android SQLite操作

blovekyo

使用Android自带的数据库SQLite,包括连接、复制、增删改查等操作。
直接看代码（直接可以运行的）

package com.named;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.SQLException;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
public class DataBaseHelper extends SQLiteOpenHelper {
private static String DB_PATH = "/data/data/com.named/databases/";
private static String DB_NAME = "mydata.db";
private static String TB_NAME = "myname";
private SQLiteDatabase myDataBase;
private final Context myContext;
public DataBaseHelper(Context context) {
super(context, DB_NAME, null, 1);
this.myContext = context;
}
/**
* 创建新的数据库
* */
public void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
} else {
this.getReadableDatabase();
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error copying database");
}
}
}
/**
* 检查目录是否有数据库
*
* @return
*/
private boolean checkDataBase() {
SQLiteDatabase checkDB = null;
try {
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
// database does't exist yet.
}
if (checkDB != null) {
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* 如果没有数据库，就把assets下面的数据库文件拷贝到sd卡data目录下
**/
private void copyDataBase() throws IOException {
InputStream myInput = myContext.getAssets().open(DB_NAME);
String outFileName = DB_PATH + DB_NAME;
OutputStream myOutput = new FileOutputStream(outFileName);
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
myOutput.flush();
myOutput.close();
myInput.close();
}
/**
* 打开数据库
*
* @throws SQLException
*/
public void openDataBase() throws SQLException {
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
}
/**
* 关闭数据库
*/
@Override
public synchronized void close() {
if (myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
/**
* 查询表数据
*
* @return
*/
public String query() {
String name = "";
Cursor cursor = myDataBase.query(TB_NAME, new String[] { "name" }, "id"
+ " = " + 1, null, null, null, null);
while (cursor.moveToNext()) {
name = cursor.getString(cursor.getColumnIndex("name"));
}
return name;
}
/*
* 增加
*/
public void save() {
myDataBase.execSQL("insert into person(name) values (?)",
new Object[] { "tom" });
}
/*
* 更新
*/
public void update() {
myDataBase.execSQL("update person set name=? where personid=?",
new Object[] { "kitty", "1" });
}
/*
* 删除
*/
public void delete(Integer id) {
myDataBase.execSQL("delete from person where personid=?",
new Object[] { id.toString() });
}
}