关于数据序列化(4),FastJson的两个bug

bug1 fastJson循环引用引发一个bug

fastJson可以将一个对象序列化为json，也可以通过反序列化出一个完整的对象。且支持循环引用。

package com.sincetimes.website.core.common.support;

import com.sincetimes.website.core.common.vo.ToStringAbstract;

/** ::new */
public class DataSimpleVO {
public String name;
public Object value;
public Object value1;

public DataSimpleVO() {
}

public DataSimpleVO(String name, Object value) {
this.name = name;
this.value = value;
}

@Override
public String toString() {
return "DataSimpleVO [name=" + name + ", value=" + value + ", value1=" + value1 + "]";
}

}

DataSimpleVO a = new DataSimpleVO("a", 1);
DataSimpleVO b = new DataSimpleVO("b", 2);
b.value = a;
Map<String, Object> map = new HashMap<>();
map.put(a.name, a);
b.value1 = map;
String jsonStr = JSON.toJSONString(b);
System.out.println(jsonStr);
DataSimpleVO obj = JSON.parseObject(jsonStr, DataSimpleVO.class);
System.out.println(obj.toString());

执行结果

{"name":"b","value":{"name":"a","value":1},"value1":{"a":{"$ref":"$.value"}}}
DataSimpleVO [name=b, value={"name":"a","value":1}, value1={"a":{"name":"a","value":1}}]

反序列化成功

改一下代码

DataSimpleVO a = new DataSimpleVO("a", 1);
DataSimpleVO b = new DataSimpleVO("b", 2);
b.value1 = a;
Map<String, Object> map = new HashMap<>();
map.put(a.name, a);
b.value = map;
String jsonStr = JSON.toJSONString(b);
System.out.println(jsonStr);
DataSimpleVO obj = JSON.parseObject(jsonStr, DataSimpleVO.class);
System.out.println(obj.toString());

执行结果

{"name":"b","value":{"a":{"name":"a","value":1}},"value1":{"$ref":"$.value.a"}}
DataSimpleVO [name=b, value={"a":{"name":"a","value":1}}, value1=null]

b中的value1为空,反序列化失败

bug2 要序列化的类含有Class类型属性引起的循环递归无法结束最后内存溢出

要序列化、反序列化的类

public class Request implements Serializable {

private static final long serialVersionUID = -3145939364922415428L;

private Class<?> clazz;

private String method;

private Object param;

public Class<?> getClazz() {
return clazz;
}

public void setClazz(Class<?> clazz) {
this.clazz = clazz;
}

public String getMethod() {
return method;
}

public void setMethod(String method) {
this.method = method;
}

public Object getParam() {
return param;
}

public void setParam(Object param) {
this.param = param;
}

public Object invoke(Object bean) throws Exception {
return clazz.getMethod(method, param.getClass()).invoke(bean, param);
}
}

触发bug

Request r = new Request();
r.setClazz(Integer.class);
String s = JSON.toJSONString(r, SerializerFeature.WriteClassName);
System.out.println(s);
JSON.parseObject(s);//bug 触发

我们看看内部

public static JSONObject parseObject(String text) {
Object obj = parse(text);
if (obj instanceof JSONObject) {
return (JSONObject) obj;
}

return (JSONObject) JSON.toJSON(obj);
}

如果改为JSON.parseObject(s, Request.class);或者直接使用JSON.parse(str)就没问题。

最后的建议：

不要使用JSON.parseObject(…)只使用JSON.parse(str);