关于jpa的Specification自定义函数,实现oracle的decode；以及如何在静态方法中调用注入的service
中秋佳节，多想吟诗一首：明月几时有，把酒问青天，不知天上宫。。。，行啦，不扯淡啦，中秋佳节也不能影响我学习的热情，说一说今天遇到问题
如何在静态方法中调用注入的service
Public class ClassA{
public static ClassA classA;
@Resource
private Service service;
//原理时在工程启动时加载，在静态方法前加载，这样就可以在静态方法中调用注入的方法啦 @PostConstruct public void init() { classA = this;
classA.service=service; }
}
关于jpa的Specification自定义函数
这个时自定义方法的源码，有注释，不多说啦
1 /** 2 * Create an expression for the execution of a database 3 * function. 4 * @param name function name 5 * @param type expected result type 6 * @param args function arguments 7 * @return expression 8 */ 9 <T> Expression<T> function(String name, Class<T> type, 10 Expression<?>... args);
咱说说这个类，也就是
ParameterizedFunctionExpression，是如何实现动态组合排序条件，实现decode
<T> Expression<T> function(String name, Class<T> type,
Expression<?>... args);
//这是function实现实际调用的方法；他调用的就是这个类ParameterizedFunctionExpression的构造方法
@Override
public <T> Expression<T> function(String name, Class<T> returnType, Expression<?>... arguments) {
return new ParameterizedFunctionExpression<T>( this, returnType, name, arguments );
}
//ParameterizedFunctionExpression的构造方法
public ParameterizedFunctionExpression(
CriteriaBuilderImpl criteriaBuilder,
Class<X> javaType,
String functionName,
Expression<?>... argumentExpressions) {
super( criteriaBuilder, javaType, functionName );
this.argumentExpressions = Arrays.asList( argumentExpressions );
this.isStandardJpaFunction = STANDARD_JPA_FUNCTION_NAMES.contains( functionName.toUpperCase(Locale.ROOT) );
}
//实现
Expression<Integer> expression = null;
//存储排序条件
List<Expression<?>> argumentExpressions = new ArrayList<Expression<?>>();
//排序字段
argumentExpressions.add(cb.literal("grade");
//排序的顺序
argumentExpressions.add(cb.literal(1));
expression = new ParameterizedFunctionExpression<Integer>((CriteriaBuilderImpl) cb, Integer.class, "decode",
argumentExpressions);
@SuppressWarnings("all")
public Specification<CT> findByCondition(List<Filter> filter, List<Reorder> reOrders) {
return new Specification<CT>() {
@Override
public Predicate toPredicate(Root<CT> root, CriteriaQuery<?> query, CriteriaBuilder cb) {
List<Predicate> predicates = new ArrayList<Predicate>();
List<Order> orders = new ArrayList<Order>();
if (!CollectionUtils.isEmpty(filter)) {
filter.stream().forEach(filter -> {
ParameterizedType pt = (ParameterizedType) this.getClass().getGenericInterfaces()[0];
Class<CT> clazz = (Class<CT>) pt.getActualTypeArguments()[0];
CT ct = null;
try {
ct = clazz.newInstance();
} catch (InstantiationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String type = JudgeParamType.getObjectValue(ct, null, filter.getField());
if (type == null) {
String str[] = filter.getField().split(",");
type = JudgeParamType.getObjectValue(ct, null, str[1]);
}
Path<Object> queryPath = obtainParamPath(root, filter.getField());
switch (filter.getFilter()) {
case "equal": {
if ("Integer".equalsIgnoreCase(type)) {
predicates.add(cb.equal(queryPath.as(Integer.class),
SieStringUtils.getIntvalueByStr(filter.getParam().trim())));
break;
}
if ("Date".equalsIgnoreCase(type)) {
predicates.add(cb.equal(queryPath.as(Date.class),
SieStringUtils.getDatevalueByStr(filter.getParam().trim())));
break;
}
predicates.add(cb.equal(queryPath.as(String.class), filter.getParam().trim()));
break;
}
case "like": {
predicates.add(cb.like(cb.upper(queryPath.as(String.class)),
"%" + filter.getParam().trim().toUpperCase() + "%"));
break;
}
case "range": {
List<String> str = Arrays.asList(filter.getParam().trim().split(","));
if ("Integer".equalsIgnoreCase(type)) {
predicates.add(cb.greaterThanOrEqualTo(queryPath.as(Integer.class),
SieStringUtils.getIntvalueByStr(str.get(0))));
predicates.add(cb.lessThanOrEqualTo(queryPath.as(Integer.class),
SieStringUtils.getIntvalueByStr(str.get(1))));
break;
}
if ("Double".equalsIgnoreCase(type)) {
predicates.add(cb.greaterThanOrEqualTo(queryPath.as(Double.class),
SieStringUtils.getDoublevalueByStr(str.get(0))));
predicates.add(cb.lessThanOrEqualTo(queryPath.as(Double.class),
SieStringUtils.getDoublevalueByStr(str.get(1))));
break;
}
if ("Date".equalsIgnoreCase(type)) {
predicates.add(cb.greaterThanOrEqualTo(queryPath.as(Date.class),
SieStringUtils.getDatevalueByStr(str.get(0))));
predicates.add(cb.lessThanOrEqualTo(queryPath.as(Date.class),
SieStringUtils.getDatevalueByStr(str.get(1))));
break;
}
predicates.add(cb.greaterThanOrEqualTo(queryPath.as(String.class), str.get(0)));
predicates.add(cb.lessThanOrEqualTo(queryPath.as(String.class), str.get(1)));
break;
}
case "gt": {
if ("Integer".equalsIgnoreCase(type)) {
predicates.add(cb.greaterThanOrEqualTo(queryPath.as(Integer.class),
SieStringUtils.getIntvalueByStr(filter.getParam().trim())));
break;
}
if ("Double".equalsIgnoreCase(type)) {
predicates.add(cb.greaterThanOrEqualTo(queryPath.as(Double.class),
SieStringUtils.getDoublevalueByStr(filter.getParam().trim())));
break;
}
if ("Date".equalsIgnoreCase(type)) {
predicates.add(cb.greaterThanOrEqualTo(queryPath.as(Date.class),
SieStringUtils.getDatevalueByStr(filter.getParam().trim())));
break;
}
predicates
.add(cb.greaterThanOrEqualTo(queryPath.as(String.class), filter.getParam().trim()));
break;
}
case "lt": {
if ("Integer".equalsIgnoreCase(type)) {
predicates.add(cb.lessThanOrEqualTo(queryPath.as(Integer.class),
SieStringUtils.getIntvalueByStr(filter.getParam().trim())));
break;
}
if ("Double".equalsIgnoreCase(type)) {
predicates.add(cb.lessThanOrEqualTo(queryPath.as(Double.class),
SieStringUtils.getDoublevalueByStr(filter.getParam().trim())));
break;
}
if ("Date".equalsIgnoreCase(type)) {
predicates.add(cb.lessThanOrEqualTo(queryPath.as(Date.class),
SieStringUtils.getDatevalueByStr(filter.getParam().trim())));
break;
}
predicates.add(cb.lessThanOrEqualTo(queryPath.as(String.class), filter.getParam().trim()));
break;
}
case "in": {
List<String> inStr = Arrays.asList(filter.getParam().trim().split(","));
List<Predicate> predicatesOr = new ArrayList<Predicate>();
inStr.forEach(param -> {
if ("null".equalsIgnoreCase(param)) {
predicatesOr.add(cb.isNull(queryPath));
} else {
predicatesOr.add(cb.equal(queryPath, param));
}
});
Predicate[] predicateOr = predicatesOr.toArray(new Predicate[predicatesOr.size()]);
predicates.add(cb.or(predicateOr));
break;
}
case "notnull": {
predicates.add(cb.isNotNull(queryPath));
cb.literal("e");
}
default:
break;
}
});
}
if (!CollectionUtils.isEmpty(reOrders)) {
reOrders.stream().forEach(sort -> {
Path<Object> sortPath = obtainParamPath(root, sort.getField());
orders.add(getDecodeOrders(root, cb, sort.getField(), sort.getDirection()));
});
}
Predicate predicate = cb.and(predicates.toArray(new Predicate[predicates.size()]));
if (!CollectionUtils.isEmpty(orders)) {
query.orderBy(orders);
}
return query.getRestriction();
}
};
}
public static class Filter { @ApiModelProperty(required = true) private String filter;// where @ApiModelProperty(required = true) private String field; @ApiModelProperty(required = true) private String param; public String getFilter() { return filter; } public void setFilter(String filter) { this.filter = filter; } public String getField() { return field; } public void setField(String field) { this.field = field; } public String getParam() { return param; } public void setParam(String param) { this.param = param; } }
public static class Reorder { @ApiModelProperty(required = true) private String direction; @ApiModelProperty(required = true) private String field; public String getDirection() { return direction; } public void setDirection(String direction) { this.direction = direction; } public String getField() { return field; } public void setField(String field) { this.field = field; } }
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