Android之Activity (一)

Activity

1. 生命周期
   

2. 生命周期函数
   继承Activitiy,实现方法的覆盖

3. 生命周期状态
   运行
   暂停
   停止
   消亡

4. 必须在AndroidMainfest.xml文件中注册

5. 启动Activity的入口

<intent-filter>
       <action android:name="android.intent.action.MAIN" />
       <category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

6. 启动Activity

显示启动activity
Intent intent = new Intent(ActivityOne.this,ActivityTow.class);
startActivity(intent);`

隐式启动Activity

1.首先在AndroidMainfest.xml中注册Activity
<activity android:name=".service.IntentActivity">
      <intent-filter>
          //这个name就是启动的指定字符串
          <action android:name="primer/intent/activity"></action>
           <category android:name="android.intent.category.DEFAULT"</category>
 </intent-filter>
</activity>


2.其次,intent指定注册的activity name
button.setOnClickListener(new View.OnClickListener() {
     @Override
     public void onClick(View view) {
         Intent intent = new Intent("primer/intent/activity");
         startActivity(intent);
     }
 });

7. 带返回值的Activity

启动一个有返回值的
 Intent intent = new Intent();
 intent.setClass(ActivityMethods.this, OtherActivity.class);
 startActivityForResult(intent, mRequestCode);

处理返回值
@Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == mRequestCode && resultCode == mResultCode) {
            String result = data.getStringExtra("str_set_result");
            Toast.makeText(this, "result :" + result, Toast.LENGTH_SHORT).show();
        }

    }

8. 结束Activity

方式一
finish();

方式二
finishActivity(int requestcode)

9. activity状态保存和恢复

// Activity 恢复数据的方法,经常在 oncreate 方法中恢复数据
  @Override
  protected void onRestoreInstanceState(Bundle savedInstanceState) {
      super.onRestoreInstanceState(savedInstanceState);
      Log.i(TAG, "----onRestoreInstanceState----");
  }

  // Activity 保存数据的方法，经常在 onPause 方法中保存数据
  @Override
  public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
      super.onSaveInstanceState(outState, outPersistentState);
      Log.i(TAG, "----onSaveInstanceState----");
  }