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本文主要研究一下PowerJob的QueryConvertUtils

QueryConvertUtils

tech/powerjob/server/persistence/QueryConvertUtils.java

public class QueryConvertUtils {

    public static <T> Specification<T> toSpecification(PowerQuery powerQuery) {

        return (Specification<T>) (root, query, cb) -> {
            List<Predicate> predicates = Lists.newLinkedList();
            Field[] fields = powerQuery.getClass().getDeclaredFields();
            try {
                for (Field field : fields) {
                    field.setAccessible(true);
                    String fieldName = field.getName();
                    Object fieldValue = field.get(powerQuery);
                    if (fieldValue == null) {
                        continue;
                    }
                    if (fieldName.endsWith(PowerQuery.EQUAL)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.EQUAL);
                        predicates.add(cb.equal(root.get(colName), fieldValue));
                    } else if (fieldName.endsWith(PowerQuery.NOT_EQUAL)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.NOT_EQUAL);
                        predicates.add(cb.notEqual(root.get(colName), fieldValue));
                    } else if (fieldName.endsWith(PowerQuery.LIKE)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.LIKE);
                        predicates.add(cb.like(root.get(colName), convertLikeParams(fieldValue)));
                    } else if (fieldName.endsWith(PowerQuery.NOT_LIKE)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.NOT_LIKE);
                        predicates.add(cb.notLike(root.get(colName), convertLikeParams(fieldValue)));
                    } else if (fieldName.endsWith(PowerQuery.LESS_THAN)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.LESS_THAN);
                        predicates.add(cb.lessThan(root.get(colName), (Comparable)fieldValue));
                    } else if (fieldName.endsWith(PowerQuery.GREATER_THAN)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.GREATER_THAN);
                        predicates.add(cb.greaterThan(root.get(colName), (Comparable)fieldValue));
                    } else if (fieldName.endsWith(PowerQuery.LESS_THAN_EQUAL)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.LESS_THAN_EQUAL);
                        predicates.add(cb.lessThanOrEqualTo(root.get(colName), (Comparable)fieldValue));
                    } else if (fieldName.endsWith(PowerQuery.GREATER_THAN_EQUAL)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.GREATER_THAN_EQUAL);
                        predicates.add(cb.greaterThanOrEqualTo(root.get(colName), (Comparable)fieldValue));
                    } else if (fieldName.endsWith(PowerQuery.IN)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.IN);
                        predicates.add(root.get(colName).in(convertInParams(fieldValue)));
                    } else if (fieldName.endsWith(PowerQuery.NOT_IN)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.NOT_IN);
                        predicates.add(cb.not(root.get(colName).in(convertInParams(fieldValue))));
                    } else if (fieldName.endsWith(PowerQuery.IS_NULL)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.IS_NULL);
                        predicates.add(cb.isNull(root.get(colName)));
                    } else if (fieldName.endsWith(PowerQuery.IS_NOT_NULL)) {
                        String colName = StringUtils.substringBeforeLast(fieldName, PowerQuery.IS_NOT_NULL);
                        predicates.add(cb.isNotNull(root.get(colName)));
                    }
                }
            } catch (Exception e) {
                log.warn("[QueryConvertUtils] convert failed for query: {}", query, e);
                throw new PowerJobException("convert query object failed, maybe you should redesign your query object!");
            }

            if (powerQuery.getAppIdEq() != null) {
                predicates.add(cb.equal(root.get("appId"), powerQuery.getAppIdEq()));
            }

            return query.where(predicates.toArray(new Predicate[0])).getRestriction();
        };
    }

    private static String convertLikeParams(Object o) {
        String s = (String) o;
        if (!s.startsWith("%")) {
            s = "%" + s;
        }
        if (!s.endsWith("%")) {
            s = s + "%";
        }
        return s;
    }

    private static Object[] convertInParams(Object o) {
        // FastJSON, 永远滴神！
        return JSONArray.parseArray(JSONArray.toJSONString(o)).toArray();
    }
}    

QueryConvertUtils提供了toSpecification静态方法，用于将PowerQuery转换为jpa的Specification

PowerQuery

public abstract class PowerQuery {

    public static String EQUAL = "Eq";

    public static String NOT_EQUAL = "NotEq";

    public static String LIKE = "Like";

    public static String NOT_LIKE = "NotLike";

    public static String LESS_THAN = "Lt";

    public static String LESS_THAN_EQUAL = "LtEq";

    public static String GREATER_THAN = "Gt";

    public static String GREATER_THAN_EQUAL = "GtEq";

    public static String IN = "In";

    public static String NOT_IN = "NotIn";

    public static String IS_NULL = "IsNull";

    public static String IS_NOT_NULL = "IsNotNull";

    private Long appIdEq;
}

PowerQuery是个抽象类，定义了一系列操作符

JobInfoQuery

tech/powerjob/common/request/query/JobInfoQuery.java

@Getter
@Setter
@Accessors(chain = true)
public class JobInfoQuery extends PowerQuery {

    private Long idEq;
    private Long idLt;
    private Long idGt;

    private String jobNameEq;
    private String jobNameLike;

    private String jobDescriptionLike;

    private String jobParamsLike;

    private List<Integer> timeExpressionTypeIn;
    private List<Integer> executeTypeIn;
    private List<Integer> processorTypeIn;

    private String processorInfoEq;
    private String processorInfoLike;

    private List<Integer> statusIn;
    private Long nextTriggerTimeGt;
    private Long nextTriggerTimeLt;

    private String notifyUserIdsLike;

    private Date gmtCreateLt;
    private Date gmtCreateGt;

    private Date gmtModifiedLt;
    private Date gmtModifiedGt;

    private Integer dispatchStrategyEq;

    private String tagEq;
}

JobInfoQuery继承了PowerQuery，它根据要查询的字段及操作定义了诸如idEq，idLt，idGt的属性

InstanceService

tech/powerjob/server/core/instance/InstanceService.java

    public List<InstanceInfoDTO> queryInstanceInfo(PowerQuery powerQuery) {
        return instanceInfoRepository
                .findAll(QueryConvertUtils.toSpecification(powerQuery))
                .stream()
                .map(InstanceService::directConvert)
                .collect(Collectors.toList());
    }

InstanceService的queryInstanceInfo方法使用QueryConvertUtils.toSpecification(powerQuery)将powerQuery转换为Specification，再利用JpaSpecificationExecutor的findAll(Specification)进行查询

小结

QueryConvertUtils提供了toSpecification静态方法，用于将PowerQuery转换为jpa的Specification，其约定query的属性以字段名+操作符构成，toSpecification根据这个规则来解析并转换为Specification，之后就可以利用jpa进行查询。