layout文件：
1 <?xml version="1.0" encoding="utf-8"?> 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 3 xmlns:tools="http://schemas.android.com/tools" 4 android:layout_width="match_parent" 5 android:layout_height="match_parent" 6 android:paddingBottom="@dimen/activity_vertical_margin" 7 android:paddingLeft="@dimen/activity_horizontal_margin" 8 android:paddingRight="@dimen/activity_horizontal_margin" 9 android:paddingTop="@dimen/activity_vertical_margin" 10 tools:context="com.hanqi.testapp3.TestActivity" 11 android:orientation="vertical"> 12 13 <Button 14 android:layout_width="match_parent" 15 android:layout_height="wrap_content" 16 android:text="初始化数据库" 17 android:onClick="bt1_onClick"/> 18 <Button 19 android:layout_width="match_parent" 20 android:layout_height="wrap_content" 21 android:text="升级数据库" 22 android:onClick="bt2_onClick"/> 23 <LinearLayout 24 android:layout_width="match_parent" 25 android:layout_height="wrap_content"> 26 <EditText 27 android:layout_width="0dp" 28 android:layout_height="wrap_content" 29 android:layout_weight="1" 30 android:id="@+id/et_id" 31 android:hint="id"/> 32 <EditText 33 android:layout_width="0dp" 34 android:layout_height="wrap_content" 35 android:layout_weight="1" 36 android:id="@+id/et_name" 37 android:hint="name"/> 38 </LinearLayout> 39 <LinearLayout 40 android:layout_width="match_parent" 41 android:layout_height="wrap_content"> 42 <EditText 43 android:layout_width="0dp" 44 android:layout_height="wrap_content" 45 android:layout_weight="1" 46 android:id="@+id/et_sex" 47 android:hint="sex"/> 48 <EditText 49 android:layout_width="0dp" 50 android:layout_height="wrap_content" 51 android:layout_weight="1" 52 android:id="@+id/et_age" 53 android:hint="age"/> 54 </LinearLayout> 55 <Button 56 android:layout_width="match_parent" 57 android:layout_height="wrap_content" 58 android:text="新增数据" 59 android:onClick="bt3_onClick"/> 60 <Button 61 android:layout_width="match_parent" 62 android:layout_height="wrap_content" 63 android:text="查询数据" 64 android:onClick="bt4_onClick"/> 65 <Button 66 android:layout_width="match_parent" 67 android:layout_height="wrap_content" 68 android:text="带条件查询数据" 69 android:onClick="bt5_onClick"/> 70 <Button 71 android:layout_width="match_parent" 72 android:layout_height="wrap_content" 73 android:text="修改数据" 74 android:onClick="bt6_onClick"/> 75 <Button 76 android:layout_width="match_parent" 77 android:layout_height="wrap_content" 78 android:text="删除数据" 79 android:onClick="bt7_onClick"/> 80 <Button 81 android:layout_width="match_parent" 82 android:layout_height="wrap_content" 83 android:text="数据库事务" 84 android:onClick="bt8_onClick"/> 85 </LinearLayout>
java类：
1 package com.hanqi.testapp3;
2
3 import android.content.ContentValues;
4 import android.database.Cursor;
5 import android.database.sqlite.SQLiteDatabase;
6 import android.database.sqlite.SQLiteOpenHelper;
7 import android.support.v7.app.AppCompatActivity;
8 import android.os.Bundle;
9 import android.util.Log;
10 import android.view.View;
11 import android.widget.EditText;
12 import android.widget.Toast;
13
14 public class TestActivity extends AppCompatActivity {
15
16 EditText et_id,et_name,et_sex,et_age;
17 @Override
18 protected void onCreate(Bundle savedInstanceState) {
19 super.onCreate(savedInstanceState);
20 setContentView(R.layout.activity_test);
21 et_id = (EditText)findViewById(R.id.et_id);
22 et_name = (EditText)findViewById(R.id.et_name);
23 et_sex = (EditText)findViewById(R.id.et_sex);
24 et_age = (EditText)findViewById(R.id.et_age);
25 }
26 //初始化数据库
27 public void bt1_onClick(View v)
28 {
29 //使用工具类得到数据库对象
30 MyDBHelper myDBHelper = new MyDBHelper("test.db",1);
31 Toast.makeText(TestActivity.this, "连接数据库成功", Toast.LENGTH_SHORT).show();
32 //得到连接
33 SQLiteDatabase sqLiteDatabase = myDBHelper.getWritableDatabase();
34 //关闭连接
35 sqLiteDatabase.close();
36 }
37 //升级数据库
38 public void bt2_onClick(View v)
39 {
40 //使用工具类得到数据库对象
41 MyDBHelper myDBHelper = new MyDBHelper("test.db",2);
42 Toast.makeText(TestActivity.this, "连接数据库成功", Toast.LENGTH_SHORT).show();
43 //得到连接
44 SQLiteDatabase sqLiteDatabase = myDBHelper.getWritableDatabase();
45 //关闭连接
46 sqLiteDatabase.close();
47 }
48 //插入新数据
49 public void bt3_onClick(View v)
50 {
51 //1.连接数据库，得到数据库连接对象
52 //得到连接
53 SQLiteDatabase sd = new MyDBHelper("test.db",2).getWritableDatabase();
54 //2.准备数据
55 ContentValues cv = new ContentValues();
56 cv.put("name",et_name.getText().toString());
57 cv.put("sex",et_sex.getText().toString());
58 cv.put("age", et_age.getText().toString());
59 //3.调用insert()，插入数据
60 long l = sd.insert("t_user", null, cv);
61 Toast.makeText(TestActivity.this, "插入数据的主键 = "+l, Toast.LENGTH_SHORT).show();
62 //4.关闭连接
63 sd.close();
64 }
65 //数据查询
66 public void bt4_onClick(View v)
67 {
68 //1.连接数据库，得到数据库连接对象
69 //得到连接
70 SQLiteDatabase sd = new MyDBHelper("test.db",2).getWritableDatabase();
71 //2.全表全字段查询
72 Cursor c = sd.query("t_user", null, null, null, null, null, null);
73 //3.遍历结果集
74 while (c.moveToNext())
75 {
76 //读取数据
77 String str ="_id ="+c.getLong(c.getColumnIndex("_id"))+"name = "
78 +c.getString(1)+" sex = "+c.getString(2)+
79 " age = "+c.getInt(3);
80 Log.e("TAG",str);
81 }
82 Toast.makeText(TestActivity.this, "结果集的记录条数 = "+c.getCount(), Toast.LENGTH_SHORT).show();
83 c.close();
84 //4.关闭连接
85 sd.close();
86 }
87 //带条件数据查询
88 public void bt5_onClick(View v)
89 {
90 //1.连接数据库，得到数据库连接对象
91 //得到连接
92 SQLiteDatabase sd = new MyDBHelper("test.db",2).getWritableDatabase();
93 String strwhere = "1 = 1";
94 //select * from t_user where _id = 1 and name like ‘%张%‘ and sex = ‘‘
95 //得到条件
96 if (et_id.getText().length()>0)
97 {
98 strwhere += " and _id = "+et_id.getText().toString();
99 }
100
101 if (et_name.getText().length()>0)
102 {
103 strwhere += " and name like ‘%"+et_name.getText().toString()+"%‘";
104 }
105 if (et_sex.getText().length()>0)
106 {
107 strwhere += " and sex = "+et_sex.getText().toString()+"‘";
108 }
109 if (et_age.getText().length()>0)
110 {
111 strwhere += " and age = ‘"+et_age.getText().toString()+"‘";
112 }
113 //2.查询
114 Cursor c = sd.query("t_user", null, strwhere, null, null, null, null);
115 //3.遍历结果集
116 while (c.moveToNext())
117 {
118 //读取数据
119 String str ="_id ="+c.getLong(c.getColumnIndex("_id"))+"name = "
120 +c.getString(1)+" sex = "+c.getString(2)+
121 " age = "+c.getInt(3);
122 Log.e("TAG",str);
123 }
124 Toast.makeText(TestActivity.this, "结果集的记录条数 = "+c.getCount(), Toast.LENGTH_SHORT).show();
125 c.close();
126 //4.关闭连接
127 sd.close();
128 }
129 //修改数据
130 public void bt6_onClick(View v)
131 {
132 //1.连接数据库，得到数据库连接对象
133 //得到连接
134 SQLiteDatabase sd = new MyDBHelper("test.db",2).getWritableDatabase();
135 //2.修改
136 ContentValues cv = new ContentValues();
137 cv.put("name",et_name.getText().toString());
138 cv.put("sex",et_sex.getText().toString());
139 cv.put("age", et_age.getText().toString());
140 int i = sd.update("t_user",cv,"_id = ?",new String[]{et_id.getText().toString()});
141 Toast.makeText(TestActivity.this, "修改的记录条数 = "+i, Toast.LENGTH_SHORT).show();
142 //4.关闭连接
143 sd.close();
144 }
145 //删除数据
146 public void bt7_onClick(View v)
147 {
148 //1.连接数据库，得到数据库连接对象
149 //得到连接
150 SQLiteDatabase sd = new MyDBHelper("test.db",2).getWritableDatabase();
151 //2.删除
152 int i = sd.delete("t_user", "_id = ?", new String[]{et_id.getText().toString()});
153 Toast.makeText(TestActivity.this, "修改的记录条数 = "+i, Toast.LENGTH_SHORT).show();
154 //4.关闭连接
155 sd.close();
156 }
157 //数据库事务
158 public void bt8_onClick(View v)
159 {
160
161 //1.连接数据库，得到数据库连接对象
162 //得到连接
163 SQLiteDatabase sd = new MyDBHelper("test.db", 2).getWritableDatabase();
164 try {
165 //启动事务
166 sd.beginTransaction();
167 //2.修改
168 ContentValues cv1 = new ContentValues();
169 cv1.put("age", "43");
170 ContentValues cv2 = new ContentValues();
171 cv2.put("age", "53");
172 //修改1
173 int i = sd.update("t_user", cv1, "_id = 1", null);
174 //抛出异常
175 if (i > 0) {
176 throw new RuntimeException("模拟事务异常");
177 }
178 //修改2
179 int k = sd.update("t_user", cv2, "_id = 2", null);
180 //设置事务是成功完成的
181 sd.setTransactionSuccessful();
182
183 Toast.makeText(TestActivity.this, "修改的记录条数 = " + (i + k), Toast.LENGTH_SHORT).show();
184
185 }
186 catch (Exception e)
187 {
188 e.printStackTrace();
189 }
190 finally {
191 //一定会被执行的代码
192 //结束事务
193 //1.没有异常，提交事务
194 //2.发生异常，回滚事务
195 sd.endTransaction();
196 //4.关闭连接
197 sd.close();
198 }
199 }
200 //实现SQLiteOpenHelper的内部类
201 class MyDBHelper extends SQLiteOpenHelper
202 {
203 //构造方法
204 public MyDBHelper(String dbname,int ver)
205 {
206 //显示调用父类的构造方法
207 //必须在第一行
208 super(TestActivity.this,dbname,null,ver);
209 }
210 //创建和初始化数据库
211 @Override
212 public void onCreate(SQLiteDatabase db) {
213 //1.执行创建数据库的语句
214 String sql = "CREATE TABLE t_user " +
215 "(_id INTEGER NOT NULL," +
216 "name VARCHAR(20) NOT NULL," +
217 "sex CHAR(1),age INTEGER,\n" +
218 "PRIMARY KEY (\"_id\"))";
219 db.execSQL(sql);
220 Log.e("TAG","表创建成功");
221 //2.执行初始化数据的语句，insert语句
222 ContentValues cv = new ContentValues();
223 cv.put("name","张三");
224 cv.put("sex","男");
225 cv.put("age",20);
226 //执行插入，返回主键
227 long l = db.insert("t_user",null,cv);
228 Log.e("TAG","初始化数据 = "+l);
229
230 }
231 //升级数据库
232 //触发条件：当版本号增大
233 @Override
234 public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
235 //修改数据
236 if (newVersion ==2)
237 {
238 ContentValues cv = new ContentValues();
239 cv.put("name","李四");
240 String sql = "update t_user set name=‘李四‘where _id=1";
241 String[] str = {"1","18"};
242 //调用db的更新方法
243 int i = db.update("t_user",cv,"_id=? and age>?",str);
244 Log.e("TAG","升级数据 数据条数 = "+i);
245 }
246 }
247 }
248 }
时间： 2024-10-13 00:25:46