从其他Activity中获取结果Result

1：使用startActivityForResult()而不是startActivity()启动另外一个Activity
方法的签名是：startActivityForResult(Intent intent, int requestCode)这个方法有几个重载的方法
注意：
传入的Intent可以是隐式Intent或者是显示Intent。但如果是启动一个你自己的Activity，则最好使用显示Intent
在调用 startActivityForResult()时传入一个请求码(这个请求码用来识别请求，即返回的结果是由那个Activity中返回的)，当返回结果时，这个请求码会被传回来
2：重写onActivityResult()这个方法接收返回的结果
方法的签名是：onActivityResult(int requestCode, int resultCode, Intent data)
第一个参数：startActivityForResult()方法执行时传入的请求码(请求码如果小于0，则和startActivity()方法一样，是不返回结果的)
第二个参数：返回操作的结果码，如果操作成功返回RESULT_OK，如果操作失败返回RESULT_CANCELED，例如用户自己回退(按BACK键)或其他原因失败
第三个参数：返回的结果，为了处理这个结果，你必须知道返回的Intent的格式。其中Android平台自带的Apps都有相应的API描述指定的结果数据
例子(摘自Android官网http://developer.android.com/training/basics/intents/result.html)：

 1     package com.example.androidgov;

 2 

 3     import android.app.Activity;

 4     import android.content.Intent;

 5     import android.database.Cursor;

 6     import android.net.Uri;

 7     import android.os.Bundle;

 8     import android.provider.ContactsContract.CommonDataKinds.Phone;

 9     import android.view.View;

10     import android.widget.TextView;

11 

12     public class ReturnResultActivity extends Activity {

13 

14         static final int PICK_CONTACT_REQUEST = 1; // The request code

15         private TextView rra_textview = null;

16         

17         @Override

18         protected void onCreate(Bundle savedInstanceState) {

19             super.onCreate(savedInstanceState);

20             setContentView(R.layout.activity_return_result);

21             rra_textview = (TextView)findViewById(R.id.rra_textview1);

22         }

23 

24         public void pickContact( View view ) {

25          Intent pickContactIntent = new Intent(Intent.ACTION_PICK, Uri.parse("content://contacts"));

26          pickContactIntent.setType(Phone.CONTENT_TYPE); // Show user only contacts w/ phone numbers

27          startActivityForResult(pickContactIntent, PICK_CONTACT_REQUEST);

28         }

29         

30         @Override

31         protected void onActivityResult(int requestCode, int resultCode, Intent data) {

32          // Check which request it is that we're responding to

33          if (requestCode == PICK_CONTACT_REQUEST) {

34          // Make sure the request was successful

35          if (resultCode == RESULT_OK) {

36          // Get the URI that points to the selected contact

37          Uri contactUri = data.getData();

38          // We only need the NUMBER column, because there will be only one row in the result

39          String[] projection = {Phone.NUMBER};

40 

41          // Perform the query on the contact to get the NUMBER column

42          // We don't need a selection or sort order (there's only one result for the given URI)

43          // CAUTION: The query() method should be called from a separate thread to avoid blocking

44          // your app's UI thread. (For simplicity of the sample, this code doesn't do that.)

45          // Consider using CursorLoader to perform the query.

46     //这个查询动作应该放到另外一个线程中，以防止阻塞UI线程,另外可以考虑使用CursorLoader来执行查询

47          Cursor cursor = getContentResolver()

48          .query(contactUri, projection, null, null, null);

49          cursor.moveToFirst();

50 

51          // Retrieve the phone number from the NUMBER column

52          int column = cursor.getColumnIndex(Phone.NUMBER);

53          String number = cursor.getString(column);

54          rra_textview.setText("You choose " + number);

55          // Do something with the phone number...

56          }

57          }

58         }

59     }

View Code

布局文件为：

 1     <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

 2         xmlns:tools="http://schemas.android.com/tools"

 3         android:id="@+id/container"

 4         android:layout_width="match_parent"

 5         android:layout_height="match_parent"

 6         android:orientation="vertical"

 7         tools:context="com.example.androidgov.ReturnResultActivity" >

 8 

 9         <Button

10             android:layout_width="match_parent"

11             android:layout_height="wrap_content"

12             android:onClick="pickContact"

13             android:text="GetContact" /><!-- 最好放到strings.xml文件中定义 -->

14 

15         <TextView

16             android:id="@+id/rra_textview1"

17             android:layout_width="match_parent"

18             android:layout_height="wrap_content" />

19 

20     </LinearLayout>

activity_return_result

运行结果截图：

选择联系人后：