spring-session自定義序列化
阿新 • • 發佈:2018-11-09
spring-session預設採用jdk序列化方法,該方法效率低下、記憶體佔用大,且需要額外修改程式碼。故需要自定義序列化方法
自定義序列方法使用jackson庫
首先需要一個類作為序列化的工具,需要實現
RedisSerializer
該介面在反序列化時沒有提供對應的class物件,因此使用jackson反序列化時,都會返回成Object物件
因此我的解決思路是,在序列化時,獲取對應bean的class,將其和bean序列化後的結果一併返回,存入redis
反序列化時,首先將byte陣列轉化成字串,在從中擷取存入的class字串,作為引數傳入jackson反序列化方法中
問題:對於帶有泛型的bean,無法將其轉化成真正適合的型別
解決方案:對於list,map,set等集合類,獲取其第一個元素的class,存入redis
缺點:要求集合類元素必須是同一個子類,不能來自於同一個父類
問題:spring-session在刪除attribute時,並沒有真正從redis中刪除,只是將value置為null,此時也會呼叫該類做序列化
解決方案:檢視spring-session原始碼得知,對於null值得處理方法為直接返回一個個數為0的byte陣列,反序列化時直接返回null即可
import cn.nsu.edu.web.four.config.BaseStatic; import com.fasterxml.jackson.core.JsonProcessingException; import com.fasterxml.jackson.databind.JavaType; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.type.TypeFactory; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.redis.serializer.RedisSerializer; import org.springframework.data.redis.serializer.SerializationException; import org.springframework.data.redis.serializer.SerializationUtils; import java.io.IOException; import java.io.UnsupportedEncodingException; import java.util.*; import java.util.regex.Matcher; import java.util.regex.Pattern; public class SessionSerializer implements RedisSerializer<Object> { @Autowired private ObjectMapper mapper; private Logger logger = LoggerFactory.getLogger(getClass()); private final String separator = "="; private final String classPrefix = "<"; private final String classSuffix = ">"; private final String classSeparator = ","; private Pattern pattern; public SessionSerializer() { pattern = Pattern.compile("<(.*)>"); } /** * 獲取class,包含集合類的泛型 * <p>暫只支援最多兩個泛型,同時集合內資料必須為同一個實現類,不可將泛型宣告成父類</p> * * @param obj 將要序列化的物件 * @return 沒有泛型,形式為java.lang.String<> * <p>一個泛型,形式為java.lang.String<java.lang.String></p> * <p>兩個個泛型,形式為java.lang.String<java.lang.String,java.lang.String></p> */ private String getBegin(Object obj) { StringBuilder builder = new StringBuilder(obj.getClass().toString().substring(6) + classPrefix); if (obj instanceof List) { List list = ((List) obj); if (!list.isEmpty()) { Object temp = list.get(0); builder.append(temp.getClass().toString().substring(6)); } } else if (obj instanceof Map) { Map map = ((Map) obj); Iterator iterator = map.keySet().iterator(); if (iterator.hasNext()) { Object key = iterator.next(); Object value = map.get(key); builder.append(key.getClass().toString().substring(6)).append(classSeparator).append(value.getClass().toString().substring(6)); } } else if (obj instanceof Set) { Set set = ((Set) obj); Iterator iterator = set.iterator(); if (iterator.hasNext()) { Object value = iterator.next(); builder.append(value.getClass().toString().substring(6)); } } builder.append(classSuffix); return builder.toString(); } @Override public byte[] serialize(Object o) throws SerializationException { if (o == null) return new byte[0]; try { String builder = getBegin(o) + separator + mapper.writeValueAsString(o); return builder.getBytes(BaseStatic.CHARSET); } catch (UnsupportedEncodingException | JsonProcessingException e) { e.printStackTrace(); } return null; } @Override public Object deserialize(byte[] bytes) throws SerializationException { if (bytes == null || bytes.length == 0) return null;//已被刪除的session try { String temp = new String(bytes, BaseStatic.CHARSET); String cl[] = getClass(temp); if (cl == null) { throw new RuntimeException("錯誤的序列化結果=" + temp); } if (cl.length == 1) { return mapper.readValue(temp.substring(temp.indexOf(separator) + 1), Class.forName(cl[0])); } else if (cl.length == 2) { TypeFactory factory = mapper.getTypeFactory(); JavaType type = factory.constructParametricType(Class.forName(cl[0]), Class.forName(cl[1])); return mapper.readValue(temp.substring(temp.indexOf(separator) + 1), type); } else if (cl.length == 3) { TypeFactory factory = mapper.getTypeFactory(); JavaType type = factory.constructParametricType(Class.forName(cl[0]), Class.forName(cl[1]), Class.forName(cl[2])); return mapper.readValue(temp.substring(temp.indexOf(separator) + 1), type); } } catch (ClassNotFoundException | IOException e) { e.printStackTrace(); } return null; } /** * 解析字串,獲取class * <p>一個型別,java.lang.String<>={}</p> * <p>兩個型別,後面為泛型,java.lang.String<java.lang.String>={}</p> * <p>三個型別,後面為泛型,java.lang.String<java.lang.String,java.lang.String>={}</p> * * @param value 包含class的字串 * @return 返回所有類的陣列 */ private String[] getClass(String value) { int index = value.indexOf(classPrefix); if (index != -1) { Matcher matcher = pattern.matcher(value.subSequence(index, value.indexOf(classSuffix) + 1)); if (matcher.find()) { String temp = matcher.group(1); if (temp.isEmpty()) {//沒有泛型 return new String[]{value.substring(0, index)}; } else if (temp.contains(classSeparator)) {//兩個泛型 int nextIndex = temp.indexOf(classSeparator); return new String[]{ value.substring(0, index), temp.substring(0, nextIndex), temp.substring(nextIndex + 1) }; } else {//一個泛型 return new String[]{ value.substring(0, index), temp }; } } } return null; } }
配置spring-session序列化,在之前的配置檔案上進行修改
<bean id="springSessionDefaultRedisSerializer" class="cn.nsu.edu.web.four.session.serializer.SessionSerializer"/> <bean id="jedisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory" destroy-method="destroy"> <property name="hostName" value="${redis.host}"/> <property name="port" value="${redis.port}"/> <property name="timeout" value="${redis.timeout}"/> <property name="password" value="${redis.password}"/> <property name="database" value="${redis.database}"/> <property name="usePool" value="true"/> <property name="poolConfig" ref="redisPoolConfig"/> </bean> <bean id="redisTemplate" class="org.springframework.data.redis.core.StringRedisTemplate"> <property name="connectionFactory" ref="jedisConnectionFactory"/> <property name="defaultSerializer" ref="springSessionDefaultRedisSerializer"/> <!--指定序列化類--> <property name="valueSerializer" ref="springSessionDefaultRedisSerializer"/> <property name="hashValueSerializer" ref="springSessionDefaultRedisSerializer"/> </bean>