一、代码
1.xml
(1)activity_main.xml
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 android:orientation="vertical" 4 android:layout_width="fill_parent" 5 android:layout_height="fill_parent" 6 > 7 <Button 8 android:id="@+id/createDatabase" 9 android:layout_width="fill_parent" 10 android:layout_height="wrap_content" 11 android:text="createDatabase" 12 /> 13 14 <Button 15 android:id="@+id/updateDatabase" 16 android:layout_width="fill_parent" 17 android:layout_height="wrap_content" 18 android:text="updateDatabase" 19 /> 20 21 <Button 22 android:id="@+id/insert" 23 android:layout_width="fill_parent" 24 android:layout_height="wrap_content" 25 android:text="insert"/> 26 <Button 27 android:id="@+id/update" 28 android:layout_width="fill_parent" 29 android:layout_height="wrap_content" 30 android:text="update"/> 31 <Button 32 android:id="@+id/query" 33 android:layout_width="fill_parent" 34 android:layout_height="wrap_content" 35 android:text="query"/> 36 37 </LinearLayout>
2.java
(1)MainActivity.java
1 package com.example.s01_original_e16_sqlite;
2
3 import android.app.Activity;
4 import android.content.ContentValues;
5 import android.database.Cursor;
6 import android.database.sqlite.SQLiteDatabase;
7 import android.database.sqlite.SQLiteOpenHelper;
8 import android.os.Bundle;
9 import android.util.Log;
10 import android.view.View;
11 import android.view.View.OnClickListener;
12 import android.widget.Button;
13
14 public class MainActivity extends Activity {
15
16 /** Called when the activity is first created. */
17 private Button createButton;
18 private Button insertButton;
19 private Button updateButton;
20 private Button updateRecordButton;
21 private Button queryButton;
22 @Override
23 public void onCreate(Bundle savedInstanceState) {
24 super.onCreate(savedInstanceState);
25 setContentView(R.layout.activity_main);
26 createButton = (Button)findViewById(R.id.createDatabase);
27 updateButton = (Button)findViewById(R.id.updateDatabase);
28 insertButton = (Button)findViewById(R.id.insert);
29 updateRecordButton = (Button)findViewById(R.id.update);
30 queryButton = (Button)findViewById(R.id.query);
31 createButton.setOnClickListener(new CreateListener());
32 updateButton.setOnClickListener(new UpdateListener());
33 insertButton.setOnClickListener(new InsertListener());
34 updateRecordButton.setOnClickListener(new UpdateRecordListener());
35 queryButton.setOnClickListener(new QueryListener());
36 }
37 class CreateListener implements OnClickListener{
38 @Override
39 public void onClick(View v) {
40 //创建一个DatabaseHelper对象
41 DBHelper dbHelper = new DBHelper(MainActivity.this, "my_sqlite_db");
42 //只有调用了DatabaseHelper对象的getReadableDatabase()方法，或者是getWritableDatabase()方法之后，才会创建，或打开一个数据库
43 SQLiteDatabase db = dbHelper.getReadableDatabase();
44 }
45 }
46 class UpdateListener implements OnClickListener{
47
48 @Override
49 public void onClick(View v) {
50 DBHelper dbHelper = new DBHelper(MainActivity.this,"my_sqlite_db",2);
51 SQLiteDatabase db = dbHelper.getReadableDatabase();
52 }
53
54 }
55 class InsertListener implements OnClickListener{
56
57 @Override
58 public void onClick(View v) {
59 //生成ContentValues对象
60 ContentValues values = new ContentValues();
61 //想该对象当中插入键值对，其中键是列名，值是希望插入到这一列的值，值必须和数据库当中的数据类型一致
62 values.put("id", 1);
63 values.put("name","zhangsan");
64 DBHelper dbHelper = new DBHelper(MainActivity.this,"my_sqlite_db",2);
65 SQLiteDatabase db = dbHelper.getWritableDatabase();
66 //调用insert方法，就可以将数据插入到数据库当中
67 db.insert("user", null, values);
68 }
69 }
70 //更新操作就相当于执行SQL语句当中的update语句
71 //UPDATE table_name SET XXCOL=XXX WHERE XXCOL=XX...
72 class UpdateRecordListener implements OnClickListener{
73
74 @Override
75 public void onClick(View arg0) {
76 // TODO Auto-generated method stub
77 //得到一个可写的SQLiteDatabase对象
78 DBHelper dbHelper = new DBHelper(MainActivity.this,"my_sqlite_db",2);
79 SQLiteDatabase db = dbHelper.getWritableDatabase();
80 ContentValues values = new ContentValues();
81 values.put("name", "zhangsanfeng");
82 //第一个参数是要更新的表名
83 //第二个参数是一个ContentValeus对象
84 //第三个参数是where子句
85 db.update("user", values, "id=?", new String[]{"1"});
86 }
87 }
88 class QueryListener implements OnClickListener{
89
90 @Override
91 public void onClick(View v) {
92 System.out.println("aaa------------------");
93 Log.d("myDebug", "myFirstDebugMsg");
94
95 DBHelper dbHelper = new DBHelper(MainActivity.this,"my_sqlite_db",2);
96 SQLiteDatabase db = dbHelper.getReadableDatabase();
97 Cursor cursor = db.query("user", new String[]{"id","name"}, "id=?", new String[]{"1"}, null, null, null);
98 while(cursor.moveToNext()){
99 String name = cursor.getString(cursor.getColumnIndex("name"));
100 System.out.println("query--->" + name);
101 }
102 }
103 }
104
105 }
(2)DBHelper.java
1 package com.example.s01_original_e16_sqlite;
2
3 import android.content.Context;
4 import android.database.sqlite.SQLiteDatabase;
5 import android.database.sqlite.SQLiteDatabase.CursorFactory;
6 import android.database.sqlite.SQLiteOpenHelper;
7
8 public class DBHelper extends SQLiteOpenHelper {
9
10 private static final int VERSION = 1;
11 //在SQLiteOepnHelper的子类当中，必须有该构造函数
12 public DBHelper(Context context, String name, CursorFactory factory,
13 int version) {
14 //必须通过super调用父类当中的构造函数
15 super(context, name, factory, version);
16 // TODO Auto-generated constructor stub
17 }
18 public DBHelper(Context context,String name){
19 this(context,name,VERSION);
20 }
21 public DBHelper(Context context,String name,int version){
22 this(context, name,null,version);
23 }
24
25 //该函数是在第一次创建数据库的时候执行,实际上是在第一次得到SQLiteDatabse对象的时候，才会调用这个方法
26 @Override
27 public void onCreate(SQLiteDatabase db) {
28 // TODO Auto-generated method stub
29 System.out.println("create a Database");
30 //execSQL函数用于执行SQL语句
31 db.execSQL("create table user(id int,name varchar(20))");
32 }
33
34 @Override
35 public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
36 // TODO Auto-generated method stub
37 System.out.println("update a Database");
38 }
39
40 }
时间： 2024-10-07 10:28:57