
import android.widget.TextView;
import static android.os.Environment.getExternalStorageDirectory;

public class MainActivity extends AppCompatActivity {

    private final int BUFFER_SIZE = 400000;
    public static final String DB_NAME = "device.db"; // 保存的数据库文件名称
    public static final String PACKAGE_NAME = "com.strongdady.qrscan";// 应用的包名
    //public static final String DB_PATH = "/data"droid.os.Environment.getDataDirectory().getAbsolutePath()+"/"
    public static final String DB_PATH =getExternalStorageDirectory()+"/data";

    String device_no,device_name, owner, register_date,device_nanm,sqlString;
    SQLiteDatabase db=null;
    Cursor cursor;

    private TextView mTextMessage;

        public void copyDBFile()
        {

            try {
                File myDataPath = new File(DB_PATH+"/device_db");
                if (!myDataPath.exists())
                {
                    myDataPath.mkdirs();// 假设没有这个文件夹,则创建
                }
                else
                {
                    //mTextMessage.append("inside copydbfile =|"+myDataPath.toString()+"|existed 2018_5-21!");
                }
                String dbfile=myDataPath+"/"+DB_NAME;
//                if (!(new File(dbfile).exists())) {// 推断数据库文件是否存在，若不存在则运行导入，否则直接打开数据库

                if (true) {// 推断数据库文件是否存在，若不存在则运行导入，否则直接打开数据库
                    InputStream is =getResources().openRawResource(R.raw.device); // 欲导入的数据库
                    FileOutputStream fos = new FileOutputStream(dbfile);
                    byte[] buffer = new byte[BUFFER_SIZE];
                    int count = 0;
                    while ((count = is.read(buffer)) > 0) {
                        fos.write(buffer, 0, count);
                    }
                    fos.close();
                    is.close();
                }
                db = SQLiteDatabase.openOrCreateDatabase(dbfile,null);

            } catch (Exception e)
            {
                mTextMessage.append(e.toString());
            }
        }

    public Device findDeviceInfo(String qrCode)
    {
        String device_no=null,device_name=null,device_owner=null,device_registerDate=null;
        Device device1;
        cursor = db.rawQuery("SELECT * FROM device where device_no = '"+qrCode+"'", null);

        while (cursor.moveToNext()) {
            device_no = qrCode;
            device_name = cursor.getString(cursor.getColumnIndex("owner"));
            device_owner = cursor.getString(cursor.getColumnIndex("device_name"));
            device_registerDate = cursor.getString(cursor.getColumnIndex("register_date"));
            register_date=cursor.getString(cursor.getColumnIndex("register_date"));
        }
        if( device_name!=null){
        device1 = new Device();

        device1.Name = device_name;
        device1.no = device_no;
        device1.Owner = device_owner;
        device1.RegisterDate = register_date;

        return device1;
    }else{
            return null;
    }


    }

    private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
            = new BottomNavigationView.OnNavigationItemSelectedListener() {


        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {

            switch (item.getItemId()) {

                case R.id.navigation_home:
                    mTextMessage.setText(R.string.title_home);

                    IntentIntegrator integrator=new IntentIntegrator(MainActivity.this);

                    List<String> oDesiredFormats = Arrays.asList("PDF_417,UPC_A,UPC_E,EAN_13,EAN_8,RSS_14,RSS_EXPANDED,CODE_39,CODE_93,CODE_128,ITF,CODABAR,QR_CODE,DATA_MATRIX".split(","));

                    integrator.setPrompt("scaning  .....");
                    integrator.initiateScan(oDesiredFormats);

                    return true;

                    case R.id.navigation_dashboard:
                    mTextMessage.setText(R.string.title_dashboard);

                    return true;

                case R.id.navigation_notifications:
                    //mTextMessage.setText(R.string.title_notifications+"before exit");
                    //return true;
                    cursor.close();
                    db.close();
                    System.exit(0);
            }
            return false;
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mTextMessage = (TextView) findViewById(R.id.message);
        BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
        navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);

        copyDBFile();

    }

    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        String qrCode;

        IntentResult scanResult = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);

        mTextMessage.setText(scanResult.getContents());
        qrCode=scanResult.getContents();

        if (scanResult != null) {
            Device device1=findDeviceInfo(qrCode);
            if (device1!=null)
            {
                mTextMessage.setText("设备编号: "+device1.no+" 设备名称："+device1.Name+" 责任人："+device1.Owner+" "+" 登记日期："+device1.RegisterDate);
            }
        }
        else
        {
           //super.onActivityResult(requestCode, resultCode, data);
            mTextMessage.setText("找不到编号为："+scanResult.toString()+"的设备");
        }

    }
}

+++++++++++++++++++++++++++++++++++++++

Device.java

package com.strongdady.qrscan;

/**
 * Created by strongdady on 2018/5/21.
 */

public class Device {
    public String no, Owner,Name,RegisterDate;

}