使用RecyclerView完成聊天界面以及消息的更新

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:orientation="vertical"
android:background="#d8e0e8"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.sky.chat.MainActivity">

<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:id="@+id/recycler_view"
></android.support.v7.widget.RecyclerView>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
>

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

<Button
android:id="@+id/send"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
</LinearLayout>
</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp">

<LinearLayout
android:layout_width="wrap_content"
android:layout_height="150dp"
android:id="@+id/left_layout"
android:layout_gravity="left"
android:background="@drawable/message"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/left_msg"
android:layout_gravity="center"
android:layout_margin="10dp"
android:textColor="#fff"/>
</LinearLayout>

<LinearLayout
android:layout_width="wrap_content"
android:layout_height="150dp"
android:id="@+id/right_layout"
android:layout_gravity="right"
android:background="@drawable/message"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/right_msg"
android:layout_gravity="center"
android:layout_margin="10dp"/>
</LinearLayout>

</LinearLayout>

package com.example.sky.chat;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {
private List<Msg> msgList = new ArrayList<>();
private EditText inputText;
private Button send;
private RecyclerView recyclerView;
private MsgAdapter adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initMsgs();//初始化消息数据
inputText = (EditText) findViewById(R.id.input_text);
send = (Button) findViewById(R.id.send);
recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
adapter = new MsgAdapter(msgList);
recyclerView.setA
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dapter(adapter);
send.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String content = inputText.getText().toString();
if (!"".equals(content)){
Msg msg = new Msg(content,Msg.TYPE_SENT);
msgList.add(msg);
adapter.notifyItemInserted(msgList.size()-1);//当有新消息时，刷新RecyclerView中的显示
recyclerView.scrollToPosition(msgList.size() - 1);//将RecyclerView定位到最后一行
inputText.setText("");//清空输入框中的内容
}
}
});
}

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

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

static class ViewHolder extends RecyclerView.ViewHolder{
LinearLayout leftLayout;
LinearLayout rightLayout;
TextView leftMsg;
TextView rightMsg;

public ViewHolder(View itemView) {
super(itemView);
leftLayout = (LinearLayout) itemView.findViewById(R.id.left_layout);
rightLayout = (LinearLayout) itemView.findViewById(R.id.right_layout);
leftMsg = (TextView) itemView.findViewById(R.id.left_msg);
rightMsg = (TextView) itemView.findViewById(R.id.right_msg);

}
}

public MsgAdapter(List<Msg> mMsgList) {
this.mMsgList = mMsgList;
}

@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);
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Msg msg = mMsgList.get(position);
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
holder.leftLayout.setVisibility(View.VISIBLE);
holder.rightLayout.setVisibility(View.GONE);
holder.leftMsg.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
holder.rightLayout.setVisibility(View.VISIBLE);
holder.leftLayout.setVisibility(View.GONE);
holder.rightMsg.setText(msg.getContent());
}

}

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

}

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

/**
* content表示消息的内容，type表示消息的类型。其中消息类型有两个值可选，TYPE_RECEIVED表示这是一条收到的消息，TYPE_SENT表示这是一条发出的消息
* @param content
* @param type
*/
public Msg(String content, int type) {
this.content = content;
this.type = type;
}

public int getType() {
return type;
}

public String getContent() {
return content;
}
}