Android编程之仿微信显示更多文字的View
微信朋友圈中，如果好友发表的文字过长，会自动收缩起来，底下有提示，当点击“显示更多”时才会展开。
首先定义布局文件（很简单，不解释）：
<?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="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/desc_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="4.0dip"
android:gravity="center_vertical"
android:textColor="#ff000000"
android:textSize="14.0dip" />
<TextView
android:id="@+id/desc_op_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="4.0dip"
android:gravity="center"
android:singleLine="true"
android:textColor="#ff576b95"
android:textSize="14.0dip"
android:visibility="gone" />
</LinearLayout>
<?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="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/desc_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="4.0dip"
android:gravity="center_vertical"
android:textColor="#ff000000"
android:textSize="14.0dip" />
<TextView
android:id="@+id/desc_op_tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="4.0dip"
android:gravity="center"
android:singleLine="true"
android:textColor="#ff576b95"
android:textSize="14.0dip"
android:visibility="gone" />
文字：
string name="desc_shrinkup">收起</string>
<string name="desc_spread">显示更多</string>
<string name="desc_shrinkup">收起</string>
<string name="desc_spread">显示更多</string>
接下来就是对文字的处理，原理就是设置TextView最大行数。
先判断文字是否超过了规定的行数，如果没超过，不显现“显示更多”的文字提示。当文字超过了，就显示“显示更多”的文字提示。用户点击“显示更多”后，设置最大行数为最大。
补一句：微信的默认最大行数是10行，我这里设置是2行。你可以自行设置该值DEFAULT_MAX_LINE_COUNT。
代码如下：
public class CollapsibleTextView extends LinearLayout implements
OnClickListener {
/** default text show max lines */
private static final int DEFAULT_MAX_LINE_COUNT = 2;
private static final int COLLAPSIBLE_STATE_NONE = 0;
private static final int COLLAPSIBLE_STATE_SHRINKUP = 1;
private static final int COLLAPSIBLE_STATE_SPREAD = 2;
private TextView desc;
private TextView descOp;
private String shrinkup;
private String spread;
private int mState;
private boolean flag;
public CollapsibleTextView(Context context, AttributeSet attrs) {
super(context, attrs);
shrinkup = context.getString(R.string.desc_shrinkup);
spread = context.getString(R.string.desc_spread);
View view = inflate(context, R.layout.collapsible_textview, this);
view.setPadding(0, -1, 0, 0);
desc = (TextView) view.findViewById(R.id.desc_tv);
descOp = (TextView) view.findViewById(R.id.desc_op_tv);
descOp.setOnClickListener(this);
}
public CollapsibleTextView(Context context) {
this(context, null);
}
public final void setDesc(CharSequence charSequence, BufferType bufferType) {
desc.setText(charSequence, bufferType);
mState = COLLAPSIBLE_STATE_SPREAD;
requestLayout();
}
@Override
public void onClick(View v) {
flag = false;
requestLayout();
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
if (!flag) {
flag = true;
if (desc.getLineCount() <= DEFAULT_MAX_LINE_COUNT) {
mState = COLLAPSIBLE_STATE_NONE;
descOp.setVisibility(View.GONE);
desc.setMaxLines(DEFAULT_MAX_LINE_COUNT + 1);
} else {
post(new InnerRunnable());
}
}
}
class InnerRunnable implements Runnable {
@Override
public void run() {
if (mState == COLLAPSIBLE_STATE_SPREAD) {
desc.setMaxLines(DEFAULT_MAX_LINE_COUNT);
descOp.setVisibility(View.VISIBLE);
descOp.setText(spread);
mState = COLLAPSIBLE_STATE_SHRINKUP;
} else if (mState == COLLAPSIBLE_STATE_SHRINKUP) {
desc.setMaxLines(Integer.MAX_VALUE);
descOp.setVisibility(View.VISIBLE);
descOp.setText(shrinkup);
mState = COLLAPSIBLE_STATE_SPREAD;
}
}
}
}
public class CollapsibleTextView extends LinearLayout implements
OnClickListener {
/** default text show max lines */
private static final int DEFAULT_MAX_LINE_COUNT = 2;
private static final int COLLAPSIBLE_STATE_NONE = 0;
private static final int COLLAPSIBLE_STATE_SHRINKUP = 1;
private static final int COLLAPSIBLE_STATE_SPREAD = 2;
private TextView desc;
private TextView descOp;
private String shrinkup;
private String spread;
private int mState;
private boolean flag;
public CollapsibleTextView(Context context, AttributeSet attrs) {
super(context, attrs);
shrinkup = context.getString(R.string.desc_shrinkup);
spread = context.getString(R.string.desc_spread);
View view = inflate(context, R.layout.collapsible_textview, this);
view.setPadding(0, -1, 0, 0);
desc = (TextView) view.findViewById(R.id.desc_tv);
descOp = (TextView) view.findViewById(R.id.desc_op_tv);
descOp.setOnClickListener(this);
}
public CollapsibleTextView(Context context) {
this(context, null);
}
public final void setDesc(CharSequence charSequence, BufferType bufferType) {
desc.setText(charSequence, bufferType);
mState = COLLAPSIBLE_STATE_SPREAD;
requestLayout();
}
@Override
public void onClick(View v) {
flag = false;
requestLayout();
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
if (!flag) {
flag = true;
if (desc.getLineCount() <= DEFAULT_MAX_LINE_COUNT) {
mState = COLLAPSIBLE_STATE_NONE;
descOp.setVisibility(View.GONE);
desc.setMaxLines(DEFAULT_MAX_LINE_COUNT + 1);
} else {
post(new InnerRunnable());
}
}
}
class InnerRunnable implements Runnable {
@Override
public void run() {
if (mState == COLLAPSIBLE_STATE_SPRE补充：移动开发 , Android ,
