Java 在打开之前在SQLite中创建数据库
我希望根据数据库中已有的表查询我的用户名。但当我执行代码时,我的应用程序强制关闭,因为“SQLite返回错误代码:1,msg=near”=”:语法错误 下面是DBAdapter.java文件Java 在打开之前在SQLite中创建数据库,java,android,sqlite,database-create,Java,Android,Sqlite,Database Create,我希望根据数据库中已有的表查询我的用户名。但当我执行代码时,我的应用程序强制关闭,因为“SQLite返回错误代码:1,msg=near”=”:语法错误 下面是DBAdapter.java文件 package com.example.usernammepassword; import android.content.ContentValues; public class DBAdapter { public static final String KEY_NAME = "UserNa
package com.example.usernammepassword;
import android.content.ContentValues;
public class DBAdapter {
public static final String KEY_NAME = "UserName";
public static final String KEY_PASS = "Password";
private static final String TAG = "DBAdapter";
private static final String DATABASE_NAME = "Test";
private static final String DATABASE_TABLE = "UsernamePassword";
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_CREATE =
"create table if not exists UsernamePassword (UserName text not null primary key, Password text not null);";
private final Context context;
DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db1) {
try {
db1.execSQL(DATABASE_CREATE);
} catch (SQLException e) {
e.printStackTrace();
}
}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public DBAdapter open() throws SQLException {
public void close() {
public long insertNewUser(String UserName, String Password) {
public boolean deleteUser(String UserName)
public Cursor getAllUserNamesAndPasswords()
{
return db.query(DATABASE_TABLE, new String[] { KEY_NAME,
KEY_PASS}, null, null, null, null, null);
}
public Cursor getPasswordForUserName(String UserName) throws SQLException
public boolean updatePasswordForUserName( String UserName, String Password) {
package com.example.usernammepassword;
import android.os.Bundle;
public class MainActivity extends Activity {
private String md5(String in) {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btn = (Button) findViewById(R.id.button1);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
EditText text = (EditText)findViewById(R.id.editText1);
EditText text1 = (EditText)findViewById(R.id.editText2);
String userid = text.getText().toString();
String pass = text1.getText().toString();
Toast.makeText(MainActivity.this,"Entered "+userid+" and password entered is "+pass,Toast.LENGTH_LONG).show();
pass = md5(pass + "@string/salt");
Toast.makeText(MainActivity.this,"Password after adding a salt and md5 hashing is now equal to " + pass,Toast.LENGTH_LONG).show();
DBAdapter db = new DBAdapter(MainActivity.this);
db.open();
Cursor c = db.getPasswordForUserName(userid);
if(c.moveToFirst())
{
if(c.getString(1) == pass)
{
Toast.makeText(MainActivity.this, "Authentication Succeded", Toast.LENGTH_SHORT).show();
//proceed
}
else
{
Toast.makeText(MainActivity.this, "@string/AuthFail", Toast.LENGTH_SHORT).show();
//AuthFailure
}
}
else
{
Toast.makeText(MainActivity.this,"@string/UserNotFound", Toast.LENGTH_SHORT).show();
//where to from here
}
}
});
}
public boolean onCreateOptionsMenu(Menu menu) {
}
以及MainActivity.java文件
package com.example.usernammepassword;
import android.content.ContentValues;
public class DBAdapter {
public static final String KEY_NAME = "UserName";
public static final String KEY_PASS = "Password";
private static final String TAG = "DBAdapter";
private static final String DATABASE_NAME = "Test";
private static final String DATABASE_TABLE = "UsernamePassword";
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_CREATE =
"create table if not exists UsernamePassword (UserName text not null primary key, Password text not null);";
private final Context context;
DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DBAdapter(Context ctx)
{
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db1) {
try {
db1.execSQL(DATABASE_CREATE);
} catch (SQLException e) {
e.printStackTrace();
}
}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
public DBAdapter open() throws SQLException {
public void close() {
public long insertNewUser(String UserName, String Password) {
public boolean deleteUser(String UserName)
public Cursor getAllUserNamesAndPasswords()
{
return db.query(DATABASE_TABLE, new String[] { KEY_NAME,
KEY_PASS}, null, null, null, null, null);
}
public Cursor getPasswordForUserName(String UserName) throws SQLException
public boolean updatePasswordForUserName( String UserName, String Password) {
package com.example.usernammepassword;
import android.os.Bundle;
public class MainActivity extends Activity {
private String md5(String in) {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btn = (Button) findViewById(R.id.button1);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
EditText text = (EditText)findViewById(R.id.editText1);
EditText text1 = (EditText)findViewById(R.id.editText2);
String userid = text.getText().toString();
String pass = text1.getText().toString();
Toast.makeText(MainActivity.this,"Entered "+userid+" and password entered is "+pass,Toast.LENGTH_LONG).show();
pass = md5(pass + "@string/salt");
Toast.makeText(MainActivity.this,"Password after adding a salt and md5 hashing is now equal to " + pass,Toast.LENGTH_LONG).show();
DBAdapter db = new DBAdapter(MainActivity.this);
db.open();
Cursor c = db.getPasswordForUserName(userid);
if(c.moveToFirst())
{
if(c.getString(1) == pass)
{
Toast.makeText(MainActivity.this, "Authentication Succeded", Toast.LENGTH_SHORT).show();
//proceed
}
else
{
Toast.makeText(MainActivity.this, "@string/AuthFail", Toast.LENGTH_SHORT).show();
//AuthFailure
}
}
else
{
Toast.makeText(MainActivity.this,"@string/UserNotFound", Toast.LENGTH_SHORT).show();
//where to from here
}
}
});
}
public boolean onCreateOptionsMenu(Menu menu) {
}
日志:
您可能将表名从某物更新为
UserNamePassword
,但没有更改数据库版本
,这将触发onUpgrade()
。
当然,还必须实现
onUpgrade()
来创建适当的表。是的,它没有因为“没有这样的表”而崩溃“,但由于其他原因,我现在要解决:)非常感谢。你能解释一下为什么这会有不同吗@霍诺,不是这样的。我试图在模拟器上调试应用程序,我不知道为什么,但模拟器没有SD卡。因此应用程序将崩溃。我在一个真实的设备上进行了调试,在编辑了一点代码之后,在DB adapter类中删除了一些bug。另一个错误是我将字符串与“==”运算符进行比较,这不起作用。应该是