判断某一款应用（通过包名）是否安装，如果安装直接打开，否则弹出下载对话框（V1.0）

MainActivity.java中 downloadApp() 方法用于调用

public void downloadApp(){
		String packageName = "org.bojoy.publish";/** Tesr 测试包名*/
		final String downloadURL = "http://www.haowanyou.com/";/**  Test  测试跳转下载的页面*/
		Intent intent = null;
		PackageManager packageManager = context.getPackageManager(); 
		if (AppIsInstall.appIsInstall(context, packageName)){
			intent = packageManager.getLaunchIntentForPackage(packageName);
			activity.startActivity(intent);
		}else {
			final BJMSdkDialog dialog = new BJMSdkDialog(context);// 这是自定义的dialog  测试请用系统的
			dialog.setTitle(Util.getString(Resource.string.bjmgf_sdk_dock_dialog_to_download_app_title, context));
			dialog.setMessage(Util.getString(Resource.string.bjmgf_sdk_dock_dialog_to_download_app_str, context));
			dialog.setNegativeButton(Util.getString(Resource.string.bjmgf_sdk_dock_dialog_sure_download_btn_str, 
					context), new OnClickListener() {
				
				@Override
				public void onClick(View v) {
					dialog.dismiss();
					Util.openUrl(activity, downloadURL);
				}
			});
			dialog.setPositiveButton(Util.getString(Resource.string.bjmgf_sdk_dock_dialog_btn_cancel_str,
							context), new OnClickListener() {
				
				@Override
				public void onClick(View v) {
					dialog.dismiss();
				}
			});
			dialog.show();
		}
	
	}

Util.java 中 openUrl()方法调用系统浏览器，这是如果没有安装调用浏览器跳转到下载页面

/**
	 * 调用浏览器打开网页
	 * @param activity
	 * @param url
	 */
	public final static void openUrl(Activity activity, String url) {
		if (stringIsEmpty(url)) {
			return;
		}
		LogProxy.i(TAG, url);
		Intent intent = new Intent();
		intent.setAction(Intent.ACTION_VIEW);
		Uri content_url = Uri.parse(url);
		intent.setData(content_url);
		activity.startActivity(Intent.createChooser(intent, "打开页面"));
//		activity.startActivity(intent);
	}

再开一个工具类Utils.java 里面的判断方法

package org.bojoy.gamefriendsdk.app.utils;

import java.util.List;

import org.bojoy.core.utils.LogProxy;

import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.Context;

/**
 * @author luzhenyu
 * AppIsInstall 判断某款应用是否安装的工具
 * @param context - Context
 * @param packageName - String
 * @return true/false
 * */
public class AppIsInstall {
	private String packageName = null;
	private static boolean flag = false;
	public static boolean appIsInstall(Context context, String packageName) {
		final PackageManager packageManager = context.getPackageManager();// 获取packagemanager
		List<PackageInfo> packageInfoList = packageManager
				.getInstalledPackages(0);
		if (packageName == null || "".equals(packageName)) {
			return false;
		}

		for (int i = 0; i < packageInfoList.size(); i++) {
			PackageInfo pak = (PackageInfo) packageInfoList.get(i);
			if (packageName.trim().equals(pak.packageName.trim())) {
				flag = true;
                                break;
			} else {
				flag = false;
			}
		}
		return flag;
	}
}

OK！！！

参考博客：http://blog.csdn.net/liguangzhenghi/article/details/8185751