Android百日程序：使用Intent回传结果

本章使用Intent，回传需要的结果；

流程：

启动主页->按下按键启动第二个activity->输入用户名，按下OK按键->回传用户名回主页->主页读取用户名并显示出来。

1 启动主页图：

2 启动第二个activity

3 输入用户名：

4 回传到主页，读取并显示：

新建项目，然后输入对应的代码就OK了。

1 主页界面代码(activity_main.xml)：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.intenttest.MainActivity" >

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/activate_secondary"
        android:onClick="onClick" />

</LinearLayout>

2 主页的响应时间代码：

public class MainActivity extends Activity {
	/*
	 * An integer value that identifies an activity you are calling.
	 * When an Activity returns a value, you must have a way to identify it
	 * If the request code is set to -1, then calling it using the 
	 * startActivityForResult() method is equivalent to calling it using
	 * the  startActivity() method. That is, no result will be returned.
	 */
	int requestCode = 1;
	
	public static<T> boolean equ(T t1, T t2){
		return t1 == t2;
	}
	
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    
    public void onClick(View view){
    	startActivityForResult(new Intent("su.bill.intenttest.SecondaryActivity"), requestCode);
    }
}

3 进入第二个activity的界面代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >

    <EditText
        android:id="@+id/txt_username"
        android:layout_weight="1"
        android:layout_width="0dp"
        android:layout_height="wrap_content"        
        android:hint="@string/your_name" />

    <Button
        android:id="@+id/btn_OK"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="onClick"
        android:text="@string/ok_button" />

</LinearLayout>

4 第二个activity的逻辑代码

package com.example.intenttest;

import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

public class SecondaryActivity extends Activity {
	@Override
	public void onCreate(Bundle savedInstanceState){
		super.onCreate(savedInstanceState);
		setContentView(R.layout.secondary_activity);
	}
	
	public void onClick(View v){
		Intent data = new Intent();
		
		EditText txt_username = (EditText) findViewById(R.id.txt_username);
		
		data.setData(Uri.parse(txt_username.getText().toString()));
		
		setResult(RESULT_OK, data);
		
		finish();
	}	

}

5 主页逻辑的读取并显示结果的代码：

    @Override
    public void onActivityResult(int reqCode, int resCode, Intent data) {
    	if (equ(reqCode, requestCode) && equ(resCode, RESULT_OK)){
    		Toast.makeText(this, data.getDataString(), Toast.LENGTH_SHORT).show();
    	}
    }

主页逻辑的完整代码如下：

package com.example.intenttest;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Toast;

public class MainActivity extends Activity {
	/*
	 * An integer value that identifies an activity you are calling.
	 * When an Activity returns a value, you must have a way to identify it
	 * If the request code is set to -1, then calling it using the 
	 * startActivityForResult() method is equivalent to calling it using
	 * the  startActivity() method. That is, no result will be returned.
	 */
	int requestCode = 1;
	
	public static<T> boolean equ(T t1, T t2){
		return t1 == t2;
	}
	
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    
    public void onClick(View view){
    	startActivityForResult(new Intent("su.bill.intenttest.SecondaryActivity"), requestCode);
    }
    
    @Override
    public void onActivityResult(int reqCode, int resCode, Intent data) {
    	if (equ(reqCode, requestCode) && equ(resCode, RESULT_OK)){
    		Toast.makeText(this, data.getDataString(), Toast.LENGTH_SHORT).show();
    	}
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

就是熟悉好Android的一些机制，理解起来倒是没有什么难度的。

说好是百日程序，看来不能百日之内完成了，因为还有很多其他事情做。

争取做快点吧，以后出点精品教程，把学到的，让更多人学会也是很有意义的事情的。