Launcher 是 Android 系统中的桌面启动器
首先看一下这个简易 launcher 的效果如下:
按下 home 键会提示进入我们的 launcher app，launcher 中有一个 GridView 显示所有的应用程序，点击可以进入相应的 app。(如果没有设置默认或者有多个 launcher 按下home键会提示选择进入哪个 launcher)
- 配置 manifest 如下 :
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
<category android:name="android.intent.category.HOME"/>
<category android:name="android.intent.category.DEFAULT"/>
</intent-filter>
</activity>
</application>
action android:name="android.intent.action.MAIN"表示所在的 Activity 为应用程序入口，启动 application 就启动这个 Activity
category android:name="android.intent.category.LAUNCHER"表示 app 会出现在 launcher 中
category android:name="android.intent.category.HOME"设置 app 可按下 home 键进入 ( launcher 形式 )
category android:name="android.intent.category.DEFAULT"设置 app 可以通过隐式意图打开
- 修改 activity_main 布局，使用一个 GridView 填充
<GridView
android:id="@+id/gv_item"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:numColumns="auto_fit"
android:columnWidth="96dp"
android:verticalSpacing="12dp"
android:horizontalSpacing="12dp"
android:stretchMode="columnWidth"
android:gravity="center">
</GridView>-
使用 GridView 实现 ImageView+TextView ( 上面显示app图标 / 下面显示app名字 -- 如上图效果 )
- 在 layout 中写一个 grid_item.xml 布局来显示 ImageView+TextView
<?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/iv_icon" android:layout_gravity="center" android:layout_width="90dp" android:layout_height="90dp" /> <TextView android:id="@+id/tv_title" android:layout_gravity="center" android:gravity="center" android:singleLine="true" android:layout_width="90dp" android:layout_height="wrap_content" /> </LinearLayout>
-
写一个 javabean 来存放要显示的数据 GridInfo.java
public class GridInfo { private Drawable appIcon; // 图标 private String title; // app 名字 private String packageName; // app 包名 (用来实现根据包名打开app) public GridInfo(Drawable appIcon,String title,String packageName) { this.appIcon = appIcon; this.title = title; this.packageName = packageName; } public Drawable getAppIcon() { return appIcon; } public String getTitle() { return title; } public String getPackageName() { return packageName; } }
-
自定义 GridItemAdapter 继承 BaseAdapter
public class GridItemAdapter extends BaseAdapter{ private List<GridInfo> mGridInfoList; //定义数据类 private LayoutInflater mInflater; //定义Inflater public GridItemAdapter(Context context, List<GridInfo> gridInfoList){ mGridInfoList = gridInfoList; mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); } public int getCount() { return mGridInfoList.size(); } public Object getItem(int position) { return mGridInfoList.get(position); } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { ViewHolder viewHolder = new ViewHolder(); if(convertView==null){ convertView = mInflater.inflate(R.layout.grid_item,null); viewHolder.iv = (ImageView) convertView.findViewById(R.id.iv_icon); viewHolder.tv = (TextView) convertView.findViewById(R.id.tv_title); convertView.setTag(viewHolder); }else{ viewHolder = (ViewHolder) convertView.getTag(); } //设置holder GridInfo mGridInfo = mGridInfoList.get(position); viewHolder.iv.setImageDrawable(mGridInfo.getAppIcon()); viewHolder.tv.setText(mGridInfo.getTitle()); return convertView; } private class ViewHolder{ ImageView iv; TextView tv; } }
-
MainActivity.java 实现点击图标进入相应程序
public class MainActivity extends AppCompatActivity {
GridView mGridView;
//应用的图标，名称，包名
GridInfo mGridInfo;
List<GridInfo> mGridInfoList;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//隐藏ActionBar
ActionBar actionBar = getSupportActionBar();
actionBar.hide();
setContentView(R.layout.activity_main);
// 初始化数据
init();
// 初始化View
initView();
}
private void init() {
// 获取所有可显示的应用信息
Intent mainInent = new Intent(Intent.ACTION_MAIN,null);
mainInent.addCategory(Intent.CATEGORY_LAUNCHER);
List<ResolveInfo> resolveInfos = getPackageManager().queryIntentActivities(mainInent, 0);
// 新建集合保存显示时需要的 app 信息
mGridInfoList = new ArrayList();
// 遍历 resolveInfos 获取 app 名字,图标,包名 保存在 mGridInfoList
for(ResolveInfo resolveInfo:resolveInfos){
Drawable icon = resolveInfo.activityInfo.loadIcon(getPackageManager());
String title = resolveInfo.activityInfo.loadLabel(getPackageManager()).toString();
String packageName = resolveInfo.activityInfo.packageName;
mGridInfo = new GridInfo(icon, title, packageName);
mGridInfoList.add(mGridInfo);
}
}
private void initView() {
mGridView = (GridView) findViewById(R.id.gv_item);
GridItemAdapter mAdapter = new GridItemAdapter(this,mGridInfoList);
mGridView.setAdapter(mAdapter);
//点击图标打开应用
mGridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
try {
String packageName = mGridInfoList.get(position).getPackageName();
Intent intent = MainActivity.this.getPackageManager().getLaunchIntentForPackage(packageName);
startActivity(intent);
}catch (Exception e){
Toast.makeText(MainActivity.this,"该应用无法直接打开",Toast.LENGTH_SHORT).show();
}
}
});
}
}只需如上几步即可实现上图演示的 Launcher app 效果