标签：android style blog http io ar color os 使用
SQLite 一个非常流行的嵌入式数据库，它支持 SQL 语言，并且只利用很少的内存就有很好的性能。此外它还是开源的，任何人都可以使用它。许多开源项目（(Mozilla, PHP, Python）都使用了 SQLite；
Android 不自动提供数据库。在 Android 应用程序中使用 SQLite，必须自己创建数据库，然后创建表、索引，往里面添加数据。Android 提供了 SQLiteOpenHelper 帮助你创建一个数据库，你只要继承 SQLiteOpenHelper 类，就可以轻松的创建数据库。SQLiteOpenHelper 类根据开发应用程序的需要，封装了创建和更新数据库使用的逻辑。SQLiteOpenHelper 的子类，至少需要实现三个方法：
详细介绍可以参考：
http://www.cnblogs.com/Excellent/archive/2011/11/19/2254888.html
http://blog.csdn.net/liuhe688/article/details/6715983
下面以一个增删改查的简单例子来说明一下：具体如图：
点击添加数据，然后点击查询数据：
然后点击修改，然后再查询：
然后删除，再查询：
实现代码如下：
MainActivity.java
package com.xiaozhang.sqltest1;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.ListView;
import android.widget.SimpleAdapter;
public class MainActivity extends Activity {
private DatabaseHelper databaseHelper;
private SQLiteDatabase sqlite;
private ListView listView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.listView);
databaseHelper = new DatabaseHelper(this);
sqlite = databaseHelper.getWritableDatabase();
}
// 添加Student信息
public void add(View view) {
ArrayList<Student> student = new ArrayList<Student>();
Student student1 = new Student("张三", 23, "河南省");
Student student2 = new Student("李四", 25, "山东省");
Student student3 = new Student("王五", 21, "陕西省");
Student student4 = new Student("赵六", 22, "福建省");
student.add(student1);
student.add(student2);
student.add(student3);
student.add(student4);
// 设置事务
sqlite.beginTransaction(); // 开始事务
try {
for (Student stu : student) {
sqlite.execSQL("INSERT INTO student VALUES(null, ?, ?, ?)",
new Object[] { stu.name, stu.age, stu.address });
}
sqlite.setTransactionSuccessful(); // 设置事务成功完成
} finally {
sqlite.endTransaction(); // 结束事务
}
}
// 将姓名为 "张三" 的地址修改为 "北京市"；
public void update(View view) {
ContentValues cv = new ContentValues();
Student student = new Student();
student.address = "北京市";
student.name = "张三";
cv.put("address", student.address);
sqlite.update("student", cv, "name = ?", new String[] { student.name });
}
// 删除年龄为22岁的人
public void delete(View view) {
Student student = new Student();
student = new Student();
student.age = 22;
sqlite.delete("student", "age = ?",
new String[] { String.valueOf(student.age) });
}
//查询全部信息
public void query(View view) {
Student student = new Student();
Cursor c = sqlite.rawQuery("SELECT * FROM student", null);
ArrayList<Student> list = new ArrayList<Student>();
while (c.moveToNext()) {
student = new Student();
student._id = c.getInt(c.getColumnIndex("_id"));
student.name = c.getString(c.getColumnIndex("name"));
student.address = c.getString(c.getColumnIndex("address"));
student.age = c.getInt(c.getColumnIndex("age"));
list.add(student);
}
ArrayList<Map<String, String>> list2 = new ArrayList<Map<String, String>>();
for (Student stu : list) {
HashMap<String, String> map = new HashMap<String, String>();
map.put("name", stu.name);
map.put("address", "-----"+stu.address + "-----" + stu.age + " years old");
list2.add(map);
}
c.close();
SimpleAdapter adapter = new SimpleAdapter(this, list2,
android.R.layout.simple_list_item_2, new String[] { "name",
"address" }, new int[] { android.R.id.text1,
android.R.id.text2 });
listView.setAdapter(adapter);
}
}
DatabaseHelper.java
package com.xiaozhang.sqltest1;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DatabaseHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "study";
private static final int DATABASE_VERSION = 1;
public DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE IF NOT EXISTS student"
+ "(_id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR, age INTEGER, address TEXT)");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("ALTER TABLE student ADD COLUMN other STRING");
}
}
activity_main.xml
<?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" >
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="add"
android:text="添加数据" />
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="update"
android:text="更新数据" />
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="delete"
android:text="删除数据" />
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="query"
android:text="查询数据" />
<ListView
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
如有需要，可以下载代码：http://download.csdn.net/detail/u012724379/8239741
标签：android style blog http io ar color os 使用
原文地址：http://www.cnblogs.com/xiaozhang2014/p/4153277.html
