}

}

if (!mRootPath.endsWith("/"))

mRootPath += “/”;

return mRootPath;

}

/**

设置工作目录

@param context app context,不然会造成内存泄漏

@param path

*/

public static void setWorkPath(Context context, String path) {

mContext = context;

if (null != getRootPath()) {

mWorkPath = mRootPath + path;

}

if (!mWorkPath.endsWith("/")) {

mWorkPath += “/”;

}

File file = new File(mWorkPath);

if (!file.exists()){

boolean b = file.mkdirs();

}

}

public static String getDBpath() {

File file = new File(mWorkPath + DB_PATH_NAME);

if (!file.exists())

file.mkdirs();

return mWorkPath + DB_PATH_NAME;

}

public static void copyAccessDB(Context context) {

try {

String[] dbNames = context.getAssets().list(“db”);

for (String dbName : dbNames) {

long startTime = System.currentTimeMillis();

String filePath = FileUtil.getDBpath() + dbName;

File dbFile = new File(filePath);

if (!dbFile.exists()) {

FileOutputStream fos = null;

try {

dbFile.createNewFile();

}catch (Exception e){

}

InputStream is = context.getAssets().open(“db/” + dbName);

fos = new FileOutputStream(dbFile);

byte[] buffer = new byte[2048];

int len = -1;

while ((len = is.read(buffer)) != -1) {

fos.write(buffer, 0, len);

}

fos.close();

long endTime = System.currentTimeMillis();

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long useTime = endTime - startTime;

copyTime += useTime;

}

}

} catch (IOException e) {

e.printStackTrace();

}

}

}

Android? 本地 操作数据库逻辑（查，删，改）

package com.example.testdemo.util;

import android.content.Context;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.os.Environment;

import com.example.testdemo.bean.User;

import java.util.ArrayList;

import java.util.List;

public class DBManager {

private Context mContext;

private SQLiteDatabase mDB;

private static String dbPath = FileUtil.getDBpath() + “/Test.db”;

private static DBManager instance = null;

public DBManager() {

}

public static DBManager getInstance() {

if (instance == null) {

instance = new DBManager();

}

return instance;

}

/**

打开数据库

*/

private void openDB() {

if (isSDCard()) {

if (mDB == null || !mDB.isOpen())

mDB = SQLiteDatabase.openDatabase(dbPath, null,

SQLiteDatabase.OPEN_READWRITE);

}

}

private boolean isSDCard() {

return Environment.getExternalStorageState().equals(

Environment.MEDIA_MOUNTED);

}

//查询选择题

public List queryUser() {

List userList = new ArrayList();

User user= null;

openDB();

try {

String sql = " select a.id,a.name,a.age,a.phoneNum,b.name as sexName from user a,gender b where a.sex= b.type";

Cursor cursor = mDB.rawQuery(sql, null);

while (cursor.moveToNext()) {

String id = cursor.getString(cursor.getColumnIndex(“id”));

String name = cursor.getString(cursor.getColumnIndex(“name”));

String sex = cursor.getString(cursor.getColumnIndex(“sexName”));

String age = cursor.getString(cursor.getColumnIndex(“age”));

String phoneNum = cursor.getString(cursor.getColumnIndex(“phoneNum”));

user= new User();

user.setId(id);

user.setName(name);

user.setAge(age);

user.setPhoneNum(phoneNum);

user.setSex(sex);

userList.add(user);

}

cursor.close();

return userList;

} catch (Exception e) {

e.printStackTrace();

}

return null;

}

public void updateUser() {

openDB();

String sql = " update user set name = ‘李四’ where name = ‘王杰’ ";

mDB.execSQL(sql);

}

public void deleteUser(String id) {

openDB();

mDB.delete(“user”, " id = ? ", new String[]{id});

}

}

基本最核心的就这些代码，不是很复杂，贴上效果图。 我知道有的小伙伴需要完整的DEMO,所以我就整理了一个 ，在这里**DEMO下载**。

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