用java和MySQL实现action层的黑名单增删改查功能

首先，你需要先创建一个名为“blacklist”的MySQL表，其中包含以下字段：

- id (INT, 主键)
- name (VARCHAR(50), 姓名)
- phone (VARCHAR(20), 手机号码)
- reason (VARCHAR(200), 拉黑原因)

接下来，你需要在Java中创建一个名为“Blacklist”的类，该类包含以下属性：

public class Blacklist {
    private int id;
    private String name;
    private String phone;
    private String reason;
    
    // getter和setter方法
}

接下来，你可以创建一个名为“BlacklistDao”的类来执行对数据库的相关操作。这个类应该实现以下方法：

- add(Blacklist blacklist)：添加一条黑名单记录到数据库中
- delete(int id)：从数据库中删除一条指定id的黑名单记录
- update(Blacklist blacklist)：更新数据库中的一条黑名单记录
- findById(int id)：通过id查找一条黑名单记录

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class BlacklistDao {
    Connection conn = null;
    PreparedStatement ps = null;
    ResultSet rs = null;

    // 添加一条黑名单记录到数据库中
    public void add(Blacklist blacklist) throws SQLException {
        conn = JdbcUtil.getConnection();
        String sql = "INSERT INTO blacklist(name, phone, reason) VALUES(?, ?, ?)";
        ps = conn.prepareStatement(sql);
        ps.setString(1, blacklist.getName());
        ps.setString(2, blacklist.getPhone());
        ps.setString(3, blacklist.getReason());
        ps.executeUpdate();
        JdbcUtil.close(conn, ps, rs);
    }

    // 从数据库中删除一条指定id的黑名单记录
    public void delete(int id) throws SQLException {
        conn = JdbcUtil.getConnection();
        String sql = "DELETE FROM blacklist WHERE id = ?";
        ps = conn.prepareStatement(sql);
        ps.setInt(1, id);
        ps.executeUpdate();
        JdbcUtil.close(conn, ps, rs);
    }

    // 更新数据库中的一条黑名单记录
    public void update(Blacklist blacklist) throws SQLException {
        conn = JdbcUtil.getConnection();
        String sql = "UPDATE blacklist SET name = ?, phone = ?, reason = ? WHERE id = ?";
        ps = conn.prepareStatement(sql);
        ps.setString(1, blacklist.getName());
        ps.setString(2, blacklist.getPhone());
        ps.setString(3, blacklist.getReason());
        ps.setInt(4, blacklist.getId());
        ps.executeUpdate();
        JdbcUtil.close(conn, ps, rs);
    }

    // 通过id查找一条黑名单记录
    public Blacklist findById(int id) throws SQLException {
        conn = JdbcUtil.getConnection();
        String sql = "SELECT * FROM blacklist WHERE id = ?";
        ps = conn.prepareStatement(sql);
        ps.setInt(1, id);
        rs = ps.executeQuery();
        Blacklist blacklist = null;
        while (rs.next()) {
            blacklist = new Blacklist();
            blacklist.setId(rs.getInt("id"));
            blacklist.setName(rs.getString("name"));
            blacklist.setPhone(rs.getString("phone"));
            blacklist.setReason(rs.getString("reason"));
        }
        JdbcUtil.close(conn, ps, rs);
        return blacklist;
    }

    // 查询所有黑名单记录
    public List<Blacklist> findAll() throws SQLException {
        conn = JdbcUtil.getConnection();
        String sql = "SELECT * FROM blacklist";
        ps = conn.prepareStatement(sql);
        rs = ps.executeQuery();
        List<Blacklist> list = new ArrayList<>();
        while (rs.next()) {
            Blacklist blacklist = new Blacklist();
            blacklist.setId(rs.getInt("id"));
            blacklist.setName(rs.getString("name"));
            blacklist.setPhone(rs.getString("phone"));
            blacklist.setReason(rs.getString("reason"));
            list.add(blacklist);
        }
        JdbcUtil.close(conn, ps, rs);
        return list;
    }
}

最后，你可以在你的Action层中调用上述方法执行相应的操作。例如：

public class BlacklistAction {

    // 添加一条黑名单记录
    public void add(Blacklist blacklist) throws SQLException {
        BlacklistDao dao = new BlacklistDao();
        dao.add(blacklist);
    }

    // 删除一条黑名单记录
    public void delete(int id) throws SQLException {
        BlacklistDao dao = new BlacklistDao();
        dao.delete(id);
    }

    // 更新一条黑名单记录
    public void update(Blacklist blacklist) throws SQLException {
        BlacklistDao dao = new BlacklistDao();
        dao.update(blacklist);
    }

    // 查找一条黑名单记录
    public Blacklist findById(int id) throws SQLException {
        BlacklistDao dao = new BlacklistDao();
        return dao.findById(id);
    }

    // 查询所有黑名单记录
    public List<Blacklist> findAll() throws SQLException {
        BlacklistDao dao = new BlacklistDao();
        return dao.findAll();
    }
}