MainActivity获取多个数据是采取多线程进行处理和优化

MainActivity获取多个数据是采用多线程进行处理和优化

按不考虑性能和执行效率、只按照正常基本的开发流程是如下代码

public class MainActivity extends Activity {private ListView listView;private File cacheDir;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        /**  检查SD卡的缓存目录是否存在      */        File sdCardDir = Environment.getExternalStorageDirectory();        cacheDir = new File(sdCardDir, "cache");        if(!cacheDir.exists()) cacheDir.mkdirs();                   try {        /**正常的处理逻辑: 获取数据传递给Adapter，为ListView设置Adapter**/listView = (ListView)findViewById(R.id.listView);List<Topic> topicList = TopicService.getContacts();BaseAdapter adapter = new TopicAdapter(this, topicList, R.layout.listview_item, cacheDir );listView.setAdapter(adapter);} catch (Exception e) {e.printStackTrace();}    }    }

?现在考虑到获取业务数据需要的时间可能比较长，所以需要用Handler作为Activity的属性，结合多线程来处理。

让子线程负责获获取数据，将取到的数据通过Hander的sendMessage()的方法回传给Handler，

再由handler的handleMessage()从Message中取出数据，转换为对应的数据类型，最后设置回ListView的适配器中。

/**正常的处理逻辑: 获取数据传递给Adapter，为ListView设置Adapter**//*List<Topic> topicList = TopicService.getContacts();BaseAdapter adapter = new TopicAdapter(this, topicList, R.layout.listview_item, cacheDir );listView.setAdapter(adapter);*/Runnable runnable = new Runnable(){@Overridepublic void run() {try {List<Topic> topicList = TopicService.getContacts();handler.sendMessage(handler.obtainMessage(100, topicList));} catch (Exception e) {e.printStackTrace();}}};new Thread(runnable).start();

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Handler handler = new Handler(){@Overridepublic void handleMessage(Message msg) {/**这里负责处理 子线程做完后的工作**/List<Topic> topicList = (List<Topic>)msg.obj;BaseAdapter adapter = new TopicAdapter(MainActivity.this, topicList, R.layout.listview_item, cacheDir );listView.setAdapter(adapter);}};

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