android学习之消息机制与异步任务_android消息机制和异步任务-优快云博客

本文链接：https://blog.youkuaiyun.com/wuweiwei001/article/details/55505017

消息机制：

1. XML文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <TextView
        android:id="@+id/tv_demo_number"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:text="10"
        android:textColor="#ff0000" 
        android:textSize="20sp"/>

    <Button
        android:id="@+id/btn_demo_increase"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="自动增加" />

    <Button
        android:id="@+id/btn_demo_decrease"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="自动减少" />

    <Button
        android:id="@+id/btn_demo_pause"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="暂停" 
        android:enabled="false"/>

</LinearLayout>

2. Activity文件

public class HandlerDemoActivity extends Activity implements OnClickListener {

	private static final int WHAT_INCREASE = 1;
	private static final int WHAT_DECREASE = 2;
	
	
	private TextView tv_demo_number;
	private Button btn_demo_increase;
	private Button btn_demo_decrease;
	private Button btn_demo_pause;
	
	private Handler handler = new Handler(){
		public void handleMessage(android.os.Message msg) {
			//得到当前显示的数值
			int number = Integer.parseInt(tv_demo_number.getText().toString());
			switch (msg.what) {
			case WHAT_INCREASE:
				//限制number<=20
				if(number==20) {
					//设置暂停不能操作
					btn_demo_pause.setEnabled(false);
					Toast.makeText(HandlerDemoActivity.this, "已经达到最大值", 0).show();
					return;
				}
				
				number++;
				tv_demo_number.setText(number+"");
				//发送增加的延迟消息
				handler.sendEmptyMessageDelayed(WHAT_INCREASE, 1000);
				break;
			case WHAT_DECREASE:
				//限制number>=1
				if(number==1) {
					//设置暂停不能操作
					btn_demo_pause.setEnabled(false);
					Toast.makeText(HandlerDemoActivity.this, "已经达到最小值", 0).show();
					return;
				}
				number--;
				tv_demo_number.setText(number+"");
				//发送减少的延迟消息
				handler.sendEmptyMessageDelayed(WHAT_DECREASE, 1000);
				break;
			default:
				break;
			}
		}
	};
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_handler_demo);
		init();
	}

	private void init() {
		tv_demo_number = (TextView) findViewById(R.id.tv_demo_number);
		btn_demo_increase = (Button) findViewById(R.id.btn_demo_increase);
		btn_demo_decrease = (Button) findViewById(R.id.btn_demo_decrease);
		btn_demo_pause = (Button) findViewById(R.id.btn_demo_pause);
		
		btn_demo_increase.setOnClickListener(this);
		btn_demo_decrease.setOnClickListener(this);
		btn_demo_pause.setOnClickListener(this);
	}

	@Override
	public void onClick(View v) {
		if(v==btn_demo_increase) {//自动增加  what =1
			//限制Button可操作性
			btn_demo_increase.setEnabled(false);
			btn_demo_decrease.setEnabled(true);
			btn_demo_pause.setEnabled(true);
			
			//停止减少(移除未处理的减少的消息)
			handler.removeMessages(WHAT_DECREASE);
			//发消息(增加)
			handler.sendEmptyMessage(WHAT_INCREASE);
		} else if(v==btn_demo_decrease) {//自动减少 what=2
			//限制Button可操作性
			btn_demo_increase.setEnabled(true);
			btn_demo_decrease.setEnabled(false);
			btn_demo_pause.setEnabled(true);
			
			//停止增加(移除未处理的增加的消息)
			handler.removeMessages(WHAT_INCREASE);
			
			//发消息(减少)
			handler.sendEmptyMessage(WHAT_DECREASE);
		} else if(v==btn_demo_pause) {//暂停
			
			//限制Button可操作性
			btn_demo_increase.setEnabled(true);
			btn_demo_decrease.setEnabled(true);
			btn_demo_pause.setEnabled(false);
			
			//停止增加/减少(移除未处理的减少/增加的消息)
			handler.removeMessages(WHAT_INCREASE);
			handler.removeMessages(WHAT_DECREASE);
		}
	}
}

异步任务：

1. XML文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.atguigu.l04_app3.MainActivity" >

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="35dp"
        android:text="下载最新版本APK" 
        android:onClick="downloadApk"/>

</RelativeLayout>

2. Activity文件

public class AsyncTaskTestActivity extends Activity {

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

	private File apkFile;
	private ProgressDialog dialog;
	
	public void downloadApk(View v) {
		//启动异步任务处理
		new AsyncTask<Void, Integer, Void>() {

			//1. 主线程, 显示提示视图
			protected void onPreExecute() {
				dialog = new ProgressDialog(AsyncTaskTestActivity.this);
				dialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
				dialog.show();
				
				//准备用于保存APK文件的File对象 : /storage/sdcard/Android/package_name/files/xxx.apk
				apkFile = new File(getExternalFilesDir(null), "update.apk");
				
			}
			
			//2. 分线程, 联网请求
			@Override
			protected Void doInBackground(Void... params) {
				try {
					//1. 得到连接对象
					String path = "http://192.168.10.165:8080/Web_Server/L04_DataStorage.apk";
					URL url = new URL(path);
					HttpURLConnection connection = (HttpURLConnection) url.openConnection();
					//2. 设置
					//connection.setRequestMethod("GET");
					connection.setConnectTimeout(5000);
					connection.setReadTimeout(10000);
					//3. 连接
					connection.connect();
					//4. 请求并得到响应码200
					int responseCode = connection.getResponseCode();
					if(responseCode==200) {
						//设置dialog的最大进度
						dialog.setMax(connection.getContentLength());
						
						
						//5. 得到包含APK文件数据的InputStream
						InputStream is = connection.getInputStream();
						//6. 创建指向apkFile的FileOutputStream
						FileOutputStream fos = new FileOutputStream(apkFile);
						//7. 边读边写
						byte[] buffer = new byte[1024];
						int len = -1;
						while((len=is.read(buffer))!=-1) {
							fos.write(buffer, 0, len);
							//8. 显示下载进度
							//dialog.incrementProgressBy(len);
							//在分线程中, 发布当前进度
							publishProgress(len);
							
							//休息一会(模拟网速慢)
							//Thread.sleep(50);
							SystemClock.sleep(50);
						}
						
						fos.close();
						is.close();
					}
					//9. 下载完成, 关闭, 进入3)
					connection.disconnect();
				} catch (Exception e) {
					e.printStackTrace();
				}
				return null;
			}
			
			//3. 主线程, 更新界面
			protected void onPostExecute(Void result) {
				dialog.dismiss();
				installAPK();
			}
			
			//在主线程中更新进度(在publishProgress()之后)
			protected void onProgressUpdate(Integer[] values) {
				dialog.incrementProgressBy(values[0]);
			}
		}.execute();
		
		//int Integer float Float void Void
	}

	/**
	 * 启动安装APK
	 */
	private void installAPK() {
		Intent intent = new Intent("android.intent.action.INSTALL_PACKAGE");
		intent.setDataAndType(Uri.fromFile(apkFile), "application/vnd.android.package-archive");
		startActivity(intent);
	}
}

JSon数据解析：

/*
1. 将json格式的字符串{}转换为Java对象, 使用原生API
2. 将json格式的字符串{}转换为Java对象, 使用GSON
3. 将json格式的字符串[]转换为Java对象的List, 使用原生API
4. 将json格式的字符串[]转换为Java对象的List, 使用GSON

5. 将Java对象转换为json字符串{}, 使用GSON
6. 将Java对象的List转换为json字符串[], 使用GSON
 */
public class JsonTest extends AndroidTestCase{

	/*
	 * 1. 将json格式的字符串{}转换为Java对象, 使用原生API
	 */
	public void testJsonToObject() throws JSONException {
		String jsonString = "{\"id\":2, \"name\":\"大虾\", \"price\":12.3,\"imagePath\":\"http://192.168.10.165:8080/L05_Server/images/f1.jpg\"}";
		
		//将json字符串封装为JSONObject对象
		JSONObject jsonObject = new JSONObject(jsonString);
		//从对象中根据key得到对应的value
		int id = jsonObject.getInt("id");
		String name = jsonObject.getString("name");
		double price = jsonObject.getDouble("price");
		String imagePath = jsonObject.getString("imagePath");
		//封装ShopInfo对象
		ShopInfo shopInfo = new ShopInfo(id, name, price, imagePath);
		
		Log.e("TAG", shopInfo.toString());
	}
	
	/*
	 * 1. 将json格式的字符串{}转换为Java对象, 使用GSON
	 */
	public void testJsonToObject2()  {
		String jsonString = "{\"id\":3, \"name\":\"大虾\", \"price\":12.3,\"imagePath\":\"http://192.168.10.165:8080/L05_Server/images/f1.jpg\"}";
		
		ShopInfo shopInfo = new Gson().fromJson(jsonString, ShopInfo.class);
		
		Log.e("TAG", shopInfo.toString());
	}
	
	
	/*
	 * 3. 将json格式的字符串[]转换为Java对象的List, 使用原生API
	 */
	public void testJsonToList() throws JSONException {
		String jsonString = "[{\"id\":3, \"name\":\"大虾\", \"price\":12.3,\"imagePath\":\"http://192.168.10.165:8080/L05_Server/images/f1.jpg\"},"
				+ "{\"id\":5, \"name\":\"大虾2\", \"price\":128.3,\"imagePath\":\"http://192.168.10.165:8080/L05_Server/images/f2.jpg\"}]";
		List<ShopInfo> list = new ArrayList<ShopInfo>();
		
		//1. 将json字符串包装JSONArray对象
		JSONArray jsonArray = new JSONArray(jsonString);
		//2. 遍历JSONArray对象所有元素(JSONObject), 并将每个元素封装为shopInfo, 并添加到List
		for(int i=0;i<jsonArray.length();i++) {
			JSONObject jsonObject = jsonArray.getJSONObject(i);
			//从对象中根据key得到对应的value
			int id = jsonObject.getInt("id");
			String name = jsonObject.getString("name");
			double price = jsonObject.getDouble("price");
			String imagePath = jsonObject.getString("imagePath");
			//封装ShopInfo对象
			ShopInfo shopInfo = new ShopInfo(id, name, price, imagePath);
			list.add(shopInfo);
		}
		
		Log.e("TAG", list.toString());
	}
	
	/*
	 * 4. 将json格式的字符串[]转换为Java对象的List, 使用GSON
	 */
	public void testJsonToList2() throws JSONException {
		String jsonString = "[{\"id\":4, \"name\":\"大虾\", \"price\":12.3,\"imagePath\":\"http://192.168.10.165:8080/L05_Server/images/f1.jpg\"},"
				+ "{\"id\":6, \"name\":\"大虾2\", \"price\":128.3,\"imagePath\":\"http://192.168.10.165:8080/L05_Server/images/f2.jpg\"}]";
		
		List<ShopInfo> list = new Gson().fromJson(jsonString, new TypeToken<List<ShopInfo>>(){}.getType());
		
		Log.e("TAG", list.toString());
	}
	
	/*
		5. 将Java对象转换为json字符串{}, 使用GSON
	*/
	public void testObjectToJson() {
		ShopInfo info = new ShopInfo(3, "KK", 1000, "http://www.sina.com");
		String json = new Gson().toJson(info);
		Log.e("TAG", json);
	}
	
	
	/*
		6. 将Java对象的List转换为json字符串[], 使用GSON
	*/
	
	public void testListToJson() {
		
		List<ShopInfo> list = new ArrayList<ShopInfo>();
		list.add(new ShopInfo(3, "KK", 1000, "http://www.sina.com"));
		list.add(new ShopInfo(4, "KK2", 2000, "http://www.sina.com222"));
		
		String json = new Gson().toJson(list);
		
		Log.e("TAG", json);
	}
	
	public void testJsonToMap() {
		String jsonString = "{\"my name\":\"大虾\", \"1\":12}";
		Map<String, Object> map = new Gson().fromJson(jsonString, new TypeToken<Map<String, Object>>(){}.getType());
		Log.e("TAG", map.toString());
	}
}