GridView网格视图和Toast消息提示的作用

<GridView

xmlns:android="http://schemas.android.com/apk/res/android"

android:id="@+id/gridview"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:numColumns="auto_fit"

android:verticalSpacing="10dp"

android:horizontalSpacing="10dp"

android:columnWidth="90dp"

android:stretchMode="columnWidth"

android:gravity="center"

/>

import android.os.Bundle;

import android.support.v7.app.ActionBarActivity;

import android.view.Gravity;

import android.view.Menu;

import android.view.MenuItem;

import android.view.View;

import android.widget.AdapterView;

import android.widget.AdapterView.OnItemClickListener;

import android.widget.GridView;

import android.widget.Toast;

//网格视图实例 继承自Activity

public class MainActivity extends ActionBarActivity {

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

// 设置一个Activity的显示界面，显示界面在res下的layout中

setContentView(R.layout.activity_main);

// 取得GridView对象

GridView gridview=(GridView)findViewById(R.id.gridview);

// 添加元素给GridView

gridview.setAdapter(new ImageAdapter(this));

// 设置Gallery的背景

gridview.setBackgroundResource(R.drawable.bg0);

// 事件监听

gridview.setOnItemClickListener(new OnItemClickListener() {

public void onItemClick(AdapterView<?> parent, View v, int position, long id)

{

DisplayToast("您单击了" + (position + 1) + " 号图片");

}

});

}

//显示Toast

public void DisplayToast(String str){

Toast toast=Toast.makeText(this, str, Toast.LENGTH_SHORT);

// 设置toast的显示位置

toast.setGravity(Gravity.TOP, 0,180);

// 显示该toast

toast.show();

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

// Inflate the menu; this adds items to the action bar if it is present.

getMenuInflater().inflate(R.menu.main, menu);

return true;

}

@Override

public boolean onOptionsItemSelected(MenuItem item) {

// Handle action bar item clicks here. The action bar will

// automatically handle clicks on the Home/Up button, so long

// as you specify a parent activity in AndroidManifest.xml.

int id = item.getItemId();

if (id == R.id.action_settings) {

return true;

}

return super.onOptionsItemSelected(item);

}

}

import android.content.Context;

import android.view.View;

import android.view.ViewGroup;

import android.widget.BaseAdapter;

import android.widget.GridView;

import android.widget.ImageView;

//数据源

public class ImageAdapter extends BaseAdapter {

// 定义Context上下文，在本例中是指MainAcitivity.java

private Context mContext;

// 定义整型数组 即图片数据资源

private Integer[] mImages={

R.drawable.img1,

R.drawable.img2,

R.drawable.img3,

R.drawable.img4,

R.drawable.img5,

R.drawable.img6,

R.drawable.img7,

};

// 构造函数

public ImageAdapter(Context c) {

// TODO Auto-generated constructor stub

mContext=c;

}

// 获得图片的个数

@Override

public int getCount() {

// TODO Auto-generated method stub

return mImages.length;

}

//获取图片在库中的位置

@Override

public Object getItem(int position) {

// TODO Auto-generated method stub

return position;

}

//获得图片ID

@Override

public long getItemId(int position) {

// TODO Auto-generated method stub

return position;

}

//当列表中每一项显示在页面的时候，都会调用Adapter的getView方法返回一个View

@Override

public View getView(int position, View convertView, ViewGroup parent) {

// TODO Auto-generated method stub

ImageView imageView;

if(convertView == null){

// 给ImageView设置资源

imageView=new ImageView(mContext);

// 设置布局 图片85*85显示

imageView.setLayoutParams(new GridView.LayoutParams(85,85));

// 设置显示比例类型

imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);

}

else

{

imageView=(ImageView) convertView;

}

imageView.setImageResource(mImages[position]);

return imageView;

}

}