SQLite简单使用

1.首先继承了一个数据库的助手类LoginDBHelper

    代码如下：

 1 package com.ll.copyqqui;
 2 import android.content.Context;
 3 import android.database.sqlite.SQLiteDatabase;
 4 import android.database.sqlite.SQLiteOpenHelper;
 5 import android.database.sqlite.SQLiteDatabase.CursorFactory;
 6 
 7 
 8 public class LoginDBHelper extends SQLiteOpenHelper {
 9     public static final int VERSION = 1;
10     LoginDBHelper(Context context, String name, CursorFactory factory,int version){
11         super(context, name, factory, VERSION);
12     }
13     
14     // 这个地方是创建数据的时候调用
15     @Override
16     public void onCreate(SQLiteDatabase db) {
17         // TODO Auto-generated method stub
18         // 创建注册表
19         String sql = "create table user_table(uname varchar(32) primary key, " +
20                                               "upassword varchar(32));";
21         db.execSQL(sql);
22     }
23 
24     @Override
25     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
26         // TODO Auto-generated method stub
27     }
28 }

 

2.定义了一个User的类，里面包含了用户的用户名和密码

 1 package com.ll.copyqqui;
 2 
 3 public class User {
 4     
 5     private String userName = null;
 6     private String userPass = null;
 7     
 8     User(){
 9         
10     }
11     
12     User(String userName, String userPass){
13         this.userName = userName;
14         this.userPass = userPass;
15     }
16     
17     void setUserName(String userName){
18         this.userName = userName;
19     }
20     
21     void setUserPass(String userPass){
22         this.userPass = userPass;
23     }
24     
25     String getUserName(){
26         return userName;
27     }
28     
29     String getUserPass(){
30         return userPass;
31     }
32 
33 }

 

3.定义了一个操作数据表user_table的类UserDao，代码如下：

     添加用户到用户表：

 1 // 添加用户到用户表
 2     public boolean addUser(User user){
 3         if(user.getUserName().equals("") || user.getUserPass().equals("")){
 4             return false;
 5         }
 6         LoginDBHelper dbHelper = new LoginDBHelper(context,"user_db", null, 1);
 7         SQLiteDatabase db = dbHelper.getWritableDatabase();
 8         ContentValues cv = new ContentValues();
 9         cv.put("uname", user.getUserName());
10         cv.put("upassword", user.getUserPass());
11         db.insert(tbName, null, cv);
12         db.close();
13         return true;
14     }

　　删除用户：

 1 // 删除用户
 2     public boolean deleteUser(User user){
 3         if(isUserExist(user)){
 4             return false;
 5         }
 6         LoginDBHelper dbHelper = new LoginDBHelper(context, "user_db", null, 1);
 7         // 得到一个可写的数据库
 8         SQLiteDatabase db = dbHelper.getWritableDatabase();
 9         // 删除的条件
10         String whereClause = "uname=?";
11         String[] whereArgs = {user.getUserName()};
12         // 调用delete方法，删除数据
13         db.delete(tbName, whereClause, whereArgs);
14         return true;
15     }

　　更改用户密码：

 1 // 改用户密码
 2     public boolean updateUserPass(User user){
 3         if(isUserExist(user) == false){
 4             return false;
 5         }
 6         LoginDBHelper dbHelper = new LoginDBHelper(context,"user_db", null, 1);
 7         SQLiteDatabase db = dbHelper.getWritableDatabase();
 8         ContentValues cv = new ContentValues();
 9         cv.put("upassword", user.getUserPass());
10         String whereClause = "uname=?";
11         String[] whereArgs = {String.valueOf(user.getUserPass())};
12         db.update(tbName, cv, whereClause, whereArgs);
13         return true;
14     }

　　查询用户表

 1 // 判断用户是否存在
 2     public boolean isUserExist(User user){
 3         // 1.当输入的用户名为空的时候，直接返回不存在false
 4         if(user.getUserName().equals("")){
 5             return false;
 6         }
 7         LoginDBHelper dbHelper = new LoginDBHelper(context,"user_db", null, 1);
 8         SQLiteDatabase db = dbHelper.getReadableDatabase();
 9         // 2.查询
10         Cursor cursor = db.query(tbName, new String[]{"uname","upassword"},
11                 null, null, null, null, null);
12         boolean exist = false;
13         while(cursor.moveToNext()){
14             String uname = cursor.getString(cursor.getColumnIndex("uname"));
15             //String upassword = cursor.getString(cursor.getColumnIndex("upassword"));
16             if(user.getUserName().equals(uname)){
17                 exist = true;
18                 break;
19             }
20         }
21         db.close();
22         return exist;
23     }

 

4.当然怎么使用LoginDBHelper更加重要啦，首先创建数据库

 // 创建数据库

 new LoginDBHelper(MainActivity.this, "user_db", null, 1);

再定义一个UserDao的对象，然后调用UserDao里面的方法，就可以对数据表进行操作啦。

posted on 2015-11-01 16:25  I*M  阅读(172)  评论(0)    收藏  举报

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