android4.X 通话记录分组算法 求问
如题:android4.X 通话记录分组算法中 有一个CallLogGroupBuilder.java 类的addGroups(Cursor)方法 是遍历cursor , 然后后一个号码跟前一个号码相同的话(最后的效果是放在一起) 计数,然后执行addGroup(int cursorPosition, int size, boolean expanded)方法 ;不相同就单独出来不处理.但是小弟能力有限 没有看懂addGroup的原理,求大神帮忙解释下.
public abstract class GroupingListAdapter extends BaseAdapter {
private static final int GROUP_METADATA_ARRAY_INITIAL_SIZE = 16;
private static final int GROUP_METADATA_ARRAY_INCREMENT = 128;
private static final long GROUP_OFFSET_MASK = 0x00000000FFFFFFFFL;
private static final long GROUP_SIZE_MASK = 0x7FFFFFFF00000000L;
private static final long EXPANDED_GROUP_MASK = 0x8000000000000000L;
public static final int ITEM_TYPE_STANDALONE = 0;
public static final int ITEM_TYPE_GROUP_HEADER = 1;
public static final int ITEM_TYPE_IN_GROUP = 2;
/**
* Information about a specific list item: is it a group, if so is it expanded.
* Otherwise, is it a stand-alone item or a group member.
*/
protected static class PositionMetadata {
int itemType;
boolean isExpanded;
int cursorPosition;
int childCount;
private int groupPosition;
private int listPosition = -1;
}
private Context mContext;
private Cursor mCursor;
private int mCount;
private int mGroupCount;
/**
* Information about where these groups are located in the list, how large they are
* and whether they are expanded.
*/
private long[] mGroupMetadata;
private SparseIntArray mPositionCache = new SparseIntArray();
private int mLastCachedListPosition;
private int mLastCachedCursorPosition;
private int mLastCachedGroup;
/**
* A reusable temporary instance of PositionMetadata
*/
private PositionMetadata mPositionMetadata = new PositionMetadata();
public GroupingListAdapter(Context context) {
mContext = context;
}
/**
* Scans over the entire cursor looking for duplicate phone numbers that need
* to be collapsed.
*/
private void findGroups() {
mGroupCount = 0;
mGroupMetadata = new long[GROUP_METADATA_ARRAY_INITIAL_SIZE];
if (mCursor == null) {
return;
}
//这里跳转到CallLogGroupBuilder中执行addGroups方法后返回执行下面addGroup方法
addGroups(mCursor);
}
/**
* Records information about grouping in the list. Should be called by the overridden
* {@link #addGroups} method.
*/
protected void addGroup(int cursorPosition, int size, boolean expanded) {
if (mGroupCount >= mGroupMetadata.length) {
int newSize = idealLongArraySize(mGroupMetadata.length + GROUP_METADATA_ARRAY_INCREMENT);
long[] array = new long[newSize];
System.arraycopy(mGroupMetadata, 0, array, 0, mGroupCount);
mGroupMetadata = array;
}
long metadata = ((long)size << 32) | cursorPosition;
if (expanded) {
metadata |= EXPANDED_GROUP_MASK;
}
mGroupMetadata[mGroupCount++] = metadata;
}
private int idealLongArraySize(int need) {
return idealByteArraySize(need * 8) / 8;
}
private int idealByteArraySize(int need) {
for (int i = 4; i < 32; i++)
if (need <= (1 << i) - 12)
return (1 << i) - 12;
return need;
}
public int getCount() {
if (mCursor == null) {
return 0;
}
if (mCount != -1) {
return mCount;
}
int cursorPosition = 0;
int count = 0;
for (int i = 0; i < mGroupCount; i++) {
long metadata = mGroupMetadata[i];
int offset = (int)(metadata & GROUP_OFFSET_MASK);
boolean expanded = (metadata & EXPANDED_GROUP_MASK) != 0;
int size = (int)((metadata & GROUP_SIZE_MASK) >> 32);
count += (offset - cursorPosition);
if (expanded) {
count += size + 1;
} else {
count++;
}
cursorPosition = offset + size;
}
mCount = count + mCursor.getCount() - cursorPosition;
return mCount;
}
/**
* Figures out whether the item at the specified position represents a
* stand-alone element, a group or a group child. Also computes the
* corresponding cursor position.
*/
public void obtainPositionMetadata(PositionMetadata metadata, int position) {
// If the description object already contains requested information, just return
if (metadata.listPosition == position) {
return;
}
int listPosition = 0;
int cursorPosition = 0;
int firstGroupToCheck = 0;
// Check cache for the supplied position. What we are looking for is
// the group descriptor immediately preceding the supplied position.
// Once we have that, we will be able to tell whether the position
// is the header of the group, a member of the group or a standalone item.
if (mLastCachedListPosition != -1) {
if (position <= mLastCachedListPosition) {
// Have SparceIntArray do a binary search for us.
int index = mPositionCache.indexOfKey(position);
// If we get back a positive number, the position corresponds to a group header.
if (index < 0) {
// We had a cache miss, but we did obtain valuable information anyway.
// The negative number will allow us to compute the location of
// the group header immediately preceding the supplied position.
index = ~index - 1;
if (index >= mPositionCache.size()) {
index--;
}
}
// A non-negative index gives us the position of the group header
// corresponding or preceding the position, so we can
// search for the group information at the supplied position
// starting with the cached group we just found
if (index >= 0) {
listPosition = mPositionCache.keyAt(index);
firstGroupToCheck = mPositionCache.valueAt(index);
long descriptor = mGroupMetadata[firstGroupToCheck];
cursorPosition = (int)(descriptor & GROUP_OFFSET_MASK);
}
} else {
// If we haven't examined groups beyond the supplied position,
// we will start where we left off previously
firstGroupToCheck = mLastCachedGroup;
listPosition = mLastCachedListPosition;
cursorPosition = mLastCachedCursorPosition;
}
}
for (int i = firstGroupToCheck; i < mGroupCount; i++) {
long group = mGroupMetadata[i];
int offset = (int)(group & GROUP_OFFSET_MASK);
// Move pointers to the beginning of the group
listPosition += (offset - cursorPosition);
cursorPosition = offset;
if (i > mLastCachedGroup) {
mPositionCache.append(listPosition, i);
mLastCachedListPosition = listPosition;
mLastCachedCursorPosition = cursorPosition;
mLastCachedGroup = i;
}
// Now we have several possibilities:
// A) The requested position precedes the group
if (position < listPosition) {
metadata.itemType = ITEM_TYPE_STANDALONE;
metadata.cursorPosition = cursorPosition - (listPosition - position);
return;
}
boolean expanded = (group & EXPANDED_GROUP_MASK) != 0;
int size = (int) ((group & GROUP_SIZE_MASK) >> 32);
// B) The requested position is a group header
if (position == listPosition) {
metadata.itemType = ITEM_TYPE_GROUP_HEADER;
metadata.groupPosition = i;
metadata.isExpanded = expanded;
metadata.childCount = size;
metadata.cursorPosition = offset;
return;
}
if (expanded) {
// C) The requested position is an element in the expanded group
if (position < listPosition + size + 1) {
metadata.itemType = ITEM_TYPE_IN_GROUP;
metadata.cursorPosition = cursorPosition + (position - listPosition) - 1;
return;
}
// D) The element is past the expanded group
listPosition += size + 1;
} else {
// E) The element is past the collapsed group
listPosition++;
}
// Move cursor past the group
cursorPosition += size;
}
// The required item is past the last group
metadata.itemType = ITEM_TYPE_STANDALONE;
metadata.cursorPosition = cursorPosition + (position - listPosition);
}
@Override
public int getItemViewType(int position) {
obtainPositionMetadata(mPositionMetadata, position);
return mPositionMetadata.itemType;
}
public View getView(int position, View convertView, ViewGroup parent) {
obtainPositionMetadata(mPositionMetadata, position);
View view = convertView;
if (view == null) {
view = ... //文本太长了,发帖有文字长度限制 我就不贴完整了
}
mCursor.moveToPosition(mPositionMetadata.cursorPosition);
switch (mPositionMetadata.itemType) {
//bind各种View
}
return view;
}
}
Android
CallLog
分组
补充：移动开发 , Android
