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):
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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 }
布局文件为:
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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>
运行结果截图:
选择联系人后: