Android数据库(SqlLite)操作和db文件查看

2019年9月8日 05:58:30Linux大全评论979 views阅读模式

package com.xiaoshan.udp.client.db;
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;
/**
* 数据库常用操作的封装类
*
* @author 单红宇
*
*/
public class DBHelper {
private static DatabaseHelper mDbHelper;
private static SQLiteDatabase mDb;
private static final String DATABASE_NAME = "shanhy.db";
private static final int DATABASE_VERSION = 1;
private final Context mCtx;
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
public DBHelper(Context ctx) {
this.mCtx = ctx;
}
public DBHelper open() throws SQLException {
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
/**
* 关闭数据源
*
* @author SHANHY
*/
public void closeConnection() {
if (mDb != null && mDb.isOpen())
mDb.close();
if (mDbHelper != null)
mDbHelper.close();
}
/**
* 插入数据参数
*
* @param tableName
* 表名
* @param initialValues
* 要插入的列对应值
* @return
* @author SHANHY
*/
public long insert(String tableName, ContentValues initialValues) {
return mDb.insert(tableName, null, initialValues);
}
/**
* 删除数据
*
* @param tableName
* 表名
* @param deleteCondition
* 条件
* @param deleteArgs
* 条件对应的值（如果deleteCondition中有“？”号，将用此数组中的值替换，一一对应）
* @return
* @author SHANHY
*/
public boolean delete(String tableName, String deleteCondition, String[] deleteArgs) {
return mDb.delete(tableName, deleteCondition, deleteArgs) > 0;
}
/**
* 更新数据
*
* @param tableName
* 表名
* @param initialValues
* 要更新的列
* @param selection
* 更新的条件
* @param selectArgs
* 更新条件中的“？”对应的值
* @return
* @author SHANHY
*/
public boolean update(String tableName, ContentValues initialValues, String selection, String[] selectArgs) {
return mDb.update(tableName, initialValues, selection, selectArgs) > 0;
}
/**
* 取得一个列表
*
* @param distinct
* 是否去重复
* @param tableName
* 表名
* @param columns
* 要返回的列
* @param selection
* 条件
* @param selectionArgs
* 条件中“？”的参数值
* @param groupBy
* 分组
* @param having
* 分组过滤条件
* @param orderBy
* 排序
* @return
* @author SHANHY
*/
public Cursor findList(boolean distinct, String tableName, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit) {
return mDb.query(distinct, tableName, columns, selection, selectionArgs, groupBy, having, orderBy, limit);
}
/**
* 取得单行记录
*
* @param tableName
* 表名
* @param columns
* 获取的列数组
* @param selection
* 条件
* @param selectionArgs
* 条件中“？”对应的值
* @param groupBy
* 分组
* @param having
* 分组条件
* @param orderBy
* 排序
* @param limit
* 数据区间
* @param distinct
* 是否去重复
* @return
* @throws SQLException
* @author SHANHY
*/
public Cursor findOne(boolean distinct,String tableName, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy, String limit) throws SQLException {
Cursor mCursor = findList(distinct, tableName, columns, selection, selectionArgs, groupBy, having, orderBy, limit);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
/**
* 执行SQL(带参数)
*
* @param sql
* @param args
* SQL中“？”参数值
* @author SHANHY
*/
public void execSQL(String sql, Object[] args) {
mDb.execSQL(sql, args);
}
/**
* 执行SQL
*
* @param sql
* @author SHANHY
*/
public void execSQL(String sql) {
mDb.execSQL(sql);
}
/**
* 判断某张表是否存在
*
* @param tabName
* 表名
* @return
*/
public boolean isTableExist(String tableName) {
boolean result = false;
if (tableName == null) {
return false;
}
try {
Cursor cursor = null;
String sql = "select count(1) as c from sqlite_master where type ='table' and name ='" + tableName.trim() + "'";
cursor = mDb.rawQuery(sql, null);
if (cursor.moveToNext()) {
int count = cursor.getInt(0);
if (count > 0) {
result = true;
}
}
cursor.close();
} catch (Exception e) {
}
return result;
}
/**
* 判断某张表中是否存在某字段(注，该方法无法判断表是否存在，因此应与isTableExist一起使用)
*
* @param tabName
* 表名
* @param columnName
* 列名
* @return
*/
public boolean isColumnExist(String tableName, String columnName) {
boolean result = false;
if (tableName == null) {
return false;
}
try {
Cursor cursor = null;
String sql = "select count(1) as c from sqlite_master where type ='table' and name ='" + tableName.trim() + "' and sql like '%" + columnName.trim() + "%'";
cursor = mDb.rawQuery(sql, null);
if (cursor.moveToNext()) {
int count = cursor.getInt(0);
if (count > 0) {
result = true;
}
}
cursor.close();
} catch (Exception e) {
}
return result;
}
}