如何在Go中使用.Read函数？ [英] How do I use the .Read function in Go?

问题描述

尝试使用Go的http包，我无法计算 .Read 的语法。下面用HERE标记是我编译的唯一东西，尽管我尝试了其他一些被编译器拒绝的东西。

  package main 
 importfmt; 
导入http; 
导入os; 
 
 func main（）{
 kinopiko_flair：=http://stackoverflow.com/users/flair/181548.json; 
 response，_，error：= http.Get（kinopiko_flair）; 
 if（error！= nil）{
 //我也想打印出错误。 
 fmt.Printf（获取％s \ n错误，kinopiko_flair）; 
 os.Exit（1）; 
} 
 fmt.Printf（Status is％s\\\
，response.Status）; 
 var nr int; 
 var buf [] byte; 
 nr，error = response.Body.Read（buf）; // HERE 
 if（error！= nil）{
 //我也想打印出错误。 
 fmt.Printf（Error reading response.\\\
）; 
 os.Exit（1）; 
} 
 response.Body.Close（）; 
 fmt.Printf（Got％d bytes \\\
，nr）; 
 fmt.Printf（Got'％s'\\\
，buf）; 
} 
  

URL是可以的，因为 wget 得到它很好，但是当我运行这个 buf 时只是一个空字符串，而且 nr 总是为零。我需要做些什么才能从 response 中获取数据？编译器拒绝了 .ReadAll 和其他我试过的东西。

输出如下所示：

 
状态为200 OK 
得到0字节
得到''
 

解决方案

尝试给切片buf一个大小，例如

  buf：= make（[] byte，128）; 
  

读取器读取缓冲区的len（）。

来自io.go

  // Reader是包装基本Read方法的接口。 
 // 
 //读取最多len（p）个字节到p。它返回字节数
 // read（0 <= n <= len（p））和遇到的任何错误。 
 //即使读取返回n < len（p），
 //在调用过程中，它可以将所有p用作临时空间。 
 //如果有些数据可用但不是len（p）字节，则通常读
 //返回可用的数据，而不是等待更多的数据。 
 // 
 //在输入流结束时，Read返回0，os.EOF。 
 //读取可能会返回一个非零数字的字节，并且不为零。 
 //特别是，耗尽输入的Read可能会返回n> 0，os.EOF。 
  

Trying to use Go's http package, I can't work out the syntax of .Read. The following marked by HERE is the only thing I have got to compile, although I tried several other things which were all rejected by the compiler.

package main
import "fmt";
import "http";
import "os";

func main () {
    kinopiko_flair := "http://stackoverflow.com/users/flair/181548.json";
    response, _, error := http.Get (kinopiko_flair);
    if (error != nil) {
        // I want to print out the error too.
        fmt.Printf ("Error getting %s\n", kinopiko_flair);
        os.Exit (1);
    }
    fmt.Printf ("Status is %s\n", response.Status);
    var nr int;
    var buf []byte;
    nr, error = response.Body.Read (buf); // HERE
    if (error != nil) {
        // I want to print out the error too.
        fmt.Printf ("Error reading response.\n");
        os.Exit (1);
    }
    response.Body.Close ();
    fmt.Printf ("Got %d bytes\n", nr);
    fmt.Printf ("Got '%s'\n", buf);
}

The URL is OK, since wget gets it fine, but when I run this buf is just an empty string and nr is always zero. What do I need to do to get the data out of response? The compiler rejected .ReadAll and other things I tried.

The output looks like this:

Status is 200 OK
Got 0 bytes
Got ''

解决方案

Try giving the slice buf a size, e.g.

 buf := make([]byte,128);

Reader reads up to len() of the buffer it is given.

From io.go

// Reader is the interface that wraps the basic Read method.
//
// Read reads up to len(p) bytes into p.  It returns the number of bytes
// read (0 <= n <= len(p)) and any error encountered.
// Even if Read returns n < len(p),
// it may use all of p as scratch space during the call.
// If some data is available but not len(p) bytes, Read conventionally
// returns what is available rather than block waiting for more.
//
// At the end of the input stream, Read returns 0, os.EOF.
// Read may return a non-zero number of bytes with a non-nil err.
// In particular, a Read that exhausts the input may return n > 0, os.EOF.

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