第一：

import android.content.pm.PackageManager.NameNotFoundException;

然后使用这个：

PackageInfo pInfo = null;
try {
     pInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
} 
catch (NameNotFoundException e) {
     e.printStackTrace();
}

String versionName = pInfo.versionName;

以下是获取版本代码的方法：

public String getAppVersion() {
    String versionCode = "1.0";
    try {
        versionCode = getPackageManager().getPackageInfo(getPackageName(), 0).versionName;
    } catch (PackageManager.NameNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return versionCode;
}

package com.sqisland.android.versionview;

import android.app.Activity;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends Activity {
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    TextView textViewversionName = (TextView) findViewById(R.id.text);

    try {
        PackageInfo packageInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
        textViewversionName.setText(packageInfo.versionName);

    }
    catch (PackageManager.NameNotFoundException e) {

    }
  }
}

对于不需要应用程序UI的BuildConfig信息，但希望使用此信息设置CI作业配置或其他信息的人，如我：

只要成功构建项目，项目目录下就会有一个自动生成的文件BuildConfig.java。

｛WORKSPACE｝/build/generated/source/buildConfig/｛debug|release｝/｛PACKAGE｝/buildConfig.java

/**
* Automatically generated file. DO NOT MODIFY
*/
package com.XXX.Project;

public final class BuildConfig {
    public static final boolean DEBUG = Boolean.parseBoolean("true");
    public static final String APPLICATION_ID = "com.XXX.Project";
    public static final String BUILD_TYPE = "debug";
    public static final String FLAVOR = "";
    public static final int VERSION_CODE = 1;
    public static final String VERSION_NAME = "1.0.0";
}

通过Python脚本或其他工具分割所需的信息。下面是一个示例：

import subprocess
# Find your BuildConfig.java
_BuildConfig = subprocess.check_output('find {WORKSPACE} -name BuildConfig.java', shell=True).rstrip()

# Get the version name
_Android_version = subprocess.check_output('grep -n "VERSION_NAME" ' + _BuildConfig, shell=True).split('"')[1]
print('Android version: ’ + _Android_version)

PackageInfo pinfo = null;
try {
    pinfo = getPackageManager().getPackageInfo(getPackageName(), 0);
}
catch (PackageManager.NameNotFoundException e) {
    e.printStackTrace();
}
int versionNumber = pinfo.versionCode;
String versionName = pinfo.versionName;

    Log.e("TAG","VERSION.RELEASE {" + Build.VERSION.RELEASE + "}");
    Log.e("TAG","\nVERSION.INCREMENTAL {" + Build.VERSION.INCREMENTAL + "}");
    Log.e("TAG","\nVERSION.SDK {" + Build.VERSION.SDK + "}");
    Log.e("TAG","\nBOARD {" + Build.BOARD + "}");
    Log.e("TAG","\nBRAND {" + Build.BRAND + "}");
    Log.e("TAG","\nDEVICE {" + Build.DEVICE + "}");
    Log.e("TAG","\nFINGERPRINT {" + Build.FINGERPRINT + "}");
    Log.e("TAG","\nHOST {" + Build.HOST + "}");
    Log.e("TAG","\nID {" + Build.ID + "}");

幸亏https://stackoverflow.com/a/40421709/2828651