自定义TextView文本收缩，展开，例如：了解更多

项目里遇到一个需求：一段描述性内容只显示三行，如果超出了三行就在第三行尾部显示---了解更多，点击了解更多能展开全部内容，点击收起，则显示三行的内容，因为项目需求，本项目吧，展开和收起代码注释了，如有需求，取消注释过的代码就行，本项目实现的点击了解更多跳转一个新的Activity(再次用Toast代替跳转效果)

效果如下：

                                 



代码如下：

MainActivity.class

package com.example.administrator.myapplication2222;

import android.annotation.SuppressLint;
import android.os.Build;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.text.Html;
import android.view.ViewTreeObserver;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
private String testStr="我怕来不及,我要抱着你直到,感觉你的皱纹有,了岁月的痕迹,直到肯定你是真,的直到失去力气为,了你 我愿意动,也不能动 也,要看着你,直到感觉,你的发线有了白雪的痕迹";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(sa
4000
vedInstanceState);
setContentView(R.layout.activity_main);
final OverTextView tv_over = (OverTextView) findViewById(R.id.tv_over);
tv_over.setText(Html.fromHtml(testStr));
tv_over.setBackColor("#ff0000");
tv_over.getViewTreeObserver().addOnGlobalLayoutListener(
new ViewTreeObserver.OnGlobalLayoutListener() {

@SuppressLint("NewApi")
@Override
public void onGlobalLayout() {
tv_over.replaceTips();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
tv_over.getViewTreeObserver()
.removeOnGlobalLayoutListener(this);
} else {
tv_over.getViewTreeObserver()
.removeGlobalOnLayoutListener(this);
}
}
});
tv_over.setOnCustomLinkClickListener(new OverTextView.OnCustomLinkClickListener() {

@Override
public void onCustomLinkClick() {
Toast.makeText(MainActivity.this, "点我干嘛", Toast.LENGTH_LONG)
.show();
}
});
}
}

 2.自定义的TextView

OverT

package com.example.administrator.myapplication2222;

import android.text.SpannableStringBuilder;
import android.widget.TextView;
import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.Color;
import android.os.Build;
import android.text.Layout;
import android.text.Selection;
import android.text.Spannable;
import android.text.SpannableString;
import android.text.Spanned;
import android.text.TextPaint;
import android.text.TextUtils;
import android.text.method.LinkMovementMethod;
import android.text.style.BackgroundColorSpan;
import android.text.style.ClickableSpan;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.TextView;
/**
* Created by Administrator on 2016/12/29.
*/

public class OverTextView extends TextView {
/**
* 文字超出时的提示信息
*/
private String mTips = "了解更多";

private OnCustomLinkClickListener mOnCustomLinkClickListener;

// 点击后背景颜色显示
private int mBackColor = -1;

private int mStart = -1;
private int mEnd = -1;

public OverTextView(Context context) {
super(context);
}

public OverTextView(Context context, AttributeSet attrs) {
super(context, attrs);
}

public OverTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
boolean result = super.onTouchEvent(event);
int action = event.getAction();

int x = (int) event.getX();
int y = (int) event.getY();

x -= getTotalPaddingLeft();
y -= getTotalPaddingTop();

x += getScrollX();
y += getScrollY();

Layout layout = getLayout();
// 获取当前点击位置所在的行
int line = layout.getLineForVertical(y);
// 获取当前点击位置的文本的偏移值
int off = layout.getOffsetForHorizontal(line, x);

CharSequence text = getText();
if (TextUtils.isEmpty(text) || !(text instanceof Spannable)) {
return result;
}

Spannable buffer = (Spannable) text;
ClickableSpan[] link = buffer.getSpans(off, off, ClickableSpan.class);

if (link.length != 0) {
if (action == MotionEvent.ACTION_DOWN) {
mStart = buffer.getSpanStart(link[0]);
mEnd = buffer.getSpanEnd(link[0]);
if (mStart >= 0 && mEnd >= mStart) {
buffer.setSpan(new BackgroundColorSpan(getBackColor()),
mStart, mEnd, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
}
} else if (action == MotionEvent.ACTION_UP
|| action == MotionEvent.ACTION_CANCEL) {

if (mStart >= 0 && mEnd >= mStart) {
buffer.setSpan(new BackgroundColorSpan(Color.TRANSPARENT),
mStart, mEnd, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);

mStart = -1;
mEnd = -1;
}
}

return true;
} else {
if (mStart >= 0 && mEnd >= mStart) {
buffer.setSpan(new BackgroundColorSpan(Color.TRANSPARENT),
mStart, mEnd, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
mStart = -1;
mEnd = -1;
}
Selection.removeSelection(buffer);
return false;
}
}

/**
* 文本宽度超出TextView的范围的具体项值
*
* @param0表示不考虑提示文本
* @return -1 表示没有超过TextView的范围。
*/
@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
private int starOverFlow(String text, float tipsWidth) {
if (TextUtils.isEmpty(text)) {
return -1;
}
text=text.trim();
TextPaint paint = getPaint();
// 文字总宽度

10593
float width = paint.measureText(text);
float rangeWidth = 0;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
rangeWidth = getLayout().getWidth() * getMaxLines() - tipsWidth;
} else {
rangeWidth = getLayout().getWidth() * getLayout().getLineCount()
- tipsWidth;
}
if (width > rangeWidth) {
/*
* \u2026为文本超出时系统显示的省略号
*/
return paint.breakText(text, true,
rangeWidth - paint.measureText("\u2026"), null);
} else {
return -1;
}
}

/**
* 测量文字宽度
*
* @param text
* @return
*/
private float measureTextWidth(String text) {
if (TextUtils.isEmpty(text)) {
return 0;
}
TextPaint paint = getPaint();
return paint.measureText(text);
}

/**
* 替换文本
*
* 请在该控件显示后调用
*
* @param tips
*            要替换的提示文本
*/
public void replaceTips(String tips) {
if (TextUtils.isEmpty(tips)) {
tips = mTips;
}
// 算出提示文本附加的位置
int index = starOverFlow(getText().toString(), measureTextWidth(tips.trim()));
if (index > 0) {
/**
* 多截取几个，避免显示不统一（有些文本时，提示文本可能会显示不全）
*/
String sl="…";//此省略号为中文的。
String willText = getText().toString()
.substring(0, index-sl.length());
willText = willText +"… "+ tips;
SpannableStringBuilder s = new SpannableStringBuilder(willText);
SpannableString style = new SpannableString(s);
// style.setSpan(new ForegroundColorSpan(Color.BLUE),
// willText.indexOf(tips), willText.length(),
// Spanned.SPAN_INCLUSIVE_INCLUSIVE);
MyClickSpan myClickSpan = new MyClickSpan();
style.setSpan(myClickSpan, willText.indexOf(tips),
willText.length(), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
setMovementMethod(LinkMovementMethod.getInstance());
setText(style);

// // 标识文本可被编辑
// setText(willText, BufferType.EDITABLE);
// Editable et = getEditableText();
// et.setSpan(new ForegroundColorSpan(Color.BLUE),
// willText.indexOf(tips), willText.length(),
// Spanned.SPAN_INCLUSIVE_INCLUSIVE);
}
}

/**
* 获取点击后背景颜色显示，默认灰色
*
* @return
*/
public int getBackColor() {
if (mBackColor == -1) {
return Color.GRAY;
}
return mBackColor;
}

/**
* 设置点击后背景颜色
*
* @param mBackColor
*            请勿填写颜色资源ID
*/
public void setBackColor(int mBackColor) {
this.mBackColor = mBackColor;
}

/**
* 设置点击后背景颜色
*
* @param mBackColor
*            颜色值 如：#000000 #00000000 或者 green red 的颜色名称
*/
public void setBackColor(String mBackColor) {
if (!TextUtils.isEmpty(mBackColor)) {
this.mBackColor = Color.parseColor(mBackColor);
}
}

/**
* 使用颜色资源ID设置点击后背景颜色
*
* @param resId
*            资源ID值
*/
public void setBackColorByRes(int resId) {
try {
this.mBackColor = getContext().getResources().getColor(resId);
} catch (Exception e) {
e.printStackTrace();
}
}

/**
* 设置自定义的链接的点击事件
*
* @param mOnCustomLinkClickListener
*/
public void setOnCustomLinkClickListener(
OnCustomLinkClickListener mOnCustomLinkClickListener) {
this.mOnCustomLinkClickListener = mOnCustomLinkClickListener;
}

/**
* 替换文本
*
* 请在该控件显示后调用
*/
public void replaceTips() {
replaceTips(null);
}

public class MyClickSpan extends ClickableSpan {

@Override
public void onClick(View arg0) {
Spannable spannable = (Spannable) ((TextView) arg0).getText();
Selection.removeSelection(spannable);
if (mOnCustomLinkClickListener != null) {
mOnCustomLinkClickListener.onCustomLinkClick();
}
}

@Override
public void updateDrawState(TextPaint ds) {
ds.setUnderlineText(false);
ds.setColor(Color.BLUE);
}
}

/**
* 自定义的链接点击事件
*
* @author frj
*
*/
public interface OnCustomLinkClickListener {
/**
* 自定义链接点击
*/
void onCustomLinkClick();
}

}

extView.class