SendGridで日本語でWebAPIを使ってメール送信しようとすると400番(Bad Request)エラーになってしまう。

SendGridで日本語でWebAPIを使ってメール送信しようとすると文字化けしてしまい、400番(Bad Request)エラーになってしまいます。

System.out
1I/System.out: HTTP Exception 400 Bad Request
2    	com.github.kittinunf.fuel.core.FuelError$Companion.wrap(FuelError.kt:84)
3    	kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:665)(中略)
4    Caused by: HTTP Exception 400 Bad Request
5    	com.github.kittinunf.fuel.core.FuelError$Companion.wrap(FuelError.kt:86)
6    Caused by: com.github.kittinunf.fuel.core.HttpException: HTTP Exception 400 Bad Request
7    	com.github.kittinunf.fuel.core.requests.SuspendableRequest.prepareResponse(SuspendableRequest.kt:32)
8    	com.github.kittinunf.fuel.core.requests.SuspendableRequest.awaitResult(SuspendableRequest.kt:43)
9    	com.github.kittinunf.fuel.core.DeserializableKt.awaitResponseResult(Deserializable.kt:276)
10    	com.example.rworksample00026.ui.dailyreports.DailyReportsSendConfirmActivity$mailSend$1$invokeSuspend$$inlined$awaitStringResponseResult$default$1.invokeSuspend(Coroutines.kt:79)
11I/System.out: 	kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
12    	kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
13    	kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:571)
14    	kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:750)
15    	kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:678)
16    	kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:665)
17I/System.out: --> POST https://api.sendgrid.com/v3/mail/send
18    Body : 
19            {
20                "personalizations": [
21                    {
22                        "to": [
23                            {
24                                "email": "xxxxxxxx@gmail.com"
25I/System.out:                         }
26                        ]
27                    }
28                ],
29                "from": {
30                    "email": "xxxxxxxxxxxxxx@gmail.com",
31                    "name": "������������"
32                },
33                "subject": "���������������",
34                "content": [
35                    {
36                        "type": "text/plain",
37I/System.out:                     "value": "Kotlin���������������"
38                    },
39                    {
40                        "type": "text/html",
41                        "value": "<html><body>������:
42    ���������2021/4/28
43    ���������������
44    -----------------------
45    ������������������������������������
46    ���������������10 : 00���15 : 00
47    ������������������������
48I/System.out: ���������������������
49    ���������
50    ���������������
51    ������������
52I/chatty: uid=10273(com.example.rworksample00026) identical 1 line
53I/System.out: ������������
54    ���������������������������
55    ���������������������������������������������������������
56    ----------------------
57    ���������������������������������������������������������������������
58    ������������������
59    ������������������������������
60    </body></html>"
61I/System.out:                 }
62                ]
63            }
64            
65    Headers : (2)
66    Content-Type : application/json
67    Authorization : Bearer 
68xx.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
69I/System.out: <-- 400 https://api.sendgrid.com/v3/mail/send
70    Response : Bad Request
71I/System.out: Length : 63
72    Body : {"errors":[{"message":"Bad Request","field":null,"help":null}]}
73   
74

kotlin
1package com.example.rworksample00026.ui.dailyreports
2
3import android.content.Intent
4import android.os.Bundle
5import android.util.Log
6import android.view.View
7import androidx.activity.viewModels
8import com.example.rworksample00026.BuildConfig
9import com.example.rworksample00026.databinding.ActivityDailyReportsSendConfirmBinding
10import com.example.rworksample00026.ui.UserViewModel
11import com.example.rworksample00026.ui.util.ScopedAppActivity
12import com.github.kittinunf.fuel.core.FuelManager
13import com.github.kittinunf.fuel.coroutines.awaitStringResponseResult
14import com.github.kittinunf.fuel.httpPost
15import kotlinx.coroutines.Dispatchers
16import kotlinx.coroutines.launch
17import java.lang.StringBuilder
18import java.util.*
19import com.github.kittinunf.result.Result
20import kotlinx.coroutines.runBlocking
21
22class DailyReportsSendConfirmActivity : ScopedAppActivity() {
23
24    private lateinit var binding: ActivityDailyReportsSendConfirmBinding
25    private val viewModel: DailyReportsViewModel by viewModels()
26    private val userViewModel : UserViewModel by viewModels()
27    private var frag = ""
28    private var title = StringBuilder()
29
30    override fun onCreate(savedInstanceState: Bundle?) {
31        super.onCreate(savedInstanceState)
32        binding = ActivityDailyReportsSendConfirmBinding.inflate(layoutInflater)
33        setContentView(binding.root)
34
35        launch (Dispatchers.IO){
36            val data = viewModel.reportsData
37            launch(Dispatchers.Main) {
38                (中略)
39                binding.nextWeekChallengeAndGoals.text = data.map{it.nextWeeksChallengeAndGoals}[0].toString()
40
41            }
42        }
43
44        val body = StringBuilder()
45        //title = StringBuilder()
46        launch (Dispatchers.IO){
47            val data = viewModel.reportsData
48            launch(Dispatchers.Main) {
49                body.append("件名:"+ data.map{it.title}[0].toString())
50                (中略)
51                body.append("⑴振り返り：" + data.map{it.lookingBack}[0].toString())
52                body.append("\n")
53                body.append("⑵次週の課題・目標：" + data.map { it.nextWeeksChallengeAndGoals }[0].toString() )
54                body.append("\n")
55
56            }
57        }
58        body.toString().trimIndent()
59
60        binding.submit.setOnClickListener (object: View.OnClickListener{
61            override fun onClick(v: View?) {
62               
63                mailSend(body)
64                Log.d("[frag]", frag)
65                
66                if (frag == true.toString()) {
67                    val intent = Intent(this@DailyReportsSendConfirmActivity, DailyReportsSendResultActivity::class.java)
68                    startActivity(intent)
69                } else if(frag == false.toString()) {
70                    
71                    Log.d("[mailerror]", "XXX")
72                } else {
73                    Log.d("[mailerror]", "XXX")
74                }
75            }
76        })
77
78        binding.backBtn.setOnClickListener (object: View.OnClickListener{
79            override fun onClick(v: View?) {
80                val intent = Intent(this@DailyReportsSendConfirmActivity, RequestDocumentsConfirmActivity::class.java)
81                startActivity(intent)
82            }
83        })
84    }
85
86    fun mailSend(body :StringBuilder) {
87
88        var to = "xxxxxxxxxxxxx@gmail.com"
89        var from = "xxxxxxxxxxxx@gmail.com"
90        var fromName = ""
91        if(userViewModel.emailList.count() >= 1){
92            fromName = userViewModel.emailList[0].name
93            println("$fromName")
94        }
95
96
97        var content = """
98        {
99            "personalizations": [
100                {
101                    "to": [
102                        {
103                            "email": "$to"
104                        }
105                    ]
106                }
107            ],
108            "from": {
109                "email": "$from",
110                "name": "$fromName"
111            },
112            "subject": "日報報告書",
113            "content": [
114                {
115                    "type": "text/plain",
116                    "value": "Kotlinから送った"
117                },
118                {
119                    "type": "text/html",
120                    "value": "<html><body>$body</body></html>"
121                }
122            ]
123        }
124        """
125
126        runBlocking {
127            FuelManager.instance.baseHeaders = mapOf("Content-Type" to "application/json", "Authorization" to "Bearer ${BuildConfig.API_KEY}")
128            val (req, res, result) = "https://api.sendgrid.com/v3/mail/send".httpPost().body(content).awaitStringResponseResult()
129            //https://github.com/kittinunf/fuel/tree/master/fuel-coroutines
130            when (result) {
131                is Result.Failure -> {
132                    val ex = result.getException()
133                    println(ex)
134                    frag = false.toString()
135                }
136                is Result.Success -> {
137                    val data = result.get()
138                    println(data)
139                    when (res.statusCode) {
140                        202 -> frag = true.toString()
141                        400, 401, 413 -> frag = false.toString()
142                        else -> frag = false.toString()
143                    }
144
145                }
146            }
147            println(req)
148            println(res)
149            println(result)
150
151
152        }
153
154
155    }
156
157}

ちなみにcontentの部分を以下のように文字列をべた書きにすると送信はできました。

kotlin
1var content = """
2        {
3            "personalizations": [
4                {
5                    "to": [
6                        {
7                            "email": "xxxxxxxxxxx@gmail.com"
8                        }
9                    ]
10                }
11            ],
12            "from": {
13                "email": "xxxxxxxxxxxx@gmail.com",
14                "name": "xxxxxx"
15            },
16            "subject": "TEST",
17            "content": [
18                {
19                    "type": "text/plain",
20                    "value": "Kotlinから送った"
21                },
22                {
23                    "type": "text/html",
24                    "value": "<html><body>Kotlinから送った</body></html>"
25                }
26            ]
27        }
28        """