android中实现一个DrawerLayout滑动菜单

activity_drawer_layout.xml：
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">

<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/colorPrimary"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
android:popupTheme="@style/ThemeOverlay.AppCompat.Light" />
</FrameLayout>

<TextView
android:id="@+id/textView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="start"
android:textSize="30sp"
android:textColor="#FFFFFF"
android:background="#000000"
android:text="This is menu" />

</android.support.v4.widget.DrawerLayout>DrawerLayoutActivity.java：
package com.example.administrator.fromnew;

import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.MenuItem;

public class DrawerLayoutActivity extends AppCompatActivity {
private DrawerLayout mDrawerLayout;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_drawer_layout);
Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mDrawerLayout = (DrawerLayout)findViewById(R.id.drawer_layout);//得到DrawerLayout实例
ActionBar actionBar = getSupportActionBar();//得到ActionBar实例
if(actionBar != null){
actionBar.setDisplayHomeAsUpEnabled(true);//让导航栏按钮显示出来，Toolbar最左侧的按钮就是HomeAsUp
actionBar.setHomeAsUpIndicator(R.drawable.arrow_right_32px);//设置导航按钮图标
}
}

@Override
public boolean onOptionsItemSelected(MenuItem item){
switch(item.getItemId()){
case android.R.id.home://HomeAsUp的ID永远都是android.R.id.home
mDrawerLayout.openDrawer(GravityCompat.START);//调用方法将滑动菜单展开，这里传入参数GravityCompat.START是为了保证这里的行为和XML中定义的一致
break;
}
return true;
}
}