修改DrawerLayout只能从屏幕边缘划出的方法_drawerlayout setdrawershadow

方法来自Stack OverFlow，利用反射，修改DrawerLayout的侧滑菜单的感应范围，代码如下：

public class MainActivity extends Activity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;
 
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
 
    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
    mDrawerList = (ListView) findViewById(R.id.left_drawer);
 
    // set a custom shadow that overlays the main content when the drawer opens
    mDrawerLayout.setDrawerShadow(R.drawable.your_drawer_shadow, GravityCompat.START);
    // set up the drawer's list view with items and click listener
    mDrawerList.setAdapter(new ArrayAdapter<String>(this,
            R.layout.your_drawer_list, yourItems));
    mDrawerList.setOnItemClickListener(new DrawerItemClickListener());
 
    // enable ActionBar app icon to behave as action to toggle nav drawer
    getActionBar().setDisplayHomeAsUpEnabled(true);
    getActionBar().setHomeButtonEnabled(true);
    //关键代码
    Field mDragger = null;
    try {
        mDragger = mDrawerLayout.getClass().getDeclaredField(
                "mLeftDragger"); //mRightDragger for right obviously
    } catch (NoSuchFieldException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    mDragger.setAccessible(true);
    ViewDragHelper draggerObj = null;
    try {
        draggerObj = (ViewDragHelper) mDragger
                .get(mDrawerLayout);
    } catch (IllegalArgumentException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
 
    Field mEdgeSize = null;
    try {
        mEdgeSize = draggerObj.getClass().getDeclaredField(
                "mEdgeSize");
    } catch (NoSuchFieldException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    mEdgeSize.setAccessible(true);
    int edge = 0;
    try {
        edge = mEdgeSize.getInt(draggerObj);
    } catch (IllegalArgumentException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
 
    try {
        mEdgeSize.setInt(draggerObj, edge * 5); //optimal value as for me, you may set any constant in dp
        //You can set it even to the value you want like mEdgeSize.setInt(draggerObj, 150); for 150dp
    } catch (IllegalArgumentException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
 
    // ActionBarDrawerToggle ties together the the proper interactions
    // between the sliding drawer and the action bar app icon
    mDrawerToggle = new ActionBarDrawerToggle(
            this,                  /* host Activity */
            mDrawerLayout,         /* DrawerLayout object */
            R.drawable.ic_drawer,  /* nav drawer image to replace 'Up' caret */
            R.string.drawer_open,  /* "open drawer" description for accessibility */
            R.string.drawer_close  /* "close drawer" description for accessibility */
            ) {
        public void onDrawerClosed(View view) {
 
        }
 
        public void onDrawerOpened(View drawerView) {
 
        }
    };
    mDrawerLayout.setDrawerListener(mDrawerToggle);
 
}
}