前言

上一篇中，我们的Cypher都用的是字符串，字符串拼接简单，但存在写错的风险，对于一些比较懒的开发者，甚至觉得之间写字符串还更自在快速，也确实，但如果在后期需要修改，如更高字段名或者一些级联的变动，会导致维护难，所以，这里这里我们模仿Mybatis-Plus写一个实体字段工具之间替换哪些字符串，以提高项目可维护性。

实体工具

我们以这篇的工具为基础进行下面的开发：Lambda表达式提取字段名-CSDN博客

然后我们再增加对于与Neo4j的实体工具：

1. 实体缓存对象信息，保存实体必要信息

   public class EntityCache {private String className;private List<String> labels;private Map<String, String> fieldNameMap;public String getClassName() {return className;}public void setClassName(String className) {this.className = className;}public List<String> getLabels() {return labels;}public void setLabels(List<String> labels) {this.labels = labels;}public Map<String, String> getFieldNameMap() {return fieldNameMap;}public void setFieldNameMap(Map<String, String> fieldNameMap) {this.fieldNameMap = fieldNameMap;}
   }

2. 解析工具，也就是反射解析

   public class EntityUtil {/*** 实体缓存*/private static final Map<String, EntityCache> ENTITY_MAP = new ConcurrentHashMap<>();public static void main(String[] args) {Job job = new Job();String column = column(Job::getName);System.out.println(column);System.out.println(label(Job.class));}/*** 从lambda转换出字段名*/public static <T, R> String column(CusFunction<T, R> column) {SerializedLambda resolve = LambdaUtils.resolve(column);return getColumn(LambdaUtils.getClass(resolve), LambdaUtils.getMethodName(resolve) , true);}/*** 从实体class解析出标签*/public static <T> String label(Class<T> clazz) {EntityCache info = ENTITY_MAP.putIfAbsent(clazz.getTypeName(), resolve(clazz));return info.getLabels().get(0);}/*** 根据类型和方法名解析字段名* @param aClass 类型* @param methodName 方法名* @param dbField 是否数据库字段* @return 字段名*/private static String getColumn(Class<?> aClass, String methodName, boolean dbField) {String fieldName = PropertyNamer.methodToProperty(methodName);if (!dbField) {return fieldName;}EntityCache info = resolve(aClass);if (!StringUtils.hasLength(fieldName)) {throw new RuntimeException(String.format("找不到实体对应的字段-[%s.%s]", aClass.getTypeName(), methodName));}Map<String, String> map = info.getFieldNameMap();return map.get(fieldName);}/*** 解析实体* @param clazz 类型* @return 实体缓存对象*/public static <T> EntityCache resolve(Class<T> clazz) {String typeName = clazz.getTypeName();EntityCache info = ENTITY_MAP.get(typeName);if (info != null) {return info;}Field[] declaredFields = clazz.getDeclaredFields();Map<String, String> fieldNameMap = new HashMap<>();for (Field declaredField : declaredFields) {declaredField.setAccessible(true);String fieldName = declaredField.getName();String dbFieldName = fieldName;Property property = declaredField.getAnnotation(Property.class);if (property != null) {if (StringUtils.hasLength(property.name())) {dbFieldName = property.name();}if (StringUtils.hasLength(property.value())) {dbFieldName = property.value();}}fieldNameMap.put(fieldName, dbFieldName);}List<String> labelList = resolveLabel(clazz);info = new EntityCache();info.setLabels(labelList);info.setClassName(typeName);info.setFieldNameMap(fieldNameMap);ENTITY_MAP.put(typeName, info);return info;}/*** 解析标签* @param clazz 类型* @return 标签列表*/private static <T> List<String> resolveLabel(Class<T> clazz) {Node node = clazz.getAnnotation(Node.class);if (node == null) {throw new RuntimeException("非数据库实体对象实体！");}String[] value = node.value();String[] labels = node.labels();List<String> result = new ArrayList<>();result.addAll(Arrays.asList(value));result.addAll(Arrays.asList(labels));if (result.isEmpty()) {result.add(clazz.getSimpleName());}return result;}
   }

3. 测试：

       @Testpublic void testEntity() {String column = EntityUtil.column(Job::getName);EntityUtil.label(Job.class);String column1 = EntityUtil.column(Job::getJobName);System.out.println(column +"  " + column1);}
   

使用

实际开发中，就可以将字符串进行替换，如下面：

查询标签Job，name='liry'，并通过id顺序排序，取第一个的cypher构建

// match(a:Job) where a.name='liry' return a order by a.id  limit 1Node temp = Cypher.node("Job").named("a");
ResultStatement statement = Cypher.match(temp).where(temp.property("name").isEqualTo(Cypher.anonParameter(job.getName()))).returning(temp.getRequiredSymbolicName()).orderBy(temp.property("id")).limit(1).build();

进行替换

// match(a:Job) where a.name='liry' return a order by a.id  limit 1// 字符串 Job  -> EntityUtil.label(Job.class)
// 字符串 name -> EntityUtil.column(Job::getName)
// 字符串 id -> EntityUtil.column(Job::getId)
Node temp = Cypher.node(EntityUtil.label(Job.class)).named("a");
ResultStatement statement = Cypher.match(temp).where(temp.property(EntityUtil.column(Job::getName)).isEqualTo(Cypher.anonParameter(job.getName()))).returning(temp.getRequiredSymbolicName()).orderBy(temp.property(EntityUtil.column(Job::getId))).limit(1).build();

创建一个节点：

create (a:Job{name:'liry',jobName:'liry-job'}) return a;          

可以看到调试中构建的Cypher是正确的。