Android studio 实现简易微信程序代码

以下是实现一个简易微信程序的代码示例：

MainActivity.java

public class MainActivity extends AppCompatActivity {
    private RecyclerView chatRecyclerView;
    private EditText messageEditText;
    private Button sendButton;
    private List<Message> messageList;
    private MessageAdapter messageAdapter;

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

        chatRecyclerView = findViewById(R.id.chatRecyclerView);
        messageEditText = findViewById(R.id.messageEditText);
        sendButton = findViewById(R.id.sendButton);

        messageList = new ArrayList<>();
        messageAdapter = new MessageAdapter(messageList);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        chatRecyclerView.setLayoutManager(layoutManager);
        chatRecyclerView.setAdapter(messageAdapter);

        sendButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String content = messageEditText.getText().toString();
                if (!content.equals("")) {
                    Message message = new Message(Message.TYPE_SENT, content);
                    messageList.add(message);
                    messageAdapter.notifyItemInserted(messageList.size() - 1);
                    chatRecyclerView.scrollToPosition(messageList.size() - 1);
                    messageEditText.setText("");
                }
            }
        });
    }
}

Message.java

public class Message {
    public static final int TYPE_RECEIVED = 0;
    public static final int TYPE_SENT = 1;

    private int type;
    private String content;

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

    public int getType() {
        return type;
    }

    public String getContent() {
        return content;
    }
}

MessageAdapter.java

public class MessageAdapter extends RecyclerView.Adapter<MessageAdapter.ViewHolder> {
    private List<Message> messageList;

    static class ViewHolder extends RecyclerView.ViewHolder {
        TextView leftMessage;
        TextView rightMessage;

        public ViewHolder(View view) {
            super(view);
            leftMessage = view.findViewById(R.id.leftMessage);
            rightMessage = view.findViewById(R.id.rightMessage);
        }
    }

    public MessageAdapter(List<Message> messageList) {
        this.messageList = messageList;
    }

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

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        Message message = messageList.get(position);
        if (message.getType() == Message.TYPE_RECEIVED) {
            holder.leftMessage.setVisibility(View.VISIBLE);
            holder.rightMessage.setVisibility(View.GONE);
            holder.leftMessage.setText(message.getContent());
        } else if (message.getType() == Message.TYPE_SENT) {
            holder.rightMessage.setVisibility(View.VISIBLE);
            holder.leftMessage.setVisibility(View.GONE);
            holder.rightMessage.setText(message.getContent());
        }
    }

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

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/chatRecyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/messageLayout"
        android:layout_alignParentTop="true" />
    <LinearLayout
        android:id="@+id/messageLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:background="#FFFFFF"
        android:orientation="horizontal"
        android:padding="10dp">
        <EditText
            android:id="@+id/messageEditText"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="@android:color/transparent"
            android:hint="Type a message..." />
        <Button
            android:id="@+id/sendButton"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Send" />
    </LinearLayout>
</RelativeLayout>

message_item.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="10dp">
    <TextView
        android:id="@+id/leftMessage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/left_message_background"
        android:padding="10dp"
        android:textColor="#FFFFFF"
        android:textSize="16sp" />
    <TextView
        android:id="@+id/rightMessage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/right_message_background"
        android:padding="10dp"
        android:textColor="#FFFFFF"
        android:textSize="16sp" />
</LinearLayout>

其中，left_message_background.xml和right_message_background.xml是自定义的背景文件，用于区分发送方和接收方。