<uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <!-- 相機 -->
    <uses-permission android:name="android.permission.CAMERA" />
    <!-- 振動 -->
    <uses-permission android:name="android.permission.VIBRATE" />

第二步：

 <Button
            android:id
 
="@+id/btnSan"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="掃描二維碼" />
        <TextView
            android:id="@+id/text_main"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
 

            android:layout_weight="1"
            android:text="23456"/>

第三步：

  </application>
    <activity
        android:name="com.xys.libzxing.zxing.activity.CaptureActivity"
        android:configChanges="orientation|keyboardHidden"
        android:screenOrientation="portrait"
        android:theme
 
="@android:style/Theme.NoTitleBar.Fullscreen"
        android:windowSoftInputMode="stateAlwaysHidden">
    </activity>

第四步：

public class MainActivity extends AppCompatActivity{

    private TextView tv_content;
    private Button but;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv_content = (TextView) findViewById(R.id.text_main);
        but = (Button) findViewById(R.id.btnSan);
       but.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivityForResult(new Intent(MainActivity.this, CaptureActivity.class), 0);
            }
        });
    }
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        // TODO Auto-generated method stub
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == RESULT_OK) {
            String result = data.getExtras().getString("result");
            tv_content.setText(result);
        }
    }

}