MVP模式的简单应用

MVP :

M-model，即javaBean 数据模型层；
V-view，视图层，常用的即Activity Fragment,这里是定义一个接口IView,Activity去实现IView的写法；
P-presenter，数据处理层，所有的数据逻辑，业务逻辑都在这里处理；

详细介绍就不多说，自己写一个Demo，基本就能理解;

MVP 实例：获取图片数据，并用ListView进行展示

效果图：

包结构：

代码：

M：MainGetImgModel

/**
 * 获取数据的Model
 * */
public class MainGetImgModel {
	//网络图片地址
	private String[] imgArr = { 
			"http://img02.sogoucdn.com/app/a/100520076/41c3c06da0ab59719a3d1b9c839b72cc",
			"http://img03.sogoucdn.com/app/a/100520076/25682e62dd4b2ac15f89d24b88c31aaa",
			"http://img02.sogoucdn.com/app/a/100520076/e3fd14fc3b20eca09b740c96da4472b7",
			"http://img01.sogoucdn.com/app/a/100520020/0b37d30dc7017f35c2c4d78732066baa" };

	public void loadData(final MyCallBack callBack) {
		//模拟线程请求
		new Thread(new Runnable() {
			public void run() {
				List<String> mList = new ArrayList<String>();
				for (int i = 0; i < imgArr.length; i++) {
					mList.add(imgArr[i]);
				}
				// 休眠两秒，用于展示加载框
				try {
					Thread.sleep(2000);
				} catch (InterruptedException e) {
					e.printStackTrace();
				} //结果回调
				callBack.onFinish(mList);
			}
		}).start();
	}
	// 请求回调
	public interface MyCallBack{
		void onFinish(List<String> mList);
	}

V：MainActivity

IView ：抽取的 MainActivity 的接口

/**
 * MainActivity 的接口
 * 操作View 的相关方法
 * */
public interface MainIView {
	// 展示旋转框
	void showProgressBar();
	// 隐藏旋转框
	void hideProgress();
	// 请求的数据，展示到View 上
	void showImg(List<String> mList);
}

View ：MainActivity

/**
 * 展示请求到的图片数据
 */
public class MainActivity extends Activity implements MainIView {
	private ListView mListView;
	private ProgressBar mBar;
	private MainPresenter mPrestener;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		mListView = (ListView) findViewById(R.id.main_lv);
		mBar = (ProgressBar) findViewById(R.id.main_pb);
		// 初始化 Presneter ,并请求数据
		mPrestener = new MainPresenter(this);
		mPrestener.loadData();
	}

	@Override
	public void showProgressBar() {
		mBar.setVisibility(View.VISIBLE);
	}

	@Override
	public void hideProgress() {
		mBar.setVisibility(View.GONE);
	}

	@Override
	public void showImg(List<String> mList) {
		// 给ListView设置数据
		MainAdapter adapter = new MainAdapter(MainActivity.this, mList);
		mListView.setAdapter(adapter);
	}

	@Override
	protected void onDestroy() {
		super.onDestroy();
		// 释放presenter
		if (mPrestener != null)
			mPrestener.destory();
	}

P： MainPresenter.class

/**
 * 将原本写在Activity或Fragment 中的逻辑写到这里
 * Model与View 的交互
 * */
public class MainPresenter {
	private MainGetImgModel mImgModel;
	private MainIView mainIView;

	public MainPresenter(MainIView mainIView) {
		mImgModel = new MainGetImgModel();
		this.mainIView = mainIView;
	}

	private Handler handler = new Handler() {
		public void handleMessage(android.os.Message msg) {
			if (msg.what == 1) {
				List<String> mList = (List<String>) msg.obj;
				// 将数据传送至View
				mainIView.showImg(mList);
				// 隐藏旋转框
				mainIView.hideProgress();
			}
		};
	};
	/**
	 * 调用Model中的加载数据的方法
	 * 并与View 结合
	 * */
	public void loadData() {
		// 显示旋转框
		mainIView.showProgressBar();
		//请求数据
		mImgModel.loadData(new MyCallBack() {
			@Override
			public void onFinish(List<String> mList) {
				//请求成功，将结果发送至主线程中。
				Message message = handler.obtainMessage();
				message.obj = mList;
				message.what = 1;
				handler.sendMessage(message);
			}
		});
	}
	// 释放内存。（防止内存泄漏）
	public void destory() {
		if (mainIView != null)
			mainIView = null;
		if (handler != null)
			handler.removeCallbacksAndMessages(null);
	}

其他：

Adapter：

public class MainAdapter extends BaseAdapter {
	private Context mContext;
	private List<String> mList;

	public MainAdapter(Context mContext, List<String> mList) {
		this.mContext = mContext;
		this.mList = mList;
	}

	@Override
	public int getCount() {
		return mList != null ? mList.size() : 0;
	}

	@Override
	public Object getItem(int position) {
		return mList != null ? mList.get(position) : null;
	}

	@Override
	public long getItemId(int position) {
		return position;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		ViewHolder holder = null;
		if (convertView == null) {
			convertView = View.inflate(mContext, R.layout.item, null);
			holder = new ViewHolder(convertView);
			convertView.setTag(holder);
		} else {
			holder = (ViewHolder) convertView.getTag();
		}
		Log.d("lijia", "handleMessage 28" + mList.get(position));
		Glide.with(mContext).load(mList.get(position)).into(holder.imageView);
		return convertView;
	}

	class ViewHolder implements AbsBaseAdapter.IViewHolder {
		private ImageView imageView;

		public ViewHolder(View view) {
			if (view == null)
				return;
			imageView = (ImageView) view.findViewById(R.id.item_iv);
		}
	}
}

布局：

activity_main.xml:

<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"
    tools:context="com.example.mvpdemo.view.MainActivity" >

    <ProgressBar
        android:visibility="gone"
        android:id="@+id/main_pb"
        android:layout_centerInParent="true"
        android:layout_width="120dp"
        android:layout_height="120dp" />

    <ListView
        android:id="@+id/main_lv"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    </ListView>

</RelativeLayout>

item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <ImageView
        android:id="@+id/item_iv"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />
</LinearLayout>

写个Demo对于理解MVP 模式是很有帮助的。但是，项目中这样写还是有很多问题的。

后面会对 MVP模式进行抽取封装。

MVP模式的简单应用

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