Define Alternative Styles 定义替代样式
让你的app,使用Material Design的主题运行在支持它的设备上,并在早期版本的设备上可以运行较早的主题:
1. 在res/values/styles.xml 定义一个主题继承较早的主题
2. 在res/values-v21/styles.xml 定义一个相同名字的继承自Material主题 的主题
3. 在manifest中应用定义的主题
注:如果你的app使用了Material 主题,而不提供较早的主题,那么将不能运行在早期版本的设备上
Provide Alternative Layouts 提供替代布局
如果你设计的layout不引用任何的5.0中的xml属性,那么可以运行在早期版本的Android设备上。否则,你可提供一个替代布局。
替代布局建立在res/layout-v21/
为了避免重复代码,可以在res/values/ 定义你的styles,新风格的在res/values-21/ 中定义,并使用style的继承,在res/values中定义一个baseStyle,在res/values-21中继承它。
Use the Support Library 使用支持库
v7 support library 包括以下的一些特性:
System widgets 系统组件
Theme.AppCompat 主题提供的Material Design 风格的组件有:
EditText Spinner CheckBox Radiobutton SwitchCompat CheckedTextViewColor Palette
使用v7支持库,获得Material Design 风格定义颜色板,应用一个Theme.AppCompat 主题:
<!-- extend one of the Theme.AppCompat themes -->
<style name="Theme.MyTheme" parent="Theme.AppCompat.Light">
<!-- customize the color palette -->
<item name="colorPrimary">@color/material_blue_500</item>
<item name="colorPrimaryDark">@color/material_blue_700</item>
<item name="colorAccent">@color/material_green_A200</item>
</style>
Lists and Cards
使用v7支持库后,在早期的Android版本上也可运行。
Dependencies
gradle 依赖:
dependencies {
compile 'com.android.support:appcompat-v7:21.0.+'
compile 'com.android.support:cardview-v7:21.0.+'
compile 'com.android.support:recyclerview-v7:21.0.+'
}
Check the System Version 检查系统版本
以下特性只能在Android 5.0(API级别21)及以上:
Activity transitions 活动转换 Touch feedback 触觉反馈 Reveal animations 显示动画 Path-based animations 基于路径动画 Vector drawables 矢量图片 Drawable tinting 图片染色检查代码:
// Check if we're running on Android 5.0 or higher
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
// Call some material design APIs here
} else {
// Implement this feature without material design
}
注:要让app支持5.0,需要在manifest中Android:targetSdkVersion=21。
PS:RecyclerView
附RecyclerView的例子:
import android.app.Activity;
import android.os.Bundle;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.RecyclerView.LayoutParams;
import android.view.LayoutInflater;
import android.view.ViewGroup;
import android.widget.TextView;
public class RecyclerViewActivity extends Activity {
/*
* recyclerview提供这些内置的布局管理器:
* linearlayoutmanager 显示垂直滚动列表或水平的项目。
* gridlayoutmanager 显示在一个网格项目。
* staggeredgridlayoutmanager 显示在交错网格项目。
* 自定义的布局管理器,需要继承recyclerview.layoutmanager类。
*
* add/remove items时的动画是默认启用的。
* 自定义这些动画需要继承RecyclerView.ItemAnimator,并实现RecyclerView.setItemAnimator()
*/
private RecyclerView mRecyclerView;
private RecyclerView.Adapter mAdapter;
private RecyclerView.LayoutManager mLayoutManager;
private String[] myDataset;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.recycler_view);
mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);
// use this setting to improve performance if you know that changes
// in content do not change the layout size of the RecyclerView
mRecyclerView.setHasFixedSize(true);
// use a linear layout manager
// mLayoutManager = new LinearLayoutManager(this);
// mLayoutManager = new GridLayoutManager(this, 3, GridLayoutManager.VERTICAL, true);
//true 表示,将layout内容反转
mLayoutManager = new GridLayoutManager(this, 3, GridLayoutManager.VERTICAL, false);
//HORIZONTAL 横向滚动显示内容 VERTICAL纵向
// mLayoutManager = new GridLayoutManager(this, 3, GridLayoutManager.HORIZONTAL, false);
//方向也是指示滚动方向,例子中横向开头的数据交错了一点, 纵向的无交错
// mLayoutManager = new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.HORIZONTAL);
// mLayoutManager = new StaggeredGridLayoutManager(4, StaggeredGridLayoutManager.VERTICAL);
mRecyclerView.setLayoutManager(mLayoutManager);
// mRecyclerView.setLayoutManager(new MyLayoutMnager()); //数据不显示,可能还需要重写什么东西。。
// specify an adapter (see also next example)
setDatas();
mAdapter = new MyAdapter(myDataset);
mRecyclerView.setAdapter(mAdapter);
}
private void setDatas() {
int len = 200;
myDataset = new String[len];
for (int i = 0; i < len; i++) {
switch (i%3) {
case 0:
myDataset[i] = "中国" + i;
break;
case 1:
myDataset[i] = "美国" + i;
break;
case 2:
myDataset[i] = "澳大利亚" + i;
break;
}
}
}
class MyLayoutMnager extends RecyclerView.LayoutManager {
@Override
public LayoutParams generateDefaultLayoutParams() {
LayoutParams params = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.topMargin = 5;
return params;
}
}
class MyAdapter extends RecyclerView.Adapter<ViewHolder> {
private String[] mDataset;
// Provide a reference to the views for each data item
// Complex data items may need more than one view per item, and
// you provide access to all the views for a data item in a view holder
// Provide a suitable constructor (depends on the kind of dataset)
public MyAdapter(String[] myDataset) {
mDataset = myDataset;
}
// Create new views (invoked by the layout manager)
@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// create a new view
TextView tv = (TextView) LayoutInflater.from(parent.getContext())
.inflate(R.layout.my_text_view, parent, false);
// set the view's size, margins, paddings and layout parameters
//...
ViewHolder vh = new ViewHolder(tv); //构建一个ViewHolder
return vh;
}
// Replace the contents of a view (invoked by the layout manager)
@Override
public void onBindViewHolder(ViewHolder holder, int position) {
// - get element from your dataset at this position
// - replace the contents of the view with that element
holder.mTextView.setText(mDataset[position]);
}
// Return the size of your dataset (invoked by the layout manager)
@Override
public int getItemCount() {
return mDataset.length;
}
}
static class ViewHolder extends RecyclerView.ViewHolder {
// each data item is just a string in this case
public TextView mTextView;
public ViewHolder(TextView v) {
super(v);
mTextView = v;
}
}
}
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