一.崩溃的stacktrace
E AndroidRuntime: FATAL EXCEPTION: OkHttp Dispatcher
E AndroidRuntime: Process: com.example.okhttpexceptionsample, PID: 13564
E AndroidRuntime: java.lang.NullPointerException: blablabla
E AndroidRuntime: at com.example.okhttpexceptionsample.MainActivity$createNPEInterceptor
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1.intercept(MainActivity.kt:61) E AndroidRuntime: at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:112) E AndroidRuntime: at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:87) E AndroidRuntime: at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.kt:184) E AndroidRuntime: at okhttp3.RealCall
1.intercept(MainActivity.kt:61)EAndroidRuntime:atokhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:112)EAndroidRuntime:atokhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:87)EAndroidRuntime:atokhttp3.RealCall.getResponseWithInterceptorChain(RealCall.kt:184)EAndroidRuntime:atokhttp3.RealCallAsyncCall.run(RealCall.kt:136)
E AndroidRuntime: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
E AndroidRuntime: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
E AndroidRuntime: at java.lang.Thread.run(Thread.java:784)
二.为什么会崩溃
从上面的stacktrace，我们可以分析到，发生了NullPointerException。发生了崩溃。
等等，我记得OkHttp有处理异常的情况呢。
嗯，确实，OkHttp有处理异常的情况，比如发生异常会调用onFailure。比如下面的Callback的内容介绍。
interface Callback {
/**
- Called when the request could not be executed due to cancellation, a connectivity problem or
- timeout. Because networks can fail during an exchange, it is possible that the remote server
- accepted the request before the failure.
*/
fun onFailure(call: Call, e: IOException)
/**
- Called when the HTTP response was successfully returned by the remote server. The callback may
- proceed to read the response body with [Response.body]. The response is still live until its
- response body is [closed][ResponseBody]. The recipient of the callback may consume the response
- body on another thread.
- Note that transport-layer success (receiving a HTTP response code, headers and body) does not
- necessarily indicate application-layer success:
responsemay still indicate an unhappy HTTP - response code like 404 or 500.
*/
@Throws(IOException::class)
fun onResponse(call: Call, response: Response)
}
是的.
- OkHttp只处理了IOException的情况，
- NullPointerException不是IOException的子类
所以没有被处理,发生了崩溃。
那么有没有办法解决，让这种崩溃不发生，对用户不进行干扰呢？其实是可以的。
三.使用Interceptor
package com.example.okhttpexceptionsample
import okhttp3.Interceptor
import okhttp3.Response
import java.io.IOException
/**
- 对于Interceptor的intercept中可能出现的Throwable包裹成IOExceptionWrapper，转成网络请求失败，而不是应用崩溃
*/
class SafeGuardInterceptor : Interceptor {
override fun intercept(chain: Interceptor.Chain): Response {
try {
return chain.proceed(chain.request())
} catch (t: Throwable) {
throw IOExceptionWrapper(“SafeGuarded when requesting ${chain.request().url}”, t)
}
}
}
/**
- 将chain.proceed处理中发生的Throwable包装成IOExceptionWrapper
*/
class IOExceptionWrapper(message: String?, cause: Throwable?) : IOException(message, cause)
上面的代码，我们将任何Throwable的转成IOExceptionWrapper（伪装成IOException），然后添加到OkHttpClient中
fun createOKHttpClient(): OkHttpClient {
return OkHttpClient.Builder()
.addInterceptor(SafeGuardInterceptor())
.build()
}
当我们再次执行有NPE的代码，日志就发生了改变(不再是崩溃的日志，而是异常的日志)
W System.err: com.example.okhttpexceptionsample.IOExceptionWrapper: SafeGuarded=blablabla
W System.err: at com.example.okhttpexceptionsample.SafeGuardInterceptor.intercept(SafeGuardInterceptor.kt:12)
W System.err: at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:112)
W System.err: at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:87)
W System.err: at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.kt:184)
W System.err: at okhttp3.RealCall
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AsyncCall.run(RealCall.kt:136) W System.err: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167) W System.err: at java.util.concurrent.ThreadPoolExecutor
AsyncCall.run(RealCall.kt:136)WSystem.err:atjava.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)WSystem.err:atjava.util.concurrent.ThreadPoolExecutorWorker.run(ThreadPoolExecutor.java:641)
W System.err: at java.lang.Thread.run(Thread.java:784)
W System.err: Caused by: java.lang.NullPointerException: blablabla
W System.err: at com.example.okhttpexceptionsample.MainActivity$createNPEInterceptor$1.intercept(MainActivity.kt:61)
W System.err: at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:112)
W System.err: at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:87)
W System.err: at com.example.okhttpexceptionsample.SafeGuardInterceptor.intercept(SafeGuardInterceptor.kt:10)
W System.err: … 7 more
上述需要注意两点
- 添加的是Interceptor,而不是NetworkInterceptor
- 顺序很重要,一定要放在第一个位置
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