Android 状态切换控件 EasyStateView

效果 GIF

简单介绍一下这个控件，像我们在实际的开发过程中，经常性的会遇到这样的场景，比如进入一个页面先出来加载动画，然后请求数据，如果网络异常就显示网络异常的布局，数据异常、数据为空也有相应的布局，以及当我们请求成功完毕数据后，根据返回的数据值去区分不同VIP等级的用户显示不同的页面，这里我放了两张图，我的女神，迪丽热巴和俞飞鸿，就当做我们在业务开发中的 Layout ，把布局全部写在 xml，然后控制显示隐藏就有点不优雅了，基于这个问题，就有了这个控件。

下面是自定义 View 的自定义属性：

<declare-styleable name="EasyStateView">

        // 是否使用过渡动画
        <attr name="esv_use_anim" format="boolean"/>

        // 加载动画 View
        <attr name="esv_loadingView" format="reference" />

        // 数据异常，加载失败 View
        <attr name="esv_errorDataView" format="reference" />

        // 网络异常 View
        <attr name="esv_errorNetView" format="reference" />

        // 空白页面 View
        <attr name="esv_emptyView" format="reference" />

        // 设置当前显示的 viewState
        <attr name="esv_viewState" format="enum">
            <enum name="content" value="0" />
            <enum name="loading" value="-1" />
            <enum name="error_data" value="-2" />
            <enum name="error_net" value="-3" />
            <enum name="empty" value="-4" />
        </attr>

    </declare-styleable>

Java代码：

package com.rzj.view;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ObjectAnimator;
import android.app.Activity;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Rect;
import android.support.annotation.IntDef;
import android.util.AttributeSet;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.WindowManager;
import android.widget.FrameLayout;
import com.rzj.stateview.R;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.util.ArrayList;

public class EasyStateView extends FrameLayout {

    // 内容 View
    public static final int VIEW_CONTENT = 0;
    // 加载 View
    public static final int VIEW_LOADING = -1;
    // 数据异常( 数据异常指原本应该是有数据，但是服务器返回了错误的、不符合格式的数据 ) View
    public static final int VIEW_ERROR_DATA = -2;
    // 网络异常 View
    public static final int VIEW_ERROR_NET = -3;
    // 数据为空 View
    public static final int VIEW_EMPTY = -4;
    // View 的 Tag 标签值
    private static final int VIEW_TAG = -5;
    // 用来存放 View
    private ArrayList<View> mViews;
    // 是否使用过渡动画
    private boolean mUseAnim;
    // 是否处于动画中
    private boolean isAniming;
    // 当前显示的 ViewTag
    private int mCurrentState;
    private Context mContext;
    private StateViewListener mListener;
    // content View 是否被添加到队列
    private boolean isAddContent;

    public interface StateViewListener {
        void onStateChanged(int state);
    }

    public EasyStateView(Context context) {
        this(context, null);
    }

    public EasyStateView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public EasyStateView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init(context, attrs);
    }

    private void init(Context context, AttributeSet attrs) {
        mContext = context;
        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.EasyStateView);
        mCurrentState = typedArray.getInt(R.styleable.EasyStateView_esv_viewState, VIEW_CONTENT);
        Log.e("init", getChildCount() + "  " + mCurrentState);
        mViews = new ArrayList<>();
        int emptyResId = typedArray.getResourceId(R.styleable.EasyStateView_esv_emptyView, VIEW_TAG);
        if (emptyResId != VIEW_TAG) {
            View view = LayoutInflater.from(getContext()).inflate(emptyResId, this, false);
            view.setTag(VIEW_EMPTY);
            mViews.add(view);
            addViewInLayout(view, -1, view.getLayoutParams());
        }
        int errorDataResId = typedArray.getResourceId(R.styleable.EasyStateView_esv_errorDataView, VIEW_TAG);
        if (errorDataResId != VIEW_TAG) {
            View view = LayoutInflater.from(getContext()).inflate(errorDataResId, this, false);
            view.setTag(VIEW_ERROR_DATA);
            mViews.add(view);
            addViewInLayout(view, -1, view.getLayoutParams());
        }
        int errorNetResId = typedArray.getResourceId(R.styleable.EasyStateView_esv_errorNetView, VIEW_TAG);
        if (errorNetResId != VIEW_TAG) {
            View view = LayoutInflater.from(getContext()).inflate(errorNetResId, this, false);
            view.setTag(VIEW_ERROR_NET);
            mViews.add(view);
            addViewInLayout(view, -1, view.getLayoutParams());
        }
        int loadingResId = typedArray.getResourceId(R.styleable.EasyStateView_esv_loadingView, VIEW_TAG);
        if (loadingResId != VIEW_TAG) {
            View view = LayoutInflater.from(getContext()).inflate(loadingResId, this, false);
            view.setTag(VIEW_LOADING);
            mViews.add(view);
            addViewInLayout(view, -1, view.getLayoutParams());
        }
        mUseAnim = typedArray.getBoolean(R.styleable.EasyStateView_esv_use_anim, true);
        typedArray.recycle();
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        for (View view : mViews) {
            if ((Integer) view.getTag() != mCurrentState) {
                view.setVisibility(GONE);
            }
        }
    }

    @Override
    public void addView(View child) {
        addContentV(child);
        super.addView(child);
    }

    private void addContentV(View child) {
        if (isContentView(child)) {
            child.setTag(VIEW_CONTENT);
            mViews.add(child);
            isAddContent = true;
        }
    }

    @Override
    public void addView(View child, int index) {
        addContentV(child);
        super.addView(child, index);
    }

    @Override
    public void addView(View child, int index, ViewGroup.LayoutParams params) {
        addContentV(child);
        super.addView(child, index, params);
    }

    @Override
    public void addView(View child, ViewGroup.LayoutParams params) {
        addContentV(child);
        super.addView(child, params);
    }

    @Override
    public void addView(View child, int width, int height) {
        addContentV(child);
        super.addView(child, width, height);
    }

    @Override
    protected boolean addViewInLayout(View child, int index, ViewGroup.LayoutParams params) {
        addContentV(child);
        return super.addViewInLayout(child, index, params);
    }

    @Override
    protected boolean addViewInLayout(View child, int index, ViewGroup.LayoutParams params, boolean preventRequestLayout) {
        addContentV(child);
        return super.addViewInLayout(child, index, params, preventRequestLayout);
    }

    private boolean isContentView(View child) {
        if (!isAddContent && null != child
                && null == child.getTag()) {
            return true;
        }
        return false;
    }

    /**
     * 切换默认状态的 View
     *
     * @param state
     */
    public void setViewState(int state) {
        if (state < VIEW_TAG) {
            throw new RuntimeException("ViewState 不在目标范围");
        }
        if (isAniming) {
            return;
        }
        showViewAnim(state);
    }

    public void setUseAnim(boolean useAnim) {
        this.mUseAnim = useAnim;
    }

    private void showViewAnim(int state) {
        View showView = getStateView(state);
        if (null == showView || state == mCurrentState) {
            return;
        }
        isAniming = true;
        View currentView = getStateView(mCurrentState);
        if (mUseAnim) {
            showAlpha(state, showView, currentView);
        } else {
            currentView.setVisibility(GONE);
            if(showView.getAlpha() == 0){
                showView.setAlpha(1f);
            }
            showView.setVisibility(VISIBLE);
            mCurrentState = state;
            isAniming = false;
        }
    }

    private void showAlpha(final int state, final View showView,
                           final View currentView) {
        ObjectAnimator currentAnim = ObjectAnimator.ofFloat(currentView, "alpha", 1, 0);
        currentAnim.setDuration(250L);
        final ObjectAnimator showAnim = ObjectAnimator.ofFloat(showView, "alpha", 0, 1);
        showAnim.setDuration(250L);
        showAnim.addListener(new AnimatorListenerAdapter() {

            @Override
            public void onAnimationEnd(Animator animation) {
                super.onAnimationEnd(animation);
                if (null != mListener) {
                    mListener.onStateChanged(state);
                }
                isAniming = false;
            }
        });
        currentAnim.addListener(new AnimatorListenerAdapter() {

            @Override
            public void onAnimationEnd(Animator animation) {
                super.onAnimationEnd(animation);
                currentView.setVisibility(GONE);
                showView.setVisibility(VISIBLE);
                showAnim.start();
                mCurrentState = state;
            }
        });
        currentAnim.start();
    }

    public int getCurrentState() {
        return mCurrentState;
    }

    public View getStateView(int state) {
        if (state < VIEW_TAG) {
            throw new RuntimeException("ViewState 不在目标范围");
        }
        for (View view : mViews) {
            if ((Integer) view.getTag() == state) {
                return view;
            }
        }
        return null;
    }

    public void addUserView(int state, int layId) {
        setUserDefView(state, null, layId);
    }

    public void addUserView(int state, View view) {
        setUserDefView(state, view, -1);
    }

    private void setUserDefView(int state, View view, int layId) {
        if (state <= 0) {
            throw new RuntimeException("自定义的 ViewState TAG 必须大于 0");
        }
        if (null == view && layId != -1) {
            view = LayoutInflater.from(mContext).inflate(layId, this, false);
        }
        view.setTag(state);
        view.setVisibility(GONE);
        addViewInLayout(view, -1, view.getLayoutParams());
        mViews.add(view);
    }

}

简单说明一下，继承 FrameLayout 是因为帧布局是效率最高的布局，添加 View 到布局中用的是addViewInLayout，这里解释一下为什么不用addView，因为addView会触发 requestLayout，addViewInLayout会先添加进去，然后再统一触发布局，这个控件的用法非常简单，控件里面已经内置了很多常用的场景类型，你可以通过 addUserView()这个方法来添加你的 View，目前只有一个过渡动画，后续考虑迭代。

项目的 Github 地址 https://github.com/MarkRaoAndroid/EasyStateView