Api demo源码学习（9）--App/Activity/Receive Result --Activity间传递数据

本节演示了父Activity跳转到子Activity后，接收子Activity传递回的数据。需要注意在Manifest.xml中注册子Activity。

基本步骤
1)在父Activity这边，Activity跳转时调用startActivityForResult方法，然后重写onActivityResult（）方法用于接收子Activity传回的数据。
2)在子Activity这边，调用setResult（）函数设置返回值。

具体解释见代码：
父Activity ReceiveResult.java：

public class ReceiveResult extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.receive_result);

mResults = (TextView)findViewById(R.id.results);

mResults.setText(mResults.getText(), TextView.BufferType.EDITABLE);
Button getButton = (Button)findViewById(R.id.get);
getButton.setOnClickListener(mGetListener);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// 如果有多个子Activity都返回数据的话，可以用requestCode来区分是哪个子Activity返回的数据，但本例中只有一个Activity.
if (requestCode == GET_CODE) {
Editable text = (Editable)mResults.getText();

// 如果子Activity启动失败或者没有传回参数，则resultCode就为RESULT_CANCELED
if (resultCode == RESULT_CANCELED) {
text.append("(cancelled)");

// Our protocol with the sending activity is that it will send
// text in 'data' as its result.
} else {
text.append("(okay ");
text.append(Integer.toString(resultCode));
text.append(") ");
if (data != null) {
text.append(data.getAction());
}
}
text.append("\n");
}
}

static final private int GET_CODE = 0;

private OnClickListener mGetListener = new OnClickListener() {
public void onClick(View v) {
// 若需获取子Activity传递回来的数值，此处就不再是调用startActivity()函数了，而是调用startActivityForResult()函数，
// 参数GET_CODE用来区分是哪个子Activity传回的数据。需要重写onActivityResult()函数。
Intent intent = new Intent(ReceiveResult.this, SendResult.class);
startActivityForResult(intent, GET_CODE);
}
};

private TextView mResults;
}

子Activity ReceiveResult.java

public class SendResult extends Activity
{
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);

setContentView(R.layout.send_result);

Button button = (Button)findViewById(R.id.corky);
button.setOnClickListener(mCorkyListener);
button = (Button)findViewById(R.id.violet);
button.setOnClickListener(mVioletListener);
}

private OnClickListener mCorkyListener = new OnClickListener()
{
public void onClick(View v)
{
// 在Activity finish之前，调用setResult函数，确定本activity返回的值

setResult(RESULT_OK, (new Intent()).setAction("Corky!"));
finish();
}
};

private OnClickListener mVioletListener = new OnClickListener()
{
public void onClick(View v)
{
// To send a result, simply call setResult() before your
// activity is finished.
setResult(RESULT_OK, (new Intent()).setAction("Violet!"));
finish();
}
};
}

[align=left]布局文件比较简单，就不放出了，以上即可。[/align]
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[align=left]下一节：Api demo源码学习（10）--App/Activity/Redirection[/align]