有效的减少应用占用的空间——使用系统资源
package com.jmeditor.sysresbrowser;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.Menu;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.TextView;public class MainActivity extends Activity {//浏览资源的序号private static int index = 0;//所有资源列表private static List<Map<String,Object>> rs;//显示图片的Viewprivate ImageView imageView;//显示图片的背景，因为有些只适合在黑背景下显示private LinearLayout imageBg;//显示数量private TextView textView;//显示当前图片的ID，方便引用private TextView tips;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);textView = (TextView)findViewById(R.id.textView);tips = (TextView)findViewById(R.id.tips);imageView = (ImageView)findViewById(R.id.imageView);imageBg = (LinearLayout)findViewById(R.id.imageBg);Button imageViewBtnPre = (Button)findViewById(R.id.imageViewBtnPre);Button imageViewBtnNext = (Button)findViewById(R.id.imageViewBtnNext);//读取系统所有的drawable资源try {Class c = Class.forName("android.R$drawable");Field[] fs = c.getDeclaredFields();rs = new ArrayList<Map<String,Object>>();for (Field field : fs) {if (field.getType().getName().equals("int") ) {Map<String,Object> m = new HashMap<String,Object>();m.put("name", field.getName());m.put("value", field.get(this));rs.add(m);}}} catch (Exception e) {e.printStackTrace();}//上一张imageViewBtnPre.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {if(index > 0){index --;showImg();}}});//下一张imageViewBtnNext.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {if(index < rs.size() - 1){index ++;showImg();}}});//背景色this.findViewById(R.id.bg_1).setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {imageBg.setBackgroundColor(getResources().getColor(R.color.white));}});this.findViewById(R.id.bg_2).setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {imageBg.setBackgroundColor(getResources().getColor(R.color.black));}});this.findViewById(R.id.bg_3).setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {imageBg.setBackgroundColor(getResources().getColor(R.color.blue));}});}private void showImg() {imageView.setBackgroundResource(Integer.valueOf(rs.get(index).get("value").toString()));String s = getResources().getString(R.string.total_msg);textView.setText(s.replaceAll("\\{1\\}", "" + rs.size()).replaceAll("\\{2\\}", "" + (index+1)));tips.setText(rs.get(index).get("name").toString());}@Overridepublic 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;}}
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布局文件activity_main.xml
<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=".MainActivity" > <TextView android:id="@+id/textView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/hello_world" /> <LinearLayout android:id="@+id/imageBg" android:layout_width="fill_parent" android:layout_height="100dip" android:padding="5dip"> <ImageView android:id="@+id/imageView" android:layout_width="wrap_content" android:layout_height="wrap_content"/> </LinearLayout> <LinearLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_marginTop="20dip"><TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/tips"/><TextView android:id="@+id/tips" android:layout_width="wrap_content" android:layout_height="wrap_content"/></LinearLayout><LinearLayout android:layout_width="fill_parent" android:layout_height="wrap_content"> <Button android:id="@+id/imageViewBtnPre" android:text="@string/pre_img" android:layout_width="wrap_content" android:layout_height="wrap_content"/> <Button android:id="@+id/imageViewBtnNext" android:text="@string/next_img" android:layout_width="wrap_content" android:layout_height="wrap_content"/></LinearLayout> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/background_title"/> <LinearLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <View android:id="@+id/bg_1" android:layout_width="50dip" android:layout_height="50dip" android:layout_margin="5dip" android:background="@color/white"/> <View android:id="@+id/bg_2" android:layout_width="50dip" android:layout_height="50dip" android:layout_margin="5dip" android:background="@color/black"/> <View android:id="@+id/bg_3" android:layout_width="50dip" android:layout_height="50dip" android:layout_margin="5dip" android:background="@color/blue"/> </LinearLayout></LinearLayout>
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