android通用的添加错误提示

     在android开发涉及到网络请求数据时，如果请求错误，一般需要添加错误提示，这个错误提示可以做成一个通用的类。
     先来看一张没有添加错误提示的图：

     再来看一张添加错误提示的图：

     先看看主界面的布局：

<?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" >

    <include layout="@layout/title_layout" />

    <Button android:id="@+id/btn_addErrorBar" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_margin="10dp" android:text="addErrorBar" />

    <Button android:id="@+id/btn_removeErrorBar" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_margin="10dp" android:text="removeErrorBar" />

    <FrameLayout  android:id="@+id/fl_root" android:layout_width="match_parent" android:layout_height="match_parent" >

        <ListView android:id="@+id/listview" android:layout_width="match_parent" android:layout_height="match_parent" android:cacheColorHint="#00000000" />

        <TextView android:layout_width="match_parent" android:layout_height="40dp" android:layout_gravity="bottom" android:text="bottom" android:textColor="#ffffff" android:gravity="center" android:background="#88ff0000" />

    </FrameLayout>


</LinearLayout>

     这个布局中，错误提示的布局将覆盖在在FrameLayout的ListView这个位置，但是不会覆盖FrameLayout的TextView。
     再看看主界面Activity:

package com.androidtest.error;

import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.ListView;
import android.widget.TextView;

import com.androidtest.R;
import com.androidtest.base.BaseActivity;
import com.androidtest.utils.ErrorBarHelper;

public class ErrorActivity extends BaseActivity implements OnClickListener{

    private TextView title;
    private FrameLayout rootView;
    private ListView mListView;
    private Button btn_addErrorBar,btn_removeErrorBar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_error);

        init();
    }

    private void init() {
        title=(TextView) findViewById(R.id.title);
        title.setText("test error");

        findViewById(R.id.back).setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                finish();
            }
        });

        btn_addErrorBar=(Button) findViewById(R.id.btn_addErrorBar);
        btn_removeErrorBar=(Button) findViewById(R.id.btn_removeErrorBar);
        btn_addErrorBar.setOnClickListener(this);
        btn_removeErrorBar.setOnClickListener(this);

        rootView=(FrameLayout) findViewById(R.id.fl_root);
        mListView=(ListView) findViewById(R.id.listview);
        mListView.setAdapter(createAdapter());
    }

    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        if(v==btn_addErrorBar) {
            ErrorBarHelper.addErrorBar(rootView, mListView, "network error");
        } else if(v==btn_removeErrorBar) {
            ErrorBarHelper.removeErrorBar(rootView);
        }
    }
}

     主要看onClick事件。
     主要的功能在ErrorBarHelper.java类中：

package com.androidtest.utils;

import com.androidtest.R;
import com.androidtest.base.BaseApplication;

import android.text.TextUtils;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class ErrorBarHelper {

    private final static int KEY_INDEX=5<<24;
    private final static int KEY_VIEW=6<<24;
    private static boolean isAdd=false;

    public static View creatErrorBar() {
        View LoadingErroBar = (View) LayoutInflater.from(BaseApplication.getInstance().getApplicationContext())
                .inflate(R.layout.error_layout, null);
        return LoadingErroBar;
    }

    public static void addErrorBar(ViewGroup container,View content, String error) {
        addErrorBar(container,content, error, -1, null, "");
    }

    public static void addErrorBar(ViewGroup container,View content, String error, final Runnable refreshRunnable) {
        addErrorBar(container,content, error, -1, refreshRunnable, "");
    }

    public static void addErrorBar(ViewGroup container,View content, String error, final Runnable refreshRunnable, String buttonName) {
        addErrorBar(container,content, error, -1, refreshRunnable, buttonName);
    }

    public static void initErrorBar(View errorView, String error, int resId, final Runnable refreshRunnable,
            String buttonName) {
        if (resId >= 0) {
            ImageView imageView = (ImageView) errorView.findViewById(R.id.iv_error);
            imageView.setImageResource(resId);
        }
        TextView title = (TextView) errorView.findViewById(R.id.tv_error);
        if(TextUtils.isEmpty(error)){
            title.setVisibility(View.GONE);
        }else{
            title.setVisibility(View.VISIBLE);
            title.setText(error);
        }
        Button button = null;
        button = (Button) errorView.findViewById(R.id.bt_refresh);
        if (button != null && !TextUtils.isEmpty(buttonName)) {
            button.setText(buttonName);
        }
        if (refreshRunnable != null) {
            button.setOnClickListener(new OnClickListener() {
                @Override
                public void onClick(View arg0) {
                    refreshRunnable.run();
                }
            });
        } else {
            button.setVisibility(View.GONE);
        }
    }

    public static void addErrorBar(final ViewGroup container,final View content, final String error, final int resId,
            final Runnable refreshRunnable, final String buttonName) {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                addErrorBarInUiThread(container,content, 
                  error, resId, refreshRunnable, buttonName);
            }
        };
        BaseApplication.getInstance().
               getHandler().post(runnable);
    }



    public static void addErrorBarInUiThread(ViewGroup container,View content,final String error, final int resId,
            final Runnable refreshRunnable, final String buttonName) {
        if(container==null || content==null)
            return;
        removeErrorBar(container);
        int index=container.indexOfChild(content);
        if(index==-1)
            return;
        isAdd=true;
        container.setTag(KEY_INDEX,index);
        container.setTag(KEY_VIEW,content);
        View errorView=creatErrorBar();
        initErrorBar(errorView, error, resId, 
           refreshRunnable, buttonName);
        container.removeViewAt(index);
        container.addView(errorView,index,
            content.getLayoutParams());
    }

    public static void removeErrorBar(ViewGroup container) {
        if(isAdd) {
            isAdd=false;
            int index=(Integer) container.getTag(KEY_INDEX);
            View view=(View) container.getTag(KEY_VIEW);
            if(view!=null && index!=-1) {
                container.removeViewAt(index);
                container.addView(
                    view,index,view.getLayoutParams());
            }
        }
    }
}

     关键的点在这两句：container.removeViewAt(index);
container.addView(errorView,index,content.getLayoutParams());
通过这个方法，可以将原有的View和errorView进行动态的替换，同时不影响container中其他的元素。