Moved database interaction into ORM class

Signed-off-by: Jim Martens <github@2martens.de>
2017-04-14 16:45:25 +02:00
parent 2629377995
commit 00fd20c980
3 changed files with 161 additions and 153 deletions
--- a/02/src/de/dis2017/data/db/ORM.java
+++ b/02/src/de/dis2017/data/db/ORM.java
@ -0,0 +1,109 @@
+package de.dis2017.data.db;
+
+import de.dis2017.data.EstateAgent;
+
+import java.sql.*;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Maps the data objects to the database and vice versa.
+ */
+public class ORM {
+    private Connection _connection;
+    
+    private Map<Integer, EstateAgent> _agents;
+    
+    /**
+     * Initializes the ORM.
+     */
+    public ORM() {
+        DB2ConnectionManager _dbManager = DB2ConnectionManager.getInstance();
+        _connection = _dbManager.getConnection();
+        _agents = new HashMap<>();
+    }
+    
+    /**
+     * Loads the estate agent with the given ID from database and returns the corresponding object.
+     *
+     * @param ID the ID of the agent to load
+     * @return returns the EstateAgent or null if there is no such agent
+     */
+    public EstateAgent getEstateAgent(int ID) {
+        if (_agents.containsKey(ID)) {
+            return _agents.get(ID);
+        }
+        
+        try {
+            // create query
+            String            selectSQL = "SELECT * FROM ESTATEAGENT WHERE ID = ?";
+            PreparedStatement pstmt     = _connection.prepareStatement(selectSQL);
+            pstmt.setInt(1, ID);
+        
+            // execute query
+            ResultSet rs = pstmt.executeQuery();
+            EstateAgent agent;
+            if (rs.next()) {
+                agent = new EstateAgent();
+                agent.setId(ID);
+                agent.setName(rs.getString("name"));
+                agent.setAddress(rs.getString("address"));
+                agent.setLogin(rs.getString("login"));
+                agent.setPassword(rs.getString("password"));
+    
+                rs.close();
+                pstmt.close();
+                
+                _agents.put(ID, agent);
+                return agent;
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        
+        return null;
+    }
+    
+    /**
+     * Persists the given agent.
+     *
+     * @param agent the agent that should be persisted
+     */
+    public void persist(EstateAgent agent)
+    {
+        try {
+            if (agent.getId() == -1) {
+                String insertSQL = "INSERT INTO ESTATEAGENT (name, address, login, password) VALUES (?, ?, ?, ?)";
+                PreparedStatement pstmt = _connection.prepareStatement(insertSQL, Statement.RETURN_GENERATED_KEYS);
+                
+                pstmt.setString(1, agent.getName());
+                pstmt.setString(2, agent.getAddress());
+                pstmt.setString(3, agent.getLogin());
+                pstmt.setString(4, agent.getPassword());
+                pstmt.executeUpdate();
+    
+                ResultSet rs = pstmt.getGeneratedKeys();
+                if (rs.next()) {
+                    agent.setId(rs.getInt(1));
+                }
+                
+                rs.close();
+                pstmt.close();
+            } else {
+                // create query
+                String updateSQL = "UPDATE ESTATEAGENT SET name = ?, address = ?, password = ? WHERE ID = ?";
+                PreparedStatement pstmt = _connection.prepareStatement(updateSQL);
+                pstmt.setString(1, agent.getName());
+                pstmt.setString(2, agent.getAddress());
+                pstmt.setString(3, agent.getPassword());
+                pstmt.setInt(4, agent.getId());
+    
+                // execute query
+                pstmt.executeUpdate();
+                pstmt.close();
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+}