执行静默安装时，需要向手机申请获取root权限，如果手机具有root权限，则可以完成安装。代码如下：

MainActivity：

package com.home.checkroot;

import java.io.DataOutputStream;
import java.io.File;
import java.io.OutputStream;

import android.os.Bundle;
import android.os.Environment;
import android.app.Activity;
import android.util.Log;

public class MainActivity extends Activity {
	private static final String TAG = "MainActivity";

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		// 笔者手机上的apk路径
		String apkName = Environment.getExternalStorageDirectory().toString()
				+ File.separator + "police.apk";
		Log.e(TAG, "root = " + haveRoot("pm install -r " + apkName));
	}

	/**
	 * 检测是否具体root权限
	 * 
	 * @param cmd
	 * @return
	 */
	private boolean haveRoot(String cmd) {
		int i = execRootCmdSilent(cmd);
		if (i != -1) {
			return true;
		}
		return false;
	}

	/**
	 * 执行静默安装
	 * 
	 * @param paramString
	 * @return
	 */
	private int execRootCmdSilent(String paramString) {
		int result = -1;
		try {
			Process localProcess = Runtime.getRuntime().exec("su");
			OutputStream os = localProcess.getOutputStream();
			DataOutputStream dos = new DataOutputStream(os);
			dos.writeBytes(paramString + "\n");
			dos.flush();
			dos.writeBytes("exit\n");
			dos.flush();
			localProcess.waitFor();
			result = localProcess.exitValue();
		} catch (Exception e) {
			e.printStackTrace();
		}
		return result;
	}
}

权限：

    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

检测手机是否具有root权限和静默安装