Android onLayout()和AsyncTask()无法一起使用

时间:2011-12-23 07:44:07

标签: android layout android-asynctask ui-thread

我需要一个带有固定标题的可滚动表格,所以我跟着this great blog,一切都很好。

这个想法是使用一个表格作为标题,一个表格用于滚动视图中添加的内容,两者都在自定义的LinearLayout中。在自定义的LinearLayout中,我们将覆盖onLayout()以获取每行的最大宽度,并为header和content表的每一行设置宽度。

以下是活动及其布局:

package com.stylingandroid.ScrollingTable;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TableLayout;
import android.widget.TableRow;

public class ScrollingTable extends LinearLayout
{
    public ScrollingTable( Context context )
    {
        super( context );
    }
public ScrollingTable( Context context, AttributeSet attrs )
{
    super( context, attrs );
}

@Override
protected void onLayout( boolean changed, int l, int t, int r, int b )
{
    super.onLayout( changed, l, t, r, b );

    TableLayout header = (TableLayout) findViewById( R.id.HeaderTable );
    TableLayout body = (TableLayout) findViewById( R.id.BodyTable );

    if (body.getChildCount() > 0 ) {
        TableRow bodyRow = (TableRow) body.getChildAt(0);
        TableRow headerRow = (TableRow) header.getChildAt(0);

        for ( int cellnum = 0; cellnum < bodyRow.getChildCount(); cellnum++ ){
            View bodyCell = bodyRow.getChildAt(cellnum);
            View headerCell = headerRow.getChildAt(cellnum);
            int bodyWidth = bodyCell.getWidth();
            int headerWidth = headerCell.getWidth();
            int max = Math.max(bodyWidth, headerWidth);
            TableRow.LayoutParams bodyParams = (TableRow.LayoutParams)bodyCell.getLayoutParams();
            bodyParams.width = max;
            TableRow.LayoutParams headerParams = (TableRow.LayoutParams)headerCell.getLayoutParams();
            headerParams.width = max;
        }       
    }
}
}

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="fill_parent"
    android:layout_height="fill_parent">

    <com.stylingandroid.ScrollingTable.ScrollingTable
        android:layout_width="match_parent"
        android:orientation="vertical"
        android:layout_height="match_parent">

        <TableLayout 
            android:layout_height="wrap_content"
            android:layout_width="match_parent" 
            android:id="@+id/HeaderTable">
        </TableLayout>

        <ScrollView 
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <TableLayout 
                android:layout_height="wrap_content"
                android:layout_width="match_parent" 
                android:id="@+id/BodyTable">
            </TableLayout>

        </ScrollView>

    </com.stylingandroid.ScrollingTable.ScrollingTable>

</LinearLayout>

主要活动

 package com.stylingandroid.ScrollingTable;

import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.TableLayout;
import android.widget.TableRow;

    import android.widget.TextView;

    public class ScrollingTableActivity extends Activity
    {
        private String[][] tableData = {
                {"header11111111111", "header2","header3","header4"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},


    {"column1", "column1",

"column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"}
        };
        /** Called when the activity is first created. */
        @Override
        public void onCreate( Bundle savedInstanceState )
        {
            super.onCreate( savedInstanceState );
            setContentView( R.layout.main );
            TableLayout tableHeader = (TableLayout)findViewById(R.id.HeaderTable);
            TableLayout tableBody = (TableLayout)findViewById(R.id.BodyTable);

        appendRows(tableHeader, tableBody, tableData);
}

private void appendRows(TableLayout tableHeader ,TableLayout tableContent, String[][] amortization) {
    int rowSize=amortization.length;
    int colSize=(amortization.length > 0)?amortization[0].length:0;
    for(int i=0; i<rowSize; i++) {
        TableRow row1 = new TableRow(this);

        for(int j=0; j<colSize; j++) {
            TextView c = new TextView(this);
            c.setText(amortization[i][j]);
            c.setPadding(3, 3, 3, 3);
            if (i == 0) {
                c.setTextColor(Color.BLACK);
            }
            row1.addView(c);
        }

        if (i == 0) { 
            row1.setBackgroundColor(Color.LTGRAY);
            tableHeader.addView(row1, new TableLayout.LayoutParams());
        } else {
            tableContent.addView(row1, new TableLayout.LayoutParams());
        }
    }
}

上面的代码完美地工作(expected),然而,当我使用AnysnTask从服务器获取数据并稍后向表中添加数据时,我的自定义视图中的onLayout()不再起作用。我通过注销一些数字模拟获取数据:

public void onCreate( Bundle savedInstanceState )
    {
        super.onCreate( savedInstanceState );
        setContentView( R.layout.main );

        new MyTask().execute();
    }

    private class MyTask extends AsyncTask<Void, Void, Void> {

        private ProgressDialog progressDialog;
        protected void onPreExecute() {
                progressDialog = ProgressDialog.show(ScrollingTableActivity.this,
                                  "", "Loading. Please wait...", true);
        }
        @Override
        protected Void doInBackground(Void... reportTypes) {
            for (int i = 0; i < 500; i++) { 
                System.out.println(i);
            } 
            return null;
        }
        @Override
        protected void onPostExecute(Void result) {
            progressDialog.dismiss();
            TableLayout tableHeader = (TableLayout)findViewById(R.id.HeaderTable);
            TableLayout tableBody = (TableLayout)findViewById(R.id.BodyTable);

            appendRows(tableHeader, tableBody, tableData);
        }

    }

所以onLayout()只有在我通过将它放在onCreate()方法中从主UI线程调用appendRows()时才有效。如果我从另一个UI线程调用(在AsyncTask的onPostExecute()中),则调用onLayout()(我通过创建一些日志来检查它),但它不会影响GUI。我尝试使用invalidate(),forceLayout(),requestLayout()但不改变任何内容。wrong

我认为我们需要调用一个方法来进行GUI刷新,但不知道它是什么,我已经在2天内搜索并尝试了很多方法但没有得到任何结果,所以如果你能做到,我们将非常感激对此有任何想法。非常感谢。

3 个答案:

答案 0 :(得分:2)

您可能想看看这个答案: Android Set textview layout width dynamically

但是,基本上,尝试将每个TextView的宽度设置为与标题相同。

这可能需要你做两次,因为你可能需要让系统进行布局,所以使用View.INVISIBLE,然后你需要退出AsyncTask,调用另一个,所以布局工作可能会发生。

然后在第二个中,您可以获取不可见的表,循环查找该列中的最大宽度,然后将该列中的所有TextView设置为最大。

这不是最佳解决方案,但应该有效。

我认为您在AsyncTask中的主要问题是需要完成布局,然后才能进行修复。

答案 1 :(得分:1)

我终于找到了答案,setColumnCollapsed()使表格布局刷新,但是我们需要将它放在另一个AsyncTask中,否则它将无法工作,奇怪:(。我把最新的代码放在这里,所以希望它对某人有帮助。此外,这只是解决方法,所以如果有的话,随时发布你的答案......

private class MyTask extends AsyncTask<Void, Void, Void> {

    private ProgressDialog progressDialog;
    protected void onPreExecute() {
            progressDialog = ProgressDialog.show(ScrollingTableActivity.this,
                              "", "Loading. Please wait...", true);
    }
    @Override
    protected Void doInBackground(Void... reportTypes) {
        for (int i = 0; i < 500; i++) { 
            System.out.println(i);
        } 
        return null;
    }
    @Override
    protected void onPostExecute(Void result) {
        progressDialog.dismiss();
        appendRows(tableHeader, tableBody, tableData);

        new My1Task().execute();
    }
}

private class My1Task extends AsyncTask<Void, Void, Void> {

    @Override
    protected Void doInBackground(Void... reportTypes) {
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        tableHeader.setColumnCollapsed(0, false);
        tableBody.setColumnCollapsed(0, false);
    }
}

答案 2 :(得分:0)

答案是你应该在onCreate()方法之外声明你的TableLayout并在onCreate()中实例化它们。这是解决方案。效果很好。

public class ScrollingTableActivity extends Activity {
    TableLayout tableHeader;
    TableLayout tableBody;

    private String[][] tableData = {
            { "header11111111111", "header2", "header3", "header4" },
            { "column1", "column1", "column1", "column1" },
            { "column1", "column1", "column1", "column1" },
            { "column1", "column1", "column1", "column1" },
            { "column1", "column1", "column1", "column1" } };

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        tableHeader = (TableLayout) findViewById(R.id.HeaderTable);
        tableBody = (TableLayout) findViewById(R.id.BodyTable);
        Log.d("ScrollingTable", "Before appendRows");
        //appendRows(tableHeader, tableBody, tableData);
        new MyTask().execute();
    }

    private void appendRows(TableLayout tableHeader, TableLayout tableContent,
            String[][] amortization) {
        int rowSize = amortization.length;
        int colSize = (amortization.length > 0) ? amortization[0].length : 0;
        for (int i = 0; i < rowSize; i++) {
            TableRow row1 = new TableRow(this);

            for (int j = 0; j < colSize; j++) {
                TextView c = new TextView(this);
                c.setText(amortization[i][j]);
                c.setPadding(3, 3, 3, 3);
                if (i == 0) {
                    c.setTextColor(Color.BLACK);
                }
                row1.addView(c);
            }

            if (i == 0) {
                row1.setBackgroundColor(Color.LTGRAY);
                tableHeader.addView(row1, new TableLayout.LayoutParams());
            } else {
                tableContent.addView(row1, new TableLayout.LayoutParams());
            }
        }
    }


    private class MyTask extends AsyncTask<Void, Void, Void> {

        private ProgressDialog progressDialog;
        protected void onPreExecute() {
                progressDialog = ProgressDialog.show(ScrollingTableActivity.this,
                                  "", "Loading. Please wait...", true);
        }
        @Override
        protected Void doInBackground(Void... reportTypes) {
            for (int i = 0; i < 500; i++) { 
                System.out.println(i);
            } 
            return null;
        }
        @Override
        protected void onPostExecute(Void result) {
            progressDialog.dismiss();
            TableLayout tableHeader = (TableLayout)findViewById(R.id.HeaderTable);
            TableLayout tableBody = (TableLayout)findViewById(R.id.BodyTable);

            appendRows(tableHeader, tableBody, tableData);
        }
    }
}