JSON使用Java中的GSON对使用HashMap成员的自定义类进行解码

问题描述

  class IndexItem {
 private String word; 
 private HashMap< String，Integer>文档; 
私人整数; 
 
 public IndexItem（字符串字）{
 this.total = 0; 
 this.docs = new HashMap< String，Integer>（）; 
 this.word = word; 
} 
 
 public IndexItem（）{
 this.total = 0; 
 this.docs = new HashMap< String，Integer>（）; 
 this.word =; 
} 
} 
  

我还有以下JSON字符串此类使用GSON的实例：

  {word：refer，docs：{c84ada58bb47e7ee8fab14d6d0ae1978.html： 7，7664010c28b7366813f52b30fd683f43.html：6，a51ed147e16ea44244d7362367caeb4e.html：2}，total：15} 
  

我试着运行下面的命令来解码这个字符串：

  IndexItem item = new Gson（）。fromJson（jsonStr ，IndexItem.class）; 
  

当我尝试运行它时，出现以下错误消息：

 线程main中的异常com.google.gson.JsonParseException：
 JsonDeserializer MapTypeAdapter未能反序列化
 json对象
 {c84ada58bb47e7ee8fab14d6d0ae1978.html：7，7664010c28b7366813f52b30fd683f43.html：6，a51ed147e16ea44244d7362367caeb4e.html：2} 
给定类型java.util.HashMap 
在
 com.google .gson.JsonDeserializerExceptionWrapper.deserialize（JsonDeserializerExceptionWrapper.java:63）
 at 
 com.google.gson.JsonDeserializationVisitor.invokeCustomDeserializer（JsonDeserializationVisitor.java:88）
 at 
 com.google .gson.JsonObjectDeserializationVisitor.visitFieldUsingCustomHandler（JsonObjectDeserializationVisitor.java:116）
  

我是GSON的新手，很长一段时间没有处理Java。所以我的问题是：

有没有办法让GSON解码我班的HashMap？或者我是否在谈论这一切都是错误的，应该采取不同的方法？如果是的话，我应该在哪里看？

>

确保在将您的JSON字符串发送给Gson之前清理了空白区域。

I have the following class:

class IndexItem {
    private String word;
    private HashMap<String, Integer> docs;
    private Integer total;

    public IndexItem(String word) {
        this.total = 0;
        this.docs = new HashMap<String, Integer>();
        this.word = word;
    }

    public IndexItem() {
        this.total = 0;
        this.docs = new HashMap<String, Integer>();
        this.word = "";
    }
}

I also have the following JSON string encoded from one of this classes instances using GSON:

{"word":"refer","docs":{"c84ada58bb47e7ee8fab14d6d0ae1978.html":7,"7664010c28b7366813f52b30fd683f43.html":6,"a51ed147e16ea44244d7362367caeb4e.html":2},"total":15}

I tried running the following command to decode this string:

IndexItem item = new Gson().fromJson(jsonStr, IndexItem.class);

And I get the following error message when I try running it:

Exception in thread "main" com.google.gson.JsonParseException: 
  The JsonDeserializer MapTypeAdapter failed to deserialized 
  json object
    {"c84ada58bb47e7ee8fab14d6d0ae1978.html":7,"7664010c28b7366813f52b30fd683f43.html":6,"a51ed147e16ea44244d7362367caeb4e.html":2} 
    given the type class java.util.HashMap
at  
   com.google.gson.JsonDeserializerExceptionWrapper.deserialize(JsonDeserializerExceptionWrapper.java:63)
at
com.google.gson.JsonDeserializationVisitor.invokeCustomDeserializer(JsonDeserializationVisitor.java:88)
at 
com.google.gson.JsonObjectDeserializationVisitor.visitFieldUsingCustomHandler(JsonObjectDeserializationVisitor.java:116)

I am new to GSON and haven't dealt with Java in a long time. So my question is:

Is there a way to get GSON to decode the HashMap in my class? OR am I going about this all wrong and should take a different approach? If so where should I look?

解决方案

Sorry to answer my own question, but...

Make sure the white space is cleaned up around your JSON string before sending it to Gson.

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