java - 使用 JDBC 将 android 与数据库连接

Question

我试图连接和应用免费服务器，尝试使用网络服务但根本无法做到，所以现在我尝试使用 jdbc 来做到这一点:

代码:

@Override
protected void onCreate(Bundle savedInstanceState) {



    super.onCreate(savedInstanceState);
    setContentView(R.layout.login);
    getActionBar().hide();

    new Con().execute();}

    private class Con extends AsyncTask<Void, Void, Void> {

    // JDBC driver name and database URL
    static final String JDBC_DRIVER = "com.mysql.jdbc.Driver";
    static final String DB_URL = "jdbc:mysql://31.170.165.253/u802222393_gp";

    // Database credentials
    static final String USER = "u802222393_books";
    static final String PASS = "aboasendar";

    @Override
    protected Void doInBackground(Void... params) {
        Connection conn = null;
        Statement stmt = null;

        try {
            // STEP 2: Register JDBC driver
            Class.forName(JDBC_DRIVER).newInstance();




            // STEP 3: Open a connection
            System.out.println("Connecting to database...");
            conn = DriverManager.getConnection(DB_URL, USER, PASS);

            // STEP 4: Execute a query
            System.out.println("Creating statement...");
            stmt = conn.createStatement();
            String sql= "SELECT id, first, last, age FROM test";
            ResultSet rs = stmt.executeQuery(sql);

            // STEP 5: Extract data from result set
            while (rs.next()) {
                // Retrieve by column name
                int id = rs.getInt("id");
                int age = rs.getInt("age");
                String first = rs.getString("first");
                String last = rs.getString("last");

                // Display values
                System.out.print("ID: " + id);
                System.out.print(", Age: " + age);
                System.out.print(", First: " + first);
                System.out.println(", Last: " + last);
            }
            // STEP 6: Clean-up environment
            rs.close();
            stmt.close();
            conn.close();
        } catch (SQLException se) {
            // Handle errors for JDBC
            se.printStackTrace();
        } catch (Exception e) {
            // Handle errors for Class.forName
            e.printStackTrace();
        } finally {
            // finally block used to close resources
            try {
                if (stmt != null)
                    stmt.close();
            } catch (SQLException se2) {
            }// nothing we can do
            catch (java.sql.SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            try {
                if (conn != null)
                    conn.close();
            } catch (SQLException se) {
                se.printStackTrace();
            }// end finally try
            catch (java.sql.SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }// end try
        System.out.println("Goodbye!");

        return null;
    }

它总是在我搜索了很多但没有找到关于我应该如何编写 URL 的答案的 URL 上给出一个异常(exception)

日志:

Answer 1

您可以使用本地主机(将您的计算机用作服务器)并随心所欲地工作要在 Android 中使用 JDBC，您会在这里找到很好的指南， http://www.vogella.com/tutorials/MySQLJava/article.html

如果你想从 jdbc 开始，你可以从这个教程开始 http://www.tutorialspoint.com/jdbc/jdbc-introduction.htm

如有任何问题，欢迎留言谢谢