Android第三天

一.Intent两种启动方式(以启动Activity为例)

1.显示启动:

//指定当前的应用程序上下文及要启动的Activity
Intent intent = new Intent(MainActivity.this, Activity2.class);
startActivity(intent);

2.隐式启动:不直接指定需要启动哪个Activity或者调用哪个Activity,而是设置一个筛选条件,满足条件才启动

//java 文件中:
Intent intent = new Intent("dog");
startActivity(intent);

//AndroidMainfest.xml文件中:
<receiver android:name="com.example.broadcastreceive.BroadCastReceive" >
            <intent-filter >
                <action android:name="dog"/>
                
                <category android:name="android.intent.category.DEFAULT"/>
            </intent-filter>       
        </receiver>

二.BroadcastReceive组件

1.添加一个Button发送广播消息,设置隐式Intent筛选条件,满足过滤条件intent-filter的才能收到广播消息.
MainActivity.java:

package com.example.broadcastreceive;


import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;


public class MainActivity extends ActionBarActivity {


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_main);


Button button = (Button) findViewById(R.id.broad);
button.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub

//隐式Intent
Intent intent = new Intent("hello");

//使用putExtra()方法将要发送的信息捆绑到Intent上
intent.putExtra("key", "go to moon...");

//发送广播
sendBroadcast(intent);
}
} );
}
}

BroadCastReceive.java:

package com.example.broadcastreceive;


import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;


public class BroadCastReceive extends BroadcastReceiver {


@Override
public void onReceive(Context arg0, Intent arg1) {
// TODO Auto-generated method stub

//将接收到的广播消息显示在LogCat上
Log.v("1 hello",arg1.getStringExtra("key"));
}
}

BroadCastReceive2.java:

package com.example.broadcastreceive;


import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;


public class BroadCastReceive2 extends BroadcastReceiver {


@Override
public void onReceive(Context arg0, Intent arg1) {
// TODO Auto-generated method stub

//将接收到的广播消息显示在LogCat上
Log.v("2 hello",arg1.getStringExtra("key"));
}
}

AndroidMainfest.xml文件:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.broadcastreceive"
android:versionCode="1"
android:versionName="1.0" >


<uses-sdk
android:minSdkVersion="7"
android:targetSdkVersion="19" />


<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.broadcastreceive.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />


<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

<receiver android:name="com.example.broadcastreceive.BroadCastReceive" >
<intent-filter >
<action android:name="hello"/>

<category android:name="android.intent.category.DEFAULT"/>
</intent-filter>       
</receiver>

<receiver android:name="com.example.broadcastreceive.BroadCastReceive2" >
<intent-filter >
<action android:name="hello"/>

<category android:name="android.intent.category.DEFAULT"/>
</intent-filter>       
</receiver>
</application>


</manifest>

2. 添加两个Button,一个Button去启动一个服务,服务开始时启动一个线程计时, 另一个Button去停止线程,但不能停止服务,线程停止后还可以点击Button继续计时,时间紧接上次停止时的时间,同是计时的时间也
要在Activity上显示出来,用户可见的.

MainActivity.java:

package com.example.broadcastreceive3;


import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;


public class MainActivity extends Activity {


public Mycast1 mycast1;
public Mycast2 mycast2;


@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_main);


// 发送广播功能:
// 发送特定广播,启动一个服务,内有一只计时器
Button button1 = (Button) findViewById(R.id.start);
button1.setOnClickListener(new OnClickListener() {


@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub


Intent intent = new Intent("97.7MHZ");


intent.putExtra("key", "来自97.7MHZ的广播...");
sendBroadcast(intent);
}
});


// 停止线程按钮功能:
// 再发送一个广播,停止服务里的计时线程
Button button2 = (Button) findViewById(R.id.stop);
button2.setOnClickListener(new OnClickListener() {


@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub


Intent intent = new Intent("st");


sendBroadcast(intent);


}
});
}


//动态注册广播信息,不用在AndroidMainfest.xml文件中去注册
@Override
protected void onResume() {
// TODO Auto-generated method stub
super.onResume();


// 构建广播接收器对象
mycast1 = new Mycast1();
// 构建广播接受的的过滤器
IntentFilter filter1 = new IntentFilter();
filter1.addAction("97.7MHZ");
// 将接收器和过滤器绑定
registerReceiver(mycast1, filter1);


mycast2 = new Mycast2();
// 构建广播接受的的过滤器
IntentFilter filter2 = new IntentFilter();
filter2.addAction("T");
// 将接收器和过滤器绑定
registerReceiver(mycast2, filter2);
}


// 创建广播接收器1
class Mycast1 extends BroadcastReceiver {


@Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub
Log.v("Tag", intent.getStringExtra("key"));


intent = new Intent(MainActivity.this, Server.class);
startService(intent);
}
}


// 创建广播接收器2
class Mycast2 extends BroadcastReceiver {


@Override
public void onReceive(Context context, Intent intent) {
// TODO Auto-generated method stub


int count = 0;
//接收Intent负载信息
count = intent.getIntExtra("T", count);

//设置TextView文本
TextView text1  = (TextView)findViewById(R.id.text); 
text1.setText("开始计时: "+count);
}
}


//Activity结束时解除广播注册信息
@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
unregisterReceiver(mycast1);
unregisterReceiver(mycast2);
}
}

Server.java:

package com.example.broadcastreceive3;


import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.IBinder;
import android.util.Log;


public class Server extends Service {


public boolean flag;
public Mythread thread;
public static int count;
public threadcast broadcast;


@Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}


@Override
public void onCreate() {
// TODO Auto-generated method stub
super.onCreate();


}


@Override
public void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
unregisterReceiver(broadcast);


}


@Override
public void onStart(Intent intent, int startId) {
// TODO Auto-generated method stub
super.onStart(intent, startId);


flag = false;

// 启动计时线程
thread = new Mythread();
thread.start();


// 构建广播接收器对象
broadcast = new threadcast();
// 设置过滤器条件
IntentFilter filter = new IntentFilter("st");
// 绑定接收器和过滤器到一块
registerReceiver(broadcast, filter);
}


// 创建计时线程
class Mythread extends Thread {


@Override
public void run() {
// TODO Auto-generated method stub
super.run();


while (!flag) {
try {
Thread.sleep(1000);
} catch (Exception e) {
// TODO: handle exception
}
Log.v("Tag", "计时" + (count++) + "秒");

Intent intent = new Intent("T");
intent.putExtra("T", count);
sendBroadcast(intent);
}
}


public void st() {
flag = true;
}
}


// 创建广播接收器
class threadcast extends BroadcastReceiver {


@Override
public void onReceive(Context arg0, Intent arg1) {
// TODO Auto-generated method stub


// 关闭线程
thread.st();
}
}
}

最后在AndroidMainfest.xml文件中注册一下Server服务:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.broadcastreceive3"
android:versionCode="1"
android:versionName="1.0" >


<uses-sdk
android:minSdkVersion="7"
android:targetSdkVersion="19" />


<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.broadcastreceive3.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />


<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

<service android:name="com.example.broadcastreceive3.Server">

</service>
</application>


</manifest>

三.调试问题

1.Warning: Activity not started, its current task has been brought to the front

修改程序以后未编译,模拟器里有之前的APK安装包,没有卸载和重新安装.
将模拟器关掉,重新编译运行一下即可.

2. 今天手抖删除了appcompat_v7_7的包,结果src和res文件夹下出现大量红叉叉,点进去一个看错误提示:

error: Error retrieving parent for item: No resource found that matches the given name 
‘Theme.AppCompat.Light’.
解决方法:
将sdk >extra>android>support>v7下的appcompat导入到eclipse中,
右键你有错误的项目,点击最下边的 properties,进去之后选择左侧列表中的Android,再把那个大红叉
那个给Remove,点击Add,添加刚导入的appcompat,保存退出即可.