Question

我试图理解Jackson（JSON），并首先创建了一个简单的POJO，并使用Jackson的ObjectMapper来回了。

之后，我想检查是否可以使用byte[]将“普通” Serialization（使用Java JSON创建）转换为Jackson。

这是完整的代码：

package com.example.domain;

import java.io.Serializable;
import java.util.List;

public class Student implements Serializable {

    private String studentName;
    private int studentID;
    List<String> subjects;

    public String getStudentName() {
        return studentName;
    }
    public void setStudentName(String studentName) {
        this.studentName = studentName;
    }

    public int getStudentID() {
        return studentID;
    }

    public void setStudentID(int studentID) {
        this.studentID = studentID;
    }

    public List<String> getSubjects() {
        return subjects;
    }

    public void setSubjects(List<String> subjects) {
        this.subjects = subjects;
    }

    @Override
    public String toString() {
        return "Student [studentName=" + studentName + ", studentID=" + studentID + ", subjects=" + subjects + "]";
    }
}

以下是主要应用

package com.example.json;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.List;

import com.example.domain.Student;
import com.fasterxml.jackson.databind.ObjectMapper;

public class MainApp1 {

    public static void main(String[] args) throws IOException {

        Student s = new Student();
        s.setStudentID(1);
        s.setStudentName("Student1");
        List<String> subs = new ArrayList<>();
        subs.add("Physics");
        subs.add("Chemistry");
        subs.add("Maths");
        s.setSubjects(subs);

        ObjectMapper mapper = new ObjectMapper();

        // Here, we are converting Student object
        // into bytes[] using Java Serialization

        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        ObjectOutput out = null;
        out = new ObjectOutputStream(bos);
        out.writeObject(s);
        out.flush();
        byte[] objBytes = bos.toByteArray();
        bos.close();

        // Now, seeing, if jackson's readValue() can "deserialize"
        // the bytes[] which we created using Java Serialization
        // as above.

        Student s3 = mapper.readValue(objBytes, Student.class);
        System.out.println("s3 is " + s3.toString());    
   }
}

我已经创建了一个POJO Student，我想使用Jackson API's将其转换为JSON。

我没有使用直接的POJO传递给Jackson的readValue()，而是首先使用Java Serialization将POJO序列化为byte []。

但是，当我运行它时，它给了我以下异常：

Exception in thread "main" com.fasterxml.jackson.core.JsonParseException: Unexpected character ('¬' (code 172)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')
 at [Source: (byte[])"��srcom.example.domain.Studentb���O*�I    studentIDLstudentNametLjava/lang/String;LsubjectstLjava/util/List;xptStudent1srjava.util.ArrayListx����a�IsizexpwtPhysicst    ChemistrytMathsx"; line: 1, column: 2]
    at com.fasterxml.jackson.core.JsonParser._constructError(JsonParser.java:1804)
    at com.fasterxml.jackson.core.base.ParserMinimalBase._reportError(ParserMinimalBase.java:693)
    at com.fasterxml.jackson.core.base.ParserMinimalBase._reportUnexpectedChar(ParserMinimalBase.java:591)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._handleUnexpectedValue(UTF8StreamJsonParser.java:2630)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser._nextTokenNotInObject(UTF8StreamJsonParser.java:832)
    at com.fasterxml.jackson.core.json.UTF8StreamJsonParser.nextToken(UTF8StreamJsonParser.java:729)
    at com.fasterxml.jackson.databind.ObjectMapper._initForReading(ObjectMapper.java:4141)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4000)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3091)
    at com.example.json.MainApp1.main

所以我的问题是：

我们不能使用Java Serialization使用byte []将Jackson转换为JSON吗？

我要问byte[]，如果要求是将字节从一个应用程序通过网络传输到另一应用程序，那该怎么办，那么接收应用程序将如何重构JSON？

对此有任何见解都会有很大帮助。

Java序列化对象：杰克逊可以反序列化吗？

0 个答案: