Android小项目——聊天室

简单介绍

Android的第二个小程序，初步实现了换头像功能、多人聊天功能。先放几张照片亮亮相吧：

更换图标

在drawale文件夹中加入.png的一张照片即可

android:icon="@drawable/icon"

网络权限

保险起见3条全加，当时只加了一条然后就连不上网。。。

    package="com.example.chartroom">
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    

登录界面

注意实时查看你连的WIFI的IP地址，Win+R输入CMD，再输入ipconfig/all查看WIFI那一栏中的IPV4

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/bd1"
    android:orientation="vertical">
    
	//这可以把上面标题改掉
    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#2FF1EEEE">

        <TextView
            android:id="@+id/tv_room"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:gravity="center"
            android:text="欢迎登录聊天室"
            android:textColor="#93FFFFFF"
            android:textSize="19sp" />
            
    androidx.appcompat.widget.Toolbar>
       

        <LinearLayout
            android:orientation="horizontal"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:layout_marginLeft="50sp"
            android:layout_marginRight="50sp"
            android:layout_marginTop="100dp">

            <TextView
                android:id="@+id/tv_name"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:gravity="center"
                android:text="用户名"
                android:textSize="20sp"
                android:textColor="#93FFFFFF"/>

            <EditText
                android:id="@+id/et_name"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="2"
                android:gravity="center"
                android:textColor="#93FFFFFF"
                android:theme="@style/CretateRoomEditTextTheme"/>

        LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:layout_marginLeft="50sp"
        android:layout_marginRight="50sp"
        android:layout_marginTop="50dp">

        <TextView
            android:id="@+id/tv_ip"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="center"
            android:text="IP地址"
            android:textSize="20sp"
            android:textColor="#93FFFFFF"/>

        <EditText
            android:id="@+id/et_ip"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="2"
            android:gravity="center"       
            android:text="192.168.1.5" 
            android:textColor="#93FFFFFF"
            android:theme="@style/CretateRoomEditTextTheme" />


    LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:layout_marginLeft="50sp"
        android:layout_marginRight="50sp"
        android:layout_marginTop="50dp">

        <TextView
            android:id="@+id/tv_port"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="center"
            android:text="端口"
            android:textSize="20sp"
            android:textColor="#93FFFFFF"/>

        <EditText
            android:id="@+id/et_port"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="2"
            android:gravity="center"
            android:textColor="#93FFFFFF"
            android:theme="@style/CretateRoomEditTextTheme"
            android:text="6666"/>

    LinearLayout>

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:layout_gravity="center"
            android:layout_marginLeft="60sp"
            android:layout_marginRight="50sp"
            android:layout_marginTop="50dp">

            <Button
                android:id="@+id/login"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight = "1"
                android:layout_gravity="center"
                android:gravity="center"
                android:layout_margin="30dp"
                android:textColor="#93FFFFFF"
                android:textSize="16sp"
                android:background="@drawable/change"
                android:text="连接"/>

            <Button
                android:id="@+id/quit"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight = "1"
                android:layout_gravity="center"
                android:gravity="center"
                android:layout_margin="30dp"
                android:textColor="#93FFFFFF"
                android:textSize="16sp"
                android:background="@drawable/change"
                android:text="退出"/>
        LinearLayout>

LinearLayout>

MainActivity.java

package com.example.chartroom;

import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    
    private Button login;
    private Button quit;
    private EditText et_name;
    private EditText et_ip;
    private EditText et_port;
    private TextView my_name;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //获取id,连接控件
        login = (Button) findViewById(R.id.login);
        quit = (Button) findViewById(R.id.quit);
        et_name = findViewById(R.id.et_name);
        et_ip = (EditText) findViewById(R.id.et_ip);
        et_port = (EditText) findViewById(R.id.et_port);
        //login点击事件
        login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                //获取一个视图View对象里的字符串
                String name = et_name.getText().toString();
                //如果没输入名字
                if("".equals(name)){
                    Toast.makeText(MainActivity.this, "请输入用户名！", Toast.LENGTH_SHORT).show();
                }else{
                    Intent intent = new Intent(MainActivity.this,ChoosePicture.class);
                    //向下一活动传递信息                                        intent.putExtra("name",et_name.getText().toString());
                    intent.putExtra("ip",et_ip.getText().toString());
                    intent.putExtra("port",et_port.getText().toString());                    
                    try{
                        startActivity(intent);
                    }catch(Exception e){
                        System.out.println("开启失败");
                        finish();
                    }                 
                }
            }
        });
        //quit点击事件
        quit.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
            	//用AlertDialog显示一个退出提示框
                AlertDialog.Builder dialog = new AlertDialog.Builder(MainActivity.this);
                dialog.setTitle("关闭提示");
                dialog.setMessage("确定退出登录？");
                dialog.setPositiveButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        System.exit(0);
                    }
                });
                dialog.setNegativeButton("取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                    }
                });
                dialog.show();
            }
        });
    }
}

选择头像

activity_choose_picture.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:background="@drawable/bd1"
    android:orientation="vertical">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#2FF1EEEE">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:gravity="center"
            android:text="选择一个喜欢的头像"
            android:textColor="#93FFFFFF"
            android:textSize="19sp" />
    androidx.appcompat.widget.Toolbar>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/one"
            android:layout_width="0dp"
            android:layout_height="115dp"
            android:layout_weight="1"
            android:background="@drawable/headofothers"
            android:layout_margin="10dp"/>

        <Button
            android:id="@+id/two"
            android:layout_width="0dp"
            android:layout_height="115dp"
            android:layout_weight="1"
            android:background="@drawable/headofmy"
            android:layout_margin="10dp"/>

        <Button
            android:id="@+id/three"
            android:layout_width="0dp"
            android:layout_height="115dp"
            android:layout_weight="1"
            android:background="@drawable/three"
            android:layout_margin="10dp"/>
            
    LinearLayout>

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal">


        <Button
            android:id="@+id/four"
            android:layout_width="0dp"
            android:layout_height="115dp"
            android:layout_weight="1"
            android:background="@drawable/six"
            android:layout_margin="10dp"/>

        <Button
            android:id="@+id/five"
            android:layout_width="0dp"
            android:layout_height="115dp"
            android:layout_weight="1"
            android:background="@drawable/four"
            android:layout_margin="10dp"/>

        <Button
            android:id="@+id/six"
            android:layout_width="0dp"
            android:layout_height="115dp"
            android:layout_weight="1"
            android:background="@drawable/five"
            android:layout_margin="10dp"/>
    LinearLayout>

LinearLayout>

ChoosePicture.java

package com.example.chartroom;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.PersistableBundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

public class ChoosePicture extends AppCompatActivity implements View.OnClickListener{

    private String et_name;
    private String et_ip;
    private String et_port;

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_choose_picture);
        System.out.println("启动2");
        //启动活动，并获取传递过来的信息
        Intent intent = getIntent();
        //传入键值得到数据
        et_name = intent.getStringExtra("name");
        et_ip = intent.getStringExtra("ip");
        et_port = intent.getStringExtra("port");
        Button button1 = (Button)findViewById(R.id.one);
        Button button2 = (Button)findViewById(R.id.two);
        Button button3 = (Button)findViewById(R.id.three);
        Button button4 = (Button)findViewById(R.id.four);
        Button button5 = (Button)findViewById(R.id.five);
        Button button6 = (Button)findViewById(R.id.six);
        button1.setOnClickListener(this);
        button2.setOnClickListener(this);
        button3.setOnClickListener(this);
        button4.setOnClickListener(this);
        button5.setOnClickListener(this);
        button6.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        //向下一活动传递信息
        Intent intent = new Intent(ChoosePicture.this,ChatRoom.class);
        intent.putExtra("name",et_name.toString());
        intent.putExtra("ip",et_ip.toString());
        intent.putExtra("port",et_port.toString());
        switch(view.getId()){
            case R.id.one:
                intent.putExtra("imageId",R.drawable.headofothers);
                break;
            case R.id.two:
                intent.putExtra("imageId",R.drawable.headofmy);
                break;
            case R.id.three:
                intent.putExtra("imageId",R.drawable.three);
                break;
            case R.id.four:
                intent.putExtra("imageId",R.drawable.six);
                break;
            case R.id.five:
                intent.putExtra("imageId",R.drawable.four);
                break;
            case R.id.six:
                intent.putExtra("imageId",R.drawable.five);
                break;
        }
        startActivity(intent);
    }

}

客户端

这是将信息传出和接收传入信息的重要板块，其中涉及到IO流、多线程、网络编程等知识。大家可以先复习一遍再来写这一块。

ChatRoom.java

package com.example.chartroom;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class ChatRoom extends AppCompatActivity implements View.OnClickListener{
    private List<Msg> msgList = new ArrayList<>();
    private MsgAdapter adapter;
    private Button back;                //退回键
    private RecyclerView recyclerView;  //对话显示框
    private EditText input_text;        //输入框
    private int imageId ;               //获取自己的头像
    private int his_imageId;            //获取对方发头像
    private String time;                //获取时间
    private Button send;                //发送按钮
    private String name;                //从主活动获取的名字
    private String hisName;             //对方昵称，从自定义的receive线程中获取，便于和自己的昵称区分
    private String content;             //获取对话内容
    private String ip ;                 //获取ip地址
    private String port;                //获取端口号
    private Socket socketSend;          //套接字，用于绑定ip号和端口号便于计算机之间的传输消息
    private DataInputStream dis;        //码头
    private DataOutputStream dos;       //集装箱
    private String recMsg;
    boolean isRunning = false;          //判断线程是否运行
    boolean isSend = false;             //判断是否发送
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_chat_room);
        //启动活动，并获取传递过来的信息
        Intent intent = getIntent();
        //传入键值得到数据
        name = intent.getStringExtra("name");
        ip = intent.getStringExtra("ip");
        port = intent.getStringExtra("port");
        //取出int要指定key，还要设置默认值，当intent中没有该key对应的value时，返回设置的默认值
        imageId = intent.getIntExtra("imageId",0);
        //获取实例
        input_text = (EditText) findViewById(R.id.input_text);
        back = (Button) findViewById(R.id.back);
        send = (Button) findViewById(R.id.send);
        //注册监听器
        back.setOnClickListener(this);
        send.setOnClickListener(this);

        //将RecyclerView和list建立联系(建立与适配器关系啥的)
        LinearLayoutManager layoutManager = new LinearLayoutManager(ChatRoom.this);
        recyclerView = (RecyclerView) findViewById(R.id.msg_recycler_view);
        recyclerView.setLayoutManager(layoutManager);
        adapter = new MsgAdapter(msgList);
        recyclerView.setAdapter(adapter);

        //如果要连网的话就不能在主线程上操作，所以要另外开启一条线程
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    System.out.println("号码");
                    socketSend = new Socket(ip, Integer.parseInt(port));
                    isRunning = true;
                    dis = new DataInputStream(socketSend.getInputStream());
                    dos = new DataOutputStream(socketSend.getOutputStream());
                    System.out.println("打开dos");
                    //开一条线程接收服务器传来的信息
                    new Thread(new receive(), "接收线程").start();
                    System.out.println("打开线程");
                } catch (Exception e) {
                    Log.e("TAG",e.toString());
                    e.printStackTrace();
                    //为当前线程准备消息队列
                    Looper.prepare();
                    //Toast只有在主线程中能显示出来
                    Toast.makeText(ChatRoom.this, "连接服务器失败", Toast.LENGTH_SHORT).show();
                    //开启循环取消息
                    Looper.loop();
                }
            }
        }).start();

    }

    //获取当前时间
    public String getCurrentTime(){
        Date d = new Date();
        //设置显示的时间格式
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日HH:mm:ss");
        //以这种格式显示
        return sdf.format(d);
    }

    @Override
    public void onClick(View view) {
        switch(view.getId()){
            case R.id.back:
                finish();
                break;
            case R.id.send:
                //显示时间
                time = getCurrentTime();
                String content = input_text.getText().toString();
                //显示信息
                StringBuilder sb = new StringBuilder();
                sb.append(content);
                if(!"".equals(content)){  //发送信息不为空
                    isSend = true;
                    new Thread(new Runnable() {
                        @Override
                        public void run() {
                            String content = input_text.getText().toString();
                            Log.d("ttw","发了一条消息");
                            System.out.println("content = "+content);
                            System.out.println("传入发送信息");
                            if(!"".equals(content) && isSend){
                                String date = getCurrentTime();
                                try {
                                    if(!"".equals(date) && !"".equals(name)){
                                        dos.writeUTF(date);
                                        dos.writeUTF(content);
                                        dos.writeUTF(name);
                                        dos.writeUTF(String.valueOf(imageId));
                                        System.out.println("发送完了");
                                    }
                                } catch (IOException e) {
                                    e.printStackTrace();
                                }
                                isSend = false;
                            }
                        }
                    }).start();
                    Msg msg = new Msg(content,Msg.TYPE_SENT,time,name,imageId);   //发送消息
                    System.out.println("imageId = "+imageId);
                    msgList.add(msg);
                    //当有新消息时，刷新ListView中的消息
                    adapter.notifyItemInserted(msgList.size()-1);
                    //将LestView定位到最后一行
                    recyclerView.scrollToPosition(msgList.size()-1);
                    input_text.setText("");
                }else{
                    Toast.makeText(ChatRoom.this, "不可发送空信息！", Toast.LENGTH_SHORT).show();
                }
                sb.delete(0,sb.length());
                break;
            default:
                break;
        }
    }

    //子线程与主线程通过Handler来进行通信。子线程可以通过Handler来通知主线程进行UI更新。
    //Handler有两个主要的用途:(1)安排消息和可运行对象在将来的某个时间点执行;(2)将一个要在不同的线程上执行的动作编入队列。
    private Handler handler = new Handler(Looper.myLooper()){
        @Override
        public void handleMessage(@NonNull Message msg) {
            if(!recMsg.isEmpty()){
                System.out.println("更新消息");
                addNewMessage(content,Msg.TYPE_RECEIVED,time,hisName,his_imageId);  //刷新接收的消息
            }
        }
    };

    public void addNewMessage(String msg,int type,String time,String name,int his_imageId){
        Msg message = new Msg(msg,type,time,name,his_imageId);
        msgList.add(message);
        //当有消息时，通知列表有新的数据插入，刷新recyclerview中消息
        adapter.notifyItemInserted(msgList.size()-1);
        //将消息一直放在显示屏的底部不随意跑上去
        recyclerView.scrollToPosition(msgList.size()-1);
    }

    //接收线程
    class receive implements Runnable{
        @Override
        public void run() {
            recMsg = "";
            while(isRunning){
                System.out.println("开始接收线程receive");
                Msg msg = null;
                try {
                    time = dis.readUTF();
                    content = dis.readUTF();
                    hisName = dis.readUTF();
                    his_imageId = Integer.parseInt(dis.readUTF());
                    System.out.println("接收信息 = "+content);
                    recMsg = hisName + time + content;
                    msg = new Msg(content,Msg.TYPE_RECEIVED,time,hisName,his_imageId);
                } catch (Exception e) {
                    System.out.println("接受失败");
                    e.printStackTrace();
                }
                //判断是否为空字符串
                if(!TextUtils.isEmpty(recMsg)){
                    System.out.println("查看名字"+msg.getName());
                    Message message = new Message();
                    message.obj = msg;
                    handler.sendMessage(message);
                }
            }
        }
    }

}

activity_chat_room.xml

要显示<这个标识符的话，得写成："<,"

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/bd2"
    android:orientation="vertical">

    <androidx.appcompat.widget.Toolbar
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#2FF1EEEE">

        <Button
            android:id="@+id/back"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textColor="#FFFFFF"
            android:textSize="30sp"
            android:background="#00FFFFFF"
            android:text="<"/>


        <TextView
            android:id="@+id/tv_room"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="ChatRoom"
            android:textColor="#CDFFFFFF"
            android:textSize="23sp" />



    androidx.appcompat.widget.Toolbar>


    <androidx.recyclerview.widget.RecyclerView
    android:id="@+id/msg_recycler_view"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1" />


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginRight="10dp"
        android:layout_marginLeft="10dp">

        <EditText
            android:id="@+id/input_text"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:layout_margin="10dp"
            android:hint="Type Something"
            android:maxLines="2" />

        <Button
            android:id="@+id/send"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="10dp"
            android:text="Send"
            android:textColor="#AAFFFFFF"/>

    LinearLayout>

LinearLayout>

msg_item.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:layout_marginTop="20dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center">

        <TextView
            android:id="@+id/time"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:gravity="center"
            android:textSize="15dp" />

    LinearLayout>

    LinearLayout>

            <LinearLayout
                android:id="@+id/left_layout"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="left"
                android:layout_marginTop="5dp">

                <ImageView
                    android:id="@+id/head_others"
                    android:layout_marginRight="5dp"
                    android:layout_width="60dp"
                    android:layout_height="60dp" />

                <LinearLayout
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:orientation="vertical"
                    android:layout_marginLeft="5dp">

                    <TextView
                        android:id="@+id/others_name"
                        android:layout_gravity="left"
                        android:layout_width="wrap_content"
                        android:layout_height="0dp"
                        android:layout_weight="1"/>

                    <LinearLayout
                        android:layout_width="wrap_content"
                        android:layout_height="0dp"
                        android:layout_weight="2"
                        android:background="@drawable/his_bubble">

                        <TextView
                            android:id="@+id/left_msg"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:layout_gravity="center"
                            android:gravity="center"
                            android:textColor="@color/black"
                            android:layout_margin="8dp"
                            android:textSize="20dp" />
                    LinearLayout>


                LinearLayout>

    LinearLayout>


    <LinearLayout
        android:id="@+id/right_layout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="right"
        android:layout_marginTop="5dp">

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="5dp"
            android:orientation="vertical">

            <TextView
                android:id="@+id/my_name"
                android:layout_width="wrap_content"
                android:layout_height="0dp"
                android:layout_gravity="right"
                android:layout_weight="1" />

            <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="0dp"
                android:layout_weight="2"
                android:background="@drawable/my_bubble">

                <TextView
                    android:id="@+id/right_msg"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center"
                    android:layout_margin="8dp"
                    android:gravity="center"
                    android:textColor="@color/black"
                    android:textSize="20dp" />
            LinearLayout>
        LinearLayout>

        <ImageView
            android:id="@+id/head_my"
            android:layout_marginLeft="5dp"
            android:layout_width="60dp"
            android:layout_height="60dp" />

        LinearLayout>

LinearLayout>

Msg.java

package com.example.chartroom;

public class Msg {
    public static final int TYPE_RECEIVED = 0;	//标记用于判断是输出消息还是接收消息
    public static final int TYPE_SENT = 1;
    private String content;		//存储消息信息
    private int type;	//存储判断信息
    private String time;
    private String name;
    private int imageId;

    public Msg(String content, int type, String time,String name,int imageId) {
        this.content = content;
        this.type = type;
        this.time = time;
        this.name = name;
        this.imageId = imageId;
    }

    public String getContent() {
        return content;
    }

    public int getType() {
        return type;
    }

    public String getTime(){
        return time;
    }

    public String getName(){
        return name;
    }

    public int getImageId(){
        return imageId;
    }
}

MsgAdapter.java

package com.example.chartroom;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List;
import java.util.zip.Inflater;

public class MsgAdapter extends RecyclerView.Adapter<MsgAdapter.ViewHolder> {
    List<Msg> mMsgList;

    //把显示的数据源传进来
    public MsgAdapter(List<Msg> msgList) {
        super();
        mMsgList = msgList;
    }

    //创建ViewHolder实例
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.msg_item,parent,false);
        return new ViewHolder(view);
    }

    //对RecyclerView子项数据进行赋值
    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Msg msg = mMsgList.get(position);
        holder.time.setText((CharSequence)msg.getTime());
        if(msg.getType() == Msg.TYPE_RECEIVED){  //接收端
            holder.his_head.setImageResource(msg.getImageId());
            holder.leftLayout.setVisibility(View.VISIBLE);  //左可见
            holder.rightLayout.setVisibility(View.GONE);    //右不可见
            holder.hisName.setText(msg.getName());
            holder.leftMsg.setText(msg.getContent());       //左边显示消息
        }else if(msg.getType() == Msg.TYPE_SENT){
			holder.my_head.setImageResource(msg.getImageId());
            holder.rightLayout.setVisibility(View.VISIBLE);
            holder.leftLayout.setVisibility(View.GONE);
            holder.name.setText(msg.getName());
            holder.rightMsg.setText(msg.getContent());
        }
    }

    //告诉RecycleView一共多少子项，返回数据源长度
    @Override
    public int getItemCount() {
        return mMsgList.size();
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {
        LinearLayout leftLayout ;
        LinearLayout rightLayout;
        TextView leftMsg;
        TextView rightMsg;
        TextView time;
        TextView name;
        TextView hisName;
        ImageView my_head;
        ImageView his_head;

        public ViewHolder(View view) {
            super(view);
            leftLayout = view.findViewById(R.id.left_layout);
            rightLayout = view.findViewById(R.id.right_layout);
            leftMsg = view.findViewById(R.id.left_msg);
            rightMsg = view.findViewById(R.id.right_msg);
            time = view.findViewById(R.id.time);              //显示时间
            name = view.findViewById(R.id.my_name);
            hisName = view.findViewById(R.id.others_name);
            my_head = view.findViewById(R.id.head_my);
            his_head = view.findViewById(R.id.head_others);
        }
    }
}

服务器

任意Java编译器即可，我用的IDEA

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.ConcurrentModificationException;

public class Server {
    public static void main(String[] args) {
        new Thread(new startServer()).start();
    }
    private static int port = 6666;
    public static ArrayList<UserThread> socketList = new ArrayList<UserThread>();
    private static class startServer extends Thread{
        public void run(){
            try {
                //绑定服务器要监听的端口
                ServerSocket serverSocket = new ServerSocket(port);
                while(true){
                    //从队列中取出连接请求，使得队列能及时腾出空位，以容纳新的连接请求
                    Socket socket = serverSocket.accept();
                    System.out.println(""+socket);
                    UserThread userThread = new UserThread(socket);
                    socketList.add(userThread);
                    new Thread(userThread).start();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private static class UserThread implements Runnable {
        private Socket skt;
        private DataInputStream dis;
        private DataOutputStream dos;

        public DataOutputStream getDos() {
            return dos;
        }

        public UserThread(Socket socket) {
            skt = socket;
        }

        //接收send过来的线程
        @Override
        public void run() {
            try {
                dos = new DataOutputStream(skt.getOutputStream());
                dis = new DataInputStream(skt.getInputStream());
                while (true) {
                    String r_content ;
                    String name ;
                    String time ;
                    String imageId ;
                    time = dis.readUTF();
                    r_content = dis.readUTF();
                    name = dis.readUTF();
                    imageId = dis.readUTF();
                    System.out.println("content = "+r_content);
                    if(time == null){
                        continue;
                    }
                    //发送出去
                    for(UserThread ut : socketList){
                        if(ut.equals(this)){  //是自己的消息就不发出
                            System.out.println("自己的");
                            continue;
                        }
                        try{
                            System.out.println(time);
                            //writeUTF在写入数据流的时候会加上两个字节以表示字节的长度
                            ut.getDos().writeUTF(time);
                            ut.getDos().writeUTF(r_content);
                            ut.getDos().writeUTF(name);
                            ut.getDos().writeUTF(imageId);
                            System.out.println("写出去");
                            //刷新
                            ut.getDos().flush();
                        }catch(Exception e){
                            socketList.remove(ut);
                            e.printStackTrace();
                        }
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}