android textView 折叠 展开 ExpandableTextView

项目过程中可能会用到可以折叠和展开的TextView , 这里给出一种实现思路，自定义控件。

package com.example.expandtextviewdemo;

import android.content.Context;
import android.content.res.TypedArray;
import android.text.SpannableStringBuilder;
import android.util.AttributeSet;
import android.view.View;
import android.widget.TextView;

public class ExpandableTextView extends TextView {
    private static final int DEFAULT_TRIM_LENGTH = 200;
    private static final String ELLIPSIS = ".....";
 
    private CharSequence originalText;
    private CharSequence trimmedText;
    private BufferType bufferType;
    private boolean trim = true;
    private int trimLength;
 
    public ExpandableTextView(Context context) {
        this(context, null);
    }
 
    public ExpandableTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
 
        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.ExpandableTextView);
        this.trimLength = typedArray.getInt(R.styleable.ExpandableTextView_trimLength, DEFAULT_TRIM_LENGTH);
        typedArray.recycle();
 
        setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                trim = !trim;
                setText();
                requestFocusFromTouch();
            }
        });
    }
 
    private void setText() {
        super.setText(getDisplayableText(), bufferType);
    }
 
    private CharSequence getDisplayableText() {
        return trim ? trimmedText : originalText;
    }
 
    @Override
    public void setText(CharSequence text, BufferType type) {
        originalText = text;
        trimmedText = getTrimmedText(text);
        bufferType = type;
        setText();
    }
 
    private CharSequence getTrimmedText(CharSequence text) {
        if (originalText != null && originalText.length() > trimLength) {
            return new SpannableStringBuilder(originalText, 0, trimLength + 1).append(ELLIPSIS);
        } else {
            return originalText;
        }
    }
 
    public CharSequence getOriginalText() {
        return originalText;
    }
 
    public void setTrimLength(int trimLength) {
        this.trimLength = trimLength;
        trimmedText = getTrimmedText(originalText);
        setText();
    }
 
    public int getTrimLength() {
        return trimLength;
    }
}

需要在你的attr.xml 中添加以下内容

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <declare-styleable name="ExpandableTextView">
        <attr name="trimLength" format="integer" />
    </declare-styleable>

</resources>

然后在你的布局文件中引用如下代码：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".ExpandableTextActivity" >

    <com.example.expandtextviewdemo.ExpandableTextView
        android:id="@+id/lorem_ipsum"
        android:textSize="20sp"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

</RelativeLayout>

最后 ， 在你的acitivty中测试一下

package com.example.expandtextviewdemo;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;

public class ExpandableTextActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_expandable_text);
        String yourText = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. "
                + "Ut volutpat interdum interdum. Nulla laoreet lacus diam, vitae "
                + "sodales sapien commodo faucibus. Vestibulum et feugiat enim. Donec "
                + "semper mi et euismod tempor. Sed sodales eleifend mi id varius. Nam "
                + "et ornare enim, sit amet gravida sapien. Quisque gravida et enim vel "
                + "volutpat. Vivamus egestas ut felis a blandit. Vivamus fringilla "
                + "dignissim mollis. Maecenas imperdiet interdum hendrerit. Aliquam"
                + " dictum hendrerit ultrices. Ut vitae vestibulum dolor. Donec auctor ante"
                + " eget libero molestie porta. Nam tempor fringilla ultricies. Nam sem "
                + "lectus, feugiat eget ullamcorper vitae, ornare et sem. Fusce dapibus ipsum"
                + " sed laoreet suscipit. ";

        ExpandableTextView expandableTextView = (ExpandableTextView) findViewById(R.id.lorem_ipsum);
        expandableTextView.setText(yourText);
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.expandable_text, menu);
        return true;
    }

}