使用为mysql-connector-java-8.0.16.jar以及mysql8.0.19
在本地测试通过
public class DBUtils {
private static String driver = "com.mysql.cj.jdbc.Driver";//MySQL 驱动
private static String url = "jdbc:mysql://192.168.2.146:3306/helper?useSSL=false&serverTimezone=UTC&allowPublicKeyRetrieval=true";//MYSQL数据库连接Url
private static String user = "wang";//用户名
private static String password = "Imissyou**";//密码
private static Connection getConnection() {
Connection conn = null;
try {
Class.forName(driver); //
conn = DriverManager.getConnection(url,user,password);
} catch (SQLException ex) {
ex.printStackTrace();
} catch (ClassNotFoundException ex) {
ex.printStackTrace();
}
return conn;
}
public static Map<String, String> login(User user) {
HashMap<String, String> map = new HashMap<>();
Connection conn = getConnection();
try {
Statement st = conn.createStatement();
String sql= "select * from user where username ='" + user.getUsername()
+ "' and password ='" + user.getPassword() + "'";
ResultSet res = st.executeQuery(sql);
if (res == null) {
return null;
} else {
int cnt = res.getMetaData().getColumnCount();
res.next();
for (int i = 1; i <= cnt; ++i) {
String field = res.getMetaData().getColumnName(i);
map.put(field, res.getString(field));
}
conn.close();
st.close();
res.close();
return map;
}
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
public static void main(String []args){
User user = new User("aaa","123456");
Map<String,String> result= DBUtils.login(user);
System.out.println(result);
}
}
但是在主界面绑定事件,访问数据库时直接闪退并报错
主界面代码如下:
package com.example.helper;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.StrictMode;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import java.util.Map;
public class MainActivity extends AppCompatActivity {
private Button register;
private Button login_user;
private TextView forget_password;
private TextView login_visitor;
private EditText et_username;
private EditText et_password;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化控件
init();
//注册界面跳转
register.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
Intent intent = new Intent(MainActivity.this, RegisterActivity.class);
startActivity(intent);
}
});
//登录功能未加载,等待后台数据库完善
login_user.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String username = et_username.getText().toString(); //获取用户名
String password = et_password.getText().toString(); //获取密码
if(TextUtils.isEmpty(username)){
Toast.makeText(MainActivity.this,"请输入用户名",Toast.LENGTH_SHORT).show();
}
else if(TextUtils.isEmpty(password)){
Toast.makeText(MainActivity.this,"请输入密码",Toast.LENGTH_SHORT).show();
}
//本地管理员帐号
else if(username.equals("admin")&&password.equals("admin")){
Intent intent = new Intent(MainActivity.this,HomePageActivity.class);
startActivity(intent);
}
//else Toast.makeText(MainActivity.this,"未连接后台数据库",Toast.LENGTH_SHORT).show();
else{
User user = new User(username,password);
checkLogin(user);
//Toast.makeText(MainActivity.this,"已获取"+username+" "+password,Toast.LENGTH_SHORT).show();
}
}
});
//首页跳转
login_visitor.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v){
Intent intent = new Intent(MainActivity.this, HomePageActivity.class);
startActivity(intent);
}
});
//找回密码界面跳转
forget_password.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this,ForgetPasswordActivity.class);
startActivity(intent);
}
});
}
private void init() {
et_username = findViewById(R.id.et_username);
et_password = findViewById(R.id.et_password);
register = findViewById(R.id.btn_2);
login_user = findViewById(R.id.btn_1);
login_visitor = findViewById(R.id.login_visitor);
forget_password = findViewById(R.id.forget_password);
}
class DBThread implements Runnable {
private User user;
private Context context;
public void setUser(User user) {
this.user = user;
}
public void setContext(Context context) {
this.context = context;
}
@Override
public void run() {
Map<String,String> result= DBUtils.login(user);
/*
if (result != null && result.size() > 0) {
Intent intent = new Intent(MainActivity.this,HomePageActivity.class);
Toast.makeText(MainActivity.this,"有此帐号",Toast.LENGTH_SHORT).show();
startActivity(intent);
}
*/
}
}
private void checkLogin(User u) {
DBThread dt = new DBThread();
dt.setUser(u);
dt.setContext(MainActivity.this);
Thread thread = new Thread(dt);
thread.start();
}
}