strings.xml
			作用:定义字符串
			定义格式:<string name="xxx">字符串值</string>
			支持占用符  例子:  <string name="xxx">今天%1$s,温度%2$d</string>
			%1 %2---代表参数所在位置
			$s,$d代表参数,s,d为参数类型
			getString(R.string.xxx,"星期一",20) = 今天星期一,温度20
			使用方法:资源文件中   @string/xxx
			代码中   getString(R.string.xxx)
		arrays.xml
			作用:定义数组,可以是int,string,char
			定义格式:<type-array name="xxx">
			<item>数组元素值</item>
			</type-array>
			使用方法:资源文件中   不支持引用
			代码中   type s[] = getResource.getTypeArray(R.array.xxx)
		colors.xml
			作用:定义颜色
			定义格式:<color name="xxx">#color值</color>
			使用方法:资源文件中 @color/xxx
			代码中getResource.getColor(R.color.xxx) 或者
			getresource.getDrawable(R.color.xxx)
		dimens.xml
			作用:定义尺寸大小
			定义格式:<dimen name="xxx">值</dimen>
			使用方法:资源文件中 @dimen/xxx
			代码中  getResource.getDimension(R.dimen.xxx)
		styles.xml
			作用:定义试图样式
			定义格式:<style name="xxx"  parent="yyy">
            			<item name="xxx2">元素值</item>
            		</style>

getDrawable(R.drawable.xxx)

setcontentView(R.layout.xxx) ;
View view = LayoutInflater.from(context).inflate(R.layout.xxx,null)

sourceSets {
    main {
        res.srcDirs =
                [
                    'src/main/res/layout/main', 
                    'src/main/res/layout/dialog',
                    ...
                //下面两个是固定兼容写法，必须放到最后
                    'src/main/res/layout',
                    'src/main/res'
                ]
    }
}

XmlResoutceParser xml = getResources().getXml(R.xml.xxx)

InputStream read =getAssets().open(R.assets.xxx)
OutputStream write = getAssets().open(R.assets.xxx)

InputStream read = getResources().openRawResource(R.raw.xxx)
OutputStream write = getResources().openRawResource(R.raw.xxx)

getResources().getAnimation(R.anim.xxx)

/**
 * @author ${USER}
 * @version ${VERSION}  
 * @description:   TODO (必填)
 * @date ${DATE}
 */

//获取屏幕区域的宽高等尺寸获取
DisplayMetrics metrics = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics);
int widthPixels = metrics.widthPixels;
int heightPixels = metrics.heightPixels;
//应用程序App区域宽高等尺寸获取
Rect rect = new Rect();
getWindow().getDecorView().getWindowVisibleDisplayFrame(rect);
//获取状态栏高度
Rect rect= new Rect();
getWindow().getDecorView().getWindowVisibleDisplayFrame(rect);
int statusBarHeight = rectangle.top;
//View布局区域宽高等尺寸获取
Rect rect = new Rect(); 
getWindow().findViewById(Window.ID_ANDROID_CONTENT).getDrawingRect(rect);

Retrofit retrofit = new Retrofit.Builder()
        .baseUrl("http://localhost:8080/")
        .build();

public interface BlogService {
    @GET("blog/{id}")
    Call<ResponseBody> getBlog(@Path("id") int id);
}

BlogService service = retrofit.create(BlogService.class);

Call<ResponseBody> call = service.getBlog(2);
// 用法和OkHttp的call如出一辙,
// 不同的是如果是Android系统回调方法执行在主线程
call.enqueue(new Callback<ResponseBody>() {
    @Override
    public void onResponse(Call<ResponseBody> call, Response<ResponseBody> response) {
        try {
            System.out.println(response.body().string());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void onFailure(Call<ResponseBody> call, Throwable t) {
        t.printStackTrace();
    }
});

public interface BlogService {
  @GET("blog/{id}")
  Call<Result<Blog>> getBlog(@Path("id") int id);
}

compile 'com.squareup.retrofit2:converter-gson:2.0.2'

Gson gson = new GsonBuilder()
      //配置你的Gson
      .setDateFormat("yyyy-MM-dd hh:mm:ss")
      .create();

Retrofit retrofit = new Retrofit.Builder()
      .baseUrl("http://localhost:4567/")
      //可以接收自定义的Gson，当然也可以不传
      .addConverterFactory(GsonConverterFactory.create(gson))
      .build();

@POST("blog")
Call<Result<Blog>> createBlog(@Body Blog blog);

BlogService service = retrofit.create(BlogService.class);
Blog blog = new Blog();
blog.content = "新建的Blog";
blog.title = "测试";
blog.author = "怪盗kidou";
Call<Result<Blog>> call = service.createBlog(blog);

引入RxJava支持:
compile 'com.squareup.retrofit2:adapter-rxjava2:2.3.0'

Retrofit retrofit = new Retrofit.Builder()
      .baseUrl("http://localhost:4567/")
      .addConverterFactory(GsonConverterFactory.create())
      .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
      // 针对rxjava2.x
      .addCallAdapterFactory(RxJava2CallAdapterFactory.create()) 
      .build();

public interface BlogService {
  @POST("/blog")
  Observable<Result<List<Blog>>> getBlogs();
}

BlogService service = retrofit.create(BlogService.class);
service.getBlogs(1)
  .subscribeOn(Schedulers.io())
  .subscribe(new Subscriber<Result<List<Blog>>>() {
      @Override
      public void onCompleted() {
        System.out.println("onCompleted");
      }

      @Override
      public void onError(Throwable e) {
        System.err.println("onError");
      }

      @Override
      public void onNext(Result<List<Blog>> blogsResult) {
        System.out.println(blogsResult);
      }
  });

android {
  ...
  // Configure only for each module that uses Java 8
  // language features (either in its source code or
  // through dependencies).
  compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
  }

(Type1 param1, Type2 param2, ..., TypeN paramN) -> {
  statment1;
  statment2;
  //.............
  return statmentM;
}

public void oldRunable() {
    new Thread(new Runnable() {
        @Override
        public void run() {
            System.out.println("The old runable now is using!");
        }
    }).start();
}
    
public void runable() {
    new Thread(() -> System.out.println("It's a lambda function!")).start();
}

public void iterTest() {
    List<String> languages = Arrays.asList("java","scala","python");
    //before java8
    for(String each:languages) {
        System.out.println(each);
    }
    //after java8
    languages.forEach(x -> System.out.println(x));
    languages.forEach(System.out::println);
}

public void mapTest() {
    List<Double> cost = Arrays.asList(10.0, 20.0,30.0);
    cost.stream().map(x -> x + x*0.05).forEach(x -> System.out.println(x));
}

public void mapReduceTest() {
    List<Double> cost = Arrays.asList(10.0, 20.0,30.0);
    double allCost = cost.stream().map(x -> x+x*0.05).reduce((sum,x) -> sum + x).get();
    System.out.println(allCost);
}

public interface IMovieView {
    //成功获取到电影数据
    void getMovieSuccess(List<MovieRes> list, int type);
    //获取电影数据失败
    void getMovieFail(int status, String desc, int type);
}

public interface IMovieMoel{
    //请求正在上映的电影数据
    Observable getPlayingMovie(int start, int count);
    ...
}

public class MovieModel implements IMovieMoel{

    @Override
    public Observable getPlayingMovie(int start,int count) {
        //提供数据源
        return DevRing.httpManager().getService(MovieApiService.class).getPlayingMovie(start, count);
    }
    ...
}

public class MoviePresenter {
    private IMovieView mIView;
    private IMovieModel mIModel;

    public MoviePresenter(IMovieView iMovieView, IMovieMoel iMovieMoel) {
        mIView = iMovieView;
        mIModel = iMovieModel;
    }

    /**
     * 获取正在上映的电影
     *
     * @param start 请求电影的起始位置
     * @param count 获取的电影数量
     * @param type  类型：初始化数据INIT、刷新数据REFRESH、加载更多数据LOADMORE
     */
    public void getPlayingMovie(int start, int count, final int type) {
        DevRing.httpManager().commonRequest( mIModel.getPlayingMovie(start, count),
         new CommonObserver<HttpResult<List<MovieRes>>>() {
            @Override
            public void onResult(HttpResult<List<MovieRes>> result) {
                if (mIView != null) {
                    mIView.getMovieSuccess(result.getSubjects(), type);
                }
            }

            @Override
            public void onError(int errType, String errMessage) {
                if (mIView != null) {
                    mIView.getMovieFail(errType, errMessage, type);
                }
            }
        }, RxLifecycleUtil.bindUntilDestroy(mIView)); 
    }

    ...

     /**
     * 释放引用，防止内存泄露
     */
    public void destroy() {
        mIView = null;
    }
}

public class MovieActivity extends Activity implements IMovieView {
    //获取电影数据成功的网络请求回调
    @Override
    public void getMovieSuccess(List<MovieRes> list, int type) {
        //成功，对数据进行展示
        ....
    }

    //获取电影数据失败的网络请求回调
    @Override
    public void getMovieFail(int status, String desc, int type) {
        //失败，界面上做出相应提示
        ...
    }

    ...
}

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ...
        mBookPresenter.onCreate();
        mBookPresenter.attachView(mBookView);
    }

private BookView mBookView = new BookView() {
    @Override
    public void onSuccess(Book mBook) {
        text.setText(mBook.toString());
    }

    @Override
    public void onError(String result) {
        Toast.makeText(MainActivity.this,result, Toast.LENGTH_SHORT).show();
    }
};

@Override
protected void onCreate(Bundle saveInstanceState) {
      ...
      mPresenter = new MoviePresenter(this, new MovieModel());
      mPresenter.getPlayingMovie(start, mCount, type);
}

@Override
public void onDestroy() {
     super.onDestroy();
     if (mPresenter != null) {
          mPresenter.destroy();
          mPresenter = null;
     }
 }

Looper
* 内部包含一个消息队列也就是MessageQueue，所有的Handler发送的消息都走向这个消息队列
* Looper.Looper方法，就是一个死循环，不断的从MessageQueue去消息，如果有消息就处理消息，没有消息就阻塞

* 在安装app时，就赋予该app的权限，即安装后立即获取到的权限
* normal和signature级别的权限都是安装时权限
* 赋予app normal和signature权限时，不会给用户提示界面，系统自动决定权限的赋予
* 对于signature权限，如果使用权限的app与声明权限的app的签名不一致，则系统拒绝赋予该signature权限

* 指在app运行过程中，赋予app的权限,会显示明显的权限授予界面，让用户决定是否授予权限
* 如果一个app的targetSdkVersion是23及以上，那么该app所申请的所有dangerous权限都是运行时权限
* Android 6及以上的环境中，该app在运行时必须主动申请这些dangerous权限（调用requestPermissions()），否则该app没有获取到dangerous权限