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Android实现聊天界面 Android实现聊天界面

Thierryxc 人气:0

文件目录

在app下的build.gradle中添加依赖库(RecyclerView)

apply plugin: 'com.android.application'

android {
  compileSdkVersion 24
  buildToolsVersion "26.0.1"
  defaultConfig {
    applicationId "com.example.uibestpractice"
    minSdkVersion 15
    targetSdkVersion 24
    versionCode 1
    versionName "1.0"
    testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
  }
  buildTypes {
    release {
      minifyEnabled false
      proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguarrules.pro'
    }
  }
}

dependencies {
  compile fileTree(dir: 'libs', include: ['*.jar'])
  androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
    exclude group: 'com.android.support', module: 'support-annotations'
  })
  compile 'com.android.support:appcompat-v7:24.2.1'
  compile 'com.android.support.constraint:constraint-layout:1.0.2'
  compile 'com.android.support:recyclerview-v7:24.2.1'//添加RecyclerView依赖库
  testCompile 'junit:junit:4.12'
}

编写主界面(activity_main.xml)

<?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="match_parent"
  android:background="#d8e0d8">

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

<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"
    android:text="Send"/>

</LinearLayout>

</LinearLayout> 

定义消息的实体类Msg

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;

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

  public String getContent() {
    return content;
  }
  public int getType() {
    return type;
  }
}

编写RecyclerView的子布局(msg_item.xml)

<?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:id="@+id/left_layout"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="left"
    android:background="@drawable/message_left">

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

  <LinearLayout
    android:id="@+id/right_layout"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="right"
    android:background="@drawable/message_right">

    <TextView
      android:id="@+id/right_msg"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_gravity="center"
      android:layout_margin="10dp"/>
  </LinearLayout>

</LinearLayout>

创建RecyclerView适配器类

package com.example.uibestpractice;

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

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 rihgtMsg;

    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);
      rihgtMsg = (TextView) view.findViewById(R.id.right_msg);
    }
  }

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

  @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) {
      holder.leftLayout.setVisibility(View.VISIBLE);
      holder.rightLayout.setVisibility(View.GONE);
      holder.leftMsg.setText(msg.getContent());
    } else if (msg.getType() == Msg.TYPE_SENT) {
      holder.rightLayout.setVisibility(View.VISIBLE);
      holder.leftLayout.setVisibility(View.GONE);
      holder.rihgtMsg.setText(msg.getContent());
    }
  }

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

使用RecyclerView(修改MainActivity)

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();
    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);
          msgRecyclerView.scrollToPosition(msgList.size()-1);
          inputText.setText("");
        }
      }
    });
  }

  private void initMsgs() {
    Msg msg1 = new Msg("Hello",Msg.TYPE_RECEIVED);
    msgList.add(msg1);
    Msg msg2 = new Msg("I'm John",Msg.TYPE_RECEIVED);
    msgList.add(msg2);
    Msg msg3 = new Msg("Hello",Msg.TYPE_SENT);
    msgList.add(msg3);
  }
}

onCreate()方法中先获得了RecyclerView的实例,然后创建了LinearLayoutManager对象,并把它设置到RecyclerView的实例中去。LayoutManager用于指定RecyclerView的布局方式,这里使用是线性布局的意思,可以实现ListView相同的效果。

设置了send按钮的响应事件,如果内容不为空则创建出一个新的Msg对象,并添加到msgList中去,之后调用了适配器的方法notifyItemInserted()来通知列表有新数据插入,这样新增的消息才能在RecyclerView中显示。接着调用RecyclerView的scrollToPosition()方法,将显示的数据定位到最后一行,最后清空输入栏。

效果图:

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