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(); } } } }

以上就是本文的全部内容，希望对大家学习Android软件编程有所帮助，也希望大家多多支持查字典教程网。