首先先开启MySQL的远程访问权限，详情请见上一个的博客。
说一说我遇到的坑吧，就是网上找了好多代码尝试着数据库，最后才连接成功，以下是我连接成功的代码
MainActivity.java
package com.example.mysqlconnectiontest;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
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("test_one");
} catch (Exception e) {
e.printStackTrace();
}
}
}).start();
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity">
<Button
android:id="@+id/bt_send"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="onClick"
android:text="查询数据表"/>
<TextView
android:id="@+id/tv_response"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textStyle="bold" />
</LinearLayout>
DBOpenHelper.java
package com.example.mysqlconnectiontest;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
public class DBOpenHelper {
private final static String driver = "com.mysql.jdbc.Driver";
private final static String url = "jdbc:mysql://172.22.64.1/test?useUnicode=true&characterEncoding=UTF-8";
private final static String username = "root";
private final static String password = "123456";
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.java
package com.example.mysqlconnectiontest;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
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;
}
}
记住下面两行代码是放在manifest之间的，可不能放在application之前，一定要避坑！！！
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />