Spring Data JPA stackoverflow
1.禁止使用lombok 的@Data 注释
使用@Data注释后,默认会重写父类的toString()方法,hashcode()等方法,在往map里存的时候,会根据equals和hashcode方法,来计算下标,而如果@Data注释的类与其他类有关联的属性(如:@onetoone,@onetomany等)且关联的属性不为空时,会不断从关联方的属性进行查找,再从关联方查找该@Data注释的类,依次循环,造成堆栈溢出。
例子:考试信息与报名信息以 1:n 进行关联
package com.apply.entity; import com.fasterxml.jackson.annotation.JsonIdentityInfo; import com.fasterxml.jackson.annotation.ObjectIdGenerator; import com.fasterxml.jackson.annotation.ObjectIdGenerators; import io.swagger.annotations.ApiModel; import io.swagger.annotations.ApiModelProperty; import lombok.Data; import javax.persistence.*; import java.util.Date; /** * @author tianp * 报名信息 apply_info */ @Data @Entity @Table(name = "apply_info") @ApiModel(value = "ApplyInfo", description = "报名信息对象") @JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id") public class ApplyInfo { @Id @GeneratedValue @ApiModelProperty(value = "id", dataType = "long") private Long id; @ManyToOne @JoinColumn(name = "examNum") private ExamInfo examInfo; }
package com.apply.entity; import com.fasterxml.jackson.annotation.JsonIdentityInfo; import com.fasterxml.jackson.annotation.JsonIgnore; import com.fasterxml.jackson.annotation.ObjectIdGenerators; import lombok.Data; import javax.persistence.*; import java.util.Date; import java.util.Set; /** * @author tianp * 考试信息设置 apply_examinfo */ @Data @Entity @Table(name = "apply_examinfo") @JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id") public class ExamInfo { @Id @GeneratedValue private Long id; @OneToMany(mappedBy = "examInfo", cascade = CascadeType.ALL) private Set<ApplyInfo> applyInfos; }
public class Test1 { @Test public void testObject() { ExamInfo examInfo = new ExamInfo(); ApplyInfo applyInfo = new ApplyInfo(); Set<ApplyInfo> set = new HashSet<>(); set.add(applyInfo); examInfo.setApplyInfos(set); applyInfo.setExamInfo(examInfo); System.out.println(examInfo.toString()); System.out.println(applyInfo.toString()); } }
java.lang.StackOverflowError at java.lang.StringBuilder.append(StringBuilder.java:136) at com.apply.entity.ExamInfo.toString(ExamInfo.java:16) at java.lang.String.valueOf(String.java:2994) at java.lang.StringBuilder.append(StringBuilder.java:131) at com.apply.entity.ApplyInfo.toString(ApplyInfo.java:17) at java.lang.String.valueOf(String.java:2994) at java.lang.StringBuilder.append(StringBuilder.java:131) at java.util.AbstractCollection.toString(AbstractCollection.java:462) at java.lang.String.valueOf(String.java:2994) at java.lang.StringBuilder.append(StringBuilder.java:131) at com.apply.entity.ExamInfo.toString(ExamInfo.java:16) at java.lang.String.valueOf(String.java:2994) at java.lang.StringBuilder.append(StringBuilder.java:131) at com.apply.entity.ApplyInfo.toString(ApplyInfo.java:17) at java.lang.String.valueOf(String.java:2994) at java.lang.StringBuilder.append(StringBuilder.java:131) at java.util.AbstractCollection.toString(AbstractCollection.java:462) at java.lang.String.valueOf(String.java:2994) at java.lang.StringBuilder.append(StringBuilder.java:131) at com.apply.entity.ExamInfo.toString(ExamInfo.java:16)
。。。。。。
2.关联属性使一方的属性在json转换时生效
使用SpringMVC 默认的jackson 进行json转换时,存在关联属性,使用@JsonIgnore忽略属性(在one的一方进行忽略,)