Android 漫游之路------ListView入门、Layout的Inflater创建View对象、常用数据适配器

---------------------- 路漫漫其修远兮，吾将上下而求索。学无止境！----------------------

 

ListView入门 

之前了解了SQLite的知识，现在考虑如何将数据由数据库中取出，并在安卓界面中展示出来。这里，要用到ListView控件。ListView,可以将数据逐条显示到用户界面。

 

activity_main.xml

<RelativeLayout 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"    tools:context=".MainActivity" >    <ListView        android:id="@+id/lv"        android:layout_width="match_parent"        android:layout_height="match_parent" >    </ListView></RelativeLayout>

MainActivity.java

package com.lee.sql;import java.util.List;import com.lee.sql.dao.PersonDao2;import com.lee.sql.model.Person;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ListView;import android.widget.TextView;import android.app.Activity;import android.graphics.Color;public class MainActivity extends Activity {private ListView listView;private List<Person> persons;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);listView = (ListView) this.findViewById(R.id.lv);PersonDao2 personDao = new PersonDao2(this);persons = personDao.findAll();for (Person person : persons) {System.out.println(person);}//将listView控件加载自定义的适配器listView.setAdapter(new MyAdapter());}/** * 我的适配器的实现，以内部类的形式 * @author Xiaobi * */private class MyAdapter extends BaseAdapter {//得到条目的总个数@Overridepublic int getCount() {// TODO Auto-generated method stubreturn persons.size();}@Overridepublic Object getItem(int arg0) {// TODO Auto-generated method stubreturn null;}@Overridepublic long getItemId(int arg0) {// TODO Auto-generated method stubreturn 0;}//设置每个条目的显示@Overridepublic View getView(int position, View convertView, ViewGroup parent) {// TODO Auto-generated method stubTextView textView = new TextView(getApplicationContext());textView.setTextSize(15);textView.setTextColor(Color.BLUE);Person person = persons.get(position);textView.setText(person.toString());return textView;}}}

所有的数据库方面的操作在上一博文。

运行后的界面：

Layout的Inflater创建View对象

这样的运行界面比较单一，不便阅读，可以再次进行优化；

首先创建一个新的布局文件list_items.xml：这个文件是使用的TextView与LinearLayout进行界面设计。

<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" >    <TextView        android:id="@+id/tv_id"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_marginLeft="10sp"        android:layout_marginTop="10sp"        android:text="id"        android:textColor="#ff0000"        android:textSize="20sp" />    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="vertical" >        <TextView            android:id="@+id/tv_name"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginLeft="15sp"            android:layout_marginTop="5sp"            android:text="姓名"            android:textColor="#000000"            android:textSize="15sp" />        <TextView            android:id="@+id/tv_age"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:layout_marginLeft="15sp"            android:layout_marginTop="5sp"            android:text="年龄"            android:textColor="#66000000"            android:textSize="15sp" />    </LinearLayout></LinearLayout>

然后就是对展示部分代码的修改，修改后的代码：

MainActivity.java

package com.lee.sql;import java.util.List;import com.lee.sql.dao.PersonDao2;import com.lee.sql.model.Person;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ListView;import android.widget.TextView;import android.app.Activity;public class MainActivity extends Activity {private ListView listView;private List<Person> persons;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);listView = (ListView) this.findViewById(R.id.lv);PersonDao2 personDao = new PersonDao2(this);persons = personDao.findAll();for (Person person : persons) {System.out.println(person);}//将listView控件加载自定义的适配器listView.setAdapter(new MyAdapter());}/** * 我的适配器的实现，以内部类的形式 * @author Xiaobi * */private class MyAdapter extends BaseAdapter {//得到条目的总个数@Overridepublic int getCount() {// TODO Auto-generated method stubreturn persons.size();}@Overridepublic Object getItem(int arg0) {// TODO Auto-generated method stubreturn null;}@Overridepublic long getItemId(int arg0) {// TODO Auto-generated method stubreturn 0;}//设置每个条目的显示@Overridepublic View getView(int position, View convertView, ViewGroup parent) {// TODO Auto-generated method stubPerson person = persons.get(position);/** * 由于这里不再是main_activity.xml文件中的配置，而是list_items.xml中的， * 因此通过View.inflate(Context context, int resource, ViewGroup root)来加载该布局文件 */View view = View.inflate(MainActivity.this,R.layout.list_items, null);//这里只能从上面的view中得到各个布局元素TextView tv_id = (TextView)view.findViewById(R.id.tv_id);tv_id.setText("id:"+person.getId());TextView tv_name = (TextView)view.findViewById(R.id.tv_name);tv_name.setText("姓名:"+person.getName());TextView tv_age = (TextView)view.findViewById(R.id.tv_age);tv_age.setText("年龄:"+person.getAge());return view;}}}

以上程序运行的结果比较适合阅读：

 常用的数据适配器

 

ArrayAdapter

public ArrayAdapter(Context context, int resource, int textViewResourceId, T[] objects)

Parameters

contextThe current context.resourceThe resource ID for a layout file containing a layout to use when instantiating views.textViewResourceIdThe id of the TextView within the layout resource to be populatedobjectsThe objects to represent in the ListView.

 

具体操作见源码

package com.lee.adapter;import android.os.Bundle;import android.widget.ArrayAdapter;import android.widget.ListView;import android.app.Activity;public class MainActivity extends Activity {//定义一个功能数组private static String[] names = {"功能1","功能2","功能3","功能4","功能5"};@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);ListView listView = (ListView)this.findViewById(R.id.lv);//ArrayAdapter的使用listView.setAdapter(new ArrayAdapter<String>(this, R.layout.text_view, R.id.tv, names));}}

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:orientation="vertical" >    <ListView        android:id="@+id/lv"        android:layout_width="wrap_content"        android:layout_height="wrap_content" >    </ListView></LinearLayout>

text_view.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="wrap_content"    android:orientation="horizontal" >    <ImageView        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:src="@drawable/ic_launcher" />    <TextView        android:layout_marginTop="15dp"        android:layout_marginLeft="15dp"        android:textColor="#555555"        android:textSize="15dp"        android:id="@+id/tv"        android:layout_width="match_parent"        android:layout_height="wrap_content" >    </TextView></LinearLayout>

SimpleAdapter

 

这里使用

android.widget.SimpleAdapter.SimpleAdapter(Context context, List<? extendsMap<String, ?>> data, int resource, String[] from,int[] to)

MainActivity.java

package com.lee.simpleAdapeter;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import android.os.Bundle;import android.widget.ListView;import android.widget.SimpleAdapter;import android.app.Activity;public class MainActivity extends Activity {private List<Map<String, Object>> datas;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);// 以下置入原始数据datas = new ArrayList<Map<String, Object>>();Map<String, Object> data1 = new HashMap<String, Object>();data1.put("name", "接电话啦");data1.put("icon", R.drawable.ic_jog_dial_answer);Map<String, Object> data2 = new HashMap<String, Object>();data2.put("name", "通话结束");data2.put("icon", R.drawable.ic_jog_dial_answer_and_end);Map<String, Object> data3 = new HashMap<String, Object>();data3.put("name", "电话繁忙");data3.put("icon", R.drawable.ic_jog_dial_answer_and_hold);Map<String, Object> data4 = new HashMap<String, Object>();data4.put("name", "挂断电话");data4.put("icon", R.drawable.ic_jog_dial_decline);Map<String, Object> data5 = new HashMap<String, Object>();data5.put("name", "调为震动");data5.put("icon", R.drawable.ic_jog_dial_vibrate_on);datas.add(data1);datas.add(data2);datas.add(data3);datas.add(data4);datas.add(data5);ListView listView = (ListView) this.findViewById(R.id.lv);// 这里是重点哦listView.setAdapter(new SimpleAdapter(this, datas, R.layout.list_items,new String[] { "name", "icon" }, new int[] { R.id.tv, R.id.iv }));}}

list_items.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:orientation="horizontal"    tools:context=".MainActivity" >    <ImageView        android:id="@+id/iv"        android:layout_width="wrap_content"        android:layout_height="wrap_content" />    <TextView        android:id="@+id/tv"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_marginLeft="15dp"        android:layout_marginTop="15dp"        android:textColor="#ff8800"        android:textSize="20sp" /></LinearLayout>

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:orientation="vertical"    tools:context=".MainActivity" >    <ListView        android:id="@+id/lv"        android:layout_width="match_parent"        android:layout_height="wrap_content" /></LinearLayout>

运行结果：

---------------------- 路漫漫其修远兮，吾将上下而求索。学无止境！---------------------- 

我的博客：http://blog.csdn.net/helloxiaobi