1.0 首先新建一个项目，名叫：UIBestPractice，目录如下：
2.0 这里需要先准备两张图片，放在app\src\main\res\drawable-xhdpi目录下。
这里图片名称已经制作成为Nine-Patch图片，原本的名字没有“.9”字样。在目录下鼠标选中图片，右击，选择“”即可进入Nine-Patch图片编辑环境，
将可见是如下的画面,鼠标点击就会在边上添加黑色线条，意味着该线条所对应的边是允许变形的，按住shift键再点击，即可取消黑边，而且鼠标只有停在图片的四条边才可以操作，才会出现黑边，鼠标也才会变成成为双箭头图案：
可以看到右侧是拉伸时的形状预览。
保存即可，自动生成相同名字的后缀名为“.9.png”的图片。
3.0 在主活动界面设置布局，activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#ffffff" tools:context=".MainActivity">
<android.support.v7.widget.RecyclerView android:id="@+id/msg_recycler_view" android:layout_width="match_parent" android:layout_height="0dp" app:layout_constraintBottom_toTopOf="@+id/linear" app:layout_constraintEnd_toEndOf="@+id/linear" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" app:layout_constraintVertical_weight="1" />
<LinearLayout android:id="@+id/linear" android:layout_width="match_parent" android:layout_height="wrap_content" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toStartOf="parent">
<EditText android:id="@+id/input_text" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_weight="1" android:hint="在这里键入内容" android:maxLines="2" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" app:layout_constraintLeft_toLeftOf="parent" app:layout_constraintRight_toLeftOf="@+id/send"/>
<Button android:id="@+id/send" android:layout_width="wrap_content" android:layout_height="wrap_content" android:baselineAligned="false" android:text="发送" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" app:layout_constraintRight_toRightOf="parent" app:layout_constraintLeft_toRightOf="@+id/input_text"/>
</LinearLayout>
</android.support.constraint.ConstraintLayout>
效果如下：
4.0 设置聊天适配器Msg.java：
package com.example.uibestpractice; public class Msg { public static final int TYPE_RECEIVED = 0; public static final int TYPE_SENT = 1; private String content; private int type; // content 消息的内容 // type 消息的类型 // TYPE_RECEIVED 表示这是一条收到的信息 // TYPE_SENT 表示这是一条发出的信息
public Msg(String content,int type){ this.content =content; this.type = type; } public String getContent(){ return content; } public int getType(){ return type; } }
5.0 MsgAdapter.java
package com.example.uibestpractice; import android.support.v7.widget.RecyclerView; import android.view.LayoutInflater; import android.view.ViewGroup; import android.widget.LinearLayout; import android.widget.TextView; import android.view.View; import java.util.List; 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 view) { super(view); leftLayout = (LinearLayout) view.findViewById(R.id.left_layout); rightLayout = (LinearLayout) view.findViewById(R.id.right_layout); leftMsg = (TextView) view.findViewById(R.id.left_msg); rightMsg = (TextView) view.findViewById(R.id.right_msg); } } public MsgAdapter(List<Msg> msgList){ mMsgList =msgList; } @Override public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) { View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.msg_item,viewGroup,false); return new ViewHolder(view); } @Override public void onBindViewHolder(ViewHolder viewHolder, int i) { Msg msg = mMsgList.get(i); if (msg.getType() == Msg.TYPE_RECEIVED){ //如果是收到的信息，则显示在左边的消息布局，将右边的消息布局隐藏
viewHolder.leftLayout.setVisibility(View.VISIBLE); viewHolder.rightLayout.setVisibility(View.GONE); viewHolder.leftMsg.setText(msg.getContent()); }else if (msg.getType() == Msg.TYPE_SENT){ //如果是发出的信息，则显示在右边的消息布局，将左边的消息布局隐藏
viewHolder.leftLayout.setVisibility(View.GONE); viewHolder.rightLayout.setVisibility(View.VISIBLE); viewHolder.rightMsg.setText(msg.getContent()); } } @Override public int getItemCount() { return mMsgList.size(); } }
6.0 针对聊天显示进行布局设置，msg_item.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="wrap_content" android:padding="10dp">
<LinearLayout android:id="@+id/left_layout" android:layout_width="wrap_content" android:layout_height="wrap_content" android:background="@drawable/juxingqipao_left" android:gravity="left" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent">
<TextView android:id="@+id/left_msg" android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="left" />
</LinearLayout>
<LinearLayout android:id="@+id/right_layout" android:layout_width="wrap_content" android:layout_height="wrap_content" android:background="@drawable/juxingqipao_right" android:gravity="right" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintTop_toTopOf="parent">
<TextView android:id="@+id/right_msg" android:layout_width="wrap_content" android:layout_height="wrap_content" android:gravity="right" />
</LinearLayout>
</android.support.constraint.ConstraintLayout>
7.0 主函数 ：MainActivity.java
package com.example.uibestpractice; 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 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 msgRecyclerView; private MsgAdapter adapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initMsgs();//初始化数据
inputText = (EditText) findViewById(R.id.input_text); send = (Button) findViewById(R.id.send); msgRecyclerView = (RecyclerView) findViewById(R.id.msg_recycler_view); LinearLayoutManager layoutManager = new LinearLayoutManager(this); msgRecyclerView.setLayoutManager(layoutManager); adapter = new MsgAdapter(msgList); msgRecyclerView.setAdapter(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
msgRecyclerView.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("你好，张三", Msg.TYPE_RECEIVED); msgList.add(msg1); Msg msg2 = new Msg("你好，请问你是？", Msg.TYPE_SENT); msgList.add(msg2); Msg msg3 = new Msg("我是tuituitui的小仙女一只，很高兴认识你啊！", Msg.TYPE_RECEIVED); msgList.add(msg3); } }
8.0 运行效果(真机)如下:
