在Android应用中，基本每个应用都会有网络加载数据的实现，也基本上需要实现在网络加载数据后出现的不同页面，一般有4种，分别是加载中页面 加载失败显示的页面，加载成功数据的页面 以及 加载没有数据的空页面。如果采用对每一个页面加载数据进行处理的方法，就会很麻烦，接下来就介绍两种方式来解决这个问题，第一种，半彻底式，第二种，彻底式。
先来看第一种方式
1.EmptyLayout(自定义ViewGroup)：
先来看看4种效果：分别是 加载错误 空页面 加载有数据 以及加载错误点击重新加载 （设置出来为加载中)
GIF.gif
上面简单模拟了下几种状态，就是一个自定义ViewGroup，里面有一个ProgressBar ImageVIew 和一个TextView，先看一下布局：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center"
android:orientation="vertical">
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal">
<ImageView
android:id="@+id/img_error_layout"
android:layout_width="100dp"
android:layout_height="100dp"
android:contentDescription="@null"
android:visibility="gone" />
<ProgressBar
android:id="@+id/animProgress"
android:layout_width="30dip"
android:layout_height="30dip" />
</RelativeLayout>
<TextView
android:id="@+id/tv_error_layout"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal"
android:layout_marginTop="10.0dip"
android:gravity="center"
android:lines="2"
android:textColor="@android:color/darker_gray"
android:textSize="17sp" />
</LinearLayout>
布局很简单，接下来看一下EmptyLayout的代码：
public class EmptyView extends LinearLayout implements View.OnClickListener {
public static final int NETWORK_LOADING = 1; // 加载中
public static final int NODATA = 2; // 没有数据
public static final int NETWORK_ERROR = 3; // 网络错误
public static final int HIDE_LAYOUT = 4; // 隐藏
private int mErrorState = NETWORK_LOADING;//初始化为加载状态
private ProgressBar animProgress;
private ImageView img;
private TextView tv;
private String strNoDataContent;
private String strErrorContent;
private int imgNoDataImage = -1;
private int imgErrorImage = -1;
private OnClickListener listener;
public EmptyView(Context context) {
this(context, null);
}
public EmptyView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
View view = LayoutInflater.from(getContext()).inflate(R.layout.view_empty, null);
animProgress = (ProgressBar) view.findViewById(R.id.animProgress);
img = (ImageView) view.findViewById(R.id.img_error_layout);
tv = (TextView) view.findViewById(R.id.tv_error_layout);
//初始化设置
if (getVisibility() == View.GONE) {
setErrorType(HIDE_LAYOUT);
} else {
setErrorType(NETWORK_LOADING);
}
setOnClickListener(this);
//图片去触发点击事件
img.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View view) {
if (listener != null) {
listener.onClick(view);
}
}
});
addView(view);
}
//自定义点击监听（图片会拦截 EmptyVIew的点击事件，所以也需要对图片进行设置点击事件）
public void setOnLayoutClickListener(OnClickListener listener) {
this.listener = listener;
}
//整个EmptyVIew去触发点击事件
@Override
public void onClick(View view) {
if (listener != null) {
listener.onClick(view);
}
}
//判断3种状态
public boolean isLoadError() {
return mErrorState == NETWORK_ERROR;
}
public boolean isLoading() {
return mErrorState == NETWORK_LOADING;
}
public boolean isLoadingNoData() {
return mErrorState == NODATA;
}
//传入不同状态的图片 文字
public void setErrorImag(int imgResource) {
imgErrorImage = imgResource;
}
public void setNoDataImag(int imgResource) {
imgNoDataImage = imgResource;
}
public void setErrorContent(String msg) {
strErrorContent = msg;
}
public void setNoDataContent(String noDataContent) {
strNoDataContent = noDataContent;
}
public void setErrorType(int type) {
setVisibility(View.VISIBLE);
mErrorState = type;
switch (type) {
case NETWORK_LOADING:
animProgress.setVisibility(View.VISIBLE);
img.setVisibility(View.GONE);
tv.setVisibility(View.VISIBLE);
tv.setText("正在加载...");
setVisibility(View.VISIBLE);
break;
case NODATA:
animProgress.setVisibility(View.GONE);
img.setImageResource(imgNoDataImage == -1 ? R.mipmap.empty : imgNoDataImage);
img.setVisibility(View.VISIBLE);
tv.setText(strNoDataContent == null ? "点击屏幕，重新加载" : strNoDataContent);
tv.setVisibility(View.VISIBLE);
setVisibility(View.VISIBLE);
break;
case NETWORK_ERROR:
animProgress.setVisibility(View.GONE);
img.setImageResource(imgErrorImage == -1 ? R.mipmap.error_no_wifi : imgErrorImage);
img.setVisibility(View.VISIBLE);
tv.setText(strErrorContent == null ? "点击屏幕，重新加载" : strErrorContent);
tv.setVisibility(View.VISIBLE);
setVisibility(View.VISIBLE);
break;
case HIDE_LAYOUT:
setVisibility(View.GONE);
break;
default:
break;
}
}
@Override
public void setVisibility(int visibility) {
if (visibility == View.GONE) {
mErrorState = HIDE_LAYOUT;
}
super.setVisibility(visibility);
}
}
也很简单，主要是注意一下逻辑清晰，实现还是蛮容易的，注释都有，就不多做解释了，接下来来看一下对EmptyLayout空间的使用
xml布局中：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:id="@+id/bill_navi_layout"
android:layout_width="match_parent"
android:layout_height="40dp"
android:background="#EFEFF4"
android:gravity="center_vertical"
android:orientation="horizontal"
android:paddingLeft="10dp">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="我是有内容的"/>
</LinearLayout>
<com.example.base.view.EmptyView
android:id="@+id/empty"
android:layout_centerInParent="true"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</com.example.base.view.EmptyView>
</RelativeLayout>
上面的线性布局简单代表了一个有内容的页面，将EmptyLayout放置在整个布局的中间，操作VIew的Visiable和Gone来显示不同的页面
使用示例：
public class EmptyActivity extends TitleActivity {
@BindView(R.id.empty)
EmptyView empty;
@BindView(R.id.bill_navi_layout)
LinearLayout billNaviLayout;
@Override
public void onInitView(Bundle savedInstanceState) {
super.onInitView(savedInstanceState);
setContentView(R.layout.activity_empty);
ButterKnife.bind(this);
billNaviLayout.setVisibility(View.GONE);//初始化内容页面为不显示
new Thread(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(2000);//模拟加载过程
runOnUiThread(new Runnable() {
@Override
public void run() {
//NETWORK_ERROR NODATA HIDE_LAYOUT NETWORK_LOADING
empty.setErrorType(EmptyView.NETWORK_ERROR);//错误页面
// empty.setErrorType(EmptyView.NODATA);//空页面
// empty.setErrorType(EmptyView.HIDE_LAYOUT);//有内容页面
// billNaviLayout.setVisibility(View.Visiable);//设置为显示
}
});
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}).start();
//点击事件
empty.setOnLayoutClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
empty.setErrorType(EmptyView.NETWORK_LOADING);
}
});
}
}
2.StateViewHelper(基类实现，一劳永逸)
第二种实现方式逻辑比较第一种较为复杂一点，但是在后续的使用上却比第一种更加灵活以及简便，且更符合Android封装的特点，实现始难后易。
看一下很挫的动画吧，功能实现妥妥的，妈的，就是不会写博客啊。。。
GIF.gif
上面一样是每一个状态延迟2s后实现，和网络加载后显示不同的VIew一一对应，和EmptyView一样
public class EmptyActivity extends TitleActivity {
@BindView(R.id.empty)
EmptyView empty;
@BindView(R.id.bill_navi_layout)
LinearLayout billNaviLayout;
@Override
public void onInitView(Bundle savedInstanceState) {
super.onInitView(savedInstanceState);
setContentView(R.layout.activity_empty);
ButterKnife.bind(this);
billNaviLayout.setVisibility(View.VISIBLE);//初始化内容页面为不显示
empty.setVisibility(View.GONE);
new Thread(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(2000);//模拟加载过程
runOnUiThread(new Runnable() {
@Override
public void run() {
// setMode(StateViewHelper.MODE_LOADING);
// setMode(StateViewHelper.MODE_ERROR);
setMode(StateViewHelper.MODE_EMPTY);
}
});
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}).start();
}
}
都是先展示自己的ContentView，然后各自设置不同网络加载后的状态VIew，接下来看具体的封装。
首先上自定义的这个StateViewHelper类
public abstract class StateViewHelper {
public static final int MODE_LOADING = 0;
public static final int MODE_CONTENT = 1;
public static final int MODE_EMPTY = 2;
public static final int MODE_ERROR = 3;
private int mMode = MODE_CONTENT;
private View[] mModeViews = new View[4];
private ViewGroup.LayoutParams[] mModeParams = new ViewGroup.LayoutParams[4];
private Context mContext;
private ViewGroup mContent ;
public StateViewHelper(Context context){
super();
this.mContext = context;
}
//将父View添加进来
public void setContentRoot(ViewGroup contentView) {
this.mContent = contentView;
}
//根据Id设置View到父View里面
public void setContentView(int layoutResID) {
View view = LayoutInflater.from(mContext).inflate(layoutResID, mContent, false);
ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT
);
setContentView(view, params);
}
//设置View到父View里面
public void setContentView(View view) {
ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT
);
setContentView(view, params);
}
//根据布局参数添加到父View里面
public void setContentView(View view, ViewGroup.LayoutParams params) {
setModeView(view, params, MODE_CONTENT);
}
//添加四种布局 的View 和 Mode
public void setModeView(View view, int mode) {
ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT
);
setModeView(view, params, mode);
}
public void setModeView(int view, int mode) {
View subView = LayoutInflater.from(mContext).inflate(view, mContent, false);
ViewGroup.LayoutParams params = new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT
);
setModeView(subView, params, mode);
}
public void setModeView(View view, ViewGroup.LayoutParams params, int mode) {
checkMode(mode);//检查，只允许4种View中的mode存在
mModeViews[mode] = view;//添加mode 和 Params到数组中
mModeParams[mode] = params;
if(mMode == mode&&mContent!=null){//如果是ContentVIew的话 就添加到父VIew中
clearContentView();
mContent.addView(view,params);
}
}
//通过父View去查找子VIew
public View findViewById(int id){
if(mContent!=null){
View view = mContent.findViewById(id);
return view;
}
return null;
}
//清楚父VIew中的子VIew
private void clearContentView() {
if( mContent!=null){
for (int i = 0, size = mContent.getChildCount(); i < size; i++) {
View subView = mContent.getChildAt(i);
if (onViewClear(subView)) {
mContent.removeView(subView);
}
}
}
}
//子类实现，如果子View不等于null 并且 不等于Toolbar，因为子VIew里面也会包含Toolbar，所以需要去掉
public abstract boolean onViewClear(View subView);
//根据逻辑设置不同的mode，然后去改变子VIew
public void setMode(int mode){
if(mode == mMode) return;
checkMode(mode);
mMode = mode;
clearContentView();
View mModeView = mModeViews[mode];
if (mModeView == null) return;
ViewGroup.LayoutParams mModeParam = mModeParams[mode];
if (mModeParam == null) {
mModeParam = new ViewGroup.LayoutParams(
ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.WRAP_CONTENT
);
}
if (mContent == null) return;
mContent.addView(mModeView,mModeParam);
//如果是加载的View，就添加动画
if(mode==MODE_LOADING){
final ImageView mAnimationView = (ImageView) findViewById(R.id.h_x_loading);
Animation hyperspaceJumpAnimation = AnimationUtils.loadAnimation(
mContext, R.anim.loading_animation);
mAnimationView.startAnimation(hyperspaceJumpAnimation);
}
}
private void checkMode(int mode) {
if (mode != MODE_LOADING && mode != MODE_ERROR
&& mode != MODE_EMPTY && mode != MODE_CONTENT) {
throw new IllegalStateException("illegal mode for content, please check StateViewHelper");
}
}
public int getMode() {
return mMode;
}
}
代码注释每一个都写好了，不讲解了，懒。。。
再来看下第2 基类，之所以说是第2基类，就是任何项目都可以去基础的类叫基类，第2基类是说在某一个项目中需要使用到这个功能，就可以定义在第2基类中。
public class TitleActivity extends BaseActivity {
private StateViewHelper stateViewHelper;
private Toolbar mToolbar;
private ActionBar mActionBar;
@Override
public void onInitView(Bundle savedInstanceState) {
super.onInitView(savedInstanceState);
super.setContentView(R.layout.common_title_bar);
mToolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(mToolbar);
mActionBar = getSupportActionBar();
if (mActionBar != null) {
mActionBar.setDisplayHomeAsUpEnabled(true);
}
//初始化 为ContentView
stateViewHelper = new BaseStateViewWrapper(this);
setMode(StateViewHelper.MODE_CONTENT);
stateViewHelper.setContentRoot((ViewGroup) findViewById(R.id.container));
//添加三种mode的View进去
stateViewHelper.setModeView(R.layout.view_activity_loading, StateViewHelper.MODE_LOADING);
stateViewHelper.setModeView(R.layout.view_activity_error, StateViewHelper.MODE_ERROR);
stateViewHelper.setModeView(R.layout.view_activity_empty, StateViewHelper.MODE_EMPTY);
}
//先去找父View一个级别的view，如果为null，则去找子VIew里面的view
public View findViewById(int id){
View view = super.findViewById(id);
if(view!=null){
return view;
} else {
return stateViewHelper.findViewById(id);
}
}
public Toolbar getToolbar() {
mToolbar = (Toolbar) findViewById(R.id.toolbar);
return mToolbar;
}
@Override
public void setTitle(CharSequence title) {
super.setTitle(title);
mToolbar.setTitle(title);
}
@Override
public void setTitle(int titleId) {
super.setTitle(titleId);
mToolbar.setTitle(titleId);
}
public void hideTitleBar() {
if (mActionBar != null) {
mActionBar.hide();
}
}
//设置ContentVIew，子类调用
public void setContentView(int layoutResID) {
stateViewHelper.setContentView(layoutResID);
}
public void setContentView(View view) {
stateViewHelper.setContentView(view);
}
public void setContentView(View view, ViewGroup.LayoutParams params) {
stateViewHelper.setContentView(view, params);
}
public void setModeView(View view, int mode) {
stateViewHelper.setModeView(view, mode);
}
public void setModeView(int view, int mode) {
stateViewHelper.setModeView(view, mode);
}
public void setMode(int mode) {
stateViewHelper.setMode(mode);
}
public int getMode() {
return stateViewHelper.getMode();
}
private class BaseStateViewWrapper extends StateViewHelper {
public BaseStateViewWrapper(Context context) {
super(context);
}
@Override
public boolean onViewClear(View subView) {
return subView != null && subView != mToolbar;
}
}
}
第2基类的xml布局：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="?attr/colorPrimary"
android:fitsSystemWindows="true"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
<include layout="@layout/toolbar_default" />
<FrameLayout
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
android:background="@color/theme_color"/>
</LinearLayout>
就是一个Toolbar和一个FrameLayout，FrameLayout用来填充子VIew的。经过这样封装之后，需要改变View，直接使用SetMode（mode）,就可以来实现。
