Groovy HttpBuilder-NG请求响应体为空问题求解（Groovy 2.5.19）

你执行HTTP请求后，返回状态码200且显示存在响应体，但读取到的内容为空。以下是正确读取响应体的几种方法：

问题复现代码 #

@Grab(group='io.github.http-builder-ng', module='http-builder-ng-apache', version='1.0.4')
import groovyx.net.http.*

HttpBuilder http = HttpBuilder.configure {
    request.uri = 'https://stackoverflow.com'
    request.accept = ['text/html']
}

http.get {
    response.success { FromServer fromServer ->
        println("Got status $fromServer.statusCode $fromServer.message")
        println("Has body: $fromServer.hasBody")
        try {
            List<String> bodyLines = fromServer.reader.withReader { it.readLines() }
            String body = bodyLines.join("\n")
            if (body.empty) {
                println("Body is empty.")
            } else {
                println("Body: $body")
            }
        } catch (Exception e) {
            println("Reading successful response failed. $e")
        }
    }
}

输出：

Got status 200 OK
Has body: true
Body is empty.

正确解决方案 #

方法一：直接在success回调中接收响应体参数 #

HttpBuilder-NG的success回调支持接收第二个参数，即框架自动解析后的响应体。只需调整回调参数列表即可直接获取：

@Grab(group='io.github.http-builder-ng', module='http-builder-ng-apache', version='1.0.4')
import groovyx.net.http.*

HttpBuilder http = HttpBuilder.configure {
    request.uri = 'https://stackoverflow.com'
    request.accept = ['text/html']
}

http.get {
    response.success { FromServer fromServer, String body ->
        println("Got status $fromServer.statusCode $fromServer.message")
        println("Has body: $fromServer.hasBody")
        if (body.empty) {
            println("Body is empty.")
        } else {
            println("Body snippet: ${body.take(500)}...") // 截取部分内容避免输出过长
        }
    }
}

方法二：显式指定响应解析器 #

如果需要自定义解析逻辑，可以显式设置response.parser来定义如何处理响应体：

@Grab(group='io.github.http-builder-ng', module='http-builder-ng-apache', version='1.0.4')
import groovyx.net.http.*

HttpBuilder http = HttpBuilder.configure {
    request.uri = 'https://stackoverflow.com'
    request.accept = ['text/html']
    // 针对text/html类型自定义解析逻辑
    response.parser('text/html') { FromServer fs, Object rawBody ->
        return rawBody instanceof String ? rawBody : fs.reader.text
    }
}

http.get {
    response.success { FromServer fromServer, String body ->
        println("Got status $fromServer.statusCode $fromServer.message")
        println("Has body: $fromServer.hasBody")
        println("Body snippet: ${body.take(500)}...")
    }
}

方法三：通过reader读取（需禁用默认解析） #

如果必须使用fromServer.reader读取，需要先禁用默认的响应解析，避免流被提前消费：

@Grab(group='io.github.http-builder-ng', module='http-builder-ng-apache', version='1.0.4')
import groovyx.net.http.*

HttpBuilder http = HttpBuilder.configure {
    request.uri = 'https://stackoverflow.com'
    request.accept = ['text/html']
    // 禁用默认解析，保留reader可用
    response.parser('text/html') { FromServer fs, Object body -> null }
}

http.get {
    response.success { FromServer fromServer ->
        println("Got status $fromServer.statusCode $fromServer.message")
        println("Has body: $fromServer.hasBody")
        try {
            String body = fromServer.reader.text
            if (body.empty) {
                println("Body is empty.")
            } else {
                println("Body snippet: ${body.take(500)}...")
            }
        } catch (Exception e) {
            println("Reading successful response failed. $e")
        }
    }
}

说明 #

最推荐使用方法一，因为HttpBuilder-NG会自动根据请求的Accept头和响应的Content-Type头匹配合适的解析器，直接获取解析后的响应体最为简洁高效。

内容的提问来源于stack exchange，提问作者xehpuk