因爲在開發客戶端的時候,服務器端的有寫數據是重複的,不需要再去訪問服務器的,然後服務器端提供的是一個sql文件,裏面包含了數據庫和數據,我們這些開發客戶端的不可能一行一行的進行手動入庫吧?所以我就想到了直接讀取sql文件進行創建數據並插入數據好了。
創建DBHelp並繼承SQLiteOpenHelper
public class DBHelper extends SQLiteOpenHelper {
private Context mContext;
public DBHelper(Context context, String databaseName,
CursorFactory factory, int version) {
super(context, databaseName, factory, version);
mContext = context;
}
/**
* 數據庫第一次創建時調用
* */
@Override
public void onCreate(SQLiteDatabase db) {
if (!tabIsExist("test", db)) {
executeAssetsSQL(db, "test.sql");
// db.execSQL(sql);
//System.out.println("創建表");
}
}
/**
* 數據庫升級時調用
* */
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// 數據庫不升級
if (newVersion <= oldVersion) {
return;
}
Configuration.oldVersion = oldVersion;
int changeCnt = newVersion - oldVersion;
for (int i = 0; i < changeCnt; i++) {
// 依次執行updatei_i+1文件 由1更新到2 [1-2],2更新到3 [2-3]
String schemaName = "update" + (oldVersion + i) + "_"
+ (oldVersion + i + 1) + ".sql";
executeAssetsSQL(db, schemaName);
}
}
/**
* 讀取數據庫文件(.sql),並執行sql語句
* */
private void executeAssetsSQL(SQLiteDatabase db, String schemaName) {
BufferedReader in = null;
try {
in = new BufferedReader(new InputStreamReader(mContext.getAssets()
.open(Configuration.DB_PATH + "/" + schemaName)));
//System.out.println("路徑:" + Configuration.DB_PATH + "/" + schemaName);
String line;
String buffer = "";
while ((line = in.readLine()) != null) {
buffer += line;
if (line.trim().endsWith(";")) {
db.execSQL(buffer.replace(";", ""));
buffer = "";
}
}
} catch (IOException e) {
Log.e("db-error", e.toString());
} finally {
try {
if (in != null)
in.close();
} catch (IOException e) {
Log.e("db-error", e.toString());
}
}
}
public List<Area> selectAllCities(SQLiteDatabase db) {
List<Area> areas = new ArrayList<Area>();
Area area;
String sql = "select * from test where area_level=?";
Cursor cursor = db.rawQuery(sql, new String[] { "" + 0 });
while(cursor.moveToNext()){
area = new Area();
area.setId(cursor.getInt(0));
area.setArea_name(cursor.getString(2));
areas.add(area);
area = null;
}
cursor.close();
return areas;
}
public List<Area> selectAllAreas(SQLiteDatabase db,int parent_id) {
List<Area> areas = new ArrayList<Area>();
Area area;
String sql = "select * from test where parent_id=?";
Cursor cursor = db.rawQuery(sql, new String[] { "" + parent_id });
while(cursor.moveToNext()){
area = new Area();
area.setId(cursor.getInt(0));
area.setArea_name(cursor.getString(2));
areas.add(area);
area = null;
}
cursor.close();
return areas;
}
/**
* 判斷是否存在某一張表
* @param tabName
* @param db
* @return
*/
public boolean tabIsExist(String tabName, SQLiteDatabase db) {
boolean result = false;
if (tabName == null) {
return false;
}
Cursor cursor = null;
try {
String sql = "select count(*) as c from sqlite_master where type ='table' and name ='" + tabName.trim() + "' ";
cursor = db.rawQuery(sql, null);
if (cursor.moveToNext()) {
int count = cursor.getInt(0);
if (count > 0) {
result = true;
}
}
} catch (Exception e) {
}
return result;
}
}
Configuration.java是一些常量
public class Configuration {
public static final String DB_PATH = "schema";
public static final String DB_NAME = "test.db";
public static final int DB_VERSION = 1;
public static int oldVersion = -1;
}
sql文件是放在assets->schema->test.sql
其實這個過程非常的簡單易懂,就是根據路徑去讀取文件,然後讀取文件裏面的內容,再根據關鍵字,sqllite會自動進行相應的操作,所以這個sql文件中的sql語句一定要規範,不然會寫入不了的。
在activity中調用:
dbHelper = new DBHelper(this, "test", null, 1);
dbHelper.onCreate(dbHelper.getWritableDatabase());