Android編程之仿微信顯示更多文字的View

微信朋友圈中，如果好友發表的文字過長，會自動收縮起來，底下有提示，當點擊“顯示更多”時才會展開。

首先定義布局文件（很簡單，不解釋）：

<?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">顯示更多</string> 

    <string name="desc_shrinkup">收起</string>
    <string name="desc_spread">顯示更多</string>

接下來就是對文字的處理，原理就是設置TextView最大行數。

先判斷文字是否超過了規定的行數，如果沒超過，不顯現“顯示更多”的文字提示。當文字超過了，就顯示“顯示更多”的文字提示。用戶點擊“顯示更多”後，設置最大行數為最大。

補一句：微信的默認最大行數是10行，我這裡設置是2行。你可以自行設置該值DEFAULT_MAX_LINE_COUNT。

代碼如下：

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_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;
            }
        }
    }
}