1. 监听GridView的onItemClick事件
设置一个监听器是为了当gridView的某项被点击时，会有一个回调函数通知我们。
我们调用appsGrid.setOnItemClickListener(listener); 设置一个监听器
appsGrid.setOnItemClickListener(listener)中的listener是一个接口，其类型为：android.widget.AdapterView.OnItemClickListener
下面我们new一个android.widget.AdapterView.OnItemClickListener类型的对象作为参数。我们直接使用eclipde的自动补全功能来完成OnItemClickListener 的定义：
private OnItemClickListener listener = new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
}
}接口OnItemClickListener 中有一个方法叫做onItemClick，我们实现它即可。下面我对onItemClick的几个参数略作说明：
parent 略
view 被点击的view
position 被点击项的位置
id 被点击项的id
2.启动被点击应用的activity
一般来讲，我们根据position即可知道被点击的项目是哪一项了。现在我们根据被点击的项目，取出对应的应用程序数据（主要是其中的主activity），然后启动activity。用下面代码实现：
private OnItemClickListener clickListener = new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
ResolveInfo info = apps.get(i);
//该应用的包名
String pkg = info.activityInfo.packageName;
//应用的主activity类
String cls = info.activityInfo.name;
ComponentName componet = new ComponentName(pkg, cls);
Intent intent = new Intent();
intent.setComponent(componet);
startActivity(intent);
}
};private OnItemClickListener clickListener = new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
ResolveInfo info = apps.get(i);
//该应用的包名
String pkg = info.activityInfo.packageName;
//应用的主activity类
String cls = info.activityInfo.name;
ComponentName componet = new ComponentName(pkg, cls);
Intent intent = new Intent();
intent.setComponent(componet);
startActivity(intent);
}
};代码中的中文注释可能会引起Gradle报错
解决办法：http://blog.csdn.net/sljjyy/article/details/11976099
现在整个类代码如下：
package com.sljjyy.sao.launcher;
import android.content.ComponentName;
import android.content.Intent;
import android.content.pm.ResolveInfo;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.AdapterView.OnItemClickListener;
import java.util.List;
public class MainActivity extends Activity {
GridView appsGrid;
private List<ResolveInfo> apps;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
loadApps();
appsGrid = (GridView) findViewById(R.id.apps_list);
appsGrid.setAdapter(new AppsAdapter());
appsGrid.setOnItemClickListener(clickListener);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
private OnItemClickListener clickListener = new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
ResolveInfo info = apps.get(i);
//该应用的包名
String pkg = info.activityInfo.packageName;
//应用的主activity类
String cls = info.activityInfo.name;
ComponentName componet = new ComponentName(pkg, cls);
Intent intent = new Intent();
intent.setComponent(componet);
startActivity(intent);
}
};
private void loadApps() {
Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
new ImageView(MainActivity.this);
apps = getPackageManager().queryIntentActivities(mainIntent, 0);
}
public class AppsAdapter extends BaseAdapter {
public AppsAdapter(){
}
@Override
public int getCount() {
return apps.size();
}
@Override
public Object getItem(int i) {
return apps.get(i);
}
@Override
public long getItemId(int i) {
return i;
}
@Override
public View getView(int i, View view, ViewGroup viewGroup) {
ImageView iv;
if(view == null){
iv = new ImageView(MainActivity.this);
iv.setScaleType(ImageView.ScaleType.FIT_CENTER);
iv.setLayoutParams(new GridView.LayoutParams(50, 50));
} else {
iv = (ImageView) view;
}
ResolveInfo info = apps.get(i);
iv.setImageDrawable(info.activityInfo.loadIcon(getPackageManager()));
return iv;
}
}
}android手把手教你开发launcher（二）——列出安装的应用程序
android手把手教你开发launcher（三）——启动安装的应用程序
android手把手教你开发launcher（四）——显示widget
android手把手教你开发launcher（五）——设置壁纸
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