Android——基本控件下（十七）

1. 文本切换：TextSwitcher

1.1 知识点

（1）理解TextSwitcher和ViewFactory的使用。

1.2 具体内容

范例：切换显示当前时间

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical" ><TextSwitcherandroid:id="@+id/myTextSwitcher"android:layout_width="match_parent"android:layout_height="wrap_content" android:layout_gravity="center_horizontal"/><Buttonandroid:id="@+id/but"android:layout_width="match_parent"android:layout_height="wrap_content" android:text="显示当前时间"android:layout_gravity="center_horizontal"/></LinearLayout>

package com.example.textswitcher;import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.TextSwitcher;
import android.widget.TextView;
import android.widget.ViewSwitcher.ViewFactory;public class TextSwitcherActivity extends Activity {private Button but = null;private TextSwitcher textSwitcher = null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);super.setContentView(R.layout.activity_text_switcher);this.but = (Button) super.findViewById(R.id.but);this.textSwitcher = (TextSwitcher) super.findViewById(R.id.myTextSwitcher);this.textSwitcher.setFactory(new ViewFactory() {@Overridepublic View makeView() {TextView textView = new TextView(TextSwitcherActivity.this);textView.setLayoutParams(new TextSwitcher.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));textView.setBackgroundColor(0xFFFFFFFF);textView.setTextSize(30);return textView;}});this.but.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {Date date = new Date();DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");String sDate = df.format(date);//将Date类型的日期转换成字符串TextSwitcherActivity.this.textSwitcher.setText("当前时间："+sDate);}});}
}

当然也可以设置动画效果。

<TextSwitcherandroid:id="@+id/myTextSwitcher"android:layout_width="match_parent"android:layout_height="wrap_content" android:layout_gravity="center_horizontal"android:inAnimation="@android:anim/slide_in_left"android:outAnimation="@android:anim/slide_out_right"/>

1.3 小结

（1）TextSwitcher与ImageSwitcher一样，如果需要转换都必须通过ViewFactory接口设置。

2. 拖拉图片：Gallery

2.1 知识点

（1）掌握Gallery组件的使用；

（2）使用Gallery + ImageSwitcher完成图片浏览功能。

2.2 具体内容

我们通过API去查找SpinnerAdapter这个接口。发现此接口有几个实现类：ArrayAdapter，SimpleAdapter，BaseAdapter

·使用ArrayAdapter，BaseAdapter实际上就是需要开发者自己去实现Adapter的操作，包括定义组件等。

第一步：编写自定义适配器

package com.example.galleryproject;import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;public class ImageGalleryAdapter extends BaseAdapter{private Context context;private int img[] = {R.drawable.head0,R.drawable.head1,R.drawable.head2,R.drawable.head3,R.drawable.head4,R.drawable.head5,R.drawable.head6,R.drawable.head7,R.drawable.head8,R.drawable.head9,R.drawable.head10,R.drawable.head11,};public ImageGalleryAdapter(Context context){this.context = context;}@Overridepublic int getCount() {//返回图片个数return img.length;}@Overridepublic Object getItem(int position) {//取得指定位置的图片return img[position];}@Overridepublic long getItemId(int position) {//取得指定位置的图片IDreturn img[position];}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {//很明显，现在我们是要浏览图片，那么图片肯定是需要使用ImageViewImageView imgView = new ImageView(context);imgView.setBackgroundColor(0xFFFFFFFF);imgView.setImageResource(this.img[position]);imgView.setScaleType(ImageView.ScaleType.CENTER);//设置居中显示imgView.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));return imgView;}
}

此时自定义的适配器就已经完成，是一个专门负责给Gallery组件填充数据的适配器，当Gallery需要显示内容的时候，直接是用setAdapter()方法设置这个自定义的适配器就OK了。

第二步：定义布局文件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical" ><Gralleryandroid:id="@+id/myGallery"android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_gravity="center_horizontal"/>
</LinearLayout>

定义了布局文件之后，我们需要编写Activity程序。

package com.example.galleryproject;import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Gallery;
import android.widget.Toast;public class GalleryActivity extends Activity {private Gallery myGallery = null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);super.setContentView(R.layout.activity_gallery);this.myGallery = (Gallery) super.findViewById(R.id.myGallery);this.myGallery.setAdapter(new ImageGalleryAdapter(this));this.myGallery.setOnItemClickListener(new OnItemClickListener(){@Overridepublic void onItemClick(AdapterView<?> adapter, View view, int position,long id) {Toast.makeText(GalleryActivity.this, "选中了第"+(position+1)+"张图片", Toast.LENGTH_SHORT).show();}});}
}

从事件处理来看，和ListView组件操作相似的。

·对于使用SimpleAdapter来说，必须要准备一个List，而这个List里面保存的是Map，而且Map中的key值要是字符串类型，如果现在有100个图片需要使用画廊组件现，这个时候我们可以做一些特殊的处理。

第一步：准备一张图片的显示的模板布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="horizontal" ><ImageViewandroid:id="@+id/mtImg"android:layout_width="wrap_content"android:layout_height="wrap_content"android:scaleType="center"/>
</LinearLayout>

第二部：编写Activity程序，实现画廊

package com.example.galleryproject;import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Gallery;
import android.widget.SimpleAdapter;
import android.widget.Toast;public class GalleryActivity extends Activity {private Gallery myGallery = null;private SimpleAdapter adapter = null;private List<Map<String,Integer>> list = new ArrayList<Map<String,Integer>>();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);super.setContentView(R.layout.activity_gallery);this.myGallery = (Gallery) super.findViewById(R.id.myGallery);this.initAdapter();//装配适配器this.myGallery.setAdapter(adapter);this.myGallery.setOnItemClickListener(new OnItemClickListener(){@Overridepublic void onItemClick(AdapterView<?> adapter, View view, int position,long id) {Toast.makeText(GalleryActivity.this, "选中了第"+(position+1)+"张图片", Toast.LENGTH_SHORT).show();}});}/*** 装配适配器*/public void initAdapter(){//我们说如果有非常多的图片，一个一个列出来非常麻烦 现在使用一些IO知识，通过图片名称的前半部分相同就全部加载进来Field field[] = R.drawable.class.getDeclaredFields();//取得drawable全部内容for (int i = 0; i < field.length; i++) {if(field[i].getName().startsWith("head")){Map<String,Integer> map = new HashMap<String,Integer>();try{map.put("img",field[i].getInt(R.drawable.class));}catch(Exception e){e.printStackTrace();}this.list.add(map);}}this.adapter = new SimpleAdapter(this,this.list,R.layout.gallery_view,new String[]{"img"},new int[]{R.id.myImg});}
}

以上的操作都是实现了简单的画廊，在很多情况下，用户可以通过选择一张图片，然后直接显示这个图片在中央，这就是说进行了图片的切换，那么需要依靠ImageSwitcher完成。

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical" ><ImageSwitcherandroid:id="@+id/myImageSwitcher"android:layout_width="match_parent"android:layout_height="wrap_content"/><Galleryandroid:id="@+id/myGallery"android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_gravity="center_horizontal"android:spacing="3px"/>
</LinearLayout>

package com.example.galleryproject;import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Gallery;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.SimpleAdapter;
import android.widget.ViewSwitcher.ViewFactory;public class GalleryActivity extends Activity {private Gallery myGallery = null;private SimpleAdapter adapter = null;private List<Map<String, Integer>> list = new ArrayList<Map<String, Integer>>();private ImageSwitcher imageSwitcher = null;private int img[] = { R.drawable.head0, R.drawable.head1, R.drawable.head2,R.drawable.head3, R.drawable.head4, R.drawable.head5,R.drawable.head6, R.drawable.head7, R.drawable.head8,R.drawable.head9, R.drawable.head10, R.drawable.head11, };@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);super.setContentView(R.layout.activity_gallery);this.myGallery = (Gallery) super.findViewById(R.id.myGallery);this.imageSwitcher = (ImageSwitcher) super.findViewById(R.id.myImageSwitcher);this.imageSwitcher.setFactory(new ViewFactory() {@Overridepublic View makeView() {ImageView imgView = new ImageView(GalleryActivity.this);imgView.setBackgroundColor(0xFFFFFFFF);imgView.setScaleType(ImageView.ScaleType.CENTER);//设置居中显示imgView.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));return imgView;}});this.imageSwitcher.setImageResource(img[0]);this.initAdapter();//装配适配器this.myGallery.setAdapter(adapter);this.myGallery.setOnItemClickListener(new OnItemClickListener(){@Overridepublic void onItemClick(AdapterView<?> adapter, View view, int position,long id) {GalleryActivity.this.imageSwitcher.setImageResource(img[position]);}});}/*** 装配适配器*/public void initAdapter() {for (int i = 0; i < img.length; i++) {Map<String, Integer> map = new HashMap<String, Integer>();try {map.put("img", img[i]);} catch (Exception e) {e.printStackTrace();}this.list.add(map);}this.adapter = new SimpleAdapter(this, this.list,R.layout.gallery_view, new String[] { "img" },new int[] { R.id.myImg });}
}

在使用BaseAdapter的时候需要自定义一个适配器类，而是用SimpleAdapter的时候必须要定义布局模板。

2.3 小结

（1）Gallery组件可以完成图片的拖拉浏览功能；

（2）使用Gallery + ImageSwitcher组件可以完成图片的切换操作；

3. 网格视图：GridView

3.1 知识点

（1）掌握GridView的特点及应用；

（2）可以使用BaseAdapter进行GridView显示内容的设置。

3.2 具体内容

主页面的布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"xmlns:tools="http://schemas.android.com/tools"android:layout_width="match_parent"android:layout_height="match_parent"android:paddingBottom="@dimen/activity_vertical_margin"android:paddingLeft="@dimen/activity_horizontal_margin"android:paddingRight="@dimen/activity_horizontal_margin"android:paddingTop="@dimen/activity_vertical_margin"android:orientation="vertical"tools:context=".GridViewActivity" ><GridView android:id="@+id/myGirdView"android:layout_width="match_parent"android:layout_height="match_parent"android:numColumns="3" – 每行加载多少个单元格android:stretchMode="columnWidth"  --设置缩放的时候保持列宽的一致/></LinearLayout>

单元格的布局：

<?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" ><ImageView android:id="@+id/img"android:layout_width="wrap_content"android:layout_height="wrap_content"android:scaleType="center"android:padding="10px"/></LinearLayout>

Activity：

package com.example.gridviewproject;import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;import android.app.Activity;
import android.os.Bundle;
import android.widget.GridView;
import android.widget.SimpleAdapter;public class GridViewActivity extends Activity {SimpleAdapter adapter = null;List<Map<String,Integer>> list = new ArrayList<Map<String,Integer>>();GridView gv = null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_grid_view);gv = (GridView) super.findViewById(R.id.myGirdView);this.initAdapter();gv.setAdapter(adapter);}public void initAdapter(){//装载adapterField[] fields = R.drawable.class.getDeclaredFields();//取得所有的图片for(int i=0;i<fields.length;i++){if(fields[i].getName().startsWith("date")){Map<String,Integer> map = new HashMap<String,Integer>();try {map.put("img", fields[i].getInt(R.drawable.class));} catch (IllegalArgumentException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IllegalAccessException e) {// TODO Auto-generated catch blocke.printStackTrace();}this.list.add(map);}}this.adapter = new SimpleAdapter(this,list,R.layout.gird_view_item,new String[]{"img"},new int[]{R.id.img});}
}

到这里为止，完成了网格视图的加载，那么接下来进行事件处理，单击显示图片

package com.example.gridviewproject;import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.SimpleAdapter;public class GridViewActivity extends Activity {SimpleAdapter adapter = null;List<Map<String,Integer>> list = new ArrayList<Map<String,Integer>>();GridView gv = null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_grid_view);gv = (GridView) super.findViewById(R.id.myGirdView);this.initAdapter();gv.setAdapter(adapter);gv.setOnItemClickListener(new OnItemClickListenerImpl());}public void initAdapter(){//装载adapterField[] fields = R.drawable.class.getDeclaredFields();//取得所有的图片for(int i=0;i<fields.length;i++){if(fields[i].getName().startsWith("date")){Map<String,Integer> map = new HashMap<String,Integer>();try {map.put("img", fields[i].getInt(R.drawable.class));} catch (IllegalArgumentException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IllegalAccessException e) {// TODO Auto-generated catch blocke.printStackTrace();}this.list.add(map);}}this.adapter = new SimpleAdapter(this,list,R.layout.gird_view_item,new String[]{"img"},new int[]{R.id.img});}private class OnItemClickListenerImpl implements OnItemClickListener{@Overridepublic void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {Map<String,Integer> map = (Map<String, Integer>) GridViewActivity.this.adapter.getItem(arg2);//取得所点击的图片ImageView showImg = new ImageView(GridViewActivity.this);showImg.setScaleType(ImageView.ScaleType.CENTER);//代表设置图片居中showImg.setLayoutParams(new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));showImg.setImageResource(map.get("img"));Dialog dialog = new AlertDialog.Builder(GridViewActivity.this).setIcon(R.drawable.ic_launcher).setTitle("显示图片").setView(showImg).setNegativeButton("取消", null).create();dialog.show();//显示对话框}}}

以上使用的是SimpleAdapter完成的，现在使用BaseAdapter完成

专门定义一个新的适配器类：

package com.example.myAdapter;import java.util.List;import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;public class ImageAdapter extends BaseAdapter {private List<Integer> list;private Context context;public ImageAdapter(List<Integer> list, Context context) {super();this.list = list;this.context = context;}@Overridepublic int getCount() {// TODO Auto-generated method stubreturn this.list.size();}@Overridepublic Object getItem(int position) {// TODO Auto-generated method stubreturn this.list.get(position);}@Overridepublic long getItemId(int position) {// TODO Auto-generated method stubreturn this.list.get(position);}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {ImageView showImg = new ImageView(this.context);showImg.setScaleType(ImageView.ScaleType.CENTER);//showImg.setImageResource(list.get(position));showImg.setPadding(10,10,10,10);return showImg;}}

package com.example.gridviewproject;import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;import com.example.myAdapter.ImageAdapter;import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.SimpleAdapter;public class GridViewActivity extends Activity {List<Integer> list = new ArrayList<Integer>();GridView gv = null;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_grid_view);gv = (GridView) super.findViewById(R.id.myGirdView);this.initAdapter();gv.setAdapter(new ImageAdapter(list, this));gv.setOnItemClickListener(new OnItemClickListenerImpl());}public void initAdapter(){//装载adapterField[] fields = R.drawable.class.getDeclaredFields();//取得所有的图片for(int i=0;i<fields.length;i++){if(fields[i].getName().startsWith("date")){try {this.list.add(fields[i].getInt(R.drawable.class));} catch (IllegalArgumentException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IllegalAccessException e) {// TODO Auto-generated catch blocke.printStackTrace();}				}}}private class OnItemClickListenerImpl implements OnItemClickListener{@Overridepublic void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {ImageView showImg = new ImageView(GridViewActivity.this);showImg.setScaleType(ImageView.ScaleType.CENTER);//代表设置图片居中showImg.setLayoutParams(new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));showImg.setImageResource(list.get(arg2));Dialog dialog = new AlertDialog.Builder(GridViewActivity.this).setIcon(R.drawable.ic_launcher).setTitle("显示图片").setView(showImg).setNegativeButton("取消", null).create();dialog.show();//显示对话框}}}