扫描二维码，生成二维码

MainActivity.java

public class MainActivity extends AppCompatActivity {

    private ImageView mImageView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Button button =findViewById(R.id.btn);
        mImageView =findViewById(R.id.img);
        button.setOnClickListener(new View.OnClickListener() { //点击按钮扫描二维码
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this,CaptureActivity.class);


                startActivityForResult(intent,2);
            }
        });

    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode==200&& resultCode==RESULT_OK){

            if (data!=null){
                String content = data.getStringExtra(Constant.CODED_CONTENT);
                if (TextUtils.isEmpty(content)){

                    Toast.makeText(MainActivity.this, "您的输入为空!", Toast.LENGTH_SHORT).show();
                    return;

                }

                Bitmap logo = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);
                try {
                    Bitmap bitmap = CodeCreator.createQRCode(content, 400, 400, logo);
                    mImageView.setImageBitmap(bitmap);
                } catch (WriterException e) {
                    e.printStackTrace();
                }

                Toast.makeText(MainActivity.this,"扫描"+content,Toast.LENGTH_SHORT).show();


            }
        }
    }
}

activity.main.xml

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="vertical">

    <Button
        android:id="@+id/btn"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="扫一扫"/>

    <ImageView
        android:id="@+id/img"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />

</android.support.constraint.ConstraintLayout>

需要配置的权限

<uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.CAMERA"></uses-permission>
    <uses-permission android:name="android.permission.VIBRATE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
    <uses-feature android:name="android.hardware.camera" />
    <uses-feature android:name="android.hardware.camera.autofocus" />
    <uses-permission android:name="android.permission.FLASHLIGHT" />

build.gradle

minSdkVersion 16                     //配置16
implementation'com.github.yuzhiqiang1993:zxing:2.2.1'    //依赖

外部build.gradle

allprojects {
    repositories {
        google()
        jcenter()
        maven { url 'https://jitpack.io' } //加这行代码
    }
}