基于LeanCloud Restful API的Retrofit编程

BaaS提供商LeanCloud提供了Restful API，没有提供Retrofit使用教程。

• 注册用户

注册API设计：

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curl -X POST \
  -H "X-LC-Id: y0crQpaNCKUq9WFaSMLByoKo-gzGzoHsz" \
  -H "X-LC-Key: ihdOweBmtk9yrDbuPEbJfyBb" \
  -H "Content-Type: application/json" \
  -d '{"username":"hjiang","password":"f32@ds*@&dsa","phone":"18612340000"}' \
  https://api.leancloud.cn/1.1/users

登录API设计：

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curl -X POST \
-H "Content-Type: application/json" \
-H "X-LC-Id: y0crQpaNCKUq9WFaSMLByoKo-gzGzoHsz" \
-H "X-LC-Key: ihdOweBmtk9yrDbuPEbJfyBb" \
-d '{"username":"hjiang","password":"f32@ds*@&dsa"}' \
https://api.leancloud.cn/1.1/login

ButterKnife vs RoboGuice

当涉及到Android上的依赖注入（DI）类库的时候，存在不少的选择，我在公司项目中用了RoboGuice，现在非常后悔。最开始认为RoboGuice节约了大量的时间。较少的代码意味着较少的错误，较少的样板代码意味着可以把更多的时间放到应用的核心逻辑上。

宿主 Activity 实现 Fragment 定义的对外接口 IOneFragmentClickListener，便可以实现 Fragment 调用 Activity 的功能。

public class OneFragment extends Fragment implements View.OnClickListener{

    private IOneFragmentClickListener clickListener;

    public interface IOneFragmentClickListener{
        void onOneFragmentClick();
    }

    public void setClickListener(IOneFragmentClickListener clickListener) {
        this.clickListener = clickListener;
    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View contentView = inflater.inflate(R.layout.fragment_one, null);
        contentView.findViewById(R.id.edt_one).setOnClickListener(this);
        return contentView;
    }

    @Override
    public void onClick(View v) {
        clickListener.onOneFragmentClick();
    }

}

准备三个工具：Apktool、dex2jar、jd-gui

• Apktool

  • 下载：downloads

  • 安装：install

    **Windows:**
    1.Download Windows wrapper script (Right click, Save Link As apktool.bat)
    2.Download apktool-2 (find newest here)
    3.Rename downloaded jar to apktool.jar
    4.Move both files (apktool.jar & apktool.bat) to your Windows directory (Usually C://Windows)
    5.If you do not have access to C://Windows, you may place the two files anywhere then add that directory to your Environment Variables System PATH variable.
    6.Try running apktool via command prompt
    

  • 使用：documentation

代码：

print(b'ABC'.decode('ascii'))
print( b'\xe4\xb8\xad\xe6\x96\x87'.decode('utf-8'))

输出：

解决方法：

import io
import sys
#改变标准输出的默认编码
sys.stdout=io.TextIOWrapper(sys.stdout.buffer,encoding='utf8')

输出：

即可。

Strong reference（强引用）

在Java中，非静态内部类会在其整个生命周期中持有对它外部类的强引用。

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        new MyAsyncTask(this).execute();
    }

    private class MyAsyncTask extends AsyncTask { 

        @Override
        protected Object doInBackground(Object[] params) {

            // 模拟耗时任务
            try {
                Thread.sleep(60000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            return doSomeStuff();
        }
        private Object doSomeStuff() {
            return new Object();
        }
        @Override
        protected void onPostExecute(Object object) {
            super.onPostExecute(object);
            // 更新UI
        }
    }
}

Android提供的下载类DownloadManager

• Usage

String downUrl = "http://downloads.jianshu.io/apps/haruki/JianShu-1.11.2.apk";


 /**获得系统下载器*/ 
DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
/**设置下载地址*/ 
DownloadManager.Request request = new DownloadManager.Request(Uri.parse(downUrl));
/**设置下载文件的类型*/ 
request.setMimeType("application/vnd.android.package-archive");
/**设置下载存放的文件夹和文件名字*/ 
request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "JianShu-1.11.2.apk");
/**设置下载时或者下载完成时，通知栏是否显示*/ 
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
request.setTitle("Download");
/**执行下载，并返回任务唯一id*/ 
long enqueue = dm.enqueue(request);

透明的系统状态栏SystemBar

• values/styles.xml

  <resources>
  
      <!-- Base application theme. -->
      <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
          <item name="colorPrimary">@color/colorPrimary</item>
          <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
          <item name="colorAccent">@color/colorAccent</item>
          <!-- Customize your theme here. -->
      </style>
  
      <style name="AppTheme.NoActionBar">
          <item name="windowActionBar">false</item>
          <item name="windowNoTitle">true</item>
      </style>
  
  </resources>
  

使用AppCompat-21适配Material Design

设置compileSdkVersion为21

android {
    compileSdkVersion 21
    buildToolsVersion "21.0.0"

    defaultConfig {
        applicationId "com.way.material"
        minSdkVersion 14
        targetSdkVersion 21
        versionCode 1
        versionName "1.0"
    }
     ...
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:21.+'
}

TextInput使用知识

TextInput

XML属性&常用方法

• counterEnabled：false or true，用于设置字符计数器的开启或关闭。

  对应方法：setCounterEnabled(boolean)

• counterMaxLength：设置字符计数器的最大长度。（仅用于设置计数器最大值，并不影响文本实际能输入的最大长度）

  对应方法：setCounterMaxLength(int)

• errorEnabled：false or true，用于设置错误提示是否开启。

  对应方法：setErrorEnabled(boolean)