完成的设备扫描项目的几个关键程序，包括activity之间的转换

module 的 gradle.build
最后三行的compile 是关键
dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:26.1.0'
    implementation 'com.android.support:design:26.1.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.0'
    implementation 'com.android.support:support-vector-drawable:26.1.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'

   compile 'com.journeyapps:zxing-android-embedded:2.3.0@aar'
    compile 'com.journeyapps:zxing-android-legacy:2.3.0@aar'
    compile 'com.journeyapps:zxing-android-integration:2.3.0@aar'

}

/******************************************/

inputActivity.java

package com.strongdady.devicescan;

        import android.app.Activity;
        import android.content.Intent;
        import android.database.sqlite.SQLiteDatabase;
        import android.os.Bundle;
        import android.view.View;
        import android.widget.Button;
        import android.widget.EditText;
        import android.widget.Toast;
        import android.database.Cursor;

        import java.io.File;
        import java.io.FileOutputStream;
        import java.io.InputStream;

        import static android.os.Environment.getExternalStorageDirectory;

public class inputActivity extends Activity {

    public static  String str=null;
    protected void onCreate(Bundle savedInstanceState) {

        final Button  buttonExit,buttonCheck;
        final EditText  editText0;

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

        editText0 = (EditText) findViewById(R.id.sample_edit_text0);

        buttonCheck = (Button) findViewById(R.id.sample_buttonCheck);
        buttonExit= (Button) findViewById(R.id.sample_buttonExit);

        buttonCheck.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {

                Intent i=new Intent();
                i.putExtra("device_no", editText0.getText().toString());
                setResult(4,i);
                finish();
            }
        });

        buttonExit.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {

                Intent i=new Intent();
                i.putExtra("device_no", editText0.getText().toString());
                setResult(0,i);
                finish();
            }
        });

    }
}

/*************MainActivity.java*************/

package com.strongdady.devicescan;

import android.os.Process;
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.os.Environment;
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
            }

            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
                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;
        //qrCode.trim()去掉前后空格
        cursor = db.rawQuery("SELECT * FROM device where device_no = '"+qrCode.trim()+"'", 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);
                    mTextMessage.setText("");

                    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.setOrientation()
                    //integrator.setBeepEnabled(true);
                    //integrator.setOrientation(0);
                    //integrator.setPrompt("scaning  .....");

                    integrator.initiateScan(oDesiredFormats);

                    return true;

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

                    startActivityForResult(new Intent(MainActivity.this,
                            inputActivity.class), 1);

                    return true;

                case R.id.navigation_notifications:

                    cursor.close();
                    db.close();
                    finish();
                    System.exit(0);
                    Process.killProcess(Process.myPid());
            }
            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) {

        IntentResult scanResult=null;

        super.onActivityResult(requestCode, resultCode, data);

        String qrCode = null;

        try {
             scanResult = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
        }catch (Exception e){
            mTextMessage.append("\nException occured during scaning :"+e+"\n");
         }

        if (requestCode == 1 && resultCode == 0) {
            return;
        }

        if (requestCode == 1 && resultCode == 4) {
            String s = data.getStringExtra("device_no");
            qrCode = s;

            Device device1 = findDeviceInfo(qrCode);
            if (device1 != null) {
                mTextMessage.setText("\n 设备编号: " + device1.no + "\n 设备名称：" + device1.Name + "\n 责任人：" + device1.Owner + " " + "\n 登记日期：" + device1.RegisterDate);
            } else {
                mTextMessage.setText("\n 找不到编号为：" + qrCode + "的设备");
            }
        } else {

            qrCode=scanResult.getContents().toString();

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

        }
    }
}

/*********************/
Device.java

package com.strongdady.devicescan;

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

}