Android布局之View.measure()动态量取高度并设置布局--（例：动态计算评论高度并显示）
需求是这样的：
在应用程序的详情介绍时，有评论的版块，该页评论最多显示5条，而每条最大字数是140个字符，每条评论可能根据字数不同，所占据的高度也不一样，如有的是1行，有的是2、3行，且评论可以翻页。
图片效果如下：
如何解决这样的问题呢？
首先必须知道的是评论控件不要固定不变，而是需要动态计算并动态添加到显示面板中的。
下面通过实例来说一下。
1.定义布局
定义布局的时候，可以用AbsoluteLayout,因为高度是动态量取的，所以具体坐标是可以求得的。参考如下：
2.显示数据
显示数据，需要根据数据来计算高度，首先把数据设置到控件中，然后通过View.measure(int widthMeasureSpec, int heightMeasureSpec)量取高度,并为该View设置坐标。参考代码：
/**
* 初始化、动态计算高度
*/
public void initCommentView() {
record_temp = new CommentRecord();
mPositionRecord = new ArrayList();
mHeightRecord = new ArrayList();
int currentHeight = 0;
int maxNum = cachedComments.size();
int sum = 0;
for (int i = comment_begin_index; i < maxNum; i++) {
if (null != mCommentCache && !mCommentCache.empty()) {
comment_temp = mCommentCache.pop();
} else {
comment_temp = new CommentSimpleView(mContext);
}
mCommentUI.add(comment_temp);
comment_temp.setData(cachedComments.get(i));
comment_temp.measure(width, height);
if (MAX_COMMENT_HEIGHT > currentHeight) {
comment_content.addView(
comment_temp,
new AbsoluteLayout.LayoutParams(1386, comment_temp
.getMeasuredHeight(), 0, FIRST_COMMENT_INTERVAL
+ currentHeight));
mPositionRecord.add(FIRST_COMMENT_INTERVAL + currentHeight);
mHeightRecord.add(comment_temp.getMeasuredHeight());
currentHeight = currentHeight
+ comment_temp.getMeasuredHeight();
comment_end_index++;
sum++;
if (sum < 5) {
comment_temp.show_Divider();
} else if (sum == 5) {
comment_temp.hide_Divider();
}
}
if (MAX_COMMENT_HEIGHT < currentHeight) {
compareHeight = 1;
isEnd = false;
RelativeLayout.LayoutParams rl = (LayoutParams) comment_content
.getLayoutParams();
rl.setMargins(0, 60, 0, 0);
rl.width = 1386;
rl.height = MAX_COMMENT_HEIGHT+20;
comment_content.setLayoutParams(rl);
break;
}
if (MAX_COMMENT_HEIGHT == currentHeight) {
compareHeight = 0;
if (maxNum == comment_end_index) {
isEnd = true;
comment_pagedown.setFocusStatus(false);
} else {
isEnd = false;
}
}
}
record_temp.setHeightRecord(mHeightRecord);
record_temp.setPositionRecord(mPositionRecord);
record_temp.setBegin_index(comment_begin_index);
record_temp.setEnd_index(comment_end_index);
if (MAX_COMMENT_HEIGHT > currentHeight) {
isEnd = true;
comment_pagedown.setFocusStatus(false);
}
} int width = MeasureSpec.makeMeasureSpec(1386, MeasureSpec.EXACTLY);
int height = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
3.翻页动态计算实现
/**
* 点击下一页时，判断是否有空间剩余，若有剩余则用上一页数据补充,false:无剩余
* @return
*/
private boolean hasExtraSpace() {
if(null != cachedComments && cachedComments.size()-comment_end_index >=5){ //剩下的评论大于5条
return false;
}
int beginIndex = 0;
if(1 == compareHeight){
beginIndex = comment_end_index;
}else if(0 == compareHeight){
beginIndex = comment_end_index+1;
}
int maxSize = cachedComments.size();
int HeightSum = 0;
for(int i = beginIndex;i position = record_temp.getPositionRecord();
List height = record_temp.getHeightRecord();
if(null == position || null == height){
return;
}
int m = 0;
for(int i= begin;i<=end;i++){
if(null != mCommentCache && !mCommentCache.empty()){
comment_temp = mCommentCache.pop();
}else{
comment_temp = new CommentSimpleView(mContext);
}
mCommentUI.add(comment_temp);
comment_temp.setData(cachedComments.get(i));
comment_content.addView(comment_temp, new AbsoluteLayout.LayoutParams(1386,height.get(m), 0, position.get(m)));
m++;
if(5 == m){
comment_temp.hide_Divider();
}else{
comment_temp.show_Divider();
}
}
isEnd = false;
comment_begin_index = begin;
comment_end_index = end;
}
4.点击上一页、下一页事件处理
public class comment_pageup_click implements OkButtonViewClick {
@Override
public void onOkButtonViewClick() {
if(1 == currentPage){
// Toast.makeText(mContext, "已是第一页", Toast.LENGTH_SHORT).show();
comment_pageup.setFocusStatus(false);
return;
}else{
currentPage = currentPage - 1;
comment_content.removeAllViews();
while (!mCommentUI.isEmpty()) {
mCommentCache.push(mCommentUI.remove(0));
}
showPageUp();
comment_pagedown.setFocusStatus(true);
}
}
}
class comment_pagedown_click implements OkButtonViewClick {
@Override
public void onOkButtonViewClick() {
if(isEnd){
// Toast.makeText(mContext, "已是最后一页", Toast.LENGTH_SHORT).show();
comment_pagedown.setFocusStatus(false);
return;
}
else if(!isEnd){ //不到最后一页
if(!hasExtraSpace()){ //下一页无剩余空间，即该页不是倒数第二页
mCommentRecord.push(record_temp);
currentPage = currentPage + 1;
if(1 == compareHeight){
comment_begin_index = comment_end_index;
comment_end_index --;
}else{
comment_begin_index = comment_end_index+1;
}
if(currentPage%4 ==0){ //预加载数据
ParserHelper.getParserHelper().requestComment("1", "30", "9", callback);
}
comment_content.removeAllViews();
while (!mCommentUI.isEmpty()) {
mCommentCache.push(mCommentUI.remove(0));
}
initCommentView();
}else { //下一页有剩余空间，即该页为倒数第二页
mCommentRecord.push(record_temp);
currentPage = currentPage + 1;
comment_content.removeAllViews();
while (!mCommentUI.isEmpty()) {
mCommentCache.push(mCommentUI.remove(0));
}
showLastPage();
}
comment_pageup.setFocusStatus(true);
}
}
}5.下一页点击时保存状态，用作恢复。（用栈保存，入栈出栈）
package com.helios.module.commentData;
import java.util.List;
public class CommentRecord {
int begin_index;
int end_index;
List positionRecord;
List heightRecord;
public CommentRecord() {
super();
}
public int getBegin_index() {
return begin_index;
}
public void setBegin_index(int begin_index) {
this.begin_index = begin_index;
}
public int getEnd_index() {
return end_index;
}
public void setEnd_index(int end_index) {
this.end_index = end_index;
}
public List getPositionRecord() {
return positionRecord;
}
public void setPositionRecord(List positionRecord) {
this.positionRecord = positionRecord;
}
public List getHeightRecord() {
return heightRecord;
}
public void setHeightRecord(List heightRecord) {
this.heightRecord = heightRecord;
}
}
6.总结语
动态计算，动态设置布局还是挺常用的。
其中的关键就是，measure()方法的使用，设置好数据就可以measure()，量好高度后，再设置到显示面板中，即调用：
ViewGroup.addView(
View child,
LayoutParams params)
第一次写动态布局，写的不好，希望大家勿喷，有疑问欢迎留言讨论，大家互相学习，慢慢进步。