refactor(lib): 重构 HTTP 请求逻辑

- 优化了 HttpRequestViewModel 中的 getNewsByPage 方法，增加了上下文参数
- 重新定义了响应头的解析逻辑，提高了代码可读性和可维护性
- 在 RetrofitFactoryFragment 中更新了对 HttpRequestViewModel 的调用方式
- 引入了 Toast消息显示，提高了用户交互体验

Author: AndroidCoderPeng

app/src/main/java/com/pengxh/kt/lib/fragments/utils/RetrofitFactoryFragment.kt

@@ -27,7 +27,7 @@ class RetrofitFactoryFragment : KotlinBaseFragment<FragmentUtilsRetrofitFactoryB
 
     override fun initOnCreate(savedInstanceState: Bundle?) {
         httpRequestViewModel = ViewModelProvider(this)[HttpRequestViewModel::class.java]
-        httpRequestViewModel.getNewsByPage("头条", 1)
+        httpRequestViewModel.getNewsByPage(requireContext(), "头条", 1)
         httpRequestViewModel.httpRequestResult.observe(this) {
             if (it.status == 0) {
                 binding.textView.text = it.result.list.first().title

app/src/main/java/com/pengxh/kt/lib/vm/HttpRequestViewModel.kt

@@ -1,25 +1,27 @@
 package com.pengxh.kt.lib.vm
 
+import android.content.Context
 import androidx.lifecycle.MutableLiveData
 import com.google.gson.Gson
-import com.google.gson.JsonParser
+import com.google.gson.JsonObject
 import com.google.gson.reflect.TypeToken
 import com.pengxh.kt.lib.model.NewsListModel
 import com.pengxh.kt.lib.utils.RetrofitServiceManager
 import com.pengxh.kt.lite.base.BaseViewModel
 import com.pengxh.kt.lite.extensions.launch
+import com.pengxh.kt.lite.extensions.show
 import com.pengxh.kt.lite.utils.LoadState
 
 class HttpRequestViewModel : BaseViewModel() {
 
-    private val kTag = "HttpRequestViewModel"
-    private val gson = Gson()
+    val gson by lazy { Gson() }
     val httpRequestResult = MutableLiveData<NewsListModel>()
 
-    fun getNewsByPage(channel: String, start: Int) = launch({
+    fun getNewsByPage(context: Context, channel: String, start: Int) = launch({
         loadState.value = LoadState.Loading
         val response = RetrofitServiceManager.getNewsByPage(channel, start)
-        when (response.getResponseCode()) {
+        val header = response.getResponseHeader()
+        when (header.first) {
             0 -> {
                 httpRequestResult.value = gson.fromJson<NewsListModel>(
                     response, object : TypeToken<NewsListModel>() {}.type
@@ -29,18 +31,20 @@ class HttpRequestViewModel : BaseViewModel() {
 
             else -> {
                 loadState.value = LoadState.Fail
+                header.second.show(context)
             }
         }
     }, {
         loadState.value = LoadState.Fail
     })
 
-    private fun String.getResponseCode(): Int {
+    private fun String.getResponseHeader(): Pair<Int, String> {
         if (this.isBlank()) {
-            return 404
+            return Pair(404, "Invalid Response")
         }
-        val element = JsonParser.parseString(this)
-        val jsonObject = element.asJsonObject
-        return jsonObject.get("status").asInt
+        val jsonObject = gson.fromJson(this, JsonObject::class.java)
+        val code = jsonObject.get("code").asInt
+        val message = jsonObject.get("message").asString
+        return Pair(code, message)
     }
 }