java.lang.OutOfMemory错误: Java heap space with JSON conversion

Question

listaDecretoSingolo = new ArrayList<>();
listaDettaglioDecretoSingolo = new ArrayList<>();

for(int i = 0; i < 1022; i++){
    decretoSingoloTemp = new DecretoSingoloViewObject("Roma", "ABCDE3593CXXE",
    "decreto singolo", date,new BigDecimal(56000), new BigDecimal(343434),
    new BigDecimal(55656), new BigDecimal(9999));

    for(int j = 0; j < 111; j++){
        listaDettaglioDecretoSingolo.add(new DettaglioDecretoSingoloViewObject(22,
                                date, "numero dec pag",
                                "tipo pag", new BigDecimal(45),
                                "nota dec"));
                    }
        decretoSingoloTemp.setDetails(listaDettaglioDecretoSingolo);
        listaDecretoSingolo.add(decretoSingoloTemp);
}
ObjectWriter ow = new ObjectMapper().writer().withDefaultPrettyPrinter();
String jsonList = null;
jsonList = ow.writeValueAsString(listaDecretoSingolo);

我想测试上面这段代码的速度。但是，当我运行它并尝试将列表转换为 JSON 字符串时，我收到此异常:

at com.fasterxml.jackson.core.util.TextBuffer.carr(TextBuffer.java:703) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.core.util.TextBuffer.expand(TextBuffer.java:664) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.core.util.TextBuffer.append(TextBuffer.java:455) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.core.io.SegmentedStringWriter.write(SegmentedStringWriter.java:67) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.core.json.WriterBasedJsonGenerator._flushBuffer(WriterBasedJsonGenerator.java:1910) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.core.json.WriterBasedJsonGenerator.writeRawLong(WriterBasedJsonGenerator.java:496) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.core.json.WriterBasedJsonGenerator.writeRaw(WriterBasedJsonGenerator.java:430) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.core.util.DefaultPrettyPrinter$Lf2SpacesIndenter.writeIndentation(DefaultPrettyPrinter.java:472) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.core.util.DefaultPrettyPrinter.beforeObjectEntries(DefaultPrettyPrinter.java:265) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.core.json.WriterBasedJsonGenerator._writePPFieldName(WriterBasedJsonGenerator.java:297) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.core.json.WriterBasedJsonGenerator._writeFieldName(WriterBasedJsonGenerator.java:227) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.core.json.WriterBasedJsonGenerator.writeFieldName(WriterBasedJsonGenerator.java:116) [jackson-core-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:539) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:100) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:21) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:100) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:21) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:114) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ObjectWriter._configAndWriteValue(ObjectWriter.java:809) [jackson-databind-2.3.3.jar:2.3.3]
at com.fasterxml.jackson.databind.ObjectWriter.writeValueAsString(ObjectWriter.java:684) [jackson-databind-2.3.3.jar:2.3.3]
at it.istruzione.hp.scuoleSicure.controller.ConsultaPagamentiController.ricercaConsultaImpegni(ConsultaPagamentiController.java:116) [classes:]
at it.istruzione.hp.scuoleSicure.controller.ConsultaPagamentiController$$FastClassBySpringCGLIB$$8a5debc0.invoke(<generated>) [spring-core-4.0.5.RELEASE.jar:]
at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) [spring-core-4.0.5.RELEASE.jar:4.0.5.RELEASE]
at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:708) [spring-aop-4.0.5.RELEASE.jar:4.0.5.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) [spring-aop-4.0.5.RELEASE.jar:4.0.5.RELEASE]

当列表尺寸较小时(例如 10、20、30..)，我不会收到此错误。但是，当我增加大小，接近数千或更少时，我遇到了这个问题......

有什么办法可以解决吗？

Answer 1

您正在创建大量对象，因此需要大量内存。尝试使用 -Xmx 选项来增加最大堆大小。

Xmx and Xms are well explained here.