新增 DefaultBeanResultMap

2024-10-03 16:27:19 +08:00
parent fda69cea6b
commit 7f31d477d6
4 changed files with 165 additions and 7 deletions
--- a/src/main/java/xyz/zhouxy/jdbc/DefaultBeanResultMap.java
+++ b/src/main/java/xyz/zhouxy/jdbc/DefaultBeanResultMap.java
@@ -0,0 +1,88 @@
+package xyz.zhouxy.jdbc;
+
+import java.beans.BeanInfo;
+import java.beans.IntrospectionException;
+import java.beans.Introspector;
+import java.beans.PropertyDescriptor;
+import java.lang.reflect.Constructor;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.sql.ResultSet;
+import java.sql.ResultSetMetaData;
+import java.sql.SQLException;
+import java.util.Arrays;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import javax.annotation.Nullable;
+
+public class DefaultBeanResultMap<T> implements ResultMap<T> {
+
+    private final Constructor<T> constructor;
+    private final Map<String, PropertyDescriptor> colPropertyMap;
+
+    private DefaultBeanResultMap(Constructor<T> constructor, Map<String, PropertyDescriptor> colPropertyMap) {
+        this.constructor = constructor;
+        this.colPropertyMap = colPropertyMap;
+    }
+
+    public static <T> DefaultBeanResultMap<T> of(Class<T> beanType) throws SQLException {
+        return of(beanType, null);
+    }
+
+    public static <T> DefaultBeanResultMap<T> of(Class<T> beanType, @Nullable Map<String, String> propertyColMap)
+            throws SQLException {
+        try {
+            BeanInfo beanInfo = Introspector.getBeanInfo(beanType);
+            PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
+            Map<String, PropertyDescriptor> colPropertyMap;
+            if (propertyColMap != null && !propertyColMap.isEmpty()) {
+                colPropertyMap = Arrays.stream(propertyDescriptors)
+                        .collect(Collectors.toMap(p -> {
+                            String propertyName = p.getName();
+                            String colName = propertyColMap.get(propertyName);
+                            return colName != null ? colName : propertyName;
+                        }, Function.identity(), (a, b) -> b));
+            }
+            else {
+                colPropertyMap = Arrays.stream(propertyDescriptors)
+                        .collect(Collectors.toMap(PropertyDescriptor::getName, Function.identity(), (a, b) -> b));
+            }
+
+            Constructor<T> constructor = beanType.getDeclaredConstructor();
+            constructor.setAccessible(true); // NOSONAR
+            return new DefaultBeanResultMap<>(constructor, colPropertyMap);
+        }
+        catch (IntrospectionException e) {
+            throw new SQLException("There is an exception occurs during introspection.", e);
+        }
+        catch (NoSuchMethodException e) {
+            throw new SQLException("Could not find a no-args constructor in " + beanType.getName(), e);
+        }
+    }
+
+    @Override
+    public T map(ResultSet rs, int rowNumber) throws SQLException {
+        try {
+            T newInstance = this.constructor.newInstance();
+            ResultSetMetaData metaData = rs.getMetaData();
+            for (int i = 1; i <= metaData.getColumnCount(); i++) {
+                String colName = metaData.getColumnName(i);
+                PropertyDescriptor propertyDescriptor = this.colPropertyMap.get(colName);
+                if (propertyDescriptor != null) {
+                    Method setter = propertyDescriptor.getWriteMethod();
+                    if (setter != null) {
+                        Class<?> propertyType = propertyDescriptor.getPropertyType();
+                        setter.setAccessible(true); // NOSONAR
+                        setter.invoke(newInstance, rs.getObject(colName, propertyType));
+                    }
+                }
+            }
+            return newInstance;
+        }
+        catch (IllegalAccessException | InstantiationException | InvocationTargetException e) {
+            throw new SQLException(e);
+        }
+    }
+}