渐进式处理Mapper

Author: chentianming11

base/src/main/java/tk/mybatis/mapper/common/progressive/ProgressiveMapper.java

@@ -0,0 +1,159 @@
+package tk.mybatis.mapper.common.progressive;
+
+import org.apache.ibatis.session.RowBounds;
+import tk.mybatis.mapper.annotation.RegisterMapper;
+import tk.mybatis.mapper.common.ExampleMapper;
+import tk.mybatis.mapper.common.rowbounds.SelectByExampleRowBoundsMapper;
+import tk.mybatis.mapper.entity.Example;
+import tk.mybatis.mapper.util.Assert;
+import tk.mybatis.mapper.util.Sqls;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.ParameterizedType;
+import java.lang.reflect.Type;
+import java.util.List;
+import java.util.function.Consumer;
+
+/**
+ * 渐进式处理Mapper，数据库必须包含id字段
+ * @author 陈添明
+ */
+@RegisterMapper
+public interface ProgressiveMapper<T> extends ExampleMapper<T>, SelectByExampleRowBoundsMapper<T> {
+
+    /**
+     * 渐进式记录处理
+     * 数据表必须包含id字段
+     * @param consumer 业务处理逻辑
+     * @throws NoSuchFieldException 没有id字段会抛出此异常
+     * @throws IllegalAccessException 无法访问id字段会抛出此异常
+     */
+    default void handleRecordProgressive(Consumer<T> consumer) throws NoSuchFieldException, IllegalAccessException {
+        Class<?> clz = getParameterType();
+        long i = 0;
+        while (true) {
+            Example example = Example.builder(clz)
+                    .andWhere(Sqls.custom().andGreaterThan("id", i))
+                    .build();
+            List<T> list = selectByExampleAndRowBounds(example, new RowBounds(0, 100));
+            if (list.isEmpty()) {
+                return;
+            }
+            for (T t : list) {
+                consumer.accept(t);
+            }
+            T t = list.get(list.size() - 1);
+
+            Field idField = t.getClass().getDeclaredField("id");
+            idField.setAccessible(true);
+            i = (Long) idField.get(t);
+        }
+
+    }
+
+    /**
+     * 渐进式全量删除
+     * 数据表必须包含id字段
+     * 不会因为数据量大导致慢sql
+     * @throws NoSuchFieldException 没有id字段会抛出此异常
+     * @throws IllegalAccessException 无法访问id字段会抛出此异常
+     */
+    default void deleteAllProgressive() throws NoSuchFieldException, IllegalAccessException {
+        Class<?> parameterType = getParameterType();
+        Long minimumId = getMinimumId();
+        if (minimumId == null) {
+            return;
+        }
+
+        Long maxId = getMaxId();
+        if (maxId == null) {
+            return;
+        }
+
+        for (Long i = minimumId; i <= maxId; ) {
+            i = i + 10000;
+            Example example = Example.builder(parameterType)
+                    .andWhere(Sqls.custom().andBetween("id", minimumId, i))
+                    .build();
+            deleteByExample(example);
+        }
+    }
+
+    /**
+     * 获取泛型参数Class
+     *
+     * @return 泛型参数Class
+     */
+    default Class<?> getParameterType() {
+        Type[] genericInterfaces = this.getClass().getGenericInterfaces();
+        Class<?> rawClass = (Class<?>) genericInterfaces[0];
+        Type[] rawClassGenericInterfaces = rawClass.getGenericInterfaces();
+        Assert.isTrue(rawClassGenericInterfaces.length > 0, "Mapper类必须继承泛型Mapper");
+        ParameterizedType mapperType = getParameterizedType(rawClassGenericInterfaces);
+        Assert.notNull(mapperType, "未找到参数化Mapper类型！");
+        return (Class<?>) mapperType.getActualTypeArguments()[0];
+    }
+
+    /**
+     * 获取ParameterizedType
+     * @param rawClassGenericInterfaces 参数化接口
+     * @return ParameterizedType
+     */
+    default ParameterizedType getParameterizedType(Type[] rawClassGenericInterfaces) {
+        for (Type genericInterface : rawClassGenericInterfaces) {
+            if (genericInterface instanceof ParameterizedType) {
+                return  (ParameterizedType) genericInterface;
+            }
+        }
+        return null;
+    }
+
+
+    /**
+     * 获取最小id
+     * @return 最小id
+     * @throws NoSuchFieldException 没有id字段会抛出此异常
+     * @throws IllegalAccessException 无法访问id字段会抛出此异常
+     */
+    default Long getMinimumId() throws NoSuchFieldException, IllegalAccessException {
+        Class<?> parameterType = getParameterType();
+        Example example = Example.builder(parameterType)
+                .select("id")
+                .orderBy("id")
+                .build();
+
+        List<T> list = selectByExampleAndRowBounds(example, new RowBounds(0, 1));
+        if (list.isEmpty()) {
+            return null;
+        }
+        T t = list.get(0);
+        Field idField = t.getClass().getDeclaredField("id");
+        idField.setAccessible(true);
+        return (Long) idField.get(t);
+    }
+
+    /**
+     * 获取最大id
+     * @return 最大id
+     * @throws NoSuchFieldException 没有id字段会抛出此异常
+     * @throws IllegalAccessException 无法访问id字段会抛出此异常
+     */
+    default Long getMaxId() throws NoSuchFieldException, IllegalAccessException {
+        Class<?> parameterType = getParameterType();
+        Example example = Example.builder(parameterType)
+                .select("id")
+                .orderByDesc("id")
+                .build();
+
+        List<T> list = selectByExampleAndRowBounds(example, new RowBounds(0, 1));
+        if (list.isEmpty()) {
+            return null;
+        }
+        T t = list.get(0);
+        Field idField = t.getClass().getDeclaredField("id");
+        idField.setAccessible(true);
+        return (Long) idField.get(t);
+    }
+
+
+}