Android编写简单的聊天室应用

最近写了一个简单的聊天室应用，可以发送表情，更改头像这些功能。主要技术点就是怎样把表情图片放到textview等Ui控件中展示。这里废话不多说，下面是效果图：

这里主要讲下怎样把文本替换到表情，先说下思路，首先我们的图片是保存在本地资源目录drawable中而所有的资源文件都是R这个类来管理，所以我们可以利用正则表达式找出图片id包装成ImageSpan然后把ImageSpan放到SpannableString中，最后把SpannableString放入edittext中，下面是源码：

package com.coreandroid.util; 

import java.lang.reflect.Field;
import java.util.regex.Matcher;
import java.util.regex.Pattern; 

import android.content.Context;
import android.text.Spannable;
import android.text.SpannableString;
import android.text.style.ImageSpan;
import android.util.Log; 

import com.coreandroid.chart.R; 

public class ExpressionUtil {
  /**
   * 对spanableString进行正则判断，如果符合要求，则以表情图片代替
   *
   * @param context
   * @param spannableString
   * @param patten
   * @param start
   */
  public static void matchExpression(Context context,
      SpannableString spannableString, Pattern patten, int start)
      throws Exception {
    Matcher matcher = patten.matcher(spannableString);
    while (matcher.find()) {
      String key = matcher.group();
      if (matcher.start() < start) {
        continue;
      }
      Field field = R.drawable.class.getDeclaredField(key);
      int resId = field.getInt(null); // 通过上面匹配得到的字符串来生成图片资源id
      if (resId != 0) {
        ImageSpan imageSpan = new ImageSpan(context, resId); // 通过图片资源id来得到bitmap，用一个ImageSpan来包装
        int end = matcher.start() + key.length(); // 计算该图片名字的长度，也就是要替换的字符串的长度
        spannableString.setSpan(imageSpan, matcher.start(), end,
            Spannable.SPAN_EXCLUSIVE_EXCLUSIVE); // 将该图片替换字符串中规定的位置中
        if (end < spannableString.length()) { // 如果整个字符串还未验证完，则继续。。
          matchExpression(context, spannableString, patten, end);
        }
        break;
      }
    }
  } 

  /**
   * 得到一个SpanableString对象，通过传入的字符串,并进行正则判断
   *
   * @param context
   * @param str
   * @return SpannableString
   */
  public static SpannableString getExpressionString(Context context,
      String str, String zhengze) {
    SpannableString spannableString = new SpannableString(str);
    Pattern sinaPatten = Pattern.compile(zhengze); // 通过传入的正则表达式来生成一个pattern
    try {
      matchExpression(context, spannableString, sinaPatten, 0);
    } catch (Exception e) {
      Log.e("dealExpression", e.getMessage());
    }
    return spannableString;
  } 

}

下面是聊天记录列表的adapter，这里主要是动态的改变每个Item的布局来区分是自己还是他人的发言，具体源码如下：

package com.coreandroid.adapter; 

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.List; 

import android.content.Context;
import android.text.SpannableString;
import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.RelativeLayout;
import android.widget.TextView; 

import com.coreandroid.chart.R;
import com.coreandroid.entity.MessageInfo;
import com.coreandroid.util.CommonUtils;
import com.coreandroid.util.ExpressionUtil; 

public class ChartListAdapter extends BaseAdapter { 

  private Context context; 

  private LayoutInflater inflater; 

  private List<MessageInfo> data; 

  private DateFormat df; 

  public ChartListAdapter(Context context, List<MessageInfo> data) {
    super();
    this.context = context;
    inflater = LayoutInflater.from(context);
    this.data = data;
    df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
  } 

  @Override
  public int getCount() {
    return data.size();
  } 

  @Override
  public Object getItem(int position) {
    return data.get(position);
  } 

  @Override
  public long getItemId(int position) {
    return position;
  } 

  @Override
  public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder holder = null;
    if (convertView == null) {
      convertView = inflater.inflate(R.layout.chart_list_item, null);
      holder = new ViewHolder(convertView);
      convertView.setTag(holder);
    } else {
      holder = (ViewHolder) convertView.getTag();
    }
    holder.setData((MessageInfo) getItem(position));
    return convertView;
  } 

  private class ViewHolder {
    private ImageView image;
    private TextView text;
    private TextView title;
    private RelativeLayout rl; 

    public ViewHolder(View convertView) {
      image = (ImageView) convertView
          .findViewById(R.id.chart_list_item_headicon);
      text = (TextView) convertView
          .findViewById(R.id.chart_list_item_message);
      title = (TextView) convertView
          .findViewById(R.id.chart_list_item_title);
      rl = (RelativeLayout) convertView
          .findViewById(R.id.rl_chart_list_bottom);
    } 

    public void setData(MessageInfo msg) {
      RelativeLayout.LayoutParams rl_tv_msg_left = (RelativeLayout.LayoutParams) text
          .getLayoutParams();
      RelativeLayout.LayoutParams rl_iv_headicon_left = (RelativeLayout.LayoutParams) image
          .getLayoutParams();
      RelativeLayout.LayoutParams rl_tv_title = (RelativeLayout.LayoutParams) title
          .getLayoutParams();
      RelativeLayout.LayoutParams rl_buttom = (RelativeLayout.LayoutParams) rl
          .getLayoutParams();
      if (!CommonUtils.getDeviceId().equalsIgnoreCase(msg.getUsermac())) {
        // 根据本地的mac地址来判断该条信息是属于本人所说还是对方所说
        // 如果是自己说的，则显示在右边；如果是对方所说，则显示在左边
        rl_buttom.addRule(RelativeLayout.ALIGN_PARENT_TOP); 

        rl_tv_title.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
        rl_tv_title.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
        rl_tv_title.addRule(RelativeLayout.BELOW,
            R.id.rl_chart_list_bottom); 

        rl_iv_headicon_left.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
        rl_iv_headicon_left.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
        rl_tv_msg_left.addRule(RelativeLayout.RIGHT_OF,
            R.id.chart_list_item_headicon);
        text.setBackgroundResource(R.drawable.incoming);
        String titleStr = msg.getUsermac() + "-"
            + df.format(new Date());
        title.setText(titleStr);
      } else {
        rl_buttom.addRule(RelativeLayout.ALIGN_PARENT_TOP); 

        rl_tv_title.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
        rl_tv_title.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
        rl_tv_title.addRule(RelativeLayout.BELOW,
            R.id.rl_chart_list_bottom); 

        rl_iv_headicon_left.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
        rl_iv_headicon_left.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
        rl_tv_msg_left.addRule(RelativeLayout.LEFT_OF,
            R.id.chart_list_item_headicon);
        text.setBackgroundResource(R.drawable.outgoing);
        String titleStr = df.format(new Date()) + "-"
            + msg.getUsermac();
        title.setText(titleStr);
      }
      if (!TextUtils.isEmpty(msg.getHeadImage())) {
        image.setImageBitmap(CommonUtils.strConvertBitmap(msg
            .getHeadImage())); // 设置头像
      } else {
        image.setImageResource(R.drawable.im);
      }
      String str = msg.getMessage(); // 消息具体内容
      try {
        SpannableString spannableString = ExpressionUtil
            .getExpressionString(context, str, CommonUtils.PATTERN);
        text.setText(spannableString);
      } catch (Exception e) {
        e.printStackTrace();
      }
    }
  } 

}

源码下载：Android聊天室应用

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