Lập trình Androi part 47 pptx

311 Chapter Handling Telephone Calls Many, if not most, Android devices will be phones.. Maybe you are writing an Android interface to a sales management application a la Salesforce.co

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Chapter Handling Telephone Calls

Many, if not most, Android devices will be phones As such, not only will users be

expecting to place and receive calls using Android, but you will have the opportunity to

help them place calls, if you wish

Why might you want to?

Maybe you are writing an Android interface to a sales management

application (a la Salesforce.com) and you want to offer users the ability

to call prospects with a single button click, and without them needing

to keep those contacts both in your application and in the phone’s

contacts application

Maybe you are writing a social networking application, and the roster

of phone numbers that you can access shifts constantly, so rather

than try to synchronize the social network contacts with the phone’s

contact database, you let people place calls directly from your

application

Maybe you are creating an alternative interface to the existing contacts

system, perhaps for users with reduced motor control (e.g., the

elderly), sporting big buttons and the like to make it easier for them to

place calls

Whatever the reason, Android has the means to let you manipulate the phone just like

any other piece of the Android system

Report to the Manager

To get at much of the phone API, you use the TelephonyManager That class lets you do

things like the following:

Determine if the phone is in use via getCallState(), with return values

of CALL_STATE_IDLE (phone not in use), CALL_STATE_RINGING (call

requested but still being connected), and CALL_STATE_OFFHOOK (call in

progress)

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CHAPTER 34: Handling Telephone Calls

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Find out the SIM ID (IMSI) via getSubscriberId()

Find out the phone type (e.g., GSM) via getPhoneType(), or find out the data connection type (e.g., GPRS or EDGE) via getNetworkType()

You Make the Call!

You can also initiate a call from your application, such as from a phone number you obtained through your own web service To do this, simply craft an ACTION_DIAL Intent with a Uri of the form tel:NNNNN (where NNNNN is the phone number to dial) and use that Intent with startActivity() This will not actually dial the phone; rather, it activates the dialer activity, from which the user can press a button to place the call

For example, let’s look at the Phone/Dialer sample application Here’s the crude (but effective) layout:

<?xml version="1.0" encoding="utf-8"?>

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

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

>

<LinearLayout

android:orientation="horizontal"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

>

<TextView

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="Number to dial:"

/>

<EditText android:id="@+id/number"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:cursorVisible="true"

android:editable="true"

android:singleLine="true"

/>

</LinearLayout>

<Button android:id="@+id/dial"

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:layout_weight="1"

android:text="Dial It!"

/>

</LinearLayout>

We have a labeled field for typing in a phone number, plus a button for dialing that number

The Java code simply launches the dialer using the phone number from the field:

package com.commonsware.android.dialer;

import android.app.Activity;

import android.content.Intent;

import android.net.Uri;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

public class DialerDemo extends Activity {

@Override

public void onCreate(Bundle icicle) {

super.onCreate(icicle);

setContentView(R.layout.main);

final EditText number=(EditText)findViewById(R.id.number);

Button dial=(Button)findViewById(R.id.dial);

dial.setOnClickListener(new Button.OnClickListener() {

public void onClick(View v) {

String toDial="tel:"+number.getText().toString();

startActivity(new Intent(Intent.ACTION_DIAL,

Uri.parse(toDial)));

}

});

}

}

The activity’s own UI is not that impressive, as you can see in Figure 34–1

Figure 34–1 The DialerDemo sample application, as initially launched

CHAPTER 34: Handling Telephone Calls

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However, the dialer you get from clicking the dial button is better, showing you the number you are about to dial, as shown in Figure 34–2

Figure 34–2 The Android Dialer activity, as launched from DialerDemo

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Chapter Development Tools

The Android SDK is more than a library of Java classes and API calls It also includes a

number of tools to assist in application development

Much of the focus has been on the Eclipse plug-in, to integrate Android development

with that IDE Secondary emphasis has been placed on the plug-in’s equivalents for use

in other IDEs or without an IDE, such as adb for communicating with a running emulator

This chapter will cover other tools beyond those two groups

Hierarchical Management

Android comes with a Hierarchy Viewer tool, designed to help you visualize your layouts

as they are seen in a running activity in a running emulator So, for example, you can

determine how much space a certain widget is taking up, or try to find where a widget

that does not appear on the screen is hiding

To use Hierarchy Viewer, you first need to fire up your emulator, install your application,

launch your activity, and navigate to spot you wish to examine Note that you cannot

use Hierarchy Viewer with a production Android device (e.g., T-Mobile G1) For

illustration purposes, we’ll use the ReadWrite demo application introduced back in

Chapter 23, as shown in Figure 35–1

You can launch Hierarchy Viewer via the hierarchyviewer program, found in the tools/

directory in your Android SDK installation This brings up the main Hierarchy Viewer

window, as shown in Figure 35–2

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CHAPTER 35: Development Tools

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Figure 35–1 ReadWrite demo application

Figure 35–2 Hierarchy Viewer main window

The list on the left shows the various emulators you have opened The number after the

hyphen should line up with the number in parentheses in your emulator’s title bar

When you click an emulator, the list of windows available for examination appears on

the right, as shown in Figure 35–3

Figure 35–3 Hierarchy Viewer list of available windows

Notice how there are many other windows besides our open activity, including the

Launcher window (i.e., the home screen), the Keyguard window (i.e., the “Press Menu to

Unlock” black screen you get when first opening the emulator), and so on Your activity

will be identified by application package and class (e.g.,

com.commonsware.android.files/ )

Things get interesting when you choose a window and click Load View Hierarchy After

a few seconds, the details spring into view, in a perspective called the Layout view, as

shown in Figure 35–4