【工具类】如何通过代码安装一个apk文件

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />
    <EditText
        android:id="@+id/et_path"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="/sdcard/queryAddress.apk" />
    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="install"
        android:text="安装" />
</LinearLayout>

import java.io.File;
import android.app.Activity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;

public class DemoActivity extends Activity {
    private EditText et_path;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        et_path = (EditText) this.findViewById(R.id.et_path);
    }

    public void install(View view) {
        String path = et_path.getText().toString().trim();

        Intent intent = new Intent();
        intent.setAction(Intent.ACTION_VIEW);
        // intent.setData(Uri.fromFile(new File(path)));
        // intent.setType("application/vnd.android.package-archive");
        intent.setDataAndType(Uri.fromFile(new File(path)),
                "application/vnd.android.package-archive");
        startActivity(intent);
    }
}