实现一个极简的 DSL

OkHttp是一个成熟且强大的网络库，在Android源码中已经使用OkHttp替代原先的HttpURLConnection。很多著名的框架例如Picasso、Retrofit也使用OkHttp作为底层框架。在这里我对OkHttp做一下简单的封装，其实封装得有点粗暴只是为了演示如何实现dsl。

import io.reactivex.BackpressureStrategy
import io.reactivex.Flowable
import io.reactivex.schedulers.Schedulers
import okhttp3.OkHttpClient
import okhttp3.Request
import okhttp3.RequestBody
import okhttp3.Response
import java.util.concurrent.TimeUnit
class RequestWrapper {
    var url:String? = null
    var method:String? = null
    var body: RequestBody? = null
    var timeout:Long = 10
    internal var _success: (String) -> Unit = { }
    internal var _fail: (Throwable) -> Unit = {}
    fun onSuccess(onSuccess: (String) -> Unit) {
        _success = onSuccess
    }
    fun onFail(onError: (Throwable) -> Unit) {
        _fail = onError
    }
}
fun http(init: RequestWrapper.() -> Unit) {
    val wrap = RequestWrapper()
    wrap.init()
    executeForResult(wrap)
}
private fun executeForResult(wrap:RequestWrapper) {
    Flowable.create<Response>({
        e -> e.onNext(onExecute(wrap))
    }, BackpressureStrategy.BUFFER)
            .subscribeOn(Schedulers.io())
            .subscribe(
                    { resp ->
                        wrap._success(resp.body()!!.string())
                    },
                    { e -> wrap._fail(e) })
}
private fun onExecute(wrap:RequestWrapper): Response? {
    var req:Request? = null
    when(wrap.method) {
        "get","Get","GET" -> req =Request.Builder().url(wrap.url).build()
        "post","Post","POST" -> req = Request.Builder().url(wrap.url).post(wrap.body).build()
        "put","Put","PUT" -> req = Request.Builder().url(wrap.url).put(wrap.body).build()
        "delete","Delete","DELETE" -> req = Request.Builder().url(wrap.url).delete(wrap.body).build()
    }
    val http = OkHttpClient.Builder().connectTimeout(wrap.timeout, TimeUnit.SECONDS).build()
    val resp = http.newCall(req).execute()
    return resp
}

封装完OkHttp之后，看看如何来编写get请求

http {
    url = "http://www.163.com/"
    method = "get"
    onSuccess {
        string -> L.i(string)
    }
    onFail {
        e -> L.i(e.message)
    }
}

是不是很像以前用jquery来写ajax？

post请求也是类似的，只不过多了body

var json = JSONObject()
json.put("xxx","yyyy")
....
val postBody = RequestBody.create(MediaType.parse("application/json; charset=utf-8"),json.toString())
http {
    url = "https://......"
    method = "post"
    body = postBody
    onSuccess {
        string -> L.json(string)
    }
    onFail {
        e -> L.i(e.message)
    }
}