Java 如何在Android中全局访问SQlite返回的数据?
我在Android上编写sip应用程序。我有一些关于用户登录的信息。我想做那样的东西Java 如何在Android中全局访问SQlite返回的数据?,java,android,sqlite,object,getter-setter,Java,Android,Sqlite,Object,Getter Setter,我在Android上编写sip应用程序。我有一些关于用户登录的信息。我想做那样的东西 具有用户设置的用户对象(存储在SQlite中) 从SQlite数据访问用户数据并存储在对象中 直接从对象使用用户数据,如(在UI活动中,片段…): 用户=新用户(); Log.i(“TAG”,user.sip\u id); 或 User user = new User(); Log.i("TAG", user.sip_id); Log.i(“TAG”,user.getSip_id()); //从表中获取用户数据
//从表中获取用户数据
公共HashMap getUserDetails(){
HashMap用户=新建HashMap();
String selectQuery=“选择*来自用户”;
SQLiteDatabase db=this.getReadableDatabase();
Cursor Cursor=db.rawQuery(selectQuery,null);
cursor.moveToFirst();
if(cursor.getCount()>0){
MainObj.User User=新的MainObj.User();
user.setSip_id(cursor.getString(1));
user.setAccount_id(cursor.getString(2));
等等
}
cursor.close();
db.close();
//返回用户
返回用户;
}
我不知道如何正确地使用谷歌,因为我已经搜索了大约3个小时。你的问题在于你的getUserDetails方法 首先,创建一个名为user的HashMap变量。。。在if块中,您还创建了一个名为User的MainObj.User变量 所以。。。那碰撞呢?在Java中,变量作用域是块。因此,在if块中创建的用户将在if块完成时自动删除,返回值为空HashMap 您可以将该方法更改为以下内容:
// get user data from table
public HashMap<String, String> getUserDetails() {
HashMap<String, String> user = new HashMap<String, String>();
String selectQuery = "SELECT * FROM user";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
cursor.moveToFirst();
if (cursor.getCount() > 0) {
MainObj.User user = new MainObj.User();
user.setSip_id(cursor.getString(1));
user.setAccount_id(cursor.getString(2));
.... and so on
}
cursor.close();
db.close();
// return user
return user;
}
只要像这样更改代码,您就可以随时随地访问数据
// get user data from table
public MainObj.User getUserDetails() {
MainObj.User user = null;
String selectQuery = "SELECT * FROM user";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
cursor.moveToFirst();
if (cursor.getCount() > 0) {
user = new MainObj.User();
user.setSip_id(cursor.getString(1));
user.setAccount_id(cursor.getString(2));
.... and so on
}
cursor.close();
db.close();
// return user or null if not data
return user;
}
您可以通过如下方式访问实例来为用户obj设置数据
import android.util.Log;
public class User {
private static final User instance = new User();
public static User getInstance() {
return instance;
}
private User() {
super();
}
private int account_id;
private String user_id;
private String sip_id;
private String username;
private String fullname;
private boolean active;
private boolean status;
public int getAccount_id() {
return account_id;
}
public void setAccount_id(int account_id) {
Log.e("myphone", account_id + "");
this.account_id = account_id;
}
public String getUser_id() {
return user_id;
}
public void setUser_id(String user_id) {
this.user_id = user_id;
}
public String getSip_id() {
return sip_id;
}
public void setSip_id(String sip_id) {
this.sip_id = sip_id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getFullname() {
return fullname;
}
public void setFullname(String fullname) {
this.fullname = fullname;
}
public boolean isActive() {
return active;
}
public void setActive(boolean active) {
this.active = active;
}
public boolean isStatus() {
return status;
}
public void setStatus(boolean status) {
this.status = status;
}
}
如果您在获得数据后需要数据,只需执行以下操作,例如:
//get user data from table
public void getUserDetails() {
String selectQuery = "SELECT * FROM user";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
cursor.moveToFirst();
if (cursor.getCount() > 0) {
//If you want you can hold the reference in a User obj = User.getInstance(); just to write less code
User.getInstance().setSip_id(cursor.getString(1));
User.getInstance().setAccount_id(cursor.getString(2));
.... and so on
}
cursor.close();
db.close();
}
您可以返回用户详细信息列表。如果您需要从应用程序中的任何位置访问它,请将此列表放在应用程序类中。它维护一个全局应用程序状态。通过调用ChildApplication app=(ChildApplication)context.getApplicationContext(),可以扩展应用程序类并在应用程序中的任何位置使用该类 公共列表getUSerDetails(){ List userDetails=new ArrayList(); String selectQuery=“选择*来自用户”; SQLiteDatabase db=this.getReadableDatabase(); Cursor Cursor=db.rawQuery(selectQuery,null); cursor.moveToFirst(); if(cursor.getCount()>0){ MainObj.User User=新的MainObj.User(); user.setSip_id(cursor.getString(1)); user.setAccount_id(cursor.getString(2)); 等等 userDetails.add(用户); } cursor.close(); db.close(); 返回用户详细信息; }
import android.util.Log;
public class User {
private static final User instance = new User();
public static User getInstance() {
return instance;
}
private User() {
super();
}
private int account_id;
private String user_id;
private String sip_id;
private String username;
private String fullname;
private boolean active;
private boolean status;
public int getAccount_id() {
return account_id;
}
public void setAccount_id(int account_id) {
Log.e("myphone", account_id + "");
this.account_id = account_id;
}
public String getUser_id() {
return user_id;
}
public void setUser_id(String user_id) {
this.user_id = user_id;
}
public String getSip_id() {
return sip_id;
}
public void setSip_id(String sip_id) {
this.sip_id = sip_id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getFullname() {
return fullname;
}
public void setFullname(String fullname) {
this.fullname = fullname;
}
public boolean isActive() {
return active;
}
public void setActive(boolean active) {
this.active = active;
}
public boolean isStatus() {
return status;
}
public void setStatus(boolean status) {
this.status = status;
}
}
//get user data from table
public void getUserDetails() {
String selectQuery = "SELECT * FROM user";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
cursor.moveToFirst();
if (cursor.getCount() > 0) {
//If you want you can hold the reference in a User obj = User.getInstance(); just to write less code
User.getInstance().setSip_id(cursor.getString(1));
User.getInstance().setAccount_id(cursor.getString(2));
.... and so on
}
cursor.close();
db.close();
}
mEditText.setText(User.getInstance().getUsername());
public List<MainObj.User> getUSerDetails(){
List<MainObj.User> userDetails = new ArrayList<MainObj.User>();
String selectQuery = "SELECT * FROM user";
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
cursor.moveToFirst();
if (cursor.getCount() > 0) {
MainObj.User user = new MainObj.User();
user.setSip_id(cursor.getString(1));
user.setAccount_id(cursor.getString(2));
.... and so on
userDetails.add(user);
}
cursor.close();
db.close();
return userDetails;
}