使用Retrofit配合GsonConverter，我们能很好地将网络响应内容转换成对应的对象。比如像下面这样。
Retrofit网络接口方法
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public interface DroidNetwork {
@GET ( "/content/test.json" )
Call < DroidResponse > jsonData ();
@GET ( "/content/helloworld.txt" )
Call < String > plainText ();
}
对应的应用方法
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val retrofit = Retrofit . Builder ()
. baseUrl ( "https://asset.droidyue.com/" )
. addConverterFactory ( GsonConverterFactory . create ())
. build ()
val droidNetwork = retrofit . create ( DroidNetwork: : class . java )
droidNetwork . jsonData (). enqueue ( object : Callback < DroidResponse > {
override fun onFailure ( call: Call < DroidResponse >?, t: Throwable ?) {
t ?. printStackTrace ()
}
override fun onResponse ( call: Call < DroidResponse >?, response: Response < DroidResponse >?) {
dumpMessage ( "onResponse content=${response?.body()}" )
}
})
上面的方法执行都很正常，可是执行这个方法的时候就会报错。
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droidNetwork . plainText (). enqueue ( object : Callback < String > {
override fun onFailure ( call: Call < String >?, t: Throwable ?) {
Exception ( "causedByPlainText" , t )?. printStackTrace ()
}
override fun onResponse ( call: Call < String >?, response: Response < String >?) {
dumpMessage ( "onResponse content=${response}" )
}
})
崩溃的信息如下
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W System . err : java . lang . Exception : causedByPlainText
W System . err : at com . example . secoo . retrofitconvertor . MainActivity $doNetworkRequest $ 2 . onFailure ( MainActivity . kt : 41 )
W System . err : at retrofit2 . ExecutorCallAdapterFactory $ExecutorCallbackCall $ 1 $ 2 . run ( ExecutorCallAdapterFactory . java : 80 )
W System . err : at android . os . Handler . handleCallback ( Handler . java : 891 )
W System . err : at android . os . Handler . dispatchMessage ( Handler . java : 102 )
W System . err : at android . os . Looper . loop ( Looper . java : 207 )
W System . err : at android . app . ActivityThread . main ( ActivityThread . java : 7470 )
W System . err : at java . lang . reflect . Method . invoke ( Native Method )
W System . err : at com . android . internal . os . RuntimeInit $MethodAndArgsCaller . run ( RuntimeInit . java : 524 )
W System . err : at com . android . internal . os . ZygoteInit . main ( ZygoteInit . java : 958 )
W System . err : Caused by: com . google . gson . stream . MalformedJsonException : Use JsonReader . setLenient ( true ) to accept malformed JSON at line 1 column 1 path $
W System . err : at com . google . gson . stream . JsonReader . syntaxError ( JsonReader . java : 1568 )
W System . err : at com . google . gson . stream . JsonReader . checkLenient ( JsonReader . java : 1409 )
W System . err : at com . google . gson . stream . JsonReader . doPeek ( JsonReader . java : 593 )
W System . err : at com . google . gson . stream . JsonReader . peek ( JsonReader . java : 425 )
W System . err : at com . google . gson . internal . bind . TypeAdapters $ 16 . read ( TypeAdapters . java : 393 )
W System . err : at com . google . gson . internal . bind . TypeAdapters $ 16 . read ( TypeAdapters . java : 390 )
W System . err : at retrofit2 . converter . gson . GsonResponseBodyConverter . convert ( GsonResponseBodyConverter . java : 39 )
W System . err : at retrofit2 . converter . gson . GsonResponseBodyConverter . convert ( GsonResponseBodyConverter . java : 27 )
W System . err : at retrofit2 . OkHttpCall . parseResponse ( OkHttpCall . java : 223 )
W System . err : at retrofit2 . OkHttpCall $ 1 . onResponse ( OkHttpCall . java : 121 )
W System . err : at okhttp3 . RealCall $AsyncCall . execute ( RealCall . java : 206 )
W System . err : at okhttp3 . internal . NamedRunnable . run ( NamedRunnable . java : 32 )
W System . err : at java . util . concurrent . ThreadPoolExecutor . runWorker ( ThreadPoolExecutor . java : 1167 )
W System . err : at java . util . concurrent . ThreadPoolExecutor $Worker . run ( ThreadPoolExecutor . java : 641 )
W System . err : at java . lang . Thread . run ( Thread . java : 784 )
原因其实很简单
http://asset.droidyue.com/content/test.json 是一个合法的json内容
https://asset.droidyue.com/content/helloworld.txt 是一个普通的文本，内容为helloworld
因为上面的retrofit 对象 设置了GSONConvertor，会尝试默认将所有的内容转成对应的对象内容，故上面的普通文本就会失败报错。
解决方法有两个
修改服务器端的https://asset.droidyue.com/content/helloworld.txt 为JSON内容
调整客户端代码支持。
这里我们介绍后者的处理方法，这里我们使用ResponseBody而不是之前的String，然后按照如下代码应用即可。
接口代码
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@GET ( "/content/helloworld.txt" )
Call < ResponseBody > plainTextAsResponseBody ();
应用代码
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droidNetwork . plainTextAsResponseBody (). enqueue ( object : Callback < ResponseBody > {
override fun onFailure ( call: Call < ResponseBody >?, t: Throwable ?) {
t ?. printStackTrace ()
}
override fun onResponse ( call: Call < ResponseBody >?, response: Response < ResponseBody >?) {
dumpMessage ( "onResponse of plainTextAsResponseBody content=${response?.body()?.string()}" )
}
})
附加内容
如果在某种情况下，我们只关心请求操作，而不关心响应内容，我们可以这样使用
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@GET ( "/content/helloworld.txt" )
Call < Void > ignoreResult ();
上面的代码相对更加高效，因为这里省略了将响应内容转成内存对象的过程。
