android:如何更改 ListView 中 row_item 的 layout_gravity 属性

Question

我正在尝试实现一个可以出现在左侧或右侧的聊天气泡。我阅读了很多已在此处发布的答案，但我没有设法让其中任何一个为我工作，也许我遗漏了什么。

如果我手动将 row_item xml 中 linearLayout 的 layout_gravity 从左更改为右，然后查看图形布局，我可以看到它按我想要的方式工作。问题是我无法控制此属性。据我了解，问题与存在的 LayoutParams 属于 listview.LayoutParams 这一事实有关，如果我尝试将 LayoutParams 获取到 listview.LayoutParams 对象，它会起作用。但这不是我想要实现的目标。

代码如下:

Activity xml

<LinearLayout 
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:ignore="MergeRootFrame" >

<ListView
    android:id="@+id/listViewMessages"
    android:layout_width="match_parent"
    android:layout_height="0dp" 
    android:layout_weight="0.98" >

</ListView>

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="0.02"
    android:background="#D3D3D3"
    android:orientation="horizontal" >

    <EditText
        android:id="@+id/editTextMessage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_toLeftOf="@+id/imageButtonSend"
        android:ems="10"
        android:hint="@string/textFieldMessage"
        android:textSize="14sp"
        android:visibility="visible" >

        <requestFocus />
    </EditText>

    <ImageButton
        android:id="@+id/imageButtonSend"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_centerVertical="true"
        android:layout_marginRight="14dp"
        android:background="?android:attr/selectableItemBackground"
        android:contentDescription="@string/imageButtonSendNow_contentDescription"
        android:src="@drawable/ic_action_send_now" 
        android:onClick="onClick" />

</RelativeLayout>

</LinearLayout>

row_item xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/singleMessageContainer"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="left"
android:orientation="horizontal"
android:padding="6dp" >

    <TextView
        android:id="@+id/textViewMessage"
        android:layout_width="wrap_content"
        android:layout_height="20dp"
        android:layout_weight="0.85"
        android:layout_marginBottom="2dp"
        android:layout_marginLeft="5dp"
        android:layout_marginTop="2dp"
        android:gravity="center_vertical"
        android:text="Message"
        android:textSize="16sp"
        tools:ignore="HardcodedText" />

    <TextView
        android:id="@+id/TextViewTime"
        android:layout_width="wrap_content"
        android:layout_height="14dp"
        android:layout_weight="0.1"
        android:layout_gravity="bottom"
        android:layout_marginLeft="22dp"
        android:gravity="center_vertical"
        android:text="Time"
        android:textSize="12sp"
        tools:ignore="HardcodedText" />

    <ImageView
        android:id="@+id/imageViewSuccess"
        android:layout_width="12dp"
        android:layout_height="12dp"
        android:layout_weight="0.05"
        android:layout_gravity="bottom"
        android:contentDescription="successIcon"
        android:src="@drawable/ic_action_accept"
        tools:ignore="HardcodedText" />

  </LinearLayout>

适配器代码:

public class ConversationAdapter extends ArrayAdapter<Message> {

private final Context context;

static class ViewHolder {
    public TextView message;
    public TextView time;
    public ImageView success;
    public LinearLayout singleMessageContainer;

}

public ConversationAdapter(Context context, ArrayList<Message> values) {
    super(context, R.layout.conversation_list_item, values);
    this.context = context;

}

  @Override
public View getView(int position, View convertView, ViewGroup parent) {
      View rowView = convertView;
        // reuse views
        if (rowView == null) {
          LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
          rowView = inflater.inflate(R.layout.conversation_list_item, parent,false);
          // configure view holder
          ViewHolder viewHolder = new ViewHolder();
          viewHolder.message = (TextView) rowView.findViewById(R.id.textViewMessage);
          viewHolder.time = (TextView) rowView.findViewById(R.id.TextViewTime);
          viewHolder.success = (ImageView) rowView.findViewById(R.id.imageViewSuccess);
          viewHolder.singleMessageContainer = (LinearLayout)     rowView.findViewById(R.id.singleMessageContainer);

          rowView.setTag(viewHolder);
        }

        // fill data
        ViewHolder holder = (ViewHolder) rowView.getTag();

        holder.message.setText(getItem(position).getMessage());
        holder.time.setText(getItem(position).getUniversalTimeString());
        holder.success.setImageResource(R.drawable.ic_action_accept);

        boolean isMine = (getItem(position).getSender() == 0);

        holder.singleMessageContainer.setBackgroundResource(
                isMine ? R.drawable.bubble_yellow : R.drawable.bubble_green);

        // This part doesn't work
        LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) 
                holder.singleMessageContainer.getLayoutParams();
        params.gravity=(isMine ? Gravity.LEFT : Gravity.RIGHT);

        holder.singleMessageContainer.setLayoutParams(params);

        return rowView; 
  }

}

Answer 1

解决方案

我继续阅读有关 gravity 和 layout_gravity 的内容，并遇到了帮助我解决此问题的更详细信息。在这里问题的几个答案中，有一个使用 warpper 布局的解决方案，但没有写下需要注意的重要事项。

首先要知道的是，如果您将线性布局设置为水平布局，您将无法将重力属性用作左或右仅顶部或底部因此外层容器必须是垂直的，而内层容器必须是水平的，以便在一行中一个接一个地显示消息和其他数据。

然后您可以使用外部容器的方法 setGravity(Gravity.LEFT) 或 setGravity(Gravity.RIGHT) 将内部 warpper 正确对齐到左侧或右侧。您还需要注意 fill_parent 和 wrap_content 的属性

这里是更新的代码:row_item xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/singleMessageContainer"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="left"
android:orientation="vertical"
android:padding="6dp" >

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

    <TextView
        android:id="@+id/textViewMessage"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:layout_marginBottom="2dp"
        android:layout_marginLeft="5dp"
        android:layout_marginRight="5dp"
        android:layout_marginTop="2dp"
        android:text="Message"
        android:textSize="14sp"
        tools:ignore="HardcodedText" />

    <TextView
        android:id="@+id/TextViewTime"
        android:layout_width="wrap_content"
        android:layout_height="14dp"
        android:layout_gravity="bottom"
        android:text="Time"
        android:textSize="12sp"
        tools:ignore="HardcodedText" />

    <ImageView
        android:id="@+id/imageViewSuccess"
        android:layout_width="wrap_content"
        android:layout_height="12dp"
        android:layout_gravity="bottom"
        android:contentDescription="successIcon"
        android:src="@drawable/ic_action_accept"
        tools:ignore="HardcodedText" />

    </LinearLayout>

</LinearLayout>

和更新后的适配器代码:

public class ConversationAdapter extends ArrayAdapter<Message> {

private final Context context;

static class ViewHolder {
    public TextView message;
    public TextView time;
    public ImageView success;
    public LinearLayout singleMessageContainer;
    // Added
    public LinearLayout warpper;

}

public ConversationAdapter(Context context, ArrayList<Message> values) {
    super(context, R.layout.conversation_list_item, values);
    this.context = context;

}

  @Override
public View getView(int position, View convertView, ViewGroup parent) {
      View rowView = convertView;
        // reuse views
        if (rowView == null) {
          LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
          rowView = inflater.inflate(R.layout.conversation_list_item, parent,false);
          // configure view holder
          ViewHolder viewHolder = new ViewHolder();
          viewHolder.message = (TextView) rowView.findViewById(R.id.textViewMessage);
          viewHolder.time = (TextView) rowView.findViewById(R.id.TextViewTime);
          viewHolder.success = (ImageView) rowView.findViewById(R.id.imageViewSuccess);
          viewHolder.singleMessageContainer = (LinearLayout) rowView.findViewById(R.id.singleMessageContainer);
          // Added
          viewHolder.warpper = (LinearLayout) rowView.findViewById(R.id.warpper);

          rowView.setTag(viewHolder);
        }

        // fill data
        ViewHolder holder = (ViewHolder) rowView.getTag();

        holder.message.setText(getItem(position).getMessage());
        holder.time.setText(getItem(position).getUniversalTimeString());
        holder.success.setImageResource(R.drawable.ic_action_accept);

        boolean isMine = (getItem(position).getSender() == 0);

        // Changed to warpper
        holder.warpper.setBackgroundResource(
                isMine ? R.drawable.bubble_yellow : R.drawable.bubble_green);
        // Added
        holder.singleMessageContainer.setGravity(isMine ? Gravity.LEFT : Gravity.RIGHT);


        return rowView; 
  }

}

它应该可以工作。唯一的问题是，您可能会在 xml 中看到一条关于线性布局之一无用的警告，但没有它就无法工作。

希望对你有所帮助。