完成了主窗口和增删改查

src/backend/dao/impl/QuestionsDao.java

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+package backend.dao.impl;
+import backend.model.Questions;
+import backend.utils.DBConnectionPool;
+import java.sql.*;
+import java.util.ArrayList;
+import java.util.List;
+
+public class QuestionsDao {
+    List<Questions> commonResultSet(ResultSet rs) throws SQLException{
+        List<Questions> questionPoList = new ArrayList<>();
+        while(rs.next()){
+            Questions questions = new Questions();
+            questions.setId(rs.getInt("id"));
+            questions.setName(rs.getString("name"));
+            questions.setDescription(rs.getString("description"));
+            questions.setAnswer(rs.getString("answer"));
+            questions.setFrequency(rs.getInt("frequency"));
+            questionPoList.add(questions);
+        }
+        return questionPoList;
+    }
+    public List<Questions> getAll() {
+        List<Questions> questionPoList = new ArrayList<>();
+        //1. 从连接池中拿到连接
+        Connection conn = DBConnectionPool.getConnection();
+        if(conn==null)
+            return null;
+        //2. 创建Statement对象
+        String sql = "select id,name,description,answer,frequency from questions";
+        try{
+            PreparedStatement stmt = conn.prepareStatement(sql);
+            ResultSet rs = stmt.executeQuery();
+            questionPoList=commonResultSet(rs);
+            rs.close();
+            stmt.close();
+
+        }catch(SQLException e){
+            System.out.println("数据库异常："+ e.getMessage());
+        }finally {
+            DBConnectionPool.releaseConnection(conn);
+        }
+        return questionPoList;
+    }
+    public List<Questions> getByCondition(Integer frequency,String key) {
+        List<Questions> wordPoList = null;
+        //1. 从连接池中拿到连接
+        Connection conn = DBConnectionPool.getConnection();
+        if(conn==null)
+            return null;
+        //2. 创建Statement对象
+        String sql = "select id,name,description,answer,frequency from questions where name like ?";
+        if(frequency != null)
+            sql += " and frequency = ?";
+        try{
+            PreparedStatement stmt = conn.prepareStatement(sql);
+            stmt.setString(1, "%"+key+"%");
+            if(frequency != null)
+                stmt.setInt(2, frequency);
+            ResultSet rs = stmt.executeQuery();
+            wordPoList=commonResultSet(rs);
+            rs.close();
+            stmt.close();
+
+        }catch(SQLException e){
+            System.out.println("数据库异常："+ e.getMessage());
+        }finally {
+            DBConnectionPool.releaseConnection(conn);
+        }
+        return wordPoList;
+    }
+
+    public boolean insert(Questions question){
+        int row = 0;
+        //1. 从连接池中拿到连接
+        Connection conn = DBConnectionPool.getConnection();
+        if(conn==null)
+            return false;
+        //2. 创建Statement对象
+        String sql = "insert into questions(name,description,answer,frequency) values(?,?,?,?)";
+        try{
+            PreparedStatement stmt = conn.prepareStatement(sql);
+            stmt.setString(1, question.getName());
+            stmt.setString(2, question.getDescription());
+            stmt.setString(3, question.getAnswer());
+            stmt.setInt(4, question.getFrequency());
+            row = stmt.executeUpdate();
+            stmt.close();
+
+        }catch(SQLException e){
+            System.out.println("数据库异常："+ e.getMessage());
+        }finally {
+            DBConnectionPool.releaseConnection(conn);
+        }
+        return row > 1;
+    }
+    public boolean delete(Integer id){
+        int row = 0;
+        //1. 从连接池中拿到连接
+        Connection conn = DBConnectionPool.getConnection();
+        if(conn==null)
+            return false;
+        //2. 创建Statement对象
+        String sql = "delete from questions where id = ?";
+        try{
+            PreparedStatement stmt = conn.prepareStatement(sql);
+            stmt.setInt(1, id);
+            row = stmt.executeUpdate();
+            stmt.close();
+
+        }catch(SQLException e){
+            System.out.println("数据库异常："+ e.getMessage());
+        }finally {
+            DBConnectionPool.releaseConnection(conn);
+        }
+        return row > 1;
+    }
+    public boolean updata(Questions question){
+        int row = 0;
+        //1. 从连接池中拿到连接
+        Connection conn = DBConnectionPool.getConnection();
+        if(conn==null)
+            return false;
+        //2. 创建Statement对象
+        String sql = "updata questions set name = ?,description = ?,answer = ?,frequency=? where id = ?";
+        try{
+            PreparedStatement stmt = conn.prepareStatement(sql);
+            stmt.setString(1, question.getName());
+            stmt.setString(2, question.getDescription());
+            stmt.setString(3, question.getAnswer());
+            stmt.setInt(4, question.getFrequency());
+            stmt.setInt(5, question.getId());
+            row = stmt.executeUpdate();
+            stmt.close();
+
+        }catch(SQLException e){
+            System.out.println("数据库异常："+ e.getMessage());
+        }finally {
+            DBConnectionPool.releaseConnection(conn);
+        }
+        return row > 1;
+
+    }
+
+//    public static void main(String[] args) {
+//        WordDao wordDao = new WordDao();
+//        //查询
+//        List<WordPo> wordPoList = wordDao.getByCondition(3,"v");
+//        if(wordPoList != null)
+//            for(WordPo wordPo:wordPoList)
+//                System.out.println(wordPo.getWord());
+//        //增加
+//        wordDao.insert(new WordPo("test", "test", "test", 1));
+//        //更新
+//        wordDao.updata(new WordPo(1, 1, "test", "test", "test"));
+//    }
+}