在项目里有一个需求，点击App介绍里面的官方微信公众号，就可以直接打开微信搜索、关注。这个功能实现起来并不复杂，获取包名，用intent跳转即可。那么如何获取某一个应用的包名呢？可以反编译apk，在文件里查看，这个方法比较麻烦。我们也可以直接通过Android系统为我们提供的类PackageManager来获得PackageInfo，这个类里面包含相关应用程序的很多信息。示例用到了SwipeMenuListView，菜单里提供打开App与卸载App两个功能。主要示例代码如下：
package com.li.applistdemo;
import android.content.ComponentName;
import android.content.Intent;
import android.content.pm.ApplicationInfo;
import android.content.pm.PackageInfo;
import android.content.pm.ResolveInfo;
import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.TypedValue;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import com.baoyz.swipemenulistview.BaseSwipListAdapter;
import com.baoyz.swipemenulistview.SwipeMenu;
import com.baoyz.swipemenulistview.SwipeMenuCreator;
import com.baoyz.swipemenulistview.SwipeMenuItem;
import com.baoyz.swipemenulistview.SwipeMenuListView;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
public final int GET_ALL_APP = 0; // 所有应用程序
public final int GET_SYSTEM_APP = 1; // 系统程序
public final int GET_THIRD_APP = 2; // 第三方应用程序
public final int GET_SDCARD_APP = 3; // 安装在SDCard的应用程序
private List<PackageInfo> mAppList;
private AppListAdapter mAdapter;
private SwipeMenuListView mListView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mAppList = getPackageInfos(GET_THIRD_APP);
mListView = (SwipeMenuListView) findViewById(R.id.swipeListView);
mAdapter = new AppListAdapter();
mListView.setAdapter(mAdapter);
SwipeMenuCreator creator = new SwipeMenuCreator() {
@Override
public void create(SwipeMenu menu) {
SwipeMenuItem openItem = new SwipeMenuItem(
getApplicationContext());
openItem.setBackground(new ColorDrawable(Color.rgb(0xC9, 0xC9,0xCE)));
openItem.setWidth(dp2px(100));
openItem.setTitle("Open");
openItem.setTitleSize(18);
openItem.setTitleColor(Color.WHITE);
menu.addMenuItem(openItem);
SwipeMenuItem deleteItem = new SwipeMenuItem(
getApplicationContext());
deleteItem.setBackground(new ColorDrawable(Color.rgb(0xF9, 0x3F, 0x25)));
deleteItem.setWidth(dp2px(100));
deleteItem.setIcon(R.mipmap.ic_delete);
menu.addMenuItem(deleteItem);
}
};
mListView.setMenuCreator(creator);
mListView.setOnMenuItemClickListener(new SwipeMenuListView.OnMenuItemClickListener() {
@Override
public boolean onMenuItemClick(int position, SwipeMenu menu, int index) {
PackageInfo item = mAppList.get(position);
switch (index) {
case 0:
open(item);
break;
case 1:
uninstall(item);
mAppList.remove(position);
mAdapter.notifyDataSetChanged();
break;
}
return false;
}
});
}
private List<PackageInfo> getPackageInfos(int type){
// 0 表示不接受任何参数。其他参数都带有限制
// 版本号、APP权限只能通过PackageInfo获取，所以这里不使用getInstalledApplications()方法
List<PackageInfo> packageInfos = getPackageManager().getInstalledPackages(0);
if (packageInfos == null){
return null;
}
List<PackageInfo> result = new ArrayList<>();
switch (type) {
case GET_ALL_APP:
result = packageInfos;
break;
case GET_SYSTEM_APP: // 系统自带APP
for (PackageInfo info : packageInfos) {
// FLAG_SYSTEM = 1<<0，if set, this application is installed in
// the device's system image.
// 下面&运算有两种结果：
// 1，则flags的末位为1，即系统APP
// 0，则flags的末位为0，即非系统APP
if ((info.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) == 1) {
result.add(info);
}
}
break;
case GET_THIRD_APP: // 第三方APP
for (PackageInfo info : packageInfos) {
// FLAG_SYSTEM = 1<<0，同上
if ((info.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) == 0) {
result.add(info);
}
// 本来是系统程序，被用户手动更新后，该系统程序也成为第三方应用程序了
// FLAG_UPDATED_SYSTEM_APP = 1<<7， this is set if this
// application has been
// install as an update to a built-in system application.
else if ((info.applicationInfo.flags & ApplicationInfo.FLAG_UPDATED_SYSTEM_APP) == 1) {
result.add(info);
}
}
break;
case GET_SDCARD_APP: // 安装在SDCard的应用程序
for (PackageInfo info : packageInfos) {
// FLAG_EXTERNAL_STORAGE = 1<<18，Set to true if the application
// is
// currently installed on external/removable/unprotected storage
if ((info.applicationInfo.flags & ApplicationInfo.FLAG_EXTERNAL_STORAGE) == 1) {
result.add(info);
}
}
break;
}
return result;
}
private void uninstall(PackageInfo item) {
try {
Intent intent = new Intent(Intent.ACTION_DELETE);
intent.setData(Uri.fromParts("package", item.packageName, null));
startActivity(intent);
} catch (Exception e) {
e.printStackTrace();
}
}
private void open(PackageInfo item) {
Intent resolveIntent = new Intent(Intent.ACTION_MAIN, null);
resolveIntent.addCategory(Intent.CATEGORY_LAUNCHER);
resolveIntent.setPackage(item.packageName);
List<ResolveInfo> resolveInfoList = getPackageManager()
.queryIntentActivities(resolveIntent, 0);
if (resolveInfoList != null && resolveInfoList.size() > 0) {
ResolveInfo resolveInfo = resolveInfoList.get(0);
String activityPackageName = resolveInfo.activityInfo.packageName;
String className = resolveInfo.activityInfo.name;
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_LAUNCHER);
ComponentName componentName = new ComponentName(
activityPackageName, className);
intent.setComponent(componentName);
startActivity(intent);
}
}
class AppListAdapter extends BaseSwipListAdapter {
@Override
public int getCount() {
return mAppList.size();
}
@Override
public PackageInfo getItem(int position) {
return mAppList.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if (convertView == null) {
convertView = View.inflate(getApplicationContext(),
R.layout.item_list_app, null);
new ViewHolder(convertView);
}
ViewHolder holder = (ViewHolder) convertView.getTag();
PackageInfo item = getItem(position);
holder.iv_icon.setImageDrawable(item.applicationInfo.loadIcon(getPackageManager()));
holder.tv_name.setText(item.applicationInfo.loadLabel(getPackageManager()) + "
" + item.packageName);
return convertView;
}
class ViewHolder {
ImageView iv_icon;
TextView tv_name;
public ViewHolder(View view) {
iv_icon = (ImageView) view.findViewById(R.id.iv_icon);
tv_name = (TextView) view.findViewById(R.id.tv_name);
view.setTag(this);
}
}
@Override
public boolean getSwipEnableByPosition(int position) {
return true;
}
}
private int dp2px(int dp) {
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp,
getResources().getDisplayMetrics());
}
}
获取App列表信息比较耗时，可能会引起ANR，所以这些操作应该放在子线程里面。
获取到结果以后，我们要通过Adapter来更新UI，但是Android不允许在非UI线程里面更新UI，可以用Handler去post一个Runnable对象来解决这个问题。为什么Handler可以呢？感兴趣的可以看看 http://blog.csdn.net/ly502541243/article/details/52062179/ ，里面分析得很详细。
简单来说，通过Handler.post(Runnable r)传入的Runnable，在回调的时候会调用run方法，而直接调用线程的run方法相当于是在一个普通的类调用方法，还是在当前线程执行，并不会开启新的线程。在post中传了个Runnable，还是在主线程中，因此可以更新UI。