换成了国内的数据库

app/src/main/java/hunnu/sj/raise_money/DataBase/DatabaseHelper.java

@@ -15,11 +15,11 @@ public class DatabaseHelper {
 
     public static Connection getConnection(){
         String username = "root";
-        String password ="SJ1126388959";
+        String password ="12345678";
         if(conn==null){
             try {
                 Class.forName("com.mysql.jdbc.Driver");
-                String url = "jdbc:mysql://139.180.223.93:3306/dogson?useSSL=true&characterEncoding=utf-8";
+                String url = "jdbc:mysql://39.105.116.16:3306/raise";
                 conn = DriverManager.getConnection(url,username,password);
                 return conn;
             }catch(Exception e){

app/src/main/java/hunnu/sj/raise_money/DataBase/UserService.java

@@ -1,5 +1,6 @@
 package hunnu.sj.raise_money.DataBase;
 import java.sql.Connection;
+import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
@@ -14,9 +15,12 @@ public class UserService {
     }
     public int login(String username,String password){
         conn = db.getConnection();
+        Statement sttmt = null;
         try{
-            Statement sttmt = conn.createStatement();
+            sttmt = conn.createStatement();
-            ResultSet rs1 = sttmt.executeQuery("select * from user where username = '"+username+"'");
+            String sql = "select * from user where username = '"+username+"'";
+            PreparedStatement ps = conn.prepareStatement(sql);
+            ResultSet rs1 = ps.executeQuery();
             boolean flag1 = rs1.next();
             if(!flag1){
                 sttmt.close();

app/src/main/java/hunnu/sj/raise_money/SignInActivity.java

@@ -6,8 +6,10 @@ import androidx.appcompat.app.AppCompatActivity;
 import android.content.Intent;
 import android.os.Bundle;
 import android.os.Handler;
+import android.os.Looper;
 import android.os.Message;
 import android.view.View;
+import android.widget.Button;
 import android.widget.EditText;
 
 
@@ -18,6 +20,7 @@ public class SignInActivity extends AppCompatActivity {
     public static final int SEND = 0;
     EditText usnm;
     EditText pswd;
+    UserService uService;
     User user;
     Handler mHandler  = new Handler(){
         int flag = -1;
@@ -44,12 +47,14 @@ public class SignInActivity extends AppCompatActivity {
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_signin);
+        uService = new UserService();
     }
 
     public void user_commit(View view){
         usnm = findViewById(R.id.user_name);
         pswd = findViewById(R.id.pass_word);
         new LoginThread().start();
+
     }
 
     public void onToRegister(View view){
@@ -63,7 +68,7 @@ public class SignInActivity extends AppCompatActivity {
             int flag = -1;
             String name = usnm.getText().toString();
             String pasd = pswd.getText().toString();
-            UserService uService = new UserService();
+            //UserService uService = new UserService();
             flag = uService.login(name,pasd);
             Message message = mHandler.obtainMessage();
             if(flag==0){