聊天发送界面

最新推荐文章于 2023-01-05 11:24:06 发布

翻译最新推荐文章于 2023-01-05 11:24:06 发布 · 351 阅读

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本文介绍了一个简单的聊天应用界面实现过程，包括定义消息类、创建消息布局、适配器设计及主活动交互逻辑。通过该教程可以快速搭建一个具备基本收发消息功能的应用。

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定义一个Msg类，用于存放数据

public class Msg {
    public static final int TYPE_RECEIVED = 0;
    public static final int TYPE_SENT = 1;
    private String content;
    private int type;

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

    public String getContent() {
        return content;
    }

    public int getType() {
        return type;
    }
}

布局msg_item.xml 对话界面

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="10dp">

    <LinearLayout
        android:id="@+id/ll_left"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="left"
        android:background="@drawable/message_left">

        <TextView
            android:id="@+id/tv_left"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_margin="10dp"
            android:textSize="18dp"
            android:textColor="#80000000" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/ll_right"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="right"
        android:background="@drawable/message_right">

        <TextView
            android:id="@+id/tv_right"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:textSize="18dp"
            android:textColor="#000000"
            android:layout_margin="10dp" />
    </LinearLayout>
</LinearLayout>

效果：

创建MsgAdapter

import android.content.Context;
import android.support.annotation.NonNull;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.TextView;
import java.util.List;

public class MsgAdapter extends ArrayAdapter<Msg> {
    private int resourceId;

    public MsgAdapter(Context context, int resource, List<Msg> objects) {
        super(context, resource, objects);
        resourceId = resource;
    }

    @NonNull
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Msg msg = getItem(position);
        View view;
        ViewHolder viewHolder;
        if (convertView == null) {
            view = LayoutInflater.from(getContext()).inflate(resourceId, null);
            viewHolder = new ViewHolder();
            viewHolder.ll_left = (LinearLayout) view.findViewById(R.id.ll_left);
            viewHolder.ll_right = (LinearLayout) view.findViewById(R.id.ll_right);
            viewHolder.tv_left = (TextView) view.findViewById(R.id.tv_left);
            viewHolder.tv_right = (TextView) view.findViewById(R.id.tv_right);
            view.setTag(viewHolder);    //用setTag()将ViewHolder对象存储在View中
        } else {
            view = convertView;
            viewHolder = (ViewHolder) view.getTag();
        }
        if (msg.getType() == Msg.TYPE_RECEIVED) {
            // 如果是收到的消息，则显示左边的消息布局，将右边的消息布局隐藏
            viewHolder.ll_left.setVisibility(View.VISIBLE);
            viewHolder.ll_right.setVisibility(View.GONE);
            viewHolder.tv_left.setText(msg.getContent());
        } else if (msg.getType() == Msg.TYPE_SENT) {
            // 如果是发出的消息，则显示右边的消息布局，将左边的消息布局隐藏
            viewHolder.ll_right.setVisibility(View.VISIBLE);
            viewHolder.ll_left.setVisibility(View.GONE);
            viewHolder.tv_right.setText(msg.getContent());
        }
        return view;
    }

    class ViewHolder {
        LinearLayout ll_left;
        LinearLayout ll_right;
        TextView tv_left;
        TextView tv_right;
    }
}

MainActivity.java

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
    private ListView lv_msg;
    private EditText et_input;
    private Button btn_send;
    private MsgAdapter adapter;
    private List<Msg> msgList = new ArrayList<Msg>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initMsgs(); // 初始化消息数据
        adapter = new MsgAdapter(MainActivity.this, R.layout.msg_item, msgList);
        et_input = (EditText) findViewById(R.id.et_input);
        btn_send = (Button) findViewById(R.id.btn_send);
        lv_msg = (ListView) findViewById(R.id.lv_msg);
        lv_msg.setAdapter(adapter);
        btn_send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String content = et_input.getText().toString();
                if (!"".equals(content)) {
                    Msg msg = new Msg(content, Msg.TYPE_SENT);
                    msgList.add(msg);
                    adapter.notifyDataSetChanged(); // 当有新消息时，刷新ListView中的显示
                    lv_msg.setSelection(msgList.size()); // 将ListView定位到最后一行
                    et_input.setText(""); // 清空输入框中的内容
                }
            }
        });
    }

    private void initMsgs() {
        Msg msg1 = new Msg("Hello guy.", Msg.TYPE_RECEIVED);
        msgList.add(msg1);
        Msg msg2 = new Msg("Hello. Who is that?", Msg.TYPE_SENT);
        msgList.add(msg2);
        Msg msg3 = new Msg("This is Tom. Nice talking to you. ", Msg.TYPE_RECEIVED);
        msgList.add(msg3);
    }
}

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="#d8e0e8"
    android:orientation="vertical">

    <ListView
        android:id="@+id/lv_msg"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:divider="#0000" />

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

        <EditText
            android:id="@+id/et_input"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:hint="Type somthing here"
            android:maxLines="2" />

        <Button
            android:id="@+id/btn_send"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Send" />
    </LinearLayout>
</LinearLayout>

效果：