在Android中与Moshi一起解析没有密钥的JSON列表

Question

我要做的是从用户存储库列表的GitHub API呼叫中获取JSON响应。

GitHub的响应示例如下所示。

[
  {
    "id": 78688034,
    "node_id": "MDEwOlJlcG9zaXRvcnk3ODY4ODAzNA==",
    "name": "py3status",
    "full_name": "randomguy/py3status",
    "private": false,
    "owner": {
      "login": "randomguy",
      "id": 798223,
      "node_id": "MDQ6VXNlcjc5ODIyMw==",
      "avatar_url": "https://avatars.githubusercontent.com/u/798223?v=4",
      "gravatar_id": "",
      "url": "https://api.github.com/users/randomguy",
      "html_url": "https://github.com/randomguy",
      "followers_url": "https://api.github.com/users/randomguy/followers",
      "following_url": "https://api.github.com/users/randomguy/following{/other_user}",
      "gists_url": "https://api.github.com/users/randomguy/gists{/gist_id}",
      "starred_url": "https://api.github.com/users/randomguy/starred{/owner}{/repo}",
      "subscriptions_url": "https://api.github.com/users/randomguy/subscriptions",
      "organizations_url": "https://api.github.com/users/randomguy/orgs",
      "repos_url": "https://api.github.com/users/randomguy/repos",
      "events_url": "https://api.github.com/users/randomguy/events{/privacy}",
      "received_events_url": "https://api.github.com/users/randomguy/received_events",
      "type": "User",
      "site_admin": false
    },
    "html_url": "https://github.com/randomguy/py3status",
    "description": "py3status is an extensible i3status wrapper written in python",
    "fork": true,
    "url": "https://api.github.com/repos/randomguy/py3status",
    "forks_url": "https://api.github.com/repos/randomguy/py3status/forks",
    "keys_url": "https://api.github.com/repos/randomguy/py3status/keys{/key_id}",
    "collaborators_url": "https://api.github.com/repos/randomguy/py3status/collaborators{/collaborator}",
    "teams_url": "https://api.github.com/repos/randomguy/py3status/teams",
    "hooks_url": "https://api.github.com/repos/randomguy/py3status/hooks",
    "issue_events_url": "https://api.github.com/repos/randomguy/py3status/issues/events{/number}",
    "events_url": "https://api.github.com/repos/randomguy/py3status/events",
    "assignees_url": "https://api.github.com/repos/randomguy/py3status/assignees{/user}",
    "branches_url": "https://api.github.com/repos/randomguy/py3status/branches{/branch}",
    "tags_url": "https://api.github.com/repos/randomguy/py3status/tags",
    "blobs_url": "https://api.github.com/repos/randomguy/py3status/git/blobs{/sha}",
    "git_tags_url": "https://api.github.com/repos/randomguy/py3status/git/tags{/sha}",
    "git_refs_url": "https://api.github.com/repos/randomguy/py3status/git/refs{/sha}",
    "trees_url": "https://api.github.com/repos/randomguy/py3status/git/trees{/sha}",
    "statuses_url": "https://api.github.com/repos/randomguy/py3status/statuses/{sha}",
    "languages_url": "https://api.github.com/repos/randomguy/py3status/languages",
    "stargazers_url": "https://api.github.com/repos/randomguy/py3status/stargazers",
    "contributors_url": "https://api.github.com/repos/randomguy/py3status/contributors",
    "subscribers_url": "https://api.github.com/repos/randomguy/py3status/subscribers",
    "subscription_url": "https://api.github.com/repos/randomguy/py3status/subscription",
    "commits_url": "https://api.github.com/repos/randomguy/py3status/commits{/sha}",
    "git_commits_url": "https://api.github.com/repos/randomguy/py3status/git/commits{/sha}",
    "comments_url": "https://api.github.com/repos/randomguy/py3status/comments{/number}",
    "issue_comment_url": "https://api.github.com/repos/randomguy/py3status/issues/comments{/number}",
    "contents_url": "https://api.github.com/repos/randomguy/py3status/contents/{+path}",
    "compare_url": "https://api.github.com/repos/randomguy/py3status/compare/{base}...{head}",
    "merges_url": "https://api.github.com/repos/randomguy/py3status/merges",
    "archive_url": "https://api.github.com/repos/randomguy/py3status/{archive_format}{/ref}",
    "downloads_url": "https://api.github.com/repos/randomguy/py3status/downloads",
    "issues_url": "https://api.github.com/repos/randomguy/py3status/issues{/number}",
    "pulls_url": "https://api.github.com/repos/randomguy/py3status/pulls{/number}",
    "milestones_url": "https://api.github.com/repos/randomguy/py3status/milestones{/number}",
    "notifications_url": "https://api.github.com/repos/randomguy/py3status/notifications{?since,all,participating}",
    "labels_url": "https://api.github.com/repos/randomguy/py3status/labels{/name}",
    "releases_url": "https://api.github.com/repos/randomguy/py3status/releases{/id}",
    "deployments_url": "https://api.github.com/repos/randomguy/py3status/deployments",
    "created_at": "2017-01-11T23:05:15Z",
    "updated_at": "2017-01-11T23:05:17Z",
    "pushed_at": "2017-08-04T18:56:56Z",
    "git_url": "git://github.com/randomguy/py3status.git",
    "ssh_url": "[email protected]:randomguy/py3status.git",
    "clone_url": "https://github.com/randomguy/py3status.git",
    "svn_url": "https://github.com/randomguy/py3status",
    "homepage": "",
    "size": 3078,
    "stargazers_count": 0,
    "watchers_count": 0,
    "language": "Python",
    "has_issues": false,
    "has_projects": true,
    "has_downloads": true,
    "has_wiki": true,
    "has_pages": false,
    "forks_count": 0,
    "mirror_url": null,
    "archived": false,
    "disabled": false,
    "open_issues_count": 0,
    "license": {
      "key": "bsd-3-clause",
      "name": "BSD 3-Clause \"New\" or \"Revised\" License",
      "spdx_id": "BSD-3-Clause",
      "url": "https://api.github.com/licenses/bsd-3-clause",
      "node_id": "MDc6TGljZW5zZTU="
    },
    "allow_forking": true,
    "is_template": false,
    "web_commit_signoff_required": false,
    "topics": [

    ],
    "visibility": "public",
    "forks": 0,
    "open_issues": 0,
    "watchers": 0,
    "default_branch": "master"
  }
]

如您所见，响应是以arraylist的形式 由于此响应对JSON列表没有钥匙值，因此自动生成的数据类如下所示（UserRepoListerSponse和UserRepoListerSponseponsem）。

class UserRepoListResponse : ArrayList<UserRepoListResponseItem>()

@JsonClass(generateAdapter = true)
data class UserRepoListResponseItem(
    @Json(name ="allow_forking") val allowForking: Boolean,
    @Json(name ="archive_url") val archiveUrl: String,
    @Json(name ="archived") val archived: Boolean,
    @Json(name ="assignees_url") val assigneesUrl: String,
    @Json(name ="blobs_url") val blobsUrl: String,
    @Json(name ="branches_url") val branchesUrl: String,
    @Json(name ="clone_url") val cloneUrl: String,
    @Json(name ="collaborators_url") val collaboratorsUrl: String,
    @Json(name ="comments_url") val commentsUrl: String,
    @Json(name ="commits_url") val commitsUrl: String,
    @Json(name ="compare_url") val compareUrl: String,
    @Json(name ="contents_url") val contentsUrl: String,
    @Json(name ="contributors_url") val contributorsUrl: String,
    @Json(name ="created_at") val createdAt: String,
    @Json(name ="default_branch") val defaultBranch: String,
    @Json(name ="deployments_url") val deploymentsUrl: String,
    @Json(name ="description") val description: String,
    @Json(name ="disabled") val disabled: Boolean,
    @Json(name ="downloads_url") val downloadsUrl: String,
    @Json(name ="events_url") val eventsUrl: String,
    @Json(name ="fork") val fork: Boolean,
    @Json(name ="forks") val forks: Int,
    @Json(name ="forks_count") val forksCount: Int,
    @Json(name ="forks_url") val forksUrl: String,
    @Json(name ="full_name") val fullName: String,
    @Json(name ="git_commits_url") val gitCommitsUrl: String,
    @Json(name ="git_refs_url") val gitRefsUrl: String,
    @Json(name ="git_tags_url") val gitTagsUrl: String,
    @Json(name ="git_url") val gitUrl: String,
    @Json(name ="has_downloads") val hasDownloads: Boolean,
    @Json(name ="has_issues") val hasIssues: Boolean,
    @Json(name ="has_pages") val hasPages: Boolean,
    @Json(name ="has_projects") val hasProjects: Boolean,
    @Json(name ="has_wiki") val hasWiki: Boolean,
    @Json(name ="homepage") val homepage: String,
    @Json(name ="hooks_url") val hooksUrl: String,
    @Json(name ="html_url") val htmlUrl: String,
    @Json(name ="id") val id: Int,
    @Json(name ="is_template") val isTemplate: Boolean,
    @Json(name ="issue_comment_url") val issueCommentUrl: String,
    @Json(name ="issue_events_url") val issueEventsUrl: String,
    @Json(name ="issues_url") val issuesUrl: String,
    @Json(name ="keys_url") val keysUrl: String,
    @Json(name ="labels_url") val labelsUrl: String,
    @Json(name ="language") val language: String,
    @Json(name ="languages_url") val languagesUrl: String,
    @Json(name ="license") val license: License,
    @Json(name ="merges_url") val mergesUrl: String,
    @Json(name ="milestones_url") val milestonesUrl: String,
    @Json(name ="mirror_url") val mirrorUrl: Any,
    @Json(name ="name") val name: String,
    @Json(name ="node_id") val nodeId: String,
    @Json(name ="notifications_url") val notificationsUrl: String,
    @Json(name ="open_issues") val openIssues: Int,
    @Json(name ="open_issues_count") val openIssuesCount: Int,
    @Json(name ="owner") val owner: Owner,
    @Json(name ="private") val privateValue: Boolean,
    @Json(name ="pulls_url") val pullsUrl: String,
    @Json(name ="pushed_at") val pushedAt: String,
    @Json(name ="releases_url") val releasesUrl: String,
    @Json(name ="size") val size: Int,
    @Json(name ="ssh_url") val sshUrl: String,
    @Json(name ="stargazers_count") val stargazersCount: Int,
    @Json(name ="stargazers_url") val stargazersUrl: String,
    @Json(name ="statuses_url") val statusesUrl: String,
    @Json(name ="subscribers_url") val subscribersUrl: String,
    @Json(name ="subscription_url") val subscriptionUrl: String,
    @Json(name ="svn_url") val svnUrl: String,
    @Json(name ="tags_url") val tagsUrl: String,
    @Json(name ="teams_url") val teamsUrl: String,
    @Json(name ="topics") val topics: List<String>,
    @Json(name ="trees_url") val treesUrl: String,
    @Json(name ="updated_at") val updatedAt: String,
    @Json(name ="url") val url: String,
    @Json(name ="visibility") val visibility: String,
    @Json(name ="watchers") val watchers: Int,
    @Json(name ="watchers_count") val watchersCount: Int
)

我正在使用Retrofit2和Moshi。依赖项如下所示

// retrofit moshi
implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation "com.squareup.retrofit2:converter-moshi:2.9.0"

//Moshi Library Dependencies - Core Moshi JSON Library and Moshi's Kotlin support and converter factory
implementation "com.squareup.moshi:moshi:1.13.0"
implementation "com.squareup.moshi:moshi-kotlin:1.13.0"

，这是我设置moshi和retrofit2的方式

val moshi = Moshi.Builder()
    .add(KotlinJsonAdapterFactory())
    .build()

private val retrofit = Retrofit.Builder()
    .addConverterFactory(MoshiConverterFactory.create(moshi))
    .baseUrl(BASE_URL)
    .client(getHttpClient())
    .build()

，这是我的API调用函数，

@GET("/users/{username}/repos")
suspend fun getUserRepos(
    @Path("username") username: String,
): UserRepoListResponse

然后我调用API调用，我得到此错误

Expected BEGIN_OBJECT but was BEGIN_ARRAY at path $

我在做什么错？请帮我..

Answer 1

因为您获得的JSON是一个数组，因此您需要返回数组（列表）类型而不是对象类型。该错误来自Moshi，试图将数组（外代码）作为对象（外代码{}）作为对象。

更改以下内容：

@GET("/users/{username}/repos")
suspend fun getUserRepos(
    @Path("username") username: String,
): UserRepoListResponse

返回列表

@GET("/users/{username}/repos")
suspend fun getUserRepos(
    @Path("username") username: String,
): List<UserRepoListResponseItem>