SimpleCursorAdapter
1. 原理参见下面代码注释
Cursor cursor = dbHelper.fetchAllCountries(); //cursor中存储需要加载到listView中的条目，可能由一行或者多行组成。每一行可能包含多列数据（多于listview中定义的）
//the desired columns to be bound
String[] columns = new String[] {
CountryDb.KEY_CODE,
CountryDb.KEY_NAME,
CountryDb.KEY_CONTINENT
}; //这个数据结构指定cursor中的那些列将显示到listview每一行中（从多列中挑选需要的）
//the XML defined views which the data will be bound to
int[] to = new int[] {
R.id.code,
R.id.name,
R.id.continent
};//这个数据结构定义listview中各组件的id，由此和上面的的colums形成了map关系，即cursor中某一行的列字段映射到listview中的控件
//create the adapter using the cursor pointing to the desired data
//as well as the layout information
SimpleCursorAdapter dataAdapter = new SimpleCursorAdapter(
this, R.layout.list_row, //listView xml控件名
cursor, //所存数据的cursor
columns,//cursor需要的字段定义
to, //映射到XML每个控件的定义
0);
ListView listView = (ListView) findViewById(R.id.listView1);
// Assign adapter to ListView
listView.setAdapter(dataAdapter); //设置adapter，所有cursor中的数据将自动加载
2. 附上一个通过实现SimpleCursorAdapter getView（）方法设置行背景颜色的例子
该例子通过检索SQLite数据库构建了基本的listView，但是默认的listView的行条目是不带有斑马线的（相邻行背景颜色不同）。通过继承SimpleCursorAdapter并实现getView（）方法可以达到目的。
Main Activity Layout - 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"
tools:context=".MainActivity"
android:padding="10dp" >
<ListView
android:id="@+id/listView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true">
</ListView>
</RelativeLayout>
ListView Row Layout - list_row.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="5dip" >
<TextView
android:id="@+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="Medium Text"
android:textAppearance="?android:attr/textAppearanceMedium"
android:textStyle="bold" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/name"
android:layout_toRightOf="@+id/name"
android:text=" - "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/code"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_toRightOf="@+id/textView1"
android:text="Medium Text"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="false"
android:layout_alignParentLeft="true"
android:layout_below="@id/name"
android:text="Continent is "
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/continent"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/textView2"
android:layout_alignBottom="@+id/textView2"
android:layout_toRightOf="@+id/textView2"
android:text="Medium Text"
android:textAppearance="?android:attr/textAppearanceMedium" />
</RelativeLayout>
Country POJO - Country.java
package com.as400samplecode;
public class Country {
String code = null;
String name = null;
String continent = null;
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getContinent() {
return continent;
}
public void setContinent(String continent) {
this.continent = continent;
}
}
Country SQLite Db Adapter - CountryDb.java
package com.as400samplecode;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class CountryDb {
public static final String KEY_ROWID = "_id";
public static final String KEY_CODE = "code";
public static final String KEY_NAME = "name";
public static final String KEY_CONTINENT = "continent";
private static final String TAG = "CountriesDbAdapter";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
private static final String DATABASE_NAME = "World";
private static final String SQLITE_TABLE = "Country";
private static final int DATABASE_VERSION = 1;
private final Context mCtx;
private static final String DATABASE_CREATE =
"CREATE TABLE if not exists " + SQLITE_TABLE + " (" +
KEY_ROWID + " integer PRIMARY KEY autoincrement," +
KEY_CODE + "," +
KEY_NAME + "," +
KEY_CONTINENT + "," +
" UNIQUE (" + KEY_CODE +"));";
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
Log.w(TAG, DATABASE_CREATE);
db.execSQL(DATABASE_CREATE);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
+ newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS " + SQLITE_TABLE);
onCreate(db);
}
}
public CountryDb(Context ctx) {
this.mCtx = ctx;
}
public CountryDb open() throws SQLException {
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
if (mDbHelper != null) {
mDbHelper.close();
}
}
public long createCountry(String code, String name, String continent) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_CODE, code);
initialValues.put(KEY_NAME, name);
initialValues.put(KEY_CONTINENT, continent);
return mDb.insert(SQLITE_TABLE, null, initialValues);
}
public boolean deleteAllCountries() {
int doneDelete = 0;
doneDelete = mDb.delete(SQLITE_TABLE, null , null);
Log.w(TAG, Integer.toString(doneDelete));
return doneDelete > 0;
}
public Cursor fetchAllCountries() {
Cursor mCursor = mDb.query(SQLITE_TABLE, new String[] {KEY_ROWID,
KEY_CODE, KEY_NAME, KEY_CONTINENT},
null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
public void insertSomeCountries() {
createCountry("AFG","Afghanistan","Asia");
createCountry("CHN","China","Asia");
createCountry("ALB","Albania","Europe");
createCountry("DZA","Algeria","Africa");
createCountry("ASM","American Samoa","Oceania");
createCountry("AND","Andorra","Europe");
createCountry("AGO","Angola","Africa");
createCountry("AIA","Anguilla","North America");
createCountry("USA","United States","North America");
createCountry("CAN","Canada","North America");
}
}
Android Main Activity - MainActivity.java
package com.as400samplecode;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.graphics.Color;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
public class MainActivity extends Activity {
private CountryDb dbHelper;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dbHelper = new CountryDb(this);
dbHelper.open();
//Clean all data
dbHelper.deleteAllCountries();
//Add some data
dbHelper.insertSomeCountries();
//Generate ListView from SQLite Database
displayListView();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
private void displayListView() {
Cursor cursor = dbHelper.fetchAllCountries();
//the desired columns to be bound
String[] columns = new String[] {
CountryDb.KEY_CODE,
CountryDb.KEY_NAME,
CountryDb.KEY_CONTINENT
};
//the XML defined views which the data will be bound to
int[] to = new int[] {
R.id.code,
R.id.name,
R.id.continent
};
//create the adapter using the cursor pointing to the desired data
//as well as the layout information
MyCursorAdapter dataAdapter = new MyCursorAdapter(
this, R.layout.list_row,
cursor,
columns,
to,
0);
ListView listView = (ListView) findViewById(R.id.listView1);
// Assign adapter to ListView
listView.setAdapter(dataAdapter);
}
//extend the SimpleCursorAdapter to create a custom class where we
//can override the getView to change the row colors
private class MyCursorAdapter extends SimpleCursorAdapter{
public MyCursorAdapter(Context context, int layout, Cursor c,
String[] from, int[] to, int flags) {
super(context, layout, c, from, to, flags);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
//get reference to the row
View view = super.getView(position, convertView, parent);
//check for odd or even to set alternate colors to the row background
if(position % 2 == 0){
view.setBackgroundColor(Color.rgb(238, 233, 233));
}
else {
view.setBackgroundColor(Color.rgb(255, 255, 255));
}
return view;
}
}
}
时间： 2024-10-24 04:45:22