监测Android Market是否被下过

 try {
        PackageManager manager = context.getPackageManager(); 
        PackageInfo appInfo = manager.getPackageInfo(
            YOUR_PACKAGE_NAME, PackageManager.GET_SIGNATURES);

        // Now test if the first signature equals your debug key.
        boolean shouldUseTestServer = 
            appInfo.signatures[0].toCharsString().equals(YOUR_DEBUG_KEY);

    } catch (NameNotFoundException e) {
        // Expected exception that occurs if the package is not present.
    }

 备用留作