使用Android编写的聊天界面代码

以下是一个简单的 Android 聊天界面的代码示例，其中使用了 RecyclerView 和自定义的适配器：

1. 在布局文件中添加 RecyclerView、EditText 和 Button：

<android.support.constraint.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/chat_recycler_view"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:clipToPadding="false"
        android:paddingTop="8dp"
        android:paddingBottom="8dp"
        app:layout_constraintBottom_toTopOf="@+id/message_layout"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <LinearLayout
        android:id="@+id/message_layout"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:padding="16dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

        <EditText
            android:id="@+id/message_edit_text"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:hint="Type a message" />

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

    </LinearLayout>

</android.support.constraint.ConstraintLayout>

2. 创建一个 ChatMessage 类，用于表示聊天消息：

public class ChatMessage {
    private String text;
    private boolean isMine;

    public ChatMessage(String text, boolean isMine) {
        this.text = text;
        this.isMine = isMine;
    }

    public String getText() {
        return text;
    }

    public boolean isMine() {
        return isMine;
    }
}

3. 创建一个自定义的适配器 ChatAdapter，用于将聊天消息展示在 RecyclerView 中：

public class ChatAdapter extends RecyclerView.Adapter<ChatAdapter.ViewHolder> {
    private List<ChatMessage> messages;

    public ChatAdapter(List<ChatMessage> messages) {
        this.messages = messages;
    }

    @Override
    public int getItemCount() {
        return messages.size();
    }

    @Override
    public int getItemViewType(int position) {
        return messages.get(position).isMine() ? 1 : 0;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(viewType == 0 ? R.layout.item_chat_received : R.layout.item_chat_sent, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        ChatMessage message = messages.get(position);
        holder.messageTextView.setText(message.getText());
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        public TextView messageTextView;

        public ViewHolder(View itemView) {
            super(itemView);
            messageTextView = itemView.findViewById(R.id.message_text_view);
        }
    }
}

4. 在 Activity 中初始化 RecyclerView、EditText 和 Button，并设置 Button 的点击事件：

public class ChatActivity extends AppCompatActivity {
    private RecyclerView chatRecyclerView;
    private EditText messageEditText;
    private Button sendButton;
    private List<ChatMessage> messages = new ArrayList<>();
    private ChatAdapter adapter;

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

        chatRecyclerView = findViewById(R.id.chat_recycler_view);
        messageEditText = findViewById(R.id.message_edit_text);
        sendButton = findViewById(R.id.send_button);

        adapter = new ChatAdapter(messages);
        chatRecyclerView.setAdapter(adapter);
        chatRecyclerView.setLayoutManager(new LinearLayoutManager(this));

        sendButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String messageText = messageEditText.getText().toString().trim();

                if (!TextUtils.isEmpty(messageText)) {
                    messages.add(new ChatMessage(messageText, true));
                    adapter.notifyItemInserted(messages.size() - 1);
                    messageEditText.setText("");
                }
            }
        });
    }
}

5. 创建两个布局文件 item_chat_sent.xml 和 item_chat_received.xml，用于分别展示发送和接收到的聊天消息：

item_chat_sent.xml：

<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/message_text_view"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="8dp"
    android:layout_marginEnd="16dp"
    android:layout_gravity="end"
    android:background="@drawable/bg_chat_sent"
    android:padding="8dp"
    android:textColor="@android:color/white" />

item_chat_received.xml：

<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/message_text_view"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="8dp"
    android:layout_marginStart="16dp"
    android:layout_gravity="start"
    android:background="@drawable/bg_chat_received"
    android:padding="8dp"
    android:textColor="@android:color/black" />

6. 创建两个 drawable 资源文件 bg_chat_sent.xml 和 bg_chat_received.xml，用于设置发送和接收到的聊天消息的背景颜色：

bg_chat_sent.xml：

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="#3F51B5" />
    <corners android:radius="16dp" />
</shape>

bg_chat_received.xml：

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <solid android:color="#EEEEEE" />
    <corners android:radius="16dp" />
</shape>

以上是一个简单的 Android 聊天界面的代码示例，你可以根据自己的需求进行修改和扩展。