实验任务5 编写聊天界面

最新推荐文章于 2022-06-29 16:04:34 发布

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本文介绍了一个简单的聊天应用UI实现过程，包括MainActivity、Msg和MsgAdapter三个核心Java类的定义及其实现细节，并展示了对应的XML布局文件。

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一、实验效果图：

二、主要代码：

1、java代码：

（1）MainActivity.java

package com.example.uibestpractice;

import java.util.ArrayList;
import java.util.List;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.view.View.OnClickListener;

public class MainActivity extends Activity {
	private ListView msgListView;
	private EditText inputText;
	private Button send;
	private MsgAdapter adapter;
	private List<Msg> msgList = new ArrayList<Msg>();

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		// requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.activity_main);
		initMsgs();
		adapter = new MsgAdapter(MainActivity.this, R.layout.msg_item, msgList);
		inputText = (EditText) findViewById(R.id.input_text);
		send = (Button) findViewById(R.id.send);
		msgListView = (ListView) findViewById(R.id.msg_list_view);
		msgListView.setAdapter(adapter);
		send.setOnClickListener(new 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.notifyDataSetChanged();
					msgListView.setSelection(msgList.size());
					inputText.setText("");
				}
			}
		});
	}

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

（2）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;

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

	public String getContent() {
		return content;
	}

	public int getType() {
		return type;
	}
}

（3）MsgAdapter.java

package com.example.uibestpractice;

import java.util.List;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;

public class MsgAdapter extends ArrayAdapter<Msg> {
	private int resourceId;

	public MsgAdapter(Context context, int textViewResourceId, List<Msg> objects) {
		super(context, textViewResourceId, objects);
		resourceId = textViewResourceId;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		Msg msg = getItem(position);
		View view;
		ViewHolder viewHolder;
		if (convertView == null) {
			view = LayoutInflater.from(getContext()).inflate(resourceId, null);
			viewHolder = new ViewHolder();
			viewHolder.leftLayout = (LinearLayout) view
					.findViewById(R.id.left_layout);
			viewHolder.rightLayout = (RelativeLayout) view
					.findViewById(R.id.right_layout);
			viewHolder.leftMsg = (TextView) view.findViewById(R.id.left_msg);
			viewHolder.rightMsg = (TextView) view.findViewById(R.id.right_msg);
			view.setTag(viewHolder);
		} else {
			view = convertView;
			viewHolder = (ViewHolder) view.getTag();
		}
		if (msg.getType() == Msg.TYPE_RECEIVED) {
			viewHolder.leftLayout.setVisibility(View.VISIBLE);
			viewHolder.rightLayout.setVisibility(View.GONE);
			viewHolder.leftMsg.setText(msg.getContent());
		} else if (msg.getType() == Msg.TYPE_SENT) {
			viewHolder.rightLayout.setVisibility(View.VISIBLE);
			viewHolder.leftLayout.setVisibility(View.GONE);
			viewHolder.rightMsg.setText(msg.getContent());
		}
		return view;
	}

	class ViewHolder {
		LinearLayout leftLayout;
		RelativeLayout rightLayout;
		TextView leftMsg;
		TextView rightMsg;
	}
}

2、布局文件：

（1）activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#d8e0e8"
    android:orientation="vertical" >

    <ListView
        android:id="@+id/msg_list_view"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        android:divider="#0000" >
    </ListView>

    <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:background="@android:drawable/edit_text"
            android:hint="Type somthing here"
            android:maxLines="2" />

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

</LinearLayout>

（2）msg_item.xml

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

    <LinearLayout
        android:id="@+id/left_layout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <LinearLayout
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="vertical" >

            <ImageView
                android:layout_width="49dp"
                android:layout_height="49dp"
                android:src="@drawable/weixin" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:text="机器人"
                android:textSize="18sp" />
        </LinearLayout>

        <TextView
            android:id="@+id/left_msg"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="@drawable/message_left"
            android:gravity="center" />
    </LinearLayout>

    <RelativeLayout
        android:id="@+id/right_layout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >

        <LinearLayout
            android:id="@+id/ly_chat"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentRight="true"
            android:orientation="vertical" >

            <ImageView
                android:layout_width="49sp"
                android:layout_height="49sp"
                android:src="@drawable/my" />

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center"
                android:text="主人"
                android:textSize="18sp" />
        </LinearLayout>

        <TextView
            android:id="@+id/right_msg"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_toLeftOf="@+id/ly_chat"
            android:background="@drawable/message_right"
            android:gravity="center" />
    </RelativeLayout>

</LinearLayout>

3、AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.uibestpractice"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/weixin"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.uibestpractice.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>