A 新增 根据实体中的属性进行查询指定属性

Author: ajie-dev

extra/src/main/java/tk/mybatis/mapper/additional/select/SelectSpecifyColumnsMapper.java

@@ -0,0 +1,46 @@
+package tk.mybatis.mapper.additional.select;
+
+import org.apache.ibatis.annotations.Param;
+import org.apache.ibatis.annotations.SelectProvider;
+import tk.mybatis.mapper.annotation.RegisterMapper;
+import tk.mybatis.mapper.weekend.Fn;
+
+import java.util.List;
+
+/**
+ * 查询指定字段
+ *
+ * @param <T> 不能为空
+ *
+ * @author xiaodiwangjie
+ * @date 2020/10/24
+ */
+@RegisterMapper
+public interface SelectSpecifyColumnsMapper<T> {
+
+    /**
+     * 根据条件查询实体, 并指定字段
+     *
+     * @param record  查询实体条件
+     * @param columns 指定的返回字段
+     * @return
+     */
+    @SelectProvider(
+            type = SelectSpecifyColumnsProvider.class,
+            method = "dynamicSQL"
+    )
+    List<T> selectByColumns(@Param("record") T record, @Param("columns") List<String> columns);
+
+    /**
+     * 根据条件查询实体, 并指定属性
+     *
+     * @param record 查询实体条件
+     * @param fns    指定的返回实体属性
+     * @return
+     */
+    @SelectProvider(
+            type = SelectSpecifyColumnsProvider.class,
+            method = "dynamicSQL"
+    )
+    List<T> selectByPropertys(@Param("record") T record, @Param("fns") List<Fn<T, ?>> fns);
+}

extra/src/main/java/tk/mybatis/mapper/additional/select/SelectSpecifyColumnsProvider.java

@@ -0,0 +1,146 @@
+package tk.mybatis.mapper.additional.select;
+
+import org.apache.ibatis.mapping.MappedStatement;
+import tk.mybatis.mapper.annotation.Version;
+import tk.mybatis.mapper.entity.EntityColumn;
+import tk.mybatis.mapper.entity.EntityTable;
+import tk.mybatis.mapper.mapperhelper.EntityHelper;
+import tk.mybatis.mapper.mapperhelper.MapperHelper;
+import tk.mybatis.mapper.mapperhelper.MapperTemplate;
+import tk.mybatis.mapper.mapperhelper.SqlHelper;
+
+import java.util.Iterator;
+import java.util.Set;
+
+/**
+ * @author xiaodiwangjie
+ * @date 2020/10/24
+ */
+public class SelectSpecifyColumnsProvider extends MapperTemplate {
+
+    public SelectSpecifyColumnsProvider(Class<?> mapperClass, MapperHelper mapperHelper) {
+        super(mapperClass, mapperHelper);
+    }
+
+    public String selectByColumns(MappedStatement ms) {
+
+        Class<?> entityClass = this.getEntityClass(ms);
+        this.setResultType(ms, entityClass);
+        StringBuilder sql = new StringBuilder();
+        sql.append("SELECT ");
+        sql.append("<foreach collection=\"columns\" item=\"item\" open=\"\" separator=\",\" close=\"\">");
+        sql.append("${item}");
+        sql.append("</foreach>");
+        sql.append(SqlHelper.fromTable(entityClass, this.tableName(entityClass)));
+        sql.append(whereAllIfColumns(entityClass, this.isNotEmpty(), false));
+        sql.append(SqlHelper.orderByDefault(entityClass));
+
+        return sql.toString();
+    }
+
+    public String selectByPropertys(MappedStatement ms) {
+
+        String propertyHelper = SelectSpecifyColumnsProvider.class.getName();
+        Class<?> entityClass = this.getEntityClass(ms);
+        this.setResultType(ms, entityClass);
+        StringBuilder sql = new StringBuilder();
+        sql.append("SELECT ");
+        String entityClassName = entityClass.getName();
+        sql.append("<foreach collection=\"fns\" item=\"item\" open=\"\" separator=\",\" close=\"\">");
+        String ognl = new StringBuilder("${@")
+                .append(propertyHelper)
+                .append("@getColumnByProperty(@java.lang.Class@forName(\"")
+                .append(entityClassName)
+                .append("\"), @tk.mybatis.mapper.weekend.reflection.Reflections@fnToFieldName(item))}").toString();
+        sql.append(ognl);
+        sql.append("</foreach>");
+        sql.append(SqlHelper.fromTable(entityClass, this.tableName(entityClass)));
+        sql.append(whereAllIfColumns(entityClass, this.isNotEmpty(), false));
+        sql.append(SqlHelper.orderByDefault(entityClass));
+
+        return sql.toString();
+    }
+
+    public static String whereAllIfColumns(Class<?> entityClass, boolean empty, boolean useVersion) {
+        StringBuilder sql = new StringBuilder();
+        sql.append("<where>");
+        Set<EntityColumn> columnSet = EntityHelper.getColumns(entityClass);
+        Iterator var5 = columnSet.iterator();
+
+        while (true) {
+            EntityColumn column;
+            do {
+                if (!var5.hasNext()) {
+                    if (useVersion) {
+                        sql.append(SqlHelper.whereVersion(entityClass));
+                    }
+
+                    sql.append("</where>");
+                    return sql.toString();
+                }
+
+                column = (EntityColumn) var5.next();
+            } while (useVersion && column.getEntityField().isAnnotationPresent(Version.class));
+
+            sql.append(getIfNotNull(column, " AND " + getColumnEqualsHolder(column), empty));
+        }
+    }
+
+    public static String getIfNotNull(EntityColumn column, String contents, boolean empty) {
+        StringBuilder sql = new StringBuilder();
+        sql.append("<if test=\"");
+
+        sql.append("record.").append(column.getProperty()).append(" != null");
+        if (empty && column.getJavaType().equals(String.class)) {
+            sql.append(" and ").append(column.getProperty()).append(" != '' ");
+        }
+
+        sql.append("\">");
+        sql.append(contents);
+        sql.append("</if>");
+        return sql.toString();
+    }
+
+    public static String getColumnEqualsHolder(EntityColumn column) {
+
+        return column.getColumn() + " = " + getColumnHolder(column);
+    }
+
+    public static String getColumnHolder(EntityColumn column) {
+
+        StringBuffer sb = new StringBuffer("#{");
+
+        sb.append("record.").append(column.getProperty());
+
+        if (column.getJdbcType() != null) {
+            sb.append(", jdbcType=");
+            sb.append(column.getJdbcType().toString());
+        }
+
+        if (column.getTypeHandler() != null) {
+            sb.append(", typeHandler=");
+            sb.append(column.getTypeHandler().getCanonicalName());
+        }
+
+        if (column.isUseJavaType() && !column.getJavaType().isArray()) {
+            sb.append(", javaType=");
+            sb.append(column.getJavaType().getCanonicalName());
+        }
+
+        sb.append("}");
+
+        return sb.toString();
+    }
+
+    /**
+     * 根据实体Class和属性名获取对应的表字段名
+     * @param entityClass 实体Class对象
+     * @param property 属性名
+     * @return
+     */
+    public static String getColumnByProperty(Class<?> entityClass, String property) {
+        EntityTable entityTable = EntityHelper.getEntityTable(entityClass);
+        EntityColumn entityColumn = entityTable.getPropertyMap().get(property);
+        return entityColumn.getColumn();
+    }
+}