今天上午睡到9点,下午用安卓连接MYSQL,最后连接成功,我来帮你踩了坑,老子帮你弄弄。首先就是你要导入5.1.49jar包驱动,别的不行,别问我,我才过坑,试了试,
再有就是改权限,mysql要支撑远程访问,
(一)改表法
在localhost登入mysql后,更改 “mysql” 数据库里的 “user” 表里的 “host” 项,将"localhost"改称"%"
update user set host = '%' where user = 'root'; select host, user from user;
FLUSH PRIVILEGES;
(二)授权法
myuser是你的那个用户,mypassword是你密码。
mysql> GRANT ALL PRIVILEGES ON *.* TO 'myuser'@'%' IDENTIFIED BY 'mypassword' WITH GRANT OPTION; mysql>FLUSH PRIVILEGES;
,代码:
DBOpenHelper类:
package com.example.lsm; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class DBOpenHelper { private final static String driver = "com.mysql.jdbc.Driver"; private final static String url = "jdbc:mysql://10.99.117.52/xinwe?useUnicode=true&characterEncoding=UTF-8"; private final static String username = "root"; private final static String password = "hzl02096"; Connection conn=null; Statement st=null; ResultSet rs=null; static { try { Class.forName(driver); } catch (ClassNotFoundException e) { System.out.println("加载驱动错误"); } } //2. 获取连接 public static Connection getConnect() throws Exception { return DriverManager.getConnection(url, username, password); } //3. 释放连接资源 public static void release(Connection conn, Statement st, ResultSet rs) throws Exception { if (rs != null) { rs.close(); } if (st != null) { st.close(); } if (conn != null) { conn.close(); } } /*private static String diver = "com.mysql.jdbc.Driver"; //加入utf-8是为了后面往表中输入中文,表中不会出现乱码的情况 private static String url = "jdbc:mysql://10.99.117.52/xinwe?characterEncoding=utf-8"; private static String user = "root";//用户名 private static String password = "hzl02096";//密码 *//* * 连接数据库 * *//* public static Connection getConn(){ Connection conn = null; try { Class.forName(diver); conn = (Connection) DriverManager.getConnection(url,user,password);//获取连接 } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); } return conn; }*/ }
UserDao类:
package com.example.lsm; import java.sql.Connection; import java.sql.ResultSet; import java.sql.Statement; import java.util.ArrayList; import java.util.List; public class UserDao { //查询用户的方法 public boolean select(String table) throws Exception { Connection conn = null; Statement state = null; ResultSet rs = null; try { conn = DBOpenHelper.getConnect(); state = conn.createStatement(); String sql = "select * from " + table; rs = state.executeQuery(sql); while (rs.next()) { System.out.println(rs.getString(1) + " " + rs.getString(2));//就是输出第一列和第二列的值 } } catch (Exception e) { e.printStackTrace(); } finally { DBOpenHelper.release(conn, state, rs); } return true; } }
MainActivity类:
package com.example.lsm; import androidx.appcompat.app.AppCompatActivity; import android.os.Bundle; import android.view.View; import android.widget.TextView; import java.util.List; public class MainActivity extends AppCompatActivity implements View.OnClickListener { private TextView textView; private String a=""; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); findViewById(R.id.bt_send).setOnClickListener(this); textView=findViewById(R.id.tv_response); } @Override public void onClick(View view) { // Android 4.0 之后不能在主线程中请求HTTP请求 new Thread(new Runnable(){ @Override public void run() { UserDao userDao = new UserDao(); try { userDao.select("user"); } catch (Exception e) { e.printStackTrace(); } } }).start(); } }
xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android"> <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> <uses-permission android:name="android.permission.INTERNET"/> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:supportsRtl="true" android:theme="@style/Theme.Lianxi"> <activity android:name=".MainActivity" android:exported="true"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
地铁系统录入困难,写个代码录入,
这是整个石家庄路线
通过下面这个servlet逻辑代码实现
public void select(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { List<zhandian> select = ditieServices.select(); for(zhandian u:select) { String[] s = u.getZhandian1().split(" "); int b=s.length; for(int i=0;i<b;i++) { ditiepojo ditiepojo=new ditiepojo(null,null,null,null); ditiepojo.setXianlu(u.getXianlu()); ditiepojo.setZhandian(s[i]); ditieServices.add(ditiepojo); } } }
最后成功:
最后cp照:
标签:java,String,18,软工,public,static,import,安卓,conn From: https://www.cnblogs.com/daitu66/p/17232009.html