Android基础（一）

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Activity

1.LifeCircle

2.Activity绑定自定义视图

• setContentView（layout）用于呈现视图 (可以自定义视图）

3.工程目录结构

• manifest（配置）
• java（源代码）
• res（资源文件）
  
  • 布局（视图资源
  • 菜单资源
  • 字符串颜色等等

4.启动另一个Activity

• 创建一个按钮

<Button        android:id="@+id/button"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_weight="1"        android:text="startAnother" />

• 实现监听事件，启动一个activity

 Button btn= (Button) findViewById(R.id.button);        btn.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                startActivity(new Intent(MainActivity.this,Another.class));//启动另一个activity                startActivity(new Intent.ACTION_VIEW,Uri.parse("url");//启动网址            }        });    }

BroadcastReceiver

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1.使用BroadcastReceiver

• Java目录下创建一个Broadcast Receiver,MyReceivpackage

konl.com.demo;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;public class MyReceiver extends BroadcastReceiver {    @Override    public void onReceive(Context context, Intent intent) {        // TODO: This method is called when the BroadcastReceiver is receiving        // an Intent broadcast.        System.out.println("接收到了信息");    }}

• 实现按钮监听事件

 Button btnSend= (Button) findViewById(R.id.btnMessage);        btnSend.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                switch(v.getId()){                    case R.id.btnMessage:                        sendBroadcast(new Intent(MainActivity.this,MyReceiver.class));                        break;                }            }        });

• 也可以用intent附加信息
  
  • putExtra函数和接收intent的用法

 Intent i=new Intent(MainActivity.this,MyReceiver.class); i.putExtra("data","kon"); sendBroadcast(i);

 System.out.println("接收到了信息,消息的内容"+intent.getStringExtra("data"));

2.动态注册和注销BroadcastReceiver

不希望一直处于监听状态
在静态发送消息的基础上
- 把Manidest中的<receiver>删除

• 在MyReceiver中定义一个字符串（隐式编程）

 public static final String ACTION="konl.com.demo.intent.action.MyReceiver";

• 实现按钮注册和注销

oncreate中findViewById(R.id.btnMessage).setOnClickListener(this);            findViewById(R.id.btnRigster).setOnClickListener(this);            findViewById(R.id.btnDelete).setOnClickListener(this);

    public void onClick(View v) {        switch (v.getId()){            case R.id.btnMessage:                //                Intent i = new Intent(this,MyReceiver.class);                Intent i = new Intent(MyReceiver.ACTION);                i.putExtra("data","jikexueyuan");                sendBroadcast(i);                break;            case R.id.btnRigster:                if (receiver == null){                    receiver = new MyReceiver();                    registerReceiver(receiver,new IntentFilter(MyReceiver.ACTION));                }                break;            case R.id.btnDelete:                if (receiver != null){                    unregisterReceiver(receiver);                    receiver = null;                }                break;        }

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3.BroadcastReceiver的优先级