Android观察者模式实例分析

本文实例讲述了Android观察者模式。分享给大家供大家参考。具体分析如下：

一、环境：

主机:WIN8
开发环境:Eclipse

二、说明:

1.打开sd卡中的xml文件，如果不存在，这新建一个，并写入默认配置
2.读取xml文件
3.Config_Info.java为配置信息数据结构
4.IF_Config.java为配置类的存取接口，其他类可以通过此接口直接获取配置信息
5.IF_Subject_Config.java为观察者模式目标类接口
6.IF_Observer_Config.java为观察者模式观察者类接口
7.Config.java为配置类，完成1，2两部工作,同时是观察者模式的目标类，一旦配置信息由变化着通知观察者类
8.TestClass.java为观察者模式的观察者
通过存取接口+观察者模式可以实现松耦合的设计。

三、xml文件格式:

<?xml version="1.0" encoding="UTF-8" standalone="true"?> 
-<config> 
<title>远程视频会见系统</title> 
<local_port>12600</local_port> 
<schedule_service_ip>10.58.1.59</schedule_service_ip>
<schedule_service_port>12601</schedule_service_port> 
</config>

四、源代码：

Config_Info.java:

 
package com.example.helloanychat; 
public class Config_Info { 
 // 
 public String title; 
 //本机ip 
 public String local_ip; 
 //本机端口 
 public int local_port; 
 //调度服务器ip 
 public String schedule_server_ip; 
 //调度服务器端口 
 public int schedule_server_port; 
}

IF_Config.java:

 
package com.example.helloanychat; 
public interface IF_Config { 
 public Config_Info get_config_info(); 
}

IF_Subject_Config.java:

 
package com.example.helloanychat; 
public interface IF_Subject_Config { 
 public void register_observer(IF_Observer_Config observer); 
 public void remove_observer(IF_Observer_Config observer); 
 public void notify_observer(); 
}

IF_Observer_Config.java：

 
package com.example.helloanychat; 
public interface IF_Observer_Config { 
 public void update(Config_Info info); 
}

Config.java:

 
package com.example.helloanychat; 
import java.io.File; 
import java.io.FileInputStream; 
import java.io.FileOutputStream; 
import java.io.IOException; 
import java.io.StringWriter; 
import java.net.Inet6Address; 
import java.net.InetAddress; 
import java.net.NetworkInterface; 
import java.net.SocketException; 
import java.util.ArrayList; 
import java.util.Enumeration; 
import java.util.List; 
import java.util.Timer; 
import java.util.TimerTask; 
import javax.xml.parsers.DocumentBuilder; 
import javax.xml.parsers.DocumentBuilderFactory; 
import android.os.Environment; 
import android.util.Log; 
import org.w3c.dom.Document; 
import org.w3c.dom.Element; 
import org.w3c.dom.NodeList; 
import org.xmlpull.v1.XmlPullParserFactory; 
import org.xmlpull.v1.XmlSerializer; 
public class Config implements IF_Config,IF_Subject_Config { 
 //配置信息 
 private Config_Info Info = new Config_Info(); 
 //存储观察者的列表 
 private List<IF_Observer_Config> Observers = new ArrayList<IF_Observer_Config>(); 
 //定时器 
 private Timer Timer_Work = new Timer(); 
 //工作间隔,单位:ms 
 private final int INTERVAL_WORK = 5000; 
  
 public Config() { 
 //生成配置信息 
 generate_config_info(); 
 //创建定时线程 
 Timer_Work.schedule(new Task(),INTERVAL_WORK,INTERVAL_WORK);
 // 定时任务 
 } 
 //接口：读写 
 @Override 
 public Config_Info get_config_info() { 
 return Info; 
 } 
 //读写，观察者模式：目标 
 @Override 
 public void register_observer(IF_Observer_Config observer) { 
 Observers.add(observer); 
 } 
 @Override 
 public void remove_observer(IF_Observer_Config observer) { 
 int index = Observers.indexOf(observer); 
 if (index >= 0) { 
  Observers.remove(observer); 
 } 
 } 
 @Override 
 public void notify_observer() { 
 for (int i = 0; i < Observers.size(); i++) { 
  IF_Observer_Config o = (IF_Observer_Config) Observers.get(i); 
  o.update(Info); 
 } 
 } 
  
 private String getLocalIpAddress() { 
 try { 
  for (Enumeration<NetworkInterface> en = NetworkInterface 
   .getNetworkInterfaces(); en.hasMoreElements();) { 
  NetworkInterface intf = en.nextElement(); 
  for (Enumeration<InetAddress> enumIpAddr = intf 
   .getInetAddresses(); enumIpAddr.hasMoreElements();) { 
   InetAddress inetAddress = enumIpAddr.nextElement(); 
   //if (!inetAddress.isLoopbackAddress()) { 
   if (!inetAddress.isLoopbackAddress() && !(inetAddress instanceof Inet6Address)) { 
   return inetAddress.getHostAddress().toString(); 
   } 
  } 
  } 
 } catch (SocketException ex) { 
  Log.e("WifiPreference IpAddress", ex.toString()); 
 } 
 return null; 
 } 
  
 private String produce_xml_string(Config_Info info) { 
 StringWriter stringWriter = new StringWriter(); 
 try { 
  // 获取XmlSerializer对象 
  XmlPullParserFactory factory = XmlPullParserFactory.newInstance(); 
  XmlSerializer xmlSerializer = factory.newSerializer(); 
  // 设置输出流对象 
  xmlSerializer.setOutput(stringWriter); 
  //开始标签 
  xmlSerializer.startDocument("utf-8", true); 
  xmlSerializer.startTag(null, "config"); 
  // 
  xmlSerializer.startTag(null, "title"); 
  xmlSerializer.text(info.title); 
  xmlSerializer.endTag(null, "title"); 
  //本机端口 
  xmlSerializer.startTag(null, "local_port"); 
  xmlSerializer.text(Integer.toString(info.local_port)); 
  xmlSerializer.endTag(null, "local_port"); 
  //调度服务器ip 
  xmlSerializer.startTag(null, "schedule_service_ip"); 
  xmlSerializer.text(info.schedule_server_ip); 
  xmlSerializer.endTag(null, "schedule_service_ip"); 
  //调度服务器端口 
  xmlSerializer.startTag(null, "schedule_service_port"); 
  xmlSerializer.text(Integer.toString(info.schedule_server_port)); 
  xmlSerializer.endTag(null, "schedule_service_port"); 
  xmlSerializer.endTag(null, "config"); 
  xmlSerializer.endDocument(); 
 } catch (Exception e) { 
  e.printStackTrace(); 
 } 
 return stringWriter.toString(); 
 } 
  
 private void generate_config_info() 
 { 
 boolean ok; 
 File sd_path; 
 File file_cfg_dir; 
 File file_cfg; 
 FileOutputStream out; 
 String str; 
 FileInputStream in; 
 Config_Info info = new Config_Info(); 
 //得到本机ip地址 
 info.local_ip = getLocalIpAddress(); 
 //获取SD卡目录 
 sd_path = Environment.getExternalStorageDirectory(); 
 //判断文件夹是否存在 
 file_cfg_dir = new File(sd_path.getPath() + "//Remote_Meeting"); 
 if (!file_cfg_dir.exists() && !file_cfg_dir.isDirectory()) { 
  System.out.println("配置文件夹Remote_Meeting不存在!"); 
  ok = file_cfg_dir.mkdirs(); 
  if (ok) { 
  System.out.println("创建文件夹成功!");
  } else { 
  System.out.println("创建文件夹失败!");
  } 
 } 
 //判断配置文件是否存在 
 file_cfg = new File(file_cfg_dir.getPath(),"cfg.xml"); 
 if (!file_cfg.exists()) 
 { 
  System.out.println("配置文件cfg.xml不存在!"); 
  try { 
  file_cfg.createNewFile(); 
  System.out.println("创建文件cfg.xml成功!"); 
  //生成初始化的配置数据 
  try { 
   out = new FileOutputStream(file_cfg); 
   //保存默认配置 
   Info.title = "远程视频会见系统"; 
   Info.local_port = 12600; 
   Info.schedule_server_ip = "10.58.1.59"; 
   Info.schedule_server_port = 12601; 
   str = produce_xml_string(Info); 
   out.write(str.getBytes()); 
   out.close(); 
   //保存本机ip 
   Info.local_ip = info.local_ip; 
   //通知观察者 
   notify_observer(); 
  } catch (IOException e) { 
   // TODO Auto-generated catch block 
   e.printStackTrace(); 
  } 
  } catch (IOException e) { 
  // TODO Auto-generated catch block 
  e.printStackTrace(); 
  } 
 } 
 else 
 { 
  //解析xml文件 
  try { 
  in = new FileInputStream(file_cfg); 
  DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); 
  DocumentBuilder builder = factory.newDocumentBuilder(); 
  Document document = builder.parse(in); 
  // 获取根节点 
  Element root = document.getDocumentElement(); 
  NodeList node = root.getChildNodes(); 
  //获得第1子节点: 
  info.title = node.item(0).getFirstChild().getNodeValue(); 
  //获得第2子节点:本机端口 
  info.local_port = Integer.parseInt(node.item(1).getFirstChild().getNodeValue()); 
  //获得第3子节点:调度服务器ip 
  info.schedule_server_ip = node.item(2).getFirstChild().getNodeValue(); 
  //获得第4子节点:调度服务器端口 
  info.schedule_server_port = Integer.parseInt(node.item(3).getFirstChild().getNodeValue()); 
  //判断配置信息是否变更 
  do 
  { 
   if (!info.title.equals(Info.title)) 
   { 
   break; 
   } 
   if (!info.local_ip.equals(Info.local_ip)) 
   { 
   break; 
   } 
   if (info.local_port != Info.local_port) 
   { 
   break; 
   } 
   if (!info.schedule_server_ip.equals(Info.schedule_server_ip)) 
   { 
   break; 
   } 
   if (info.schedule_server_port != Info.schedule_server_port) 
   { 
   break; 
   } 
   //全部相同 
   return; 
  } while (false); 
  //赋值 
  Info.title = info.title; 
  Info.local_ip = info.local_ip; 
  Info.local_port = info.local_port; 
  Info.schedule_server_ip = info.schedule_server_ip; 
  Info.schedule_server_port = info.schedule_server_port; 
  //通知观察者 
  notify_observer(); 
  } catch (Exception e) { 
  e.printStackTrace(); 
  } 
 } 
 } 
  
 private class Task extends TimerTask { 
 @Override 
 public void run() { 
  generate_config_info(); 
 } 
 } 
}

TestClass.java：

package com.example.helloanychat; 
public class TestClass implements IF_Observer_Config { 
 public TestClass () { 
 } 
 @Override 
 public void update(Config_Info info) { 
 System.out.printf("-------------更新数据：%s,%s,%d,%s,%d\n", 
 info.title,info.local_ip,info.local_port,info.schedule_server_ip,info.schedule_server_port); 
 } 
}

MainActivity:

TestClass testclass = new TestClass(); 
Config config = new Config(); 
mEditIP.setText(config.get_config_info().local_ip); 
config.register_observer(testclass); 

希望本文所述对大家的Android程序设计有所帮助。

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