按正常情况下，前端不应该直接进行远程数据库操作，这不是一个明智的方式，应该是后端提供对应接口来处理，奈何公司各方面原因需要前端这样做。
对此，我对远程数据库操作做了总结，便于自己复盘，同时，也分享给有需要的朋友们。
0、下载jdbc库
下载mysql官网：https://dev.mysql.com/downloads/connector/j/，按图片步骤下载所需jdbc的库
1、添加jdbc驱动依赖包
在Android studio的项目工程app-bulid.grade添加依赖：implementation files(‘libs/mysql-connector-java-5.1.48.jar’)或implementation 'mysql:mysql-connector-java:5.1.48’这两种方式
2、数据库连接操作
private String DB_URL = "jdbc:mysql://127.0.0.1:3306/远程数据库名";//换成远程地址
private String USER = "admin";//账号
private String PASS = "123456"; //密码
// Step 1: 加载 JDBC driver
Class.forName("com.mysql.jdbc.Driver");//mysql高版本这里：com.mysql.cj.jdbc.Driver
// Step 2: 打开连接
Connection connection = DriverManager.getConnection(DB_URL, USER, PASS);
3、执行数据库语句操作，进行相关业务处理
String sql = "select name, age, sex from User";// sql语句
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery(sql);
while (rs.next() && !isStopped) {
// todo 相应业务处理
}
4、数据库关闭
// 操作完毕，数据库关闭
rs.close();
statement.close();
connection.close();
5、完整代码
远程数据库操作工具类DatabaseAccessUtil，由于是耗时动作，需要在线程处理。
public class DatabaseAccessUtil {
private static final String TAG = "F100 DatabaseAccess";
private String DB_URL = "jdbc:mysql://127.0.0.1:3306/数据库名";
private String USER = "admin";
private String PASS = "123456";
private static DatabaseAccessUtil instance;
private ExecutorService executorService;
private volatile boolean isStopped = false;
private Future<?> currentTask = null; // 用于保存当前的任务
private ProgressDialogUtil progressDialogUtil;
private Handler mainHandler;
private DatabaseAccessUtil() {
this.executorService = Executors.newSingleThreadExecutor();
mainHandler = new Handler(Looper.getMainLooper());
}
public static synchronized DatabaseAccessUtil getInstance() {
if (instance == null) {
instance = new DatabaseAccessUtil();
}
return instance;
}
public void start(Context context) {
stop();
isStopped = false;
if (executorService == null || executorService.isShutdown()) {
executorService = Executors.newSingleThreadExecutor();
}
if (!isStopped && !executorService.isShutdown()) {
currentTask = executorService.submit(() -> downloadData(context));
}
}
public void stop() {
isStopped = true;
if (currentTask != null) {
currentTask.cancel(true); // 尝试取消当前任务
currentTask = null;
executorService.shutdownNow(); // 停止执行器服务
}
}
private void showProgressDialog(Context context) {
mainHandler.post(() -> {
if (progressDialogUtil == null) {
progressDialogUtil = new ProgressDialogUtil(context);
progressDialogUtil.setOnCancelListener(() -> {
stop();
});
}
progressDialogUtil.showProgressDialog();
});
}
// 查询表的总数量
private int getTotalCountFromDB(Connection connection) throws SQLException {
String sql = "select count(*) from User";
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery(sql);
rs.next();
int totalCount = rs.getInt(1);
rs.close();
statement.close();
return totalCount;
}
// 下载数据（相应业务处理）
private void downloadData(Context context) {
if (isStopped) return;
try {
String sql = "select name, age, sex from User";
// Step 1: Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");//mysql高版本这里：com.mysql.cj.jdbc.Driver
// Step 2: Open a connection
Connection connection = DriverManager.getConnection(DB_URL, USER, PASS);
// Step 3: Execute a query
int totalCount = getTotalCountFromDB(connection);
if (totalCount == 0) {
connection.close();
EventBus.getDefault().post(new CommonEvent(EventCode.FLAG_NO_DATA));
return;
}
// 显示进度条
// todo showProgressDialog(context);
// 执行sql 业务逻辑
Statement statement = connection.createStatement();
ResultSet rs = statement.executeQuery(sql);
int count = 0;
while (rs.next() && !isStopped) {
// 进度条更新
count++;
int progress = (count * 100) / totalCount;
updateProgress(progress);
// Retrieve by column name
String name = rs.getString("name");
int age = rs.getInt("age");
String sex = rs.getString("sex");
// todo 业务逻辑处理
}
// 关闭
rs.close();
statement.close();
connection.close();
// 主线程回调， 这里我使用订阅
EventBus.getDefault().post(new CommonEvent(EventCode.FLAG_SUCCESS));
} catch (Exception e) {
// 主线程回调
EventBus.getDefault().post(new CommonEvent(EventCode.FLAG_FAIL));
} finally {
// 进度条关闭
mainHandler.post(() -> {
if (progressDialogUtil != null) progressDialogUtil.dismissProgressDialog();
});
}
}
// 进度条更新
private void updateProgress(int progress) {
mainHandler.post(() -> {
if (progressDialogUtil != null) {
progressDialogUtil.updateProgress(progress);
}
});
}
}
进度条ProgressDialogUtil，布局：一个进度条+进度条进度+取消按钮，【取消】按钮是1分钟后可点击。代码如下：
public class ProgressDialogUtil {
private final long DELAY_TIME = 1 * 60 * 1000;//2分钟 2 * 60 * 1000
private Dialog progressDialog;
private ProgressBar progressBar;
private TextView tvProgress;
private Button btnCancel;
private Handler handler;
private boolean cancelEnabled = false;
public ProgressDialogUtil(Context context) {
progressDialog = new Dialog(context, R.style.CustomProgressDialog);
progressDialog.setContentView(R.layout.dialog_progress);
progressDialog.setCancelable(false);
progressBar = progressDialog.findViewById(R.id.progressBar);
tvProgress = progressDialog.findViewById(R.id.tvProgress);
btnCancel = progressDialog.findViewById(R.id.btnCancel);
btnCancel.setEnabled(false);
handler = new Handler();
}
public void showProgressDialog() {
Window window = progressDialog.getWindow();
if (window != null) {
WindowManager.LayoutParams params = window.getAttributes();
params.width = 650;
window.setAttributes(params);
}
progressDialog.show();
// 2分钟后显示
handler.postDelayed(new Runnable() {
@Override
public void run() {
if (progressDialog.isShowing()) {
cancelEnabled = true;
btnCancel.setEnabled(true);
}
}
}, DELAY_TIME);
}
public void dismissProgressDialog() {
if (progressDialog != null && progressDialog.isShowing()) progressDialog.dismiss();
}
public void updateProgress(int progress) {
// while (progress <= 97) {
progressBar.setProgress(progress);
tvProgress.setText(progress + "%");
// }
}
public void setOnCancelListener(Runnable cancelAction) {
btnCancel.setOnClickListener(v->{
if (cancelEnabled) {
cancelAction.run();
dismissProgressDialog();
}
});
}
}
这篇文章提供全部代码和操作思路，拿来就可以使用。
如果觉得还不错，给个一键三连呗~~~
