Activity詳解三 啟動(dòng)activity并返回結(jié)果
來源：程序員人生 發(fā)布時(shí)間：2016-12-13 15:16:21 閱讀次數(shù)：2548次
1 簡介
、如果想在Activity中得到新打開Activity 關(guān)閉后返回的數(shù)據(jù)，需要使用系統(tǒng)提供的startActivityForResult(Intent intent, int requestCode)方法打開新的Activity，新的Activity 關(guān)閉后會(huì)向前面的Activity傳回?cái)?shù)據(jù)，為了得到傳回的數(shù)據(jù)，必須在前面的Activity中重寫onActivityResult(int requestCode, int resultCode, Intent data)方法。
public class MainActivity extends Activity {
private final static String TAG="MainActivity";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button btnOpen=(Button)this.findViewById(R.id.btnOpen);
btnOpen.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
//得到新打開Activity關(guān)閉后返回的數(shù)據(jù)
//第2個(gè)參數(shù)為要求碼，可以根據(jù)業(yè)務(wù)需求自己編號(hào)
startActivityForResult(new Intent(MainActivity.this, OtherActivity.class), 1);
}
});
}
/**
* 為了得到傳回的數(shù)據(jù)，必須在前面的Activity中（指MainActivity類）重寫onActivityResult方法
*
* requestCode 要求碼，即調(diào)用startActivityForResult()傳遞過去的值
* resultCode 結(jié)果碼，結(jié)果碼用于標(biāo)識(shí)返回?cái)?shù)據(jù)來自哪一個(gè)新Activity
*/
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
String result = data.getExtras().getString("result");//得到新Activity 關(guān)閉后返回的數(shù)據(jù)
Log.i(TAG, result);
}
}
當(dāng)新Activity關(guān)閉后，新Activity返回的數(shù)據(jù)通過Intent進(jìn)行傳遞，android平臺(tái)會(huì)調(diào)用前面Activity 的onActivityResult()方法，把寄存了返回?cái)?shù)據(jù)的Intent作為第3個(gè)輸入?yún)?shù)傳入，在onActivityResult()方法中使用第3個(gè)輸入?yún)?shù)可以取出新Activity返回的數(shù)據(jù)。
2 setResult
使用startActivityForResult(Intent intent, int requestCode)方法打開新的Activity，新Activity關(guān)閉前需要向前面的Activity返回?cái)?shù)據(jù)需要使用系統(tǒng)提供的setResult(int resultCode, Intent data)方法實(shí)現(xiàn)：
public class OtherActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.other);
Button btnClose=(Button)findViewById(R.id.btnClose);
btnClose.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
//數(shù)據(jù)是使用Intent返回
Intent intent = new Intent();
//把返回?cái)?shù)據(jù)存入Intent
intent.putExtra("result", "My name is linjiqin");
//設(shè)置返回?cái)?shù)據(jù)
OtherActivity.this.setResult(RESULT_OK, intent);
//關(guān)閉Activity
OtherActivity.this.finish();
}
});
}
}
setResult()方法的第1個(gè)參數(shù)值可以根據(jù)業(yè)務(wù)需要自己定義，上面代碼中使用到的RESULT_OK是系統(tǒng)Activity類定義的1個(gè)常量，值為⑴，代碼片斷以下：
public class android.app.Activity extends ......{
public static final int RESULT_CANCELED = 0;
public static final int RESULT_OK = ⑴;
public static final int RESULT_FIRST_USER = 1;
}
說明：當(dāng)點(diǎn)擊“打開新的Activity”按鈕，會(huì)跳轉(zhuǎn)到“我是新打開的Activity”頁面；
當(dāng)點(diǎn)擊“關(guān)閉”按鈕，關(guān)閉當(dāng)前頁面，同時(shí)跳轉(zhuǎn)到“我是舊的Activity”頁面，且會(huì)傳遞result參數(shù)給前1個(gè)Activity
3要求碼的作用
使用startActivityForResult(Intent intent, int requestCode)方法打開新的Activity，我們需要為startActivityForResult()方法傳入1個(gè)要求碼(第2個(gè)參數(shù))。要求碼的值是根據(jù)業(yè)務(wù)需要由自已設(shè)定，用于標(biāo)識(shí)要求來源。例如：1個(gè)Activity有兩個(gè)按鈕，點(diǎn)擊這兩個(gè)按鈕都會(huì)打開同1個(gè)Activity，不論是那個(gè)按鈕打開新Activity，當(dāng)這個(gè)新Activity關(guān)閉后，系統(tǒng)都會(huì)調(diào)用前面Activity的onActivityResult(int
requestCode, int resultCode, Intent data)方法。在onActivityResult()方法如果需要知道新Activity是由那個(gè)按鈕打開的，并且要做出相應(yīng)的業(yè)務(wù)處理，這時(shí)候可以這樣做：
@Override public void onCreate(Bundle savedInstanceState) {
....
button1.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
startActivityForResult (new Intent(MainActivity.this, NewActivity.class), 1);
}
});
button2.setOnClickListener(new View.OnClickListener(){
public void onClick(View v) {
startActivityForResult (new Intent(MainActivity.this, NewActivity.class), 2);
}
});
@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch(requestCode){
case 1:
//來自按鈕1的要求，作相應(yīng)業(yè)務(wù)處理
case 2:
//來自按鈕2的要求，作相應(yīng)業(yè)務(wù)處理
}
}
}
4 結(jié)果碼的作用
在1個(gè)Activity中，可能會(huì)使用startActivityForResult()方法打開多個(gè)不同的Activity處理不同的業(yè)務(wù)，當(dāng)這些新Activity關(guān)閉后，系統(tǒng)都會(huì)調(diào)用前面Activity的onActivityResult(int requestCode, int resultCode, Intent data)方法。為了知道返回的數(shù)據(jù)來自于哪一個(gè)新Activity，在onActivityResult()方法中可以這樣做(ResultActivity和NewActivity為要打開的新Activity)：
public class ResultActivity extends Activity {
.....
ResultActivity.this.setResult(1, intent);
ResultActivity.this.finish();
}
public class NewActivity extends Activity {
......
NewActivity.this.setResult(2, intent);
NewActivity.this.finish();
}
public class MainActivity extends Activity { // 在該Activity會(huì)打開ResultActivity和NewActivity
@Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch(resultCode){
case 1:
// ResultActivity的返回?cái)?shù)據(jù)
case 2:
// NewActivity的返回?cái)?shù)據(jù)
}
}
}
5 Demo源碼：
TestResultActivity.java
package mm.shandong.com.testresult;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;
public class TestResultActivity extends AppCompatActivity {
EditText editTextBrand;
RadioGroup radioGroup;
TextView textViewXH;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test_result);
editTextBrand = (EditText) findViewById(R.id.editTextBrand);
radioGroup = (RadioGroup) findViewById(R.id.radioGroup);
textViewXH = (TextView) findViewById(R.id.textViewXH);
RadioButton radionButton = (RadioButton) radioGroup.getChildAt(0);
radionButton.setChecked(true);
}
///跳轉(zhuǎn)到選擇品牌界面
public void selectBrand(View view) {
Intent intent = new Intent(this, TestResultActivity1.class);
startActivityForResult(intent, 1);
}
///選擇要購買的電腦
public void selectCompute(View view) {
Intent intent = new Intent(this, TestResultActivity2.class);
String brand = editTextBrand.getText().toString();
RadioButton radionButton =
(RadioButton) radioGroup.findViewById(radioGroup.getCheckedRadioButtonId());
String nc = radionButton.getText().toString();
intent.putExtra("brand", brand);
intent.putExtra("nc", nc);
startActivityForResult(intent, 2);
textViewXH.setText("");
}
///activity要求返回的回調(diào)
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
switch (requestCode) { //resultCode為回傳的標(biāo)記
case 1:
if (resultCode == 2) {
String brand = intent.getStringExtra("brand");
editTextBrand.setText(brand);
}
break;
case 2:
if (resultCode == 3) {
String xh = intent.getStringExtra("xh");
textViewXH.setText(xh);
}
break;
}
}
}
TestResultActivity1
package mm.shandong.com.testresult;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
public class TestResultActivity1 extends AppCompatActivity {
ListView listView;
String[] brands = new String[]{"聯(lián)想", "戴爾"};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test_result1);
listView = (ListView) findViewById(R.id.listView);
ArrayAdapter arrayAdapter = new ArrayAdapter(this,
android.R.layout.simple_list_item_checked, brands);
listView.setAdapter(arrayAdapter);
listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
}
///提交選擇的品牌結(jié)果
public void submit(View view) {
int index = listView.getCheckedItemPosition();
if (index < 0) {
Toast.makeText(this, "請(qǐng)選擇品牌", Toast.LENGTH_SHORT).show();
return;
}
String brand = (String) listView.getItemAtPosition(index);
int resultCode = 2;
Intent intent = getIntent();
intent.putExtra("brand", brand);
setResult(2, intent);
finish();
}
}
TestResultActivity2
package mm.shandong.com.testresult;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class TestResultActivity2 extends AppCompatActivity {
ListView listView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test_result2);
Intent intent=getIntent();
String brand=intent.getStringExtra("brand");
String nc=intent.getStringExtra("nc");
Map map=initData();
List<String> lists= (List<String>) map.get(brand+nc);
listView= (ListView) findViewById(R.id.listView);
ArrayAdapter arrayAdapter=new ArrayAdapter(this,
android.R.layout.simple_list_item_checked,lists);
listView.setAdapter(arrayAdapter);
listView.setChoiceMode(ListView.CHOICE_MODE_SINGLE);
}
///提交選擇的電腦型號(hào)
public void submit(View view){
int index= listView.getCheckedItemPosition();
if(index<0){
Toast.makeText(this,"請(qǐng)選擇型號(hào)",Toast.LENGTH_SHORT).show();
return ;
}
String xh= (String) listView.getItemAtPosition(index);
int resultCode=2;
Intent intent=getIntent();
intent.putExtra("xh",xh);
setResult(3,intent);
finish();
}
///初始化數(shù)據(jù)源
public Map initData(){
Map map=new HashMap();
List<String> lists=new ArrayList<>();
lists.add("聯(lián)想1G0001");
lists.add("聯(lián)想1G0002");
map.put("聯(lián)想1G",lists);
lists=new ArrayList<>();
lists.add("聯(lián)想2G0001");
lists.add("聯(lián)想2G0002");
map.put("聯(lián)想2G",lists);
lists=new ArrayList<>();
lists.add("戴爾1G0001");
lists.add("戴爾1G0002");
map.put("戴爾1G",lists);
lists=new ArrayList<>();
lists.add("戴爾2G0001");
lists.add("戴爾2G0002");
map.put("戴爾2G",lists);
return map;
}
}
本人微博：honey_11
Demo下載
最后，以上例子都來源與安卓無憂，請(qǐng)去利用寶或豌豆莢下載：例子源碼，源碼例子文檔1網(wǎng)打盡
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