Android开发中我们经常会用到各种各样的loading，于是自己总结了常用的loading并分享出来。首先来看下具体效果图：
完整源码参见：stormzhang / CustomLoading
下面主要说下代码的关键部分：
1. Frame Loading
第一个就是在app中常见的loading效果，主要是用帧动画实现的，所谓帧动画就是一组组图片顺序播放； 下面直接看下代码实现:
首先在drawable文件夹下建立一个xml文件，内容如下：
frame_loading.xml
<?xml version="1.0" encoding="UTF-8"?>
<animation-list xmlns:android="http://schemas.android.com/apk/res/android"
android:oneshot="false" >
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_01"
android:gravity="left" />
</item>
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_02"
android:gravity="left" />
</item>
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_03"
android:gravity="left" />
</item>
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_04"
android:gravity="left" />
</item>
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_05"
android:gravity="left" />
</item>
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_06"
android:gravity="left" />
</item>
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_07"
android:gravity="left" />
</item>
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_08"
android:gravity="left" />
</item>
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_09"
android:gravity="left" />
</item>
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_10"
android:gravity="left" />
</item>
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_11"
android:gravity="left" />
</item>
<item android:duration="150">
<clip
android:clipOrientation="horizontal"
android:drawable="@drawable/loading_12"
android:gravity="left" />
</item>
</animation-list>注意上面item下得clip标签，这个是必须的，不然不同的屏幕尺寸适配会有问题。然后在布局文件里这样调用：
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:indeterminateDrawable="@drawable/frame_loading" />2. Rotate Loading
第二种主要是用rotate动画来实现的，具体代码如下：
rotate_loading.xml
<rotate xmlns:android="http://schemas.android.com/apk/res/android"
android:fromDegrees="0"
android:interpolator="@android:anim/accelerate_decelerate_interpolator"
android:pivotX="50%"
android:pivotY="50%"
android:toDegrees="360" >
<bitmap
android:antialias="true"
android:filter="true"
android:src="@drawable/loading_360" />
</rotate>然后调用方法和第一种一样。
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:indeterminateDrawable="@drawable/rotate_loading" />3. Clip Loading
第三种loading的是自定义了一个组件，主要用到了ClipDrawable的setLevel()方法，代码如下：
public class CustomClipLoading extends FrameLayout {
private static final int MAX_PROGRESS = 10000;
private ClipDrawable mClipDrawable;
private int mProgress = 0;
private boolean running;
private Handler handler = new Handler() {
@Override
public void handleMessage(Message msg) {
// 如果消息是本程序发送的
if (msg.what == 0x123) {
mClipDrawable.setLevel(mProgress);
}
}
};
public CustomClipLoading(Context context) {
this(context, null, 0);
}
public CustomClipLoading(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public CustomClipLoading(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context);
}
private void init(Context context) {
View view = LayoutInflater.from(context).inflate(layout.custom_loading, null);
addView(view);
ImageView imageView = (ImageView) findViewById(id.iv_progress);
mClipDrawable = (ClipDrawable) imageView.getDrawable();
Thread s = new Thread(r);
s.start();
}
public void stop() {
mProgress = 0;
running = false;
}
Runnable r = new Runnable() {
@Override
public void run() {
running = true;
while (running) {
handler.sendEmptyMessage(0x123);
if (mProgress > MAX_PROGRESS) {
mProgress = 0;
}
mProgress += 100;
try {
Thread.sleep(18);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
};
}其中custom_loading布局文件的内容如下：
custom_loading.xml
<?xml version="1.0" encoding="utf-8"?>
<ImageView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/iv_progress"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:background="@drawable/loading_bg"
android:paddingLeft="3dp"
android:paddingTop="3dp"
android:scaleType="centerInside"
android:src="@drawable/clip_loading" />然后clip_loading的内容如下：
clip_loading.xml
<?xml version="1.0" encoding="utf-8"?>
<clip xmlns:android="http://schemas.android.com/apk/res/android"
android:clipOrientation="vertical"
android:drawable="@drawable/loading_progress"
android:gravity="bottom" >
</clip>至此这个组件就定义好了，那么接下来就是在avtivity布局文件的使用了：
<com.storm.ui.CustomClipLoading
android:layout_width="wrap_content"
android:layout_height="wrap_content" />4. Progress Wheel
第四和第五种loading只要是用到了一个开源的项目ProgressWheel,使用方法也很简单，具体见项目说明。