<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="com.example.administrator.day18">
 <application
 android:allowBackup="true"
 android:icon="@mipmap/ic_launcher"
 android:label="@string/app_name"
 android:supportsRtl="true"
 android:theme="@style/AppTheme">
 <activity android:name=".Main2Activity"
 //添加screenOrientation属性（portrait为保持竖屏，landscape为保持横屏）
  android:screenOrientation="landscape">
  <intent-filter>
  <action android:name="android.intent.action.MAIN" />
  <category android:name="android.intent.category.LAUNCHER" />
  </intent-filter>
 </activity>
 </application>
</manifest>

import android.content.pm.ActivityInfo;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
/**
 * Created by panchengjia on 2016/12/9.
 */
public class Test extends AppCompatActivity {
 @Override
 protected void onCreate(@Nullable Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main2);
 //添加setRequestedOrientation方法实现锁定横屏（portrait为保持竖屏，landscape为保持横屏）
 setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
 }
}

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Toast;
/**
 * Created by panchengjia on 2016/12/9.
 */
public class Main2Activity extends AppCompatActivity {
 int num=1;//初始点击次数为1
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main2);
 if(savedInstanceState!=null){
  num=savedInstanceState.getInt("data");
 }
 Log.i("Tag","onCreate");
 }
 //设置点击事件土司记录数据
 public void show(View v){
 Toast.makeText(this, num++ +"", Toast.LENGTH_SHORT).show();
 }
 @Override
 protected void onSaveInstanceState(Bundle outState) {
 super.onSaveInstanceState(outState);
 outState.putInt("data",num);
 Log.i("Tag","onSaveInstanceState");
 }
 @Override
 protected void onStart() {
 super.onStart();
 Log.i("Tag","onStart");
 }
 @Override
 protected void onResume() {
 super.onResume();
 Log.i("Tag","onResume");
 }
 @Override
 protected void onRestart() {
 super.onRestart();
 Log.i("Tag","onRestart");
 }
 @Override
 protected void onPause() {
 super.onPause();
 Log.i("Tag","onPause");
 }
 @Override
 protected void onStop() {
 super.onStop();
 Log.i("Tag","onStop");
 }
 @Override
 protected void onDestroy() {
 super.onDestroy();
 Log.i("Tag","onDestroy");
 }
}

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
 package="com.example.administrator.day18">
 <application
 android:allowBackup="true"
 android:icon="@mipmap/ic_launcher"
 android:label="@string/app_name"
 android:supportsRtl="true"
 android:theme="@style/AppTheme">
 <activity android:name=".Main2Activity"
 //添加configChanges属性  android:configChanges="orientation|keyboard|screenSize">
  <intent-filter>
  <action android:name="android.intent.action.MAIN" />
  <category android:name="android.intent.category.LAUNCHER" />
  </intent-filter>
 </activity>
 <!--<activity android:name=".Main2Activity"></activity>-->
 </application>
</manifest>

@Override
 public void onConfigurationChanged(Configuration newConfig) {
 super.onConfigurationChanged(newConfig);
 Log.i("Tag","onConfigurationChanged");
 }