RecycleView加载布局和分割线

RecyclerView 是Android L版本中新添加的一个用来取代ListView的SDK，它的灵活性与可替代性比listview更好。详细介绍看下面的链接

compile 'com.android.support:recyclerview-v7:26.1.0'

主页面和布局

<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerview"
android:layout_width="match_parent"
android:layout_height="wrap_content">

</android.support.v7.widget.RecyclerView>

public class MainActivity extends AppCompatActivity {

private RecyclerView mRecy;
List<Student> mList;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

/**
* 注意两个方法执行先后顺序，先初始化数据再初始化视图，否则报空指针
*/
initData();//初始化数据
initView();//初始化view
}

private void initView() {
// 初始化组件
mRecy = findViewById(R.id.recyclerview);
/**
* 加载布局管理器（三种管理器）
*/
// 1.线性布局管理器
mRecy.setLayoutManager(new LinearLayoutManager(this));
// 2.网格布局管理器
//        mRecy.setLayoutManager(new GridLayoutManager(this,3));
// 3.流式布局管理器
//         mRecy.setLayoutManager(new StaggeredGridLayoutManager(4,StaggeredGridLayoutManager.VERTICAL));

//添加自定义分割线
mRecy.addItemDecoration(new MyDecoration(this, MyDecoration.VERTICAL_LIST));

// 初始化适配器
StudentListAdapter mStu = new StudentListAdapter(this, mList);
mRecy.setAdapter(mStu);
}

private void initData() {
mList = new ArrayList<Student>();
for (int i = 0; i < 60; i++) {
Student s = new Student();
s.setUserName("我是第" + i + "个");
mList.add(s);
}
}
}

public class Student {
String userName;

public String getUserName() {
return userName;
}

public void setUserName(String userName) {
this.userName = userName;
}
}

public class StudentListAdapter extends RecyclerView.Adapter<StudentListAdapter.StudentViewHolder> {
Context mContext;
List<Student> mList;

public StudentListAdapter(Context mcontext, List mlist) {
this.mContext = mcontext;
this.mList = mlist;
}

// 加载视图
@Override
public StudentViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

StudentViewHolder viewHolder = new StudentViewHolder(LayoutInflater.from(mContext)
.inflate(R.layout.name_tv, parent, false));
return viewHolder;
}

// 绑定视图
@Override
public void onBindViewHolder(StudentViewHolder holder, int position) {
if (mList != null && mList.size() > 0) {
Student student = mList.get(position);
holder.name_tv.setText(student.getUserName());
}
}

// 获取当前数据条目数量
@Override
public int getItemCount() {
return mList.size();
}

// 自定义的ViewHolder，持有每个Item的的所有界面元素
class StudentViewHolder extends RecyclerView.ViewHolder {

private TextView name_tv;

public StudentViewHolder(View itemView) {
super(itemView);
name_tv = (TextView) itemView.findViewById(R.id.name_tv);
}
}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">

<<
4000
span class="hljs-title">TextView
android:id="@+id/name_tv"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="10dp"
android:paddingTop="10dp"
android:textSize="26sp" />

<ImageView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="@mipmap/ic_launcher" />

</LinearLayout>

添加RecycleView分割线

public class MyDecoration extends RecyclerView.ItemDecoration {

private Context mContext;
private Drawable mDivider;
private int mOrientation;
public static final int HORIZONTAL_LIST = LinearLayoutManager.HORIZONTAL;
public static final int VERTICAL_LIST = LinearLayoutManager.VERTICAL;

//我们通过获取系统属性中的listDivider来添加，在系统中的AppTheme中设置
public static final int[] ATRRS = new int[]{
android.R.attr.listDivider
};

public MyDecoration(Context context, int orientation) {
this.mContext = context;
final TypedArray ta = context.obtainStyledAttributes(ATRRS);
this.mDivider = ta.getDrawable(0);
ta.recycle();
setOrientation(orientation);
}

//设置屏幕的方向
public void setOrientation(int orientation) {
if (orientation != HORIZONTAL_LIST && orientation != VERTICAL_LIST) {
throw new IllegalArgumentException("invalid orientation");
}
mOrientation = orientation;
}

@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
if (mOrientation == HORIZONTAL_LIST) {
drawVerticalLine(c, parent, state);
} else {
drawHorizontalLine(c, parent, state);
}
}

//画横线, 这里的parent其实是显示在屏幕显示的这部分
public void drawHorizontalLine(Canvas c, RecyclerView parent, RecyclerView.State state) {
int left = parent.getPaddingLeft();
int right = parent.getWidth() - parent.getPaddingRight();
final int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);

//获得child的布局信息
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
final int top = child.getBottom() + params.bottomMargin;
final int bottom = top + mDivider.getIntrinsicHeight();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
//Log.d("wnw", left + " " + top + " "+right+"   "+bottom+" "+i);
}
}

//画竖线
public void drawVerticalLine(Canvas c, RecyclerView parent, RecyclerView.State state) {
int top = parent.getPaddingTop();
int bottom = parent.getHeight() - parent.getPaddingBottom();
final int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);

//获得child的布局信息
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
final int left = child.getRight() + params.rightMargin;
final int right = left + mDivider.getIntrinsicWidth();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}

//由于Divider也有长宽高，每一个Item需要向下或者向右偏移
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
if (mOrientation == HORIZONTAL_LIST) {
//画横线，就是往下偏移一个分割线的高度
outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
} else {
//画竖线，就是往右偏移一个分割线的宽度
outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
}
}
}