Android 聊天界面对话

转载请注明出处：http://blog.csdn.net/htwhtw123/article/details/77510010
实现Android 聊天界面对话 ，可以设计成接受到的消息在左显示，发送的消息右边显示。使用RecyclerView实现，主要思路是：在子项布局中同时设置左边和右边的TextView，选择性的让TextView可见或不可见。源码见github:点击跳转。下面是在 Androidd 8.0模拟器运行的效果。

1.导入RecyclerView:
ctr+al+shift+s:打开Project Structure对话框，点击Dependencies标签->点击右边的加号->点击libray dependence->在搜索框输入recyclerview->回车->双击选中下图所示项

2.添加图片，设置图片的拉伸方式：自己找一个一个对话框图片->复制到drawable目录下->右击图片文件->create 9 patch file …->弄成如下的样子->把原图片删除。左右各一个，可以在选择图片时，将图片水平旋转，就有了对称的另一张图。例如下面的communicate_left.9.png

3.设置RecyclerVeiw的子布局:
item_layout.xml中的代码：

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginTop="20dp"
    android:orientation="vertical">

    <TextView
        android:id="@+id/leftTv"
        android:textSize="25sp"
        android:text="左边发出:\n右边你好"
        android:paddingRight="5dp"
        android:paddingLeft="10dp"
        android:paddingTop="5dp"
        android:paddingBottom="5dp"
        android:background="@drawable/communicate_left"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

    <TextView
        android:id="@+id/rightTv"

        android:text="右边发出:\n左边你好"
        android:paddingRight="10dp"
        android:paddingLeft="5dp"
        android:paddingTop="5dp"
        android:paddingBottom="5dp"
        android:background="@drawable/communicate_right"
        android:textSize="25sp"
        android:gravity="right"
        android:layout_marginRight="2dp"
        android:layout_width="wrap_content"
        android:layout_gravity="right"
        android:layout_height="wrap_content"/>

LinearLayout>

4.ItemAdpter适配器代码:

package com.xingyi.chatui;

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

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

public class ItemAdapter extends RecyclerView.Adapter.MyViewHolder> {


    List list;
    Context context;
    int leftOrRight;


    public ItemAdapter( Context context) {
        this.context = context;
        list=new ArrayList<>();
    }


    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

        MyViewHolder holder = new MyViewHolder(LayoutInflater.from(
                context).inflate(R.layout.item_layout, parent,
                false));
        return holder;
    }

    @Override
    public void onBindViewHolder(MyViewHolder holder,  int position) {
        if(leftOrRight==MainActivity.LEFT){
            holder.tvLeft.setVisibility(View.VISIBLE);
            holder.tvRight.setVisibility(View.GONE);
            holder.tvLeft.setText(list.get(position));
        }else if(leftOrRight==MainActivity.RIGHT){
            holder.tvLeft.setVisibility(View.GONE);
            holder.tvRight.setVisibility(View.VISIBLE);
            holder.tvRight.setText(list.get(position));
        }
    }

    //添加子项
    public void addItem(String str,int leftOrRight) {
        this.leftOrRight=leftOrRight;
        list.add(str);
        notifyItemInserted(list.size()-1);
    }




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

    class MyViewHolder extends RecyclerView.ViewHolder {
        TextView tvLeft,tvRight;

        public MyViewHolder(View itemView) {
            super(itemView);
            tvLeft = (TextView) itemView.findViewById(R.id.leftTv);
            tvRight = (TextView) itemView.findViewById(R.id.rightTv);

        }
    }
}

5.主活动的布局activity_main：

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.xingyi.test.MainActivity"
    android:orientation="vertical">

    <LinearLayout
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <Button
            android:onClick="leftClick"
            android:text="左边发送"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>
        <Button

            android:onClick="rightClick"
            android:layout_marginLeft="29dp"
            android:text="右边发送"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>
    LinearLayout>

    <android.support.v7.widget.RecyclerView
        android:id="@+id/rv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

LinearLayout>

6.MainActivity
这里需要注意的是，Recyclerview的导入语句，选择：
import android.support.v7.widget.RecyclerView;

package com.xingyi.chatui;

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

public class MainActivity extends AppCompatActivity {

    RecyclerView recyclerView;
    ItemAdapter itemAdapter;
    final  static int LEFT=1;
    final  static int RIGHT=2;
    int i=0;


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

    private void initView(){
        recyclerView= (RecyclerView) findViewById(R.id.rv);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        itemAdapter=new ItemAdapter(this);
        recyclerView.setAdapter(itemAdapter);
    }

    public void leftClick(View v){
        //第一个参数指定发出内容，第二参数指定发出的是左还是右
        itemAdapter.addItem("左边发出:\n右边你好"+i,LEFT);
        recyclerView.smoothScrollToPosition(i);//移动到指定位置
        i++;
    }

    public void rightClick(View v){
        //第一个参数指定发出内容，第二参数指定发出的是左还是右
        itemAdapter.addItem("右边发出:\n左边你好"+i,RIGHT);
        recyclerView.smoothScrollToPosition(i);//移动到指定位置
        i++;
    }


}