本地缓存Caffeine的使用
缓存的用途：
用于减小对数据库的访问次数，频繁的访问数据库产生很大的开销，影响程序的执行效率！引入缓存，效率能几何倍递增。
缓存的应用思想：
初次查询时，添加缓存。修改方法时去除缓存
// 最大缓存数量
public static final int MAX_SIZE = 10000;
// 自动失效时间(分钟)
public static long expireAfterWriteMinutes = 60;插入代码片
private LoadingCache<Long, Object> idCacheFunction = null;
@Autowired
IdCacheFunctionLoader idCacheFunctionLoader;
@Override
public SecuritysFunction findById(Integer id) {
if(id==null){
return null;
}
Object object;
try {
securitysFunction = getIdCache().get(id);
} catch (Exception e) {
return null;
}
return securitysFunction;
}
private LoadingCache<Long, SecuritysFunction> getIdCache() {
if (null != this.idCacheFunction) {
return this.idCacheFunction;
}
// 临界区-排队
synchronized (this) {
//
if (null != this.idCacheFunction) {
return this.idCacheFunction;
}
this.idCacheFunction = Caffeine.newBuilder()
.maximumSize(MAX_SIZE)
.expireAfterWrite(expireAfterWriteMinutes, TimeUnit.MINUTES)
.build(idCacheFunctionLoader);
}
return this.idCacheFunction;
}
/**
缓存加载器
*/
@Component
public class IdCacheFunctionLoader implements CacheLoader<Long, Object> {
@Override
public SecuritysFunction load(Long id) throws Exception {
if (null == id){
return null;}
SecuritysFunction entity = ecuritysFunctionMapper.selectByPrimaryKey(id);
return entity;
}
}
（2）之前封装的一个缓存方法
package com.mepu.mygis.manager.util;
import com.github.benmanes.caffeine.cache.Cache;
import com.github.benmanes.caffeine.cache.Caffeine;
import com.mepu.mygis.manager.config.Constant;
import com.mepu.mygis.manager.config.Enum;
import com.mepu.mygis.manager.domain.po.mygis.ObjectAndShape;
import com.mepu.mygis.manager.domain.po.mygis.ThirdInvCcwjq;
import com.mepu.mygis.manager.util.GetGeometryUtil;
import org.apache.poi.ss.formula.functions.T;
import org.locationtech.jts.geom.Envelope;
import org.locationtech.jts.geom.Geometry;
import org.springframework.stereotype.Component;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;
/**
* @创建人
* @创建时间 2019/12/4 09:53
* @描述
*/
@Component
public class CacheUtil{
// 最大缓存数量
public static final int MAX_SIZE = 10000;
// 自动失效时间(分钟)
public static long expireAfterWriteMinutes = 60;
//正确数据缓存容器
public static Cache <String, List<Object>> cache=null;
//不正确数据缓存容器
public static Cache <String, List<ObjectAndShape>> cacheError=null;
public static Cache<String, Long> cacheCount=null;
ObjectAndShape objectAndShape = null;
public Cache <String, List<Object>> cacheShapeList(Object entity) throws NoSuchFieldException, IllegalAccessException, InstantiationException {
synchronized (this){
Class <?> aClass = entity.getClass();
Object o = aClass.newInstance();
Field[] declaredFields = aClass.getDeclaredFields();
for (int i=0;i<declaredFields.length-1;i++) {
Field declaredField = aClass.getDeclaredField(declaredFields[i].getName());
declaredField.setAccessible(true);
declaredField.set(o,declaredField.get(entity));
}
Field shapeField = aClass.getDeclaredField("shape");
Field maxXField = aClass.getDeclaredField("maxX");
Field maxYField = aClass.getDeclaredField("maxY");
Field minXField = aClass.getDeclaredField("minX");
Field minYField = aClass.getDeclaredField("minY");
Field batchField =aClass.getDeclaredField("batchId");
shapeField.setAccessible(true);
maxXField.setAccessible(true);
maxYField.setAccessible(true);
minXField.setAccessible(true);
minYField.setAccessible(true);
batchField.setAccessible(true);
String shape = shapeField.get(o).toString();
String batchId = batchField.get(o).toString();
//生成几何图形
Geometry geometry = GetGeometryUtil.getGemetrys(shape);
//获取几何图形的最小边界
Envelope envelope = geometry.getEnvelopeInternal();
Double minX = envelope.getMinX();
Double minY = envelope.getMinY();
Double maxX = envelope.getMaxX();
Double maxY = envelope.getMaxY();
minXField.set(o,new BigDecimal(minX).setScale(15, BigDecimal.ROUND_HALF_UP));
minYField.set(o,new BigDecimal(minY).setScale(15, BigDecimal.ROUND_HALF_UP));
maxXField.set(o,new BigDecimal(maxX).setScale(15, BigDecimal.ROUND_HALF_UP));
maxYField.set(o,new BigDecimal(maxY).setScale(15, BigDecimal.ROUND_HALF_UP));
StringBuilder key=new StringBuilder();
key.append(aClass.getSimpleName());
key.append(batchId);
if(cache!=null){
List <Object> ifPresent = CacheUtil.cache.getIfPresent(key.toString());
if(ifPresent!=null){
ifPresent.add(o);
cache.put(key.toString(), ifPresent);
}else{
List <Object> list = new ArrayList <>();
list.add(o);
cache.put(key.toString(), list);
}
return CacheUtil.cache;
}else{
cache = Caffeine.newBuilder()
.expireAfterWrite(expireAfterWriteMinutes, TimeUnit.MINUTES)
.maximumSize(10)
.build();
List <Object> list = new ArrayList <>();
list.add(o);
cache.put(key.toString(), list);
}
}
return cache;
}
/**
* 处理添加数据不正常数据的缓存
* @param entity
* @return
* @throws NoSuchFieldException
* @throws IllegalAccessException
*/
public Cache <String, List<ObjectAndShape>> cacheErrorList(Object entity, Integer errorCheckStatus) throws NoSuchFieldException, IllegalAccessException, InstantiationException {
synchronized (this){
if(cacheError!=null){
Class <?> aClass = entity.getClass();
List <ObjectAndShape> ifPresent = CacheUtil.cacheError.getIfPresent(aClass.getSimpleName());
System.err.println("**********缓存数之前*************"+ifPresent.size());
Field objectidField = aClass.getDeclaredField("objectid");
Field shapeField = aClass.getDeclaredField("shape");
objectidField.setAccessible(true);
shapeField.setAccessible(true);
Integer objectId = Integer.valueOf(objectidField.get(entity).toString());
String shape=shapeField.get(entity).toString();
objectAndShape = new ObjectAndShape();
objectAndShape.setObjectId(objectId);
//objectAndShape.setShape(shape);
objectAndShape.setErrorCheckName(Enum.ErrorDataStatus.getName(errorCheckStatus));
ifPresent.add(objectAndShape);
cacheError.put(aClass.getSimpleName(), ifPresent);
System.err.println("**********缓存数*************"+ifPresent.size());
return CacheUtil.cacheError;
}else{
cacheError = Caffeine.newBuilder()
.expireAfterWrite(expireAfterWriteMinutes, TimeUnit.MINUTES)
.maximumSize(10)
.build();
List <ObjectAndShape> list = new ArrayList <>();
System.err.println(entity);
Class <?> aClass = entity.getClass();
System.err.println(aClass.getSimpleName());
Field objectidField = aClass.getDeclaredField("objectid");
Field shapeField = aClass.getDeclaredField("shape");
objectidField.setAccessible(true);
shapeField.setAccessible(true);
Integer objectId = Integer.valueOf(objectidField.get(entity).toString());
//String shape=shapeField.get(entity).toString();
objectAndShape = new ObjectAndShape();
objectAndShape.setObjectId(objectId);
//objectAndShape.setShape(shape);
list.add(objectAndShape);
cacheError.put(aClass.getSimpleName(), list);
}
}
return cacheError;
}
public Cache<String, Long> createCacheCount(String key, Long value){
/**
* @Author:
* @Description: 创建缓存容器,如果没有则创建。有则添加key
* @param: [key, value]
* @return: com.github.benmanes.caffeine.cache.Cache
* @CreateDate: 2019/12/5
* @UpdateUser:
* @UpdateDate: 2019/12/5
* @UpdateRemark: 修改内容
* @Version: 1.0
*/
synchronized(this){
if(cacheCount!=null){
cacheCount.put(key, value);
return cacheCount;
}else{
cacheCount = Caffeine.newBuilder()
.expireAfterWrite(expireAfterWriteMinutes, TimeUnit.MINUTES)
.maximumSize(10)
.build();
cacheCount.put(key, value);
}
}
return cacheCount;
}
}
(3)踩过的坑
本地缓存主要存放在内存，不要放太大太多的数据，容易内存溢出