预计 FromJson BEGIN_OBJECT

Question

您好，我很难找到我的 Json 解析器的问题。

你好有一个对象学生（ID，姓名，年级）这就是我在文档中写我的学生的方式： public无效运行(){

        System.out.println("Server get:" + value);
        Gson gson = new Gson();
            System.out.println("this record will be created in the source document");
             String json = gson.toJson(value);
          //   System.out.println(json);

             //2. Convert object to JSON string and save into a file directly
                try (FileWriter writer = new FileWriter(File,true)) {

                    gson.toJson(value, writer);
                    writer.write("\n");
                } catch (IOException e) {
                    e.printStackTrace();
                }
    }

在文档中我得到了 {"SID":"fd36ac24-4487-49aa-bdd0-40535b55d081","Name":"Marie","Major":"IT"}

这是一个很好的学生对象。现在我想再次将此文件信息放入学生对象中。这就是我尝试这样做的方式：

    public Student Creation_Two() {
            String fichier ="C:\Users\programming\Personne_source.txt";              
         Student s1 = new Student();        

                    Gson gson = new Gson();
                    System.out.println("we try to parse the document with json to the object");



                    JsonReader reader = new JsonReader(new StringReader(fichier));    
                    reader.setLenient(true);
                    System.out.println("reader value "+reader);                 
                    try
                    {                                                       
                    s1 = gson.fromJson(reader, Student.class);                                      
                    System.out.println(s1 +" s1 have been serialized");
                    return s1;  

                    }
                    catch (IllegalStateException | JsonSyntaxException e1)
                    {
                         System.out.println("error in getting the object");
                         e1.printStackTrace();
                    }
                    return s1;              
    }

但这没有用我有错误：预期 BEGIN_OBJECT 但在第 1 行第 2 列是 STRING。

这位同学class

public class Student {
private static final long serialVersionUID = 1L;
private String SID;
    private String Name;
    private String Major;

public Student(String SID, String Name, String Major)
{
    this.setSID(SID);
    this.setName(Name);
    this.setMajor(Major);
}

public Student() {
    // TODO Auto-generated constructor stub
}

@Override
public String toString() {
    return "Student SID= " + SID + ", Name= " + Name + ", Major= " + Major + "";
}
//all the get set

Answer 1

试试这个：

Gson gson = new Gson();
System.out.println("this record will be created in the source document");
String fichier ="C:\Users\programming\Personne_source.txt";
byte[] encoded =Files.readAllBytes(Paths.get(fichier));
System.out.println("JSON: " + new String(encoded, "UTF-8"));
Student s1 = new Student();
try
{
    s1 = gson.fromJson(new String(encoded, "UTF-8"), Student.class);
    System.out.println(s1 +" s1 have been serialized");
}
catch (IllegalStateException | JsonSyntaxException e1)
{
    System.out.println("error in getting the object");
    e1.printStackTrace();
}
System.out.println(s1.toString());

Answer 2

好的，我试过你的代码，这就是我在控制台中得到的结果

JSON: {"SID":"577f484b-6ff8-4fbd-aa9d-1d7842874a03","Name":"Paul","Major":"IT"}
{"SID":"fd36ac24-4487-49aa-bdd0-40535b55d081","Name":"Marie","Major":"IT"}
error in getting the object
com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Expected EOF at line 2 column 1
Student SID= null, Name= null, Major= null
at com.google.gson.Gson.assertFullConsumption(Gson.java:772)
at com.google.gson.Gson.fromJson(Gson.java:762)
at com.google.gson.Gson.fromJson(Gson.java:710)
at com.google.gson.Gson.fromJson(Gson.java:682)
at Accepter_clients_Two.Creation_Two(Serveur_Two.java:275)
at Accepter_clients_Two.run(Serveur_Two.java:71)
at java.lang.Thread.run(Unknown Source)

类似的东西，我不明白，因为 JSON 输出输入很好。但会不会是因为我的文档中有多个 JSON 对象？

预计 FromJson BEGIN_OBJECT

FromJson Expected BEGIN_OBJECT

java

serialization

file

streamwriter

gson