靠谱好用，ANDROID SQLITE 增删查改
布局文件main实现简单的功能：
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:layout_width="fill_parent" 4 android:layout_height="fill_parent" 5 android:orientation="vertical" > 6 7 <TextView 8 android:id="@+id/showsomething" 9 android:layout_width="fill_parent" 10 android:layout_height="wrap_content" 11 android:text="@string/hello" /> 12 13 <Button 14 android:id="@+id/btn_create" 15 android:layout_width="wrap_content" 16 android:layout_height="wrap_content" 17 android:text="创建数据库" /> 18 <TextView 19 android:layout_width="wrap_content" 20 android:layout_height="wrap_content" 21 android:text="用户名:" 22 /> 23 <EditText 24 android:id="@+id/username" 25 android:layout_width="fill_parent" 26 android:layout_height="40dp" 27 /> 28 <TextView 29 android:layout_width="wrap_content" 30 android:layout_height="wrap_content" 31 android:text="密码:" 32 /> 33 <EditText 34 android:id="@+id/password" 35 android:layout_width="fill_parent" 36 android:layout_height="40dp" 37 /> 38 <Button 39 android:id="@+id/btn_insert" 40 android:layout_width="wrap_content" 41 android:layout_height="wrap_content" 42 android:text="添加用户" 43 android:textSize="20sp" 44 /> 45 46 <Button 47 android:id="@+id/btn_update" 48 android:layout_width="wrap_content" 49 android:layout_height="wrap_content" 50 android:text="更新" 51 android:textSize="20sp" 52 /> 53 54 <Button 55 android:id="@+id/btn_show" 56 android:layout_width="wrap_content" 57 android:layout_height="wrap_content" 58 android:text="显示用户" 59 android:textSize="20sp" 60 /> 61 62 <Button 63 android:id="@+id/btn_showall" 64 android:layout_width="wrap_content" 65 android:layout_height="wrap_content" 66 android:text="显示all用户" 67 android:textSize="20sp" 68 /> 69 <Button 70 android:id="@+id/btn_deleteusertable" 71 android:layout_width="wrap_content" 72 android:layout_height="wrap_content" 73 android:text="删除用户表" 74 android:textSize="20sp" 75 /> 76 </LinearLayout>
工具类DBUtil.java是实现数据库的创建连接、断接、增删改查等操作。
package com.db.util;
import java.util.ArrayList;
import java.util.List;
import java.util.Vector;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
import android.widget.EditText;
public class DBUtil
{
static SQLiteDatabase sld;
public static void createOrOpenDatabase() throws Exception
{
sld=SQLiteDatabase.openDatabase
(
"/data/data/com.db/dbtest", //数据库所在路径
null, //CursorFactory
SQLiteDatabase.OPEN_READWRITE|SQLiteDatabase.CREATE_IF_NECESSARY //读写、若不存在则创建
);
String sql0="create table if not exists user(username varchar2(20),password varchar2(20))";
sld.execSQL(sql0);
}
public static void closeDatabase() throws Exception
{
try
{
sld.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
/*=====================================begin==========================================================*/
//获取用户信息-winxiang
public static List<String> searchuser(String username){
List<String> list=new ArrayList<String>();
try
{
createOrOpenDatabase();
String sql="select * from user where username='"+username+"'";
Cursor cur=sld.rawQuery(sql, new String[]{});
while(cur.moveToNext())
{
list.add(cur.getString(0)); //username
list.add(cur.getString(1)); //password
}
cur.close();
closeDatabase();
}
catch(Exception e)
{
e.printStackTrace();
}
return list;
}
//获取所有用户信息-winxiang
public static List<String> searchalluser(){
List<String> list=new ArrayList<String>();
try
{
createOrOpenDatabase();
String sql="select * from user";
Cursor cur=sld.rawQuery(sql, new String[]{});
while(cur.moveToNext())
{
list.add(cur.getString(0)); //username
list.add(cur.getString(1)); //password
}
cur.close();
closeDatabase();
}
catch(Exception e)
{
e.printStackTrace();
}
return list;
}
public static void updatetable(String sql)
{
try
{
createOrOpenDatabase();
sld.execSQL(sql);
closeDatabase();
}
catch(Exception e)
{
e.printStackTrace();
}
}
//舍弃user表
public static void droptable(){
try
{
String sql="drop table user";
createOrOpenDatabase();
sld.execSQL(sql);
closeDatabase();
}
catch(Exception e)
{
e.printStackTrace();
}
Log.d("DB","had deleted table: user->");
}
/*=====================================end==========================================================*/
}
DBTestactivity：
1 package com.db;
2
3
4 import java.util.List;
5
6 import com.db.util.DBUtil;
7 import android.app.Activity;
8 import android.os.Bundle;
9 import android.view.View;
10 import android.view.View.OnClickListener;
11 import android.widget.Button;
12 import android.widget.EditText;
13 import android.widget.TextView;
14 import android.widget.Toast;
15
16 public class DBtestActivity extends Activity {
17 Button btn_createdb,btn_insert,btn_show,btn_update,btn_showall,deleteusertable;
18 EditText username,password;
19 TextView showsomething;
20
21 @Override
22 public void onCreate(Bundle savedInstanceState) {
23 super.onCreate(savedInstanceState);
24 setContentView(R.layout.main);
25 init();
26 }
27
28 public void init(){
29 username = (EditText) findViewById(R.id.username);
30 password = (EditText) findViewById(R.id.password);
31 btn_createdb = (Button) findViewById(R.id.btn_create);
32 btn_insert = (Button) findViewById(R.id.btn_insert);
33 btn_show = (Button) findViewById(R.id.btn_show);
34 btn_update = (Button) findViewById(R.id.btn_update);
35 deleteusertable = (Button) findViewById(R.id.btn_deleteusertable);
36 btn_showall= (Button) findViewById(R.id.btn_showall);
37 showsomething = (TextView) findViewById(R.id.showsomething);
38
39 btn_createdb.setOnClickListener(listener);
40 btn_insert.setOnClickListener(listener);
41 btn_createdb.setOnClickListener(listener);
42 btn_show.setOnClickListener(listener);
43 btn_update.setOnClickListener(listener);
44 btn_showall.setOnClickListener(listener);
45 deleteusertable.setOnClickListener(listener);
46 }
47
48 public OnClickListener listener = new OnClickListener() {
49 @Override
50 public void onClick(View v) {
51 Button button = (Button) v;
52 if(button.getId()==btn_createdb.getId()){
53 try {
54 DBUtil.createOrOpenDatabase();
55 } catch (Exception e) {
56 e.printStackTrace();
57 }
58 }else if(button.getId()==btn_insert.getId()){
59 String sql="insert into user values ('"+username.getText()+"','"+password.getText()+"')";
60 DBUtil.updatetable(sql);
61 }else if(button.getId()==btn_show.getId()){
62 List<String>user = DBUtil.searchuser(username.getText().toString());
63 showsomething.setText(user.toString());
64 }else if(button.getId()==btn_update.getId()){
65 String sql="update user set username='"+username.getText()+"',password='"+password.getText()+"' where username = '"+username.getText()+"'";
66 System.out.println(sql);
67 DBUtil.updatetable(sql);
68 }else if(button.getId()==btn_showall.getId()){
69 List<String>users = DBUtil.searchalluser();
70 showsomething.setText(users.toString());
71 }else if(button.getId()==deleteusertable.getId()){
72 DBUtil.droptable();
73 Toast.makeText(getApplicationContext(), "用户表删除成功", Toast.LENGTH_SHORT).show();
74 }
75 }
76 };
77 }
浙公网安备 33010602011771号