android手把手教你开发launcher（三）——启动安装的应用程序

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：/article/1870369.html

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（一）（AndroidStudio版）



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

转自：http://www.bangchui.org/read.php?tid=12208