Android RecyclerView实现水平、垂直方向分割线

Android RecyclerView不像过去的ListView那样随意的设置水平方向的分割线，如果要实现RecyclerView的水平/垂直分割线，则需要继承自RecyclerView.ItemDecoration重写getItemOffsets方法，从而增加水平/垂直分割线。

写一个例子。

MainActivity.Java：

package zhangphil.app;import android.content.Context;import android.graphics.Color;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.support.v7.widget.RecyclerView;import android.support.v7.widget.StaggeredGridLayoutManager;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;public class MainActivity extends AppCompatActivity {  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    RecyclerView mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView);    // 两列    int spanCount = 2;    // StaggeredGridLayoutManager管理RecyclerView的布局。    StaggeredGridLayoutManager mLayoutManager = new StaggeredGridLayoutManager(spanCount, StaggeredGridLayoutManager.VERTICAL);    mRecyclerView.setLayoutManager(mLayoutManager);    //为RecyclerView增加分割线，水平和垂直方向都有。增加分割线值比如为32。    RecyclerViewItemDecoration decoration = new RecyclerViewItemDecoration(32);    mRecyclerView.addItemDecoration(decoration);    RecyclerViewAdapter mAdapter = new RecyclerViewAdapter(this);    mRecyclerView.setAdapter(mAdapter);  }  private class ItemViewHolder extends RecyclerView.ViewHolder {    private TextView text;    public ItemViewHolder(View itemView) {      super(itemView);      text = (TextView) itemView.findViewById(android.R.id.text1);      text.setTextColor(Color.WHITE);    }  }  public class RecyclerViewAdapter extends RecyclerView.Adapter<ItemViewHolder> {    private Context context;    public RecyclerViewAdapter(Context context) {      super();      this.context = context;    }    @Override    public ItemViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {      View view = View.inflate(context, android.R.layout.simple_list_item_1, null);      view.setBackgroundColor(Color.RED);      ItemViewHolder holder = new ItemViewHolder(view);      return holder;    }    @Override    public void onBindViewHolder(ItemViewHolder viewHolder, int pos) {      viewHolder.text.setText(String.valueOf(pos));    }    @Override    public int getItemCount() {      return 15;    }  }}