Spring Data JPA stackoverflow

1.禁止使用lombok 的@Data 註釋

　　使用@Data註釋後，默認會重寫父類的toString()方法，hashcode()等方法，在往map裏存的時候，會根據equals和hashcode方法，來計算下標，而若是@Data註釋的類與其餘類有關聯的屬性（如：@onetoone,@onetomany等）且關聯的屬性不爲空時，會不斷從關聯方的屬性進行查找，再從關聯方查找該@Data註釋的類，依次循環，形成堆棧溢出。

 

　　例子：考試信息與報名信息以 1：n  進行關聯

　　

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
 * 報名信息 apply_info
 */
@Data
@Entity
@Table(name = "apply_info")
@ApiModel(value = "ApplyInfo", description = "報名信息對象")
@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
 * 考試信息設置 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.關聯屬性使一方的屬性在json轉換時生效

使用SpringMVC 默認的jackson 進行json轉換時，存在關聯屬性，使用@JsonIgnore忽略屬性（在one的一方進行忽略，）