安卓之直播间效果

一、需求

　　窗口的高度是固定的，新的文字消息总是加入窗口末尾，同时窗口内部的文本整体向上滚动，窗口的大小、位置固定不变

二、用到的属性与方法说明

三、布局xml文件

<?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/tv_control"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:layout_marginBottom="20dp"
        android:gravity="center"
        android:text="聊天室效果，点击添加聊天记录，长按删除聊天记录" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:orientation="vertical"
        android:background="@drawable/shape">

        <TextView
            android:id="@+id/tv_bbs"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="5dp"
            android:layout_marginBottom="5dp"
            android:scrollbars="vertical"
            android:textColor="#000000"
            android:textSize="17sp" />
    </LinearLayout>
</LinearLayout>

四、shape.xml文件

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >

    <solid android:color="#FFFFFF" />

    <stroke
        android:width="1dp"
        android:color="#000000" />

    <padding
        android:bottom="0dp"
        android:left="10dp"
        android:right="10dp"
        android:top="0dp" />
</shape>

五、java代码

package com.example.chatroom;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.method.ScrollingMovementMethod;
import android.view.Gravity;
import android.view.View;
import android.widget.TextView;

import com.example.chatroom.util.DateUtil;

public class MainActivity extends AppCompatActivity implements
        View.OnClickListener, View.OnLongClickListener {

    private TextView tv_bbs;
    private TextView tv_control;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        tv_control = findViewById(R.id.tv_control);
        tv_control.setOnClickListener(this);
        tv_control.setOnLongClickListener(this);
        tv_bbs = findViewById(R.id.tv_bbs);
        tv_bbs.setOnClickListener(this);
        tv_bbs.setOnLongClickListener(this);
        tv_bbs.setGravity(Gravity.LEFT|Gravity.BOTTOM);
        tv_bbs.setLines(9);
        tv_bbs.setMaxLines(9);
        tv_bbs.setMovementMethod(new ScrollingMovementMethod());
    }

    private String[] mChatStr = { "你吃饭了吗？", "今天天气真好呀。",
            "我中奖啦！", "我们去看电影吧", "晚上干什么好呢？", };

    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.tv_control || v.getId() == R.id.tv_bbs) {
            int random = (int)(Math.random()*10) % 5;
            String newStr = String.format("%s
%s %s",
                    tv_bbs.getText().toString(), DateUtil.getNowTime(), mChatStr[random]);
            tv_bbs.setText(newStr);
        }
    }

    @Override
    public boolean onLongClick(View v) {
        if (v.getId() == R.id.tv_control || v.getId() == R.id.tv_bbs) {
            tv_bbs.setText("");
        }
        return true;
    }
}

六、DateUtil类

package com.example.chatroom.util;

import android.annotation.SuppressLint;

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * Created by ouyangshen on 2016/9/14.
 */
public class DateUtil {
    @SuppressLint("SimpleDateFormat")
    public static String getNowDateTime() {
        SimpleDateFormat s_format = new SimpleDateFormat("yyyyMMddhhmmss");
        return s_format.format(new Date());
    }

    @SuppressLint("SimpleDateFormat")
    public static String getNowTime() {
        SimpleDateFormat s_format = new SimpleDateFormat("HH:mm:ss");
        return s_format.format(new Date());
    }

}