spring data jpa 组合条件查询封装

/** 
 * 定义一个查询条件容器 
 * @author lee 
 * 
 * @param <T> 
 */  
public class Criteria<T> implements Specification<T>{  
    private List<Criterion> criterions = new ArrayList<Criterion>();  
  
    public Predicate toPredicate(Root<T> root, CriteriaQuery<?> query,  
            CriteriaBuilder builder) {  
        if (!criterions.isEmpty()) {  
            List<Predicate> predicates = new ArrayList<Predicate>();  
            for(Criterion c : criterions){  
                predicates.add(c.toPredicate(root, query,builder));  
            }  
            // 将所有条件用 and 联合起来  
            if (predicates.size() > 0) {  
                return builder.and(predicates.toArray(new Predicate[predicates.size()]));  
            }  
        }  
        return builder.conjunction();  
    }  
    /** 
     * 增加简单条件表达式 
     * @Methods Name add 
     * @Create In 2012-2-8 By lee 
     * @param expression0 void 
     */  
    public void add(Criterion criterion){  
        if(criterion!=null){  
            criterions.add(criterion);  
        }  
    }  
}  

 然后是各种条件组装类，我首先做了一个接口来包装各种条件

/** 
 * 条件接口 
 * 用户提供条件表达式接口 
 * @Class Name Criterion 
 * @Author lee 
 * @Create In 2012-2-8 
 */  
public interface Criterion {  
    public enum Operator {  
        EQ, NE, LIKE, GT, LT, GTE, LTE, AND, OR  
    }  
    public Predicate toPredicate(Root<?> root, CriteriaQuery<?> query,  
            CriteriaBuilder builder);  
}

 然后是针对不同类型条件处理的实现

一个是简单比较类型的处理

Java代码  

/** 
 * 简单条件表达式 
 * @author lee 
 * 
 */  
public class SimpleExpression implements Criterion{  
      
    private String fieldName;       //属性名  
    private Object value;           //对应值  
    private Operator operator;      //计算符  
  
    protected SimpleExpression(String fieldName, Object value, Operator operator) {  
        this.fieldName = fieldName;  
        this.value = value;  
        this.operator = operator;  
    }  
  
    public String getFieldName() {  
        return fieldName;  
    }  
    public Object getValue() {  
        return value;  
    }  
    public Operator getOperator() {  
        return operator;  
    }  
    @SuppressWarnings({ "rawtypes", "unchecked" })  
    public Predicate toPredicate(Root<?> root, CriteriaQuery<?> query,  
            CriteriaBuilder builder) {  
        Path expression = null;  
        if(fieldName.contains(".")){  
            String[] names = StringUtils.split(fieldName, ".");  
            expression = root.get(names[0]);  
            for (int i = 1; i < names.length; i++) {  
                expression = expression.get(names[i]);  
            }  
        }else{  
            expression = root.get(fieldName);  
        }  
          
        switch (operator) {  
        case EQ:  
            return builder.equal(expression, value);  
        case NE:  
            return builder.notEqual(expression, value);  
        case LIKE:  
            return builder.like((Expression<String>) expression, "%" + value + "%");  
        case LT:  
            return builder.lessThan(expression, (Comparable) value);  
        case GT:  
            return builder.greaterThan(expression, (Comparable) value);  
        case LTE:  
            return builder.lessThanOrEqualTo(expression, (Comparable) value);  
        case GTE:  
            return builder.greaterThanOrEqualTo(expression, (Comparable) value);  
        default:  
            return null;  
        }  
    }  
      
}  

 一个逻辑条件计算实现

Java代码  

/** 
 * 逻辑条件表达式 用于复杂条件时使用，如但属性多对应值的OR查询等 
 * @author lee 
 * 
 */  
public class LogicalExpression implements Criterion {  
    private Criterion[] criterion;  // 逻辑表达式中包含的表达式  
    private Operator operator;      //计算符  
  
    public LogicalExpression(Criterion[] criterions, Operator operator) {  
        this.criterion = criterions;  
        this.operator = operator;  
    }  
  
    public Predicate toPredicate(Root<?> root, CriteriaQuery<?> query,  
            CriteriaBuilder builder) {  
        List<Predicate> predicates = new ArrayList<Predicate>();  
        for(int i=0;i<this.criterion.length;i++){  
            predicates.add(this.criterion[i].toPredicate(root, query, builder));  
        }  
        switch (operator) {  
        case OR:  
            return builder.or(predicates.toArray(new Predicate[predicates.size()]));  
        default:  
            return null;  
        }  
    }  
  
}  

 添加一个组装工厂类

Java代码  

/** 
 * 条件构造器 
 * 用于创建条件表达式 
 * @Class Name Restrictions 
 * @Author lee 
 */  
public class Restrictions {  
  
    /** 
     * 等于 
     * @param fieldName 
     * @param value 
     * @param ignoreNull 
     * @return 
     */  
    public static SimpleExpression eq(String fieldName, Object value, boolean ignoreNull) {  
        if(StringUtils.isEmpty(value))return null;  
        return new SimpleExpression (fieldName, value, Operator.EQ);  
    }  
      
    /** 
     * 不等于 
     * @param fieldName 
     * @param value 
     * @param ignoreNull 
     * @return 
     */  
    public static SimpleExpression ne(String fieldName, Object value, boolean ignoreNull) {  
        if(StringUtils.isEmpty(value))return null;  
        return new SimpleExpression (fieldName, value, Operator.NE);  
    }  
  
    /** 
     * 模糊匹配 
     * @param fieldName 
     * @param value 
     * @param ignoreNull 
     * @return 
     */  
    public static SimpleExpression like(String fieldName, String value, boolean ignoreNull) {  
        if(StringUtils.isEmpty(value))return null;  
        return new SimpleExpression (fieldName, value, Operator.LIKE);  
    }  
  
    /** 
     *  
     * @param fieldName 
     * @param value 
     * @param matchMode 
     * @param ignoreNull 
     * @return 
     */  
    public static SimpleExpression like(String fieldName, String value,  
            MatchMode matchMode, boolean ignoreNull) {  
        if(StringUtils.isEmpty(value))return null;  
        return null;  
    }  
  
    /** 
     * 大于 
     * @param fieldName 
     * @param value 
     * @param ignoreNull 
     * @return 
     */  
    public static SimpleExpression gt(String fieldName, Object value, boolean ignoreNull) {  
        if(StringUtils.isEmpty(value))return null;  
        return new SimpleExpression (fieldName, value, Operator.GT);  
    }  
  
    /** 
     * 小于 
     * @param fieldName 
     * @param value 
     * @param ignoreNull 
     * @return 
     */  
    public static SimpleExpression lt(String fieldName, Object value, boolean ignoreNull) {  
        if(StringUtils.isEmpty(value))return null;  
        return new SimpleExpression (fieldName, value, Operator.LT);  
    }  
  
    /** 
     * 大于等于 
     * @param fieldName 
     * @param value 
     * @param ignoreNull 
     * @return 
     */  
    public static SimpleExpression lte(String fieldName, Object value, boolean ignoreNull) {  
        if(StringUtils.isEmpty(value))return null;  
        return new SimpleExpression (fieldName, value, Operator.GTE);  
    }  
  
    /** 
     * 小于等于 
     * @param fieldName 
     * @param value 
     * @param ignoreNull 
     * @return 
     */  
    public static SimpleExpression gte(String fieldName, Object value, boolean ignoreNull) {  
        if(StringUtils.isEmpty(value))return null;  
        return new SimpleExpression (fieldName, value, Operator.LTE);  
    }  
  
    /** 
     * 并且 
     * @param criterions 
     * @return 
     */  
    public static LogicalExpression and(Criterion... criterions){  
        return new LogicalExpression(criterions, Operator.AND);  
    }  
    /** 
     * 或者 
     * @param criterions 
     * @return 
     */  
    public static LogicalExpression or(Criterion... criterions){  
        return new LogicalExpression(criterions, Operator.OR);  
    }  
    /** 
     * 包含于 
     * @param fieldName 
     * @param value 
     * @return 
     */  
    @SuppressWarnings("rawtypes")  
    public static LogicalExpression in(String fieldName, Collection value, boolean ignoreNull) {  
        if(ignoreNull&&(value==null||value.isEmpty())){  
            return null;  
        }  
        SimpleExpression[] ses = new SimpleExpression[value.size()];  
        int i=0;  
        for(Object obj : value){  
            ses[i]=new SimpleExpression(fieldName,obj,Operator.EQ);  
            i++;  
        }  
        return new LogicalExpression(ses,Operator.OR);  
    }  
}  

 使用方法如下

Java代码  

Criteria<Event> c = new Criteria<Event>();  
c.add(Restrictions.like("code", searchParam.getCode(), true));  
        c.add(Restrictions.eq("level", searchParam.getLevel(), false));  
        c.add(Restrictions.eq("mainStatus", searchParam.getMainStatus(), true));  
        c.add(Restrictions.eq("flowStatus", searchParam.getFlowStatus(), true));  
        c.add(Restrictions.eq("createUser.userName", searchParam.getCreateUser(), true));  
        c.add(Restrictions.lte("submitTime", searchParam.getStartSubmitTime(), true));  
        c.add(Restrictions.gte("submitTime", searchParam.getEndSubmitTime(), true));  
        c.add(Restrictions.eq("needFollow", searchParam.getIsfollow(), true));  
        c.add(Restrictions.ne("flowStatus", CaseConstants.CASE_STATUS_DRAFT, true));  
        c.add(Restrictions.in("solveTeam.code",teamCodes, true));  
eventDao.findAll(c);