Java将Json数组转换为类型化列表<；T>；

我有一个Web服务，它发送一个类型化的arraylist，我通过HttpResponse捕获它，如下所示：

// create GET request
HttpGet httpGet = new HttpGet("http://localhost:8084/MinecraftRestServer/webresources/Items");
// execute GET request
HttpResponse response = client.execute(httpGet);
// check response
StatusLine statusLine = response.getStatusLine();
int statusCode = statusLine.getStatusCode();
if (statusCode == 200) { // response OK
    // retreive response
    List<Recipe> recipesList = new ArrayList<Recipe>();
    HttpEntity jsonObj = response.getEntity();
            //What's next?

并以以下格式发布：

[{"recipeCategory":11,"recipeImageID":"diamond_ingot","recipeDescription":"Diamond ingot","recipeLocations":"0,0,0,0,0,0,0,0,1","usedImages":"air,diamond_ore","recipeID":1},{"recipeCategory":11,"recipeImageID":"iron_ingot","recipeDescription":"Iron ingot","recipeLocations":"0,0,0,0,0,0,0,0,1","usedImages":"air,iron_ore","recipeID":2},{"recipeCategory":11,"recipeImageID":"gold_ingot","recipeDescription":"Gold ingot","recipeLocations":"0,0,0,0,0,0,0,0,1","usedImages":"air,gold_ore","recipeID":3},{"recipeCategory":11,"recipeImageID":"diamond_ore","recipeDescription":"Diamond ore","recipeLocations":"0,0,0,0,0,0,0,0,1","usedImages":"air,wooden_pickaxe","recipeID":4},{"recipeCategory":11,"recipeImageID":"iron_ore","recipeDescription":"Iron ore","recipeLocations":"0,0,0,0,0,0,0,0,1","usedImages":"air,wooden_pickaxe","recipeID":5},{"recipeCategory":11,"recipeImageID":"gold_ore","recipeDescription":"Gold ore","recipeLocations":"0,0,0,0,0,0,0,0,1","usedImages":"air,wooden_pickaxe","recipeID":6},{"recipeCategory":2,"recipeImageID":"diamond_boots","recipeDescription":"Boots (Diamond)","recipeLocations":"0,0,0,1,0,1,1,0,1","usedImages":"air,diamond_ingot","recipeID":7},{"recipeCategory":2,"recipeImageID":"gold_boots","recipeDescription":"Boots (Gold)","recipeLocations":"0,0,0,1,0,1,1,0,1","usedImages":"air,gold_ingot","recipeID":8},{"recipeCategory":2,"recipeImageID":"iron_boots","recipeDescription":"Boots (Iron)","recipeLocations":"0,0,0,1,0,1,1,0,1","usedImages":"air,iron_ingot","recipeID":9},{"recipeCategory":2,"recipeImageID":"diamond_leggings","recipeDescription":"Leggings (Diamond)","recipeLocations":"1,1,1,1,0,1,1,0,1","usedImages":"air,diamond_ingot","recipeID":10},{"recipeCategory":2,"recipeImageID":"gold_leggings","recipeDescription":"Leggings (Gold)","recipeLocations":"1,1,1,1,0,1,1,0,1","usedImages":"air,gold_ingot","recipeID":11},{"recipeCategory":2,"recipeImageID":"iron_leggings","recipeDescription":"Leggings (Iron)","recipeLocations":"1,1,1,1,0,1,1,0,1","usedImages":"air,iron_ingot","recipeID":12},{"recipeCategory":2,"recipeImageID":"diamond_chestplate","recipeDescription":"Chestplate (Diamond)","recipeLocations":"1,0,1,1,1,1,1,1,1","usedImages":"air,diamond_ingot","recipeID":13},{"recipeCategory":2,"recipeImageID":"gold_chestplate","recipeDescription":"Chestplate (Gold)","recipeLocations":"1,0,1,1,1,1,1,1,1","usedImages":"air,gold_ingot","recipeID":14},{"recipeCategory":2,"recipeImageID":"iron_chestplate","recipeDescription":"Chestplate (Iron)","recipeLocations":"1,0,1,1,1,1,1,1,1","usedImages":"air,iron_ingot","recipeID":15},{"recipeCategory":2,"recipeImageID":"diamond_helmet","recipeDescription":"Helmet (Diamond)","recipeLocations":"1,1,1,1,0,1,0,0,0","usedImages":"air,diamond_ingot","recipeID":16},{"recipeCategory":2,"recipeImageID":"gold_helmet","recipeDescription":"Helmet (Gold)","recipeLocations":"1,1,1,1,0,1,0,0,0","usedImages":"air,gold_ingot","recipeID":17},{"recipeCategory":2,"recipeImageID":"iron_helmet","recipeDescription":"Helmet 

我的问题是，如何将其转换回arraylist（

arraylist

） 客户端应用程序中已存在一个Item类

我已经阅读了有关Gson库的示例，但在API 17中编译时似乎不再包含它

---

最简单的方法是什么？

伙计，谷歌是你的朋友！快速搜索“android json”或“android json parse”可以为您提供一些不错的教程，如或。

您可以使用这些教程来解析传入的json。（）

如果您已经有了一个具有适当属性的类，那么它可以像下面这样简单：

recipesList.add(new Item(1, 11, "diamond_ingot", "Diamond ingot",
                "0,0,0,0,0,0,0,0,1", "air,diamond_ore"));
recipesList.add(new Item(2, 11, "iron_ingot", "Iron ingot",
                "0,0,0,0,0,0,0,0,1", "air,iron_ore"));

public class Items {
    private List<Item> items;
    // getter+setter
}

ObjectMapper mapper = new ObjectMapper();
Items = mapper.readValue(src, Items.class);

公共类项目{
私人清单项目；
//getter+setter
}
ObjectMapper mapper=新的ObjectMapper（）；
Items=mapper.readValue（src，Items.class）；

---

有关更多信息，请参阅。

我认为您应该使用json简单库将字符串json解析为JsonObject并转换为简单数据类型。

Step 1 : Item obj=new Item;

Step 2: Parse the json formar for example here :

[[Example1][1]

Step 3: while parsing put ur values in obj :

obj.recipeCategory=value1;

Step 4: insret ur obj into arraylist:

arrayList.add(obj);

例如：

获取JSONArray中的每个元素JSONObject，然后将其解析为简单数据类型：

long recipeCategory = (long) jsonObject.get("recipeCategory");

---

如果使用Eclipse，请从项目中下载并包括

GSON

jar

如果使用Android Studio，请打开

build.gradle

并将以下内容添加到

依赖项

块中。或者，您也可以选择不使用maven，只需将jar放在lib文件夹中

compile 'com.google.code.gson:gson:2.2.4'

接下来，使用

GSON

构建项目列表。 确保您的

Item.java

类具有与

JSON

响应中相同的成员名称

 List<Recipe> recipesList = new ArrayList<Recipe>();
 HttpEntity jsonObj = response.getEntity();
 String data = EntityUtils.toString(entity);
 Log.d("TAG", data);
 Gson gson = new GsonBuilder().create();
 recipesList = gson.fromJson(data, new TypeToken<List<Item>>() {}.getType());

List recipesList=new ArrayList（）；
HttpEntity jsonObj=response.getEntity（）；
字符串数据=EntityUtils.toString（实体）；
Log.d（“标签”，数据）；
Gson Gson=new GsonBuilder（）.create（）；
recipesList=gson.fromJson（数据，newTypeToken（）{}.getType（））；

---

请确保适当地处理异常。

您可以使用

Gson

正如许多用户所说，下面是一个使用

Gson

的RESTfull客户端示例：

public class RestRequest {
    Gson gson = new Gson();

    public <T> T post(String url, Class<T> clazz,
        List<NameValuePair> parameters) {
    // Create a new HttpClient and Post Header
    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost = new HttpPost(url);
    try {
        // Add your data
        httppost.setEntity(new UrlEncodedFormEntity(parameters));
        // Execute HTTP Post Request
        HttpResponse response = httpclient.execute(httppost);
        StringBuilder json = inputStreamToString(response.getEntity()
                .getContent());
        T gsonObject = gson.fromJson(json.toString(), clazz);
        return gsonObject;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
    }

    // Fast Implementation
    private StringBuilder inputStreamToString(InputStream is)
        throws IOException {
    String line = "";
    StringBuilder total = new StringBuilder();

    // Wrap a BufferedReader around the InputStream
    BufferedReader rd = new BufferedReader(new InputStreamReader(is));

    // Read response until the end
    while ((line = rd.readLine()) != null) {
        total.append(line);
    }

    // Return full string
    return total;
    }

}

公共类重新请求{
Gson Gson=新的Gson（）；
公共T帖子（字符串url、类clazz、，
列表参数）{
//创建一个新的HttpClient和Post头
HttpClient HttpClient=新的DefaultHttpClient（）；
HttpPost HttpPost=新的HttpPost（url）；
试一试{
//添加您的数据
setEntity（新的UrlEncodedFormEntity（参数））；
//执行HTTP Post请求
HttpResponse response=httpclient.execute（httppost）；
StringBuilder json=inputStreamToString（response.getEntity（）
.getContent（））；
T gsonObject=gson.fromJson（json.toString（），clazz）；
返回gsonObject；
}捕获（例外e）{
e、 printStackTrace（）；
}
返回null；
}
//快速实现
私有StringBuilder inputStreamToString（InputStream为）
抛出IOException{
字符串行=”；
StringBuilder总计=新StringBuilder（）；
//在InputStream周围包装一个BufferedReader
BufferedReader rd=新的BufferedReader（新的InputStreamReader（is））；
//读取响应直到结束
而（（line=rd.readLine（））！=null）{
合计.追加（行）；
}
//返回完整字符串
返回总数；
}
}

用法如下所示：

new RestRequest（“myserver.com/rest/somewebservice”、SomeClass.class、Arrays.asList（新的基本值对（“后参数”、“someParameterValue”）））

其中
SomeClass.class
将是
Recipe[].class
。还要检查问题以正确处理服务器端错误。
u的意思是说要将json解析为arraylist？@MT8是的，它是一个类型化的arraylist，类项为typecreate a arraylist instance，解析json，存储在arraylist中，问题是什么？
我已经阅读了有关Gson库的示例，但在API 17中编译时似乎不再包含它了。
这是错误的
GSON
从未与android api一起包含。如果使用
Android Studio
@RobbieVercammen，您需要下载jar或将其添加到
build.gradle
中的
dependencies
块看看我的答案。它展示了如何将JSON字符串解析为一个类型化列表。更多的是评论，更多的是回答感谢批评者。。。对于教程，它们非常有用。如果你不知道你要用谷歌搜索什么，用谷歌搜索是不容易的。我猜我在谷歌上搜索得太具体了。我正在尝试你的方法！我已经添加了gson库，但是现在我遇到了networkonmain线程异常。等等：）您不应该在主线程上执行任何网络操作。如果您在修复
NetworkOnMainThreadException
时遇到问题，那么已经有很多答案了-我已经找到了答案，我用一个新的runable包围了它，并设法让列表在填充内容之前等待。但是，在本地主机上调用我的Web服务时，我仍然被拒绝连接。我认为在模拟器或设备上使用本地主机将不起作用。您可能需要使用承载WebDevice的计算机的IP地址。不，是缺少权限！它成功了，我已经从网络服务中得到了我的数据。谢谢。顺便说一句，如果您为专用设备打开端口，它在本地主机上也可以工作；）Inputstream到string是我的第一种方法，但Varuns的答案更准确。谢谢你的意见
public class RestRequest {
    Gson gson = new Gson();

    public <T> T post(String url, Class<T> clazz,
        List<NameValuePair> parameters) {
    // Create a new HttpClient and Post Header
    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost = new HttpPost(url);
    try {
        // Add your data
        httppost.setEntity(new UrlEncodedFormEntity(parameters));
        // Execute HTTP Post Request
        HttpResponse response = httpclient.execute(httppost);
        StringBuilder json = inputStreamToString(response.getEntity()
                .getContent());
        T gsonObject = gson.fromJson(json.toString(), clazz);
        return gsonObject;
    } catch (Exception e) {
        e.printStackTrace();
    }
    return null;
    }

    // Fast Implementation
    private StringBuilder inputStreamToString(InputStream is)
        throws IOException {
    String line = "";
    StringBuilder total = new StringBuilder();

    // Wrap a BufferedReader around the InputStream
    BufferedReader rd = new BufferedReader(new InputStreamReader(is));

    // Read response until the end
    while ((line = rd.readLine()) != null) {
        total.append(line);
    }

    // Return full string
    return total;
    }

}