Android：使用GSON失敗的JSON到對象

我是Android開發的新手，並且有一個關於如何使用GSON版本2.6.1將JSON字符串轉換爲類實例的問題。Android：使用GSON失敗的JSON到對象

我有一個需要轉換的字符串這樣的對象：

{ 
"Messages": [{ 
    "ForwardMsg": true, 
    "IsAdmin": true, 
    "MsgBody": "Some text", 
    "SysInfo": null, 
    "Recipients": ["Some test"] 
}, { 
    "ForwardMsg": true, 
    "IsAdmin": false, 
    "MsgBody": "Some other text", 
    "SysInfo": null, 
    "Recipients": ["Some test", "Some more text"] 
}] 
}

有了這個（http://howtodoinjava.com/best-practices/google-gson-tutorial-convert-java-object-to-from-json/）爲靈感，我想出了以下內容：我有一個類DemoMessageList，看起來像這樣的：

import java.util.List; 

public class DemoMessageList { 

private List< DemoMessage> messages; 

public DemoMessageList() { 
} 

public List<DemoMessage> getMessages() { 
    return messages; 
} 

public void setMessages(List<DemoMessage> messages) { 
    this.messages = messages; 
} 

@Override 
public String toString() 
{ 
    return "Messages ["+ messages + "]"; 
} 
}

和A類DemoMessage，看起來像這樣：

import java.util.List; 

public class DemoMessage { 
private Boolean forwardMsg; 
private Boolean isAdmin; 
private String msgBody; 
private String sysInfo; 
private List<String> recipients; 

public Boolean getForwardMsg() { 
    return forwardMsg; 
} 

public void setForwardMsg(Boolean forwardMsg) { 
    this.forwardMsg = forwardMsg; 
} 

public Boolean doForwardMsg() { 
    return forwardMsg; 
} 

public Boolean getIsAdmin() { 
    return isAdmin; 
} 

public void setIsAdmin(Boolean isAdmin) { 
    this.isAdmin = isAdmin; 
} 

public String getMsgBody() { 
    return msgBody; 
} 

public void setMsgBody(String msgBody) { 
    this.msgBody = msgBody; 
} 

public String getSysInfo() { 
    return sysInfo; 
} 

public void setSysInfo(String sysInfo) { 
    this.sysInfo = sysInfo; 
} 

public List<String> getRecipients() { 
    return recipients; 
} 

public void setRecipients(List<String> recipients) { 
    this.recipients = recipients; 
} 
}

當我做到這一點，嘗試變換：

public void test() { 
String demoData = {"Messages": [{ "ForwardMsg": true, "IsAdmin": false,"MsgBody": "Some other text", "SysInfo": null, "Recipients": ["Some test", "Some more text"]}]} 
Log.d("AsData ", "demoData: " + demoData); 
Gson gson = new Gson(); 
DemoMessageList dmList = gson.fromJson(demoData, DemoMessageList.class); 
Log.d("AsList ", "dmList: " + dmList.toString()); 
Log.d("ListSize ", "dmList - Size: " + String.valueOf(dmList.getMessages().size())); 
}

我得到這樣的記錄：

demoData: {"Messages": [{ "ForwardMsg": true, "IsAdmin": false, "MsgBody": "Some other text", "SysInfo": null, "Recipients": ["Some test", "Some more text"]}]} 
dmList: Messages [null] 
dmList - Size: 0

爲什麼這裏會失敗？請幫忙!!!

來源

2016-04-06 Morny

您的JSON名稱與您的班級字段名稱不同。 GSON會查看您的字段名稱以進行轉換。

使用模型類這樣的自定義命名，

@SerializedName("ForwardMsg") 
private Boolean forwardMsg; 
@SerializedName("IsAdmin") 
private Boolean isAdmin; 
@SerializedName("MsgBody") 
private String msgBody; 
@SerializedName("SysInfo") 
private String sysInfo; 
@SerializedName("Recipients") 
private List<String> recipients;

，並保持你的其他類，

@SerializedName("Messages") 
private List< DemoMessage> messages;

來源

2016-04-06 10:22:04

使用駱駝在你的JSON屬性名稱：

{ 
"messages": [{ 
    "forwardMsg": true, 
    "isAdmin": true, 
    "msgBody": "Some text", 
    "sysInfo": null, 
    "recipients": ["Some test"] 
}, { 
    "forwardMsg": true, 
    "isAdmin": false, 
    "msgBody": "Some other text", 
    "sysInfo": null, 
    "recipients": ["Some test", "Some more text"] 
}] 
}

..並使字段名匹配JSON屬性名稱的大小寫，例如：

private List<DemoMessage> messages;

簡而言之：JSON屬性名稱必須與您的類中定義的字段（拼音和字母大小寫）匹配。

來源

2016-04-06 10:23:38 jaolstad

你們搖滾傢伙！增加這個時候

巴拉斯鎂的回答完美的作品在我的小測試，：

import com.google.gson.annotations.SerializedName;

我有在包含JSON在現實世界中的應用，因爲它是通過一個Web服務提供的字符串沒有控制權。

這一直在困擾我2天，所以我期待與項目繼續。

再次感謝

來源

2016-04-06 10:35:52 Morny

Bharat的回答是正確的。字段名稱區分大小寫。

來源

2016-05-05 10:06:47 Pehlaj

Android：使用GSON失敗的JSON到對象

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